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Global
environmental
change
Global environmental changes are the result of human and natural processes. In this unit the focus is on the ways in which the
biophysical landscape is changed by human interactions with natural ecosystems and how these create anthropogenic or human
biomes (anthromes). To study the extent of the changes produced by human/natural ecosystem interactions, the primary method
is to assess the degree of land cover change using direct primary fieldwork observations, secondary mapping data and remote
sensing technologies.
As the impact of human activity increases and natural ecosystems are changed, further transformations take place including
biodiversity loss, climate change, soil degradation and changes to environmental flows. There are few truly natural biomes in
existence today. All have been modified to a greater or lesser extent by human activity. It is however, still important to study the
characteristics and dynamics of global natural biomes in order to understand the degree to which they have been changed by
human activity.
By studying global environmental change we seek to:
l Understand the nature and extent of changing land cover at the local, regional and global scales.
l Understand the causes of changing land cover and the emergence of anthromes.
l Recognise and understand the various interactions between human activities and natural ecosystems, and in particular, how
these interactions result in biodiversity loss and climate change.
l Identify and evaluate sustainable actions aimed at reducing or overcoming the negative impacts of land cover changes by
assessing the costs and benefits of these actions.
l Apply key geographical concepts and inquiry methods when evaluating land cover changes, its consequences and sustainable
solutions.
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Chapter One
An overview of envirnomental change
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l The natural environment
l Changing the land
l Spatial technology and science
Chapter Two
Depth study one: Global climate change
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l Global climate systems and patterns
l The nature and causes of climate change
l Climate change and land cover
Chapter Three
Land cover change
- Page 94
l Evaluating land cover changes
l A case study in land cover management
l Mitigating and adapting to climate change
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An overview of environmental change ­ Chapter 1
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Chapter one
An overview
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environmental
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Humans have been modifying the earth’s natural environments
for thousands of years. Population, technology, trade, material
wealth and the desire to achieve higher living standards drive
people to change the environments in which they live. In
today’s world, land–use and land cover change is far greater
than at any time in the past. It is producing unprecedented
changes in ecosystems and environmental processes at local,
regional and global scales. In 1700 CE (Common Era or AD),
nearly half of the terrestrial biosphere was wild, without human
settlements or substantial land use. Most of the remainder was
in a semi-natural state (45 per cent) having only minor use for
agriculture and settlements. By 2000 CE, the opposite was true,
with the majority of the biosphere found in agricultural and
settled anthromes. Less than 20 per cent of the world’s
biosphere was semi-natural and only 25 per cent was left wild.
These wild-lands are nearly all barren and sparse. They include
remote desert areas, bare rock surfaces and icefields.
Biodiversity loss, soil degradation, changes to the water cycle
(in terms of natural drainage systems) and climate change are
some of the major consequences of global population and
economic growth. Comparing the differences between
traditional indigenous cultures and commercial industrial
cultures is one way of illustrating the nature of land cover
change, as are the variations between nation states with their
political and institutional differences. The rise of the nation
state has created a world where political or national boundaries
produce large variations in the way different parts of the world
are managed, with significant environmental consequences.
Careful measurement of land cover change is essential in
gaining an accurate picture of the nature and extent of this
change, while investigation of interactions, systems and
processes help to identify the causes and consequences.
Remote sensing technologies play an important part in the
measurement of land cover change and spatial science
provides different methods of interpreting and understanding
this change.
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Topic one
The natural
environment
All living and non-living features on the earth that are not the result of human actions make up the natural environment.
These include ecological units – the biomes and ecosystems – that occupy distinctive geographical locations and the
universal natural resources that lack clear cut regional boundaries. The universal features include air, water, heat energy,
radiation and magnetism. Interactions between natural elements such as plants, animals, heat, water, soils, landforms and
geology create complex and dynamic natural environments.
geology, landforms and water. If any of these things
change over time then this will cause a change in the
characteristics and the extent of the biome. Climate
change can cause living things in a biome to change
and even move to new locations.
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BIOMES –
CHARACTERISTICS AND
TYPES
The earth has many different living things. Some are
very complex highly specialised organisms whereas
others are simple single celled plants or animals. Each
depends in some way on other living and non-living
things within its environment. The variety of organisms
and the way they interact, and depend on each other in
a biome is called biodiversity. The fully developed
natural ecosystems within biomes have a high degree
of biodiversity. Biodiversity is an important
characteristic of biomes in their natural state.
Biodiversity loss is one way of assessing the extent of
land cover change.
A biome is a large geographical area of distinctive plant
and animal groups, which have adapted to that
particular environment. Climate and geography
determines what type of biome can exist in a region.
Biomes are most commonly identified by their
dominant vegetation types which are closely linked to
climatic conditions as shown in figure 1.1. Major biomes
include deserts, forests, grasslands, tundra, and several
types of aquatic environments. Each biome consists of
many ecosystems whose communities have adapted to
the small differences in climate and other
environmental factors inside the biome.
The actual amount of organisms within a biome or an
individual ecosystem is known as its biomass. Some
biomes have a large amount of biomass while others
have very little. Measurement and observation of
biomass levels assists in identifying and classifying
different biomes and their related ecosystems. There are
Characteristics
The distinctive characteristics of each major biome are
shaped by the way in which plants and animals interact
with each other, and the influences of climate, soils,
Decreasing rainfall
Very dry in summer
and winter
30 deg. south
20
Wet in summer
dry in winter
Very wet in summer
and winter
10
0
Latitude
Desert
Semi-arid grassland
Tropical savanna grassland
Monsoon forest
Rainforest
Figure 1.1 Variations in climates and biomes
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World Terrestrial
Biomes
Tropical rainforest
Tropical monsoon forest
and savanna grasslands
Mediterranean evergreen forest
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Broadleaf evergeeen forest
Broadleaf deciduous forest
Boreal forest
Desert
Mid-latitude grasslands
Tundra
Alpine
Ice cap
Figure 1.2 Major world biomes
several ways to measure a biome’s biomass. One is to
measure the amount of energy produced. This is often
used to determine plant biomass. Another common
way is to measure the amount of organic carbon stored
in both plants and animals in a biome. This is usually
expressed as tonnes or kilograms per hectare of land.
Using this method the total live biomass on the Earth
has been estimated at about 560 billion tonnes. About
a 100 billion tonnes of this is replaced each year by new
plant and animal growth or reproduction.
Climate and biome characteristics are related in a
number of ways and through a variety of spatial
interactions. Features such as plant growth, growing
seasons, adaptations and biodiversity are all the result
of climate/biome interactions. Climatic factors such as
rainfall and temperature mainly determine the length
of a growing season for different biomes and the
amount of growth that takes place. Climate plays a
major part in influencing the level of biomass within a
biome. Soil nutrients, landforms and seasonal changes
in the length of day and night are also factors affecting
biomass. The forests of the tropical areas of the Earth
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have the greatest amount of biomass per hectare while
the deserts have the lowest. Marine coral reef biomes
have similar biomass levels to that of the tropical forests.
Types
There are very large areas of the world with quite
distinctive groups of plants and animals. They include
forests, grasslands, deserts, tundra and aquatic
environments. These are the major world biomes - see
figure 1.2. Each of these contains smaller distinctive
groupings that can also be further broken down into
many different types of ecosystems.
Forest biomes
The world’s forests cover some 30 per cent of the Earth’s
land area and contain around 70 per cent of the total
global biomass. Rainfall totals and the seasonal pattern
of both rainfall and temperature are major influences
on the location and distribution of the different types
of forests. There are three main forest biomes produced
by these climatic differences. They are the tropical
forests, which are found between the Tropics of
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The natural environment
Activities
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Figure 1.3 Rainforest structure
areas receive year round rainfall, are hot in summer and
cool to mild in winter. The evergreen forests are
dominated by oaks, laurels and magnolias in the
northern hemisphere, and eucalypts or ‘gum trees’ in
Australia. The lack of a cold winter allows the trees to
keep their leaves all year round.
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Capricorn and Cancer, the temperate forests in the midlatitude regions and the boreal forests in the high
latitude areas. Within the three main forest biomes other
smaller distinctive forest ecosystems can also be
observed.
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1. Explain the difference between natural and
anthropogenic biomes (anthromes)
2. Explain the difference between a biome and an
ecosystem.
3. Identify and list the major types of biomes found
on the Earth.
4. Explain the terms biodiversity, biomass and
growing season.
5. Study figure 1.2. Identify and describe any
differences between the types and extent of the
major terrestrial biomes in the Northern and
Southern Hemispheres.
6. Compare and contrast the terrestrial biomes
found in Australia and South America. Suggest
reasons for the differences.
The tropical forests include the evergreen rainforests
and the deciduous monsoon forests. Evergreen
rainforests have the greatest biodiversity of all of the
terrestrial biomes. One square kilometre of these forests
may contain more than 1,000 different plant species,
while one square kilometre of forest produces about
2,000 tonnes of biomass per year. The complex nature
of the rainforest can be seen in the structure or
arrangement of the different plants as shown by figure
1.3 and the many habitats that this creates for the
animals that live there. Constant rainfall of more than
2,000 millimetres (mm) per year and average
temperatures of 20 to 25 degrees Celsius (C) with little
seasonal variation allows for a year-long continuous
growing season. This is why rainforests have the highest
biomass productivity of all biomes.
Found in the middle latitudes outside of the tropical
areas are the temperate forests. They include broadleaf
evergreen
and
deciduous
forests,
mixed
broadleaf/boreal forests, Mediterranean forests and
temperate rainforests. These forests are characterised by
distinctive seasonal climatic patterns. Unlike the tropical
forests this includes significant variations in the
temperatures from summer to winter. There are also
differences in the amount and seasonal distribution of
rain or snowfall.
The warm temperate evergreen broadleaf forest is
found along the eastern edges of continents such as
Asia, Australia, North America and South America. These
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The temperate broadleaf deciduous forests are only
found in the Northern Hemisphere. They are located in
western and central Europe, eastern Asia including
Korea and Japan, and eastern North America. The
autumn season or ‘fall’ is a time when the trees shed
their leaves, which often turn from green to brilliant red,
gold and orange. This is triggered by the shorter days as
winter approaches. Chlorophyll is withdrawn from the
leaves allowing other colours to show through. Like the
rainforest there are distinctive layers in the forest
structure. The trees which include, oaks, maples, beech,
elm and walnut, form a thick canopy of broad leaves in
summer.
Mediterranean forests or woodlands are located around
the Mediterranean Sea in Europe and on the western
sides of continents such as Africa, Australia, North and
South America. They have developed in response to the
unique climatic conditions of mild wet winters and hot
dry summers found in these parts of the world. Plant
growth occurs mainly in spring, before the onset of
summer and in autumn as rainfall is increasing. This
biome includes the wet and dry sclerophyllous forests
of south-western Australia. These are the karri and jarrah
forests of Western Australia.
The wet sclerophyll forests contain the tallest trees in
Australia. They include the mountain ash in Victoria and
the karri in Western Australia - see figure 1.4. These tall
eucalypt forests occur where annual rainfall is greater
than 1,000 mm. Currently, this forest type covers slightly
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Found between latitudes 50 and 60 degrees north,
these forests form a broad belt running from Europe
through Asia and across North America. This includes
large areas of Siberia, Scandinavia, Alaska, and Canada.
Seasons are divided into short, moist and moderately
warm summers and long, cold and dry winters. The
average temperature is below freezing point for at least
six months of the year. Minimum temperatures can fall
as low as minus 54o C during winter. Global warming
may see this forest shift northwards as average
temperatures rise. The length of the growing season in
boreal forests is 130 days, which corresponds to the
short summer period.
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Figure 1.4 Karri forest south of Pemberton W.A.
Vegetation in the boreal forest consists mainly of
conifers such as spruce, hemlock, pine and fir. Most
conifers are evergreen with special features that allow
them to survive during the long cold winters. These
features include sap, which does not freeze in the plant’s
cells and the shape of the branches, which allow snow
to slide off rather than breaking the tree with this added
weight.
less than one per cent of the continent. The karri forest
of Western Australia is mainly located on the south coast
between Denmark and Manjimup. Other smaller areas
include the Boranup forest near Margaret River. Karri
trees can grow to heights up to 90 metres and are one
of Australia’s tallest trees. They tend to be found on deep
loamy soils. Nutrients from the extensive amount of
decaying vegetation or humus on the forest floor help
to support this biome.
Large areas of karri forest are now located in national
parks and conservation reserves. The clearing of the
karri forest for dairy and other small farms as well as the
cutting of timber for building construction and
firewood has significantly reduced the original extent
of the forest. Karri is still logged in some areas and
continues to be an important source of hardwood
timber for the forest industry.
The more extensive forest type in both Eastern and
Western Australia is the dry sclerophyllous forest. This is
a more open forest than the wet sclerophyllous and the
trees are shorter. They currently cover about 3.5 per cent
of the continent and are most commonly found on the
Eastern Highlands from central Queensland through to
the eastern half of Tasmania. They contain a variety of
hardwood trees that provide valuable timber for
construction and furniture making. The logging of these
forests and their clearing for farming has seen their area
reduced by almost half in the last 200 years.
In the colder regions of the world the temperate forests
are replaced by the boreal forests, or taiga. They
represent the largest of the world’s land based biomes.
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Grassland biomes
Grasslands are found across most regions of the earth
and on all continents with the exception of Antarctica.
While they are dominated by grasses, sedges and reeds
some also contain a variety of wildflowers as well as
shrubs and scattered trees. Grasses can grow from
underground runners called rhizomes or from seeds.
Grasses such as wild wheat, barley, oats and rice have
been changed by humans to become important cereal
crops. Most grasslands tend to be found where there is
moderate rainfall between 600 and 1500mm per year,
and temperatures between minus 5 and 20oC, however
some also occur outside these limits. Some grasslands
may have been caused by long term use of fire by
indigenous peoples. Frequent fires destroy slower
growing shrubs and trees and promote the quicker
growing grasses. The world’s grasslands include tropical
savanna, mid-latitude prairie and steppe, flooded grass
swamps, high altitude mountain grassland pastures and
semi-arid sparse grasslands, such as the Australian
Spinifex regions.
The tropical savanna grasslands occur where rainfall is
limited to the summer months. This is the wet season
with frequent tropical storms. Winters are warm and dry
and the plants have features that allow them to survive
this extended dry period. Annual rainfall is between 500
and 1200 mm per year. Where rainfall is less than 500
mm, semi-arid grass and shrubs become more
common. While the dominant type of vegetation is
grass there are also scattered trees in this biome giving
it a parkland appearance.
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Fire plays an important part in the biodiversity of the
savanna biome. These often occur naturally as a result
of lightning strikes at the end of the dry season. Fire
removes dead grass and the ash provides nutrients for
new grass to grow when the rains come again in the
following summer. Fire also prevents the growth of
more permanent shrubs and trees. Humans have played
a role in turning tropical woodland areas into grassland
savanna by the lighting of fires and the removal of
vegetation.
Activities
1. Identify the main types of forest biomes and
explain why they are different.
2. Draw and annotate the structure of a rainforest.
Explain how this structure illustrates the high
biodiversity and biomass of this forest biome.
Identify and describe other factors that also
contribute to this abundance.
3. Explain the difference between evergreen and
deciduous plants.
4. What special features allow boreal forests to
keep their leaves throughout the long cold
winters?
5. Identify the main types of grassland biomes and
briefly describe the factors that have
encouraged the development of these
grasslands.
6. With reference to figure 1.5 and library or
internet sources write a detailed description of
the Spinifex vegetation, environment and land
cover.
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The drier mid-latitude areas of the world contain
extensive areas of grassland. Annual rainfall in this
biome is between 500mm and 800mm and
temperatures change greatly from summer to winter.
Most of these mid-latitude or temperate grasslands are
also found in the interiors of continents, well away from
the moderating effects of the ocean. As a result winter
temperatures can fall well below freezing point while
summers are warm to hot. Temperate grasslands
include the veldts of South Africa, the pampas of
Argentina, the steppes of central Asia and the prairies
of North America.
Aboriginal people harvested and ground the seeds of
Spinifex grasses to make a type of flour which was then
mixed with water and cooked on heated stones.
Spinifex has rigid, thin spiky leaves that can cause
painful sores if they pierce your skin. This protects the
plant against the effects of grazing animals.
Apart from different types of grasses, there are also
many different types of wildflowers growing in this
biome. They include asters, sunflowers, clovers and cone
flowers. Due to its rich soils and lack of trees much of
the world’s temperate grasslands have been greatly
changed by humans growing crops or grazing sheep
and cattle on these natural pastures.
Desert biomes
Most of Australia’s grasslands have scattered trees or
shrubs. These are widely spaced and allow different
types of grasses to develop as a ground cover. Spinifex
or hummock grasses (Triodia) cover some 25 per cent
of the continent and are located in arid and semi-arid
climatic zones - see figure 1.5. Extensive areas of Spinifex
cover the Pilbara region of Western Australia and extend
eastwards across large areas of the Northern Territory.
Figure 1.5 Spinifex grass (Triodia) with seed stalks
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Desert biomes can be found in tropical and sub-tropical
regions. They form the hot and cold deserts of the world.
These hot and cold arid and semi-arid regions of the
world represent almost 40 per cent of the land-based
biomes. Very low, unreliable rainfall and high
evaporation rates have produced biomes with very little
biomass and plants that have a number of ways to save
water or minimise water loss. Desert animals also have
a number of characteristics that minimise water needs
and loss.
The main factors that influence the desert climate are
the global pressure belts, distance from the sea, ocean
temperatures and mountains which are barriers to
rainfall. A large proportion of the arid regions are
dominated by high pressure cells. These produce fine
stable atmospheric conditions and prevent rainfall. Cold
ocean currents result in any moisture in winds from the
sea falling as rain before it reaches the land. Rainfall
decreases as winds move inland with the central areas
of most continents being dry. Finally, high mountain
ranges are very effective in producing heavy rain on
their windward side and very dry conditions on their
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Figure 1.6 The rainshadow effect produced by mountain barriers
Cold deserts include arid regions in higher latitudes
away from the tropics as well as regions of high altitude.
They have little rain or snow fall and a number of
months when temperatures drop below zero. While
evaporation rates are much lower than in the tropical
deserts, plants and animals must adapt to the limited
availability of moisture, cold winters and the effects of
strong prevailing winds, which blow for a large part of
the year. These winds form extensive dune fields as well
as increasing the effects (chill factor) of the low
temperatures.
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leeward side. This is called the rain-shadow effect which
is illustrated in figure 1.6.
Tropical or hot deserts can be found in areas between
latitudes 15 and 30 degrees north and south of the
Equator. They cover some 15 per cent of the earth’s land
area, generally extending inland from the western sides
of most continents. The largest hot deserts can be found
in Africa, the Middle East, Australia and South Asia, while
smaller areas occur in North and South America.
Desert areas are regions of low, unreliable rainfall. They
occur where annual precipitation is less than 250 mm.
In the hot desert evaporation greatly exceeds total
rainfall. The potential evaporation and water loss from
plants could be up to 3,000 mm per year if this water
was available. A pool of water three metres deep could
evaporate in one year in the hot desert. Temperatures
in the desert vary greatly throughout the year and from
day to night. The large daily change is due to low
humidity levels and clear skies. As night falls the heat of
the day is rapidly lost and desert nights can be very cold.
The shorter days in winter also bring lower
temperatures.
Desert plants and animals have adapted to the extreme
climatic conditions. Plants in both hot and cold deserts
have developed special features called xerophytic
adaptations. These include the ability to store water in
stems and leaves. Plants also reduce moisture loss by
having small leaves and thick protective bark or by
having leaves with waxy surfaces. Cacti and other types
of plants have this characteristic. Some desert plants
only germinate and grow after rainfall. These are short
lived or ephemeral plants, which include a variety of
wildflowers.
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Vegetation is extremely sparse covering on average
about ten per cent of the desert landscape. It consists
of small shrubs and grasses that are able to resist the
extreme temperatures and lack of moisture. The
vegetation in the Gobi Desert, for example, is mainly a
type of spiky grass that grows on the sandy soils.
Common animals here include camels, goats, sheep,
foxes, wolves and lizards. The Gobi is a cold rain shadow
desert in Mongolia.
Soils in deserts are low in nutrients and poorly
developed. They tend to be rocky or sandy. In some
cases they have high levels of minerals such as salt,
which make them infertile. Climate and soil makes it
difficult for life to exist in the world’s deserts. Plants are
small and often spaced well apart with areas of bare
ground between them. It is because of these factors that
deserts have limited biodiversity and one of the lowest
levels of biomass of all the major biomes.
The arid and semi-arid climate areas of Australia are
unusual in having a larger percentage of vegetation
cover than is found in most of the world’s deserts. There
are large areas of low shrub plants that include mallee
and mulga bushes. Mulga bushes and small trees cover
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around 20 per cent of the Australian continent making
it one of the most widespread biomes. Mulga is an
acacia. It produces seed pods, which are an important
food source for a range of insects and animals such as
the red kangaroo and emu as well as the many different
types of birds that live in the deserts of Australia.
When rain comes to the Australian desert it is quickly
transformed into a garden of colourful plants, which just
as quickly die after flowering and producing seeds.
These seeds may lay dormant in the desert soils for years
until it next rains. Animal populations in deserts rapidly
rise and fall in response to the infrequent blooming of
the desert. In Australia a good season in the desert can
bring mice and locust plagues, while large flocks of birds
may migrate from the coast to take advantage of the
food supply and the temporary lakes formed by the
rainfall.
Tundra biomes
Aquatic biomes
Aquatic biomes include freshwater and marine
environments. They are the largest part of the earth’s
biosphere, covering over 70 per cent of the planet’s
surface. Freshwater biomes include rivers, lakes,
swamps and groundwater reservoirs. Marine biomes
include the oceans and seas. Different zones within the
marine biomes have their own distinctive ecosystems.
They include the intertidal zones, the continental
shelves and the deep-ocean or abyss. Other important
ecosystems within the marine biome are the coral reefs
of the tropical seas and the coastal estuaries where
marine and freshwater environments meet. Marine or
salt-water environments and freshwater environments
each have their own communities of plants and animals.
Each environment has variations both in biodiversity
and biomass in the same way as land based biomes do.
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The tundra biome is found in the Northern Hemisphere,
north of the boreal forests. It is the last major vegetation
zone before the regions of permanent Arctic ice cover
and extends in a broad belt through Eurasia and across
northern Canada. The absence of significant areas of
land in the higher latitudes in the Southern Hemisphere
accounts for the general absence of the tundra biome
from the southern regions of the globe. The tundra has
a long cold winter when average temperatures are
around minus 34o Celsius followed by a short summer
period when temperatures are high enough to support
plant growth. This results in a growing season of
approximately two months. Like the world’s deserts the
tundra has limited biodiversity and biomass.
Very high altitude areas also have tundra like conditions.
These occur on mountains above the tree-line and are
the alpine tundra biomes. While the growing season is
slightly longer here than in the Arctic tundra regions,
night time temperatures fall below freezing point and
this affects the plants and animals found in this biome.
Unlike the Arctic tundra the alpine biome has soils
which are well drained and plants can develop deeper
root systems. They do, however, have similar
characteristics to the Arctic tundra plants, being short
and clumping together. They include tussock grasses
and low heath shrubs.
Annual precipitation is between 150 to 250 mm, mainly
falling as snow, while the soil is slow forming and acidic
with permanently frozen subsoil. This permafrost soil
can only support shallow rooted plants that grow in the
topsoil. Permafrost soils contain very large amounts of
carbon dioxide. There is a concern that with increased
warming of temperatures in the Arctic regions that this
gas will be released, further speeding up global
warming. Permafrost soils also prevent water from
soaking in making large areas of the tundra boggy and
swampy.
Tundra plants have adapted to low temperatures strong
winds and the permafrost soils. They are short and
bunch together to form a thick ground cover, which
helps protect them from the cold and snow of winter.
They also have the ability to photosynthesise at low
temperatures and in low light intensity. Rather than
flowering and producing seeds, most plants in the
tundra biome reproduce by budding and division.
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Freshwater biomes can be defined as water bodies
where salt concentrations are less than one per cent.
They include lake, pond, swamp, wetland and river
ecosystems. In lakes and ponds, water tends to be still
with limited circulation or mixing - see figure 1.7. This
produces different environments from the shoreline to
the deeper sections. As a result these areas are home to
a variety of plants and animals.
Figure 1.7 Ponds are freshwater ecosystems
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Rivers vary from their source to their
mouth. The headwaters or source generally
have higher oxygen levels, lower
temperatures and less turbidity than
sections further downstream. The greatest
biodiversity usually occurs in the middle
parts where the river widens and deeper
sections are found. Where the river meets
its final destination, such as a lake or the
ocean, oxygen levels are lower and the
water becomes murky with the sediment
picked up over its journey. Different types
of plants and animals are therefore found
in the last sections of a river.
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Oceans cover most of the earth’s surface.
Like the freshwater lakes the oceans have
distinctive zones and layers. Along the
shoreline is the intertidal zone. This zone is
regularly submerged by daily tidal Figure 1.8 Coral reef ecosystems contain many different marine plants and animals
movements. Plants and animals in the
Estuaries occur where rising sea levels have ‘drowned’
intertidal zone have adapted to daily exposure to the
river mouths and valleys. The old river channels are
atmosphere. Beyond the intertidal zones are extensive
often shown on navigation maps as deeper areas
areas of shallow sea extending outwards across the
beneath the wide expanse of the waters of the estuary.
continental shelves of the larger landmasses. This zone
In different seasons estuaries experience changes in
is rarely deeper than 200 metres. It contains animals
salinity as fresh water flows into and mixes with
that live in the top layer of water, where there is greater
seawater. Plant and animal species have adapted to
light, while there are other plant and animal species that
these changes. They are able to tolerate quite wide
have adapted to life on the floor of the continental
variations in salt levels as well as changes in water
shelves.
temperatures.
In the shallow tropical seas the development of coral
reefs has resulted in an environment of great
biodiversity as illustrated by figure 1.8. These reefs
contain some of the highest biomass of all marine
ecosystems. Coral reefs are constructed from the
skeletons of tiny marine organisms. These coral polyps
also contain algae making them both plant and animal
organisms. New coral builds on the skeletons of older
ones and takes on a variety of shapes. Other plants and
animals attach themselves to the reef and complex
communities of fish live in and around the reef habitat.
Ningaloo Reef and the Great Barrier Reef are two major
reef environments in Australia’s coastal waters. Coral
atolls form islands and lagoons in the tropical seas of
the Pacific and Indian Oceans. These islands are home
to a range of land animals that are often unique to these
remote locations.
The deep ocean or abyss is found beyond the edge of
the continental shelves. It is a region of total darkness,
very high water pressures and extreme cold, with low
levels of nutrients. The animals that inhabit the deep
ocean are highly adapted to survive in this environment.
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Chapter 1 ­ An overview of environmental change
Activities
1. With
reference
to
the
website
www.mapsofworld.com select the map of
deserts and mark these on a world map. For each
one label as a hot, cold and/or rainshadow
desert. Using examples from the named deserts
explain how atmospheric pressure, distance
from the sea and mountain barriers produce arid
environments.
2. Explain why deserts have extreme variations in
daily and seasonal temperatures and the
significance of this for the plants and animals
found there.
3. Identify and describe any similarities between
desert and tundra biomes.
4. Using examples from desert, tundra and aquatic
biomes describe and explain two types of
seasonal or spatial land cover differences
associated with these natural biomes
5. Identify and describe two examples of land cover
changes associated with human impacts on
desert, tundra or aquatic biomes.
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ECOSYSTEMS –
STRUCTURE AND
DYNAMICS
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Ecosystems are distinctive communities of plants and
animals interacting with each other and with the nonliving or abiotic environment. The combination of
organisms (biota) and the non-living abiotic
animals, micro-organisms, detritus and organic fossils.
The abiotic elements include atmospheric conditions –
weather and climate, inorganic nutrients and minerals,
water, rocks, landforms and solar energy. Soils contain
both biotic and abiotic elements and are important in
the makeup of land-based or terrestrial ecosystems.
Over time, changes in the structural characteristics
result in ecosystems changing. Many ecosystems
therefore, are characterised by being at different stage
of progression or development. Some will be
dominated by pioneering and immature
organisms while others will exhibit
characteristics of a maturing system.
Finally, an undisturbed ecosystem may
reach a final stage where organisms form a
climax community. At this stage the
ecosystem has reached a level of stability
and balance and will tend to remain this
way until there is some type of disturbance
in the form of extreme weather, fire,
earthquakes, volcanic eruptions and
landslides. Human actions and climate
change are increasingly impacting on the
structure and functioning of fully mature
ecosystems. Old growth forests are an
example of a climax community or
ecosystem, while secondary forests such as
jungle and regrowth forests result from
logging and clearing of primary (old
growth) forests.
Dynamics
Figure 1.9 Hierarchy of biological organisation
environment, produces many different ecosystems.
These ecosystems vary in size (spatial structure) and
exist for many different periods of time (temporal
structure). As shown in figure 1.9 ecosystems form part
of biological hierarchy where the largest unit is the
biome. There are a number of different interactions and
processes that occur within all ecosystems including
energy, flows, nutrient cycles and biological processes
– reproduction and evolution, as well as changes to the
abiotic elements – erosion, tectonic activity,
atmospheric composition, weather and climatic
variations.
Structure
Biotic elements within an ecosystem consist of plants,
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Ecosystem interactions and dynamics can
be studied by looking at trophic level
interactions. This includes the study of
ecological succession, energy flows and
biogeochemical process. These ecosystem
dynamics help to explain the biodiversity
of a natural ecosystem and its relationship with the
abiotic environment.
Ecological succession
Biomes and the biological communities that occur
within them undergo changes over time. These are the
result of new organisms that enter the ecosystem, the
gradual evolution of existing organisms and changes
that occur within the abiotic environment. There are two
different types of succession – primary and secondary.
Primary succession occurs where a biological
community establishes itself in what was essentially a
lifeless location. These may include a lava field, surfaces
recently exposed by a retreating glacier, a new island
formed by a volcanic eruption or newly formed sand
dunes. Secondary succession occurs in areas where a
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community that previously existed was removed by
some event. Such an event does not completely
eliminate all life and nutrients from the environment.
Wildfires, land-clearing, flooding and tsunamis all have
the capacity to remove most of the organisms in an
ecosystem.
Food chains and food webs pass nutrients and energy
from one trophic level to the next in an ecosystem - see
figure 1.10. The plants or autotrophs have the ability to
take energy directly from sunlight in a process known
as photosynthesis and combine it with nutrients to
produce food for growth. Less than one per cent of all
solar energy reaching the surface of the earth is used in
this way. Most is held in the atmosphere to produce
global weather systems. As energy passes through an
ecosystem it is consumed at each level. With the
consumers, most of the energy is used to grow,
maintain body-heat, provide energy to muscles and
replace organism cells. Some is lost through respiration
and excretion of body wastes as well as decomposition,
when organisms die. Only a small amount of the energy
is available for the higher level consumers. As much as
95 per cent of transferred energy is lost at each trophic
level through respiration, excretion and decomposition.
This factor explains why there are far fewer secondary
and tertiary consumers in an ecosystem. The availability
of nutrients and energy at each trophic level is a natural
population control mechanism.
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Both primary and secondary succession is the way in
which plants and animals establish themselves in a new
environment. As these biological communities become
established they continually change with some species
maturing while other pioneering species may disappear
to be replaced by new arrivals. At every stage of an
ecosystem’s development certain types of plants and
animals have characteristics that allow them to flourish
in the current conditions. Newer species are more
successful as the environment is further modified and
these invaders then replace some of the earlier plants
and animals. In time an ecosystem may develop to a
point where some degree of balance or equilibrium is
established. This is described as a climax community.
This is thought to result when the web of biotic
interactions becomes so intricate that no other species
can be admitted. In other environments, continual
small-scale disturbances produce communities that are
a diverse mix of species, and any species may become
dominant at one time or another.
make up the primary secondary and tertiary level
consumers in a trophic pyramid. These form
progressively smaller numbers at higher trophic levels
and are subsequently the smallest part of an ecosystem
biomass.
Energy flows
Animals and plants in an ecosystem occupy different
levels. Together they form a trophic pyramid. The
bottom of the pyramid or the first trophic level is made
up of the autotrophs. These are the plants and they are
the largest part of an ecosystem biomass. The animals
Figure 1.10 Example of a food chain
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Chapter 1 ­ An overview of environmental change
Biogeochemical processes
Biogeochemical processes involve the cycling and
transfer of substances through the biotic and the abiotic
components of an ecosystem. This includes the cycling
of nutrients, such as water, oxygen, carbon dioxide,
nitrogen and phosphorous. Unlike energy flows,
nutrients can be continually recycled within a natural
ecosystem. This is important when understanding the
dynamics of natural, undisturbed environments
compared to anthropogenic biomes where biomass,
biodiversity, energy flows and nutrient cycles are
changed by intentional and unintentional human
actions.
Water plays an essential role within an ecosystem by
regulating temperature, sustaining life and transporting
nutrients. On average it makes up about 70 per cent of
the body weight of an organism. Along with carbon
dioxide it is essential in plant photosynthesis.
Transpiration or the evaporation of water from plants is
an important temperature control mechanism, while
ground water helps transport organic and inorganic
nutrients through roots, stems and leaves. Over time
water will weather and erode rocks to release minerals
and produce the inorganic component of soils as well
as combining with heat to support decomposition of
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dead organisms. Some specialised consumers in
different ecosystems gain all their water needs via food
chains and webs, while others rely on regular water
supplies for drinking and for habitat. Variations in water
availability and its different states – ice, liquid and
vapour, have a major influence on the different types of
biomes and ecosystems found on the Earth. This can be
seen in the variations between aquatic and terrestrial
biomes, between forest and desert biomes as well as
between tropical and Arctic biomes.
1. Explain the difference between the terms
structure and dynamics when applied to
ecosystems
2. Identify and describe two ecosystem structural
characteristics.
3. Identify and describe two ecosystem dynamics
processes.
4. Using library or internet sources find a trophic
pyramid diagram and explain the different levels
and the variations in biomass found at each
level.
5. Working in pairs, discuss and identify different
ways in which human activity and land use may
affect the structure and dynamics of ecosystems.
Produce a dot point summary of your
discussions.
CLIMATE – GLOBAL
PATTERNS AND
WEATHER SYSTEMS
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Atmospheric carbon dioxide enters the nutrient cycle
through the process of plant photosynthesis. It
combines with water to form carbohydrates. While
some returns to the atmosphere during respiration
most is absorbed by plants to form woody cells. It
remains in this form during the life of the plant and is
either returned to the atmosphere during
decomposition or is retained in the soil. Some deposits
of plant organic matter may, in time, become fossil coal
and peat deposits. In a similar manner carbon from the
shells of aquatic animals or from coral can be deposited
to form limestone. Carbon is an essential component of
all living things and it is continually recycled within the
trophic pyramid, and between the land and the
atmosphere.
Activities
Atmospheric nitrogen cannot be used by plants until it
is converted in nitrates by soil bacteria or lightning.
Nitrogen found within dead organisms or excreta is also
processed by bacteria to produce nitrates. Nitrates are
high soluble and their cycling is closely associated with
the operation of the water cycle within an ecosystem.
Where soils are particularly poor in nitrates and other
nutrients, some plants have developed special features
that allow them to trap insects and absorb their bodies.
In this way they gain the minerals and other nutrients
that they need for survival.
Phosphorous is an essential nutrient for both plants and
animals - the consumers, within the trophic pyramid. It
is important in the development of bones and teeth in
humans and animals. There are several sources of
phosphates in an ecosystem including decomposing
organisms, rock phosphate and excreta such as guano.
Unlike the other types of nutrient cycles mentioned
previously, the phosphorous cycle does not involve
atmospheric exchanges. Phosphates that are not taken
up again in the nutrient cycle within an ecosystem will
be eroded and deposited in soils, lakes and oceans,
where over many years it will eventually be changed
into sedimentary rock. It may take millions of years
before the rocks are once again eroded to release the
phosphate. In this way the phosphorous cycle is the
slowest of all the biogeochemical cycles.
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Up until the last 200 years or so the world’s climatic
patterns and weather systems had been largely the
result of natural systems and interactions. The
interaction between the energy or heat budget, the
water cycle, atmospheric circulation, land-masses and
landforms, the carbon cycle and the world’s biomes
have resulted in distinctive weather patterns and
regional climate zones. Land cover change, biodiversity
loss and the development of anthropogenic biomes
have all had an impact on the natural climate system
and global climatic patterns.
There is a close relationship between global climatic
patterns and world biomes. Biomes have largely been
shaped by variations in temperature and precipitation.
Like the biomes, climates vary from tropical through to
temperate and Arctic types as well as having maritime
to continental variations. These variations illustrate the
way temperature differences produce distinctive
climatic regions. In addition regional differences in the
amounts and distribution patterns of precipitation also
produce distinctive climatic regions. Some regions
mainly receive summer or winter precipitation, while
other areas have relatively uniform levels throughout
the year. In addition there are significant variations in
the total amounts, ranging from more than 2,000
millimetres in tropical regions and some mountainous
areas to less than 250 millimetres in arid climates.
Finally each climatic region has distinctive weather
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patterns and events associated with certain
atmospheric features, such as air pressure,
winds, humidity, cloud cover, temperature,
precipitation and sunlight.
Climate change
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Throughout the earth’s long geologic
history the global climate patterns have
changed. These changes include changes
in overall patterns of temperature and
precipitation. There are a number of drivers
of natural changes in climate. They include
changes in the earth’s axis, distance from
the sun and solar intensity, volcanic events,
changes in atmospheric composition and
gradual changes in land-masses and ocean
basins. Long term changes are illustrated
by periods of low temperatures and
extensive glaciations and interglacial or
greenhouse climate periods.
World population growth and large scale
industrialisation the last 200 years has seen
human environmental impacts reach a
point where there is strong evidence of
anthropogenic climate change. Evidence of
this more recent climate change can be
seen in rising global temperatures,
changing precipitation patterns and
changes in the levels of greenhouse gases
in the atmosphere. Atmospheric carbon
dioxide levels have increased from around
280 parts per million (ppm), prior to the
beginning of the Industrial Revolution
(1750 onwards), to some 400 ppm in 2015.
In addition, the very great increase in farm
Figure 1.11 -Changing sea-ice in the Arctic Ocean affects the global energy budget
animals such as cattle and sheep, along
atmospheric air pressure and wind systems produce
with widespread clearing of forests and woodlands has
new patterns and regional impacts; and changes in
produced much higher levels of methane gas. Both
atmospheric composition in terms of greenhouse gases,
carbon dioxide and methane are greenhouse gases.
including water vapour produce regional differences.
Industrial development and the much higher rates of
fossil fuel use have also added another greenhouse gas
Global temperatures since 1850, when instrument data
- sulphur dioxide – to the atmosphere. These land cover
became reasonably reliable, show a gradual increase.
changes to the biosphere by human activities are
Compared to the average for the period from 1901 to
significant anthropogenic caused drivers of climate
2000 nine of the ten warmest years have been in the
change.
period 2000 to 2014. The warmest year to date was 2014
when global temperature was 0.7o C above the 20th
century global average of 13.9o C. Regionally the
greatest variation was in the Arctic regions of the
Climate change is not uniformly affecting all areas of the
Northern Hemisphere, where the differences are up to
world. There are significant regional differences.
2.0o C. The dramatic reduction in the area of ice cover in
Changes in snow/ice accumulation and melt varies from
this region, illustrated by the changes shown in figure
place to place; changes in ocean and atmospheric
1.11, allows more sunlight to be absorbed by the oceans
temperatures and currents are not uniform; changes in
Regional climate change
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causing air temperatures to rise. They are projected to
rise by some 9o C by the end of the 21st century.
Global ocean temperatures are not uniform. There are
warm and cool ocean currents circulating within the
earth’s major ocean basins. In addition there are
regional ocean temperature anomalies. In the oceans
surrounding Australia the south-eastern and southwestern coastal regions are experiencing above average
ocean temperatures. In turn this affects marine
ecosystems as well as weather patterns in areas such as
south-western Australia, Tasmania and Victoria.
The clearing of forests in particular can change the
amount of evaporation and transpiration. There is some
evidence that rainfall declines these regions when large
areas of forest are cleared due to reduced transpiration
rates.
Urban heat islands
The replacement of natural ecosystems with their
complex plant and animal communities, by large urban
areas has, in a number of instances, produced localised
weather changes. Humans have tended to settle in
areas of good water supplies - rivers and precipitation.
These areas often had forest or woodland ecosystems.
When forests are replaced by urban structures such as
roads, buildings and open parklands there is a
significant change in evapotranspiration, albedo and
wind patterns. The result may be a marked increase in
day and night-time temperatures. Densely built, urban
areas where the moderating influences of trees and
other forms of vegetation is absent, become hotter than
the surrounding rural/forest/woodland environments see figure 1.12. These urban areas are classified as heat
islands. Urban heat islands illustrate the impact that
land cover change has on localised weather and climate
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The loss of ice in both the Arctic and the Antarctic is
reducing the percentage of sunlight reflection or
albedo, thus accelerating global warming as well as
producing a gradual rise in world sea levels. The ocean
today is warmer and the sea levels are higher than at
any time since accurate instrument measurement
began. This is beginning to affect some islands and
lowland regions. A combination of rising sea levels,
storm surges and flooding from periods of heavy rainfall
will produce greater environmental impacts linked to
climate change in these low lying regions.
effect is the amount of infiltration and runoff associated
with land clearing. Clearing of slopes can result in
greater amounts of surface runoff after rainfall. This may
then lead to accelerated soil erosion and in some
instances landslides. Increased flooding of lower areas
can be also a consequence as more water arrives in a
shorter period of time.
In regions such as Australia and Africa, rising
atmospheric temperatures are projected to produce
more intense heatwave conditions, shorter but more
intense rainfall periods, longer droughts and greater
impacts of climate induced bushfire periods.
Water cycle change
As the lower atmosphere becomes warmer,
evaporation rates are increasing. This is
resulting in an increase in the amount of
moisture circulating throughout the
troposphere (lower atmosphere). One
consequence of higher water vapour
concentrations is the increased frequency of
intense precipitation events, mainly over land
areas. Warmer atmospheric temperatures are
resulting in more moisture falling as rain rather
than snow. More recently increases in water
vapour in the upper part of the troposphere
have been noted. The effect of this is to
increase the heat holding capacity of the
atmosphere – the greenhouse effect. Unlike
glacial climatic periods a greenhouse world is
one where global precipitation rates are higher
overall.
Changes to the surface of the land as a result
of human activities can affect the natural
operation of the water cycle. One significant
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Figure 1.12 Thermal imaging detected by satellite shows the heat
generated by the City of London buildings compared to the parkland
areas and water bodies shown in green and blue
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The natural environment
patterns. With more than 50 per cent of the world’s
population living in urban environments the urban heat
island effect impacts on many of the world’s people.
Activities
1. Define the term climate change and briefly
describe the difference between natural climate
change and anthropogenic climate change.
2. Identify and describe two ways in which climate
change may be caused by land cover change.
3. Identify and explain two ways in which land
cover change causes changes to the water cycle.
4. With reference to figure 1.12 as well as library or
internet sources explain why urban land cover
can produce local variations in atmospheric
temperatures – the heat island effect.
Chernozem soils are common in the grassland regions
of North America. They are rich in organic material and
have good retention characteristics. These soils support
extensive wheat and maize farming on the plains of the
USA and Canada. Land use and land cover change are
greatly altering soils in most of the world’s agriculture
regions. Urban settlement also affects soils both at the
actual settlement site and in the surrounding
countryside. Local and regional soil erosion and
degradation is one consequence of land cover change.
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SOILS – FORMATION,
STRUCTURE AND
IMPACTS
vegetation, topography and time. Characteristics such
as fertility, texture, depth, profile and moisture content
are all shaped by the five soil forming factors. Most soils
are described as being zonal as they have developed in
zones with specific combinations of the soil forming
factors. Soils have played a significant role in the way
that human rural settlement has developed. Deep,
fertile soils such as those found in mid-latitude forest
and grassland regions have supported the
development of a variety of agricultural types.
While there are a wide variety of soils around the world
they are the product of five main factors. These are
parent material, climate, living organisms – especially
Types of soil
degradation
Soil degradation is the decline in the ecological quality
of soil caused by chemical, physical and biological
factors and processes. Changes to soil quality due to
ecosystem degradation and land cover
changes produces soils which cannot
maintain healthy plants, animals and soil
organisms.
Chemical degradation
Figure 1.13 Potential impacts of soil salinity in Australia
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Chapter 1 ­ An overview of environmental change
Many soils contain soluble salts. In an
undisturbed ecosystem they are kept in
check by a balance between weather
patterns and vegetation. Some salts still
accumulate naturally on the surface in the
form of salt/gypsum pans and lakes. Land
cover change and changes to the water
cycle can result in soil salts being brought
to the surface. The loss of natural deep
rooted vegetation and its replacement with
shallow rooted crops reduces transpiration
and causes the water table to rise. This
water-logs the surface soil and transports
salt upwards. Evaporation then removes
the water, leaving the salt behind to create
salt scalds and soil degradation. Soil salinity
is a major problem in some areas of the
Australian wheat-belt where the original
woodland biome has been largely
removed - see figure 1.13. In some regions,
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such as the Mediterranean areas of Europe the use of
brackish water for irrigation adds to the problem of soil
salinisation.
As most cropping systems remove nutrients from the
soil farm fertilisers are needed to maintain their
agricultural productivity. The removal of calcium is one
such nutrient loss. This results in a gradual acidification
of the soil. In Australia many of the different soil types
are very old and already are slightly acidic. The
replacement of acid tolerant vegetation with crops and
pastures adds to this problem. In other regions, such as
North America and Europe the issue of acid rainfall
associated with airborne industrial pollutants has had
an effect on soil acidity levels. Lime must be added to
reduce soil acidity.
Biological degradation
Plants, insects and micro-organisms play an important
role in maintaining soil quality. The use of insecticides
and herbicides to control pest plants and insects in
modern commercial farming is widespread. Over time
these chemicals have been improved to reduce their
negative environmental impacts. However, they still
have the capacity to affect beneficial organisms.
In Australia and other industrial commercial farming
countries the use of antibiotics to treat animal diseases
and to prevent infection has been a common practice.
These antibiotics can be excreted by farm animals and
then affect important soil bacteria. In this way there is
biological degradation of farm soils. Currently some 700
tonnes of antibiotics are imported into Australia. Over
half of this is added to stockfeed, while about 30 per
cent is for human use. Antibiotics are even used in
orchards, where it is sprayed on fruit to kill bacteria that
can damage the crop.
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Important soil nutrients such as phosphate and
potassium are recycled in an undisturbed ecosystem as
plants and animals die and decompose. The planting of
crops and plantation forests removes large amounts of
nutrients that can only be replaced by the use of organic
and artificial fertilisers. Eucalyptus and pine tree
plantations harvested for woodchips and construction
timber remove between 60 and 80 per cent of the soils
important nutrients. While the remaining root systems
and smaller branches eventually breakdown to recycle
the remaining nutrients the impact of plantation
forestry on soil fertility is significant.
resists water infiltration. In Australia the introduction of
hard hoofed animals including cattle and sheep has had
a significant impact on many soil types. Their
movements have produced a fine powdery dust which
is then very susceptible to wind and water erosion.
Physical degradation
Agricultural practices including ploughing, harvesting
and the impacts from grazing animals all have the
capacity to physically degrade the soil. Compaction is
one consequence. As farm machinery is driven over
farmland the soil is gradually compacted until the
necessary air spaces are removed. This affects soil
permeability – the infiltration or surface movement of
water. It also affects the ability of plant roots to
penetrate and has a negative effect on beneficial soil
microbes and soil biological activity. The use of larger
and larger farm and forestry machinery has increased
the effects of soil compaction in many industrialised
commercial farming regions. In Australia the
application of ‘no till’ farming methods is an attempt to
overcome the problem of soil compaction.
The loss of soil structure and disruption to the soil
profile is another type of physical degradation.
Traditional ploughing methods and irrigation when
used on certain soil types including shallow sandy and
clay soils has the effect of breaking down the soil
horizons and the texture. It can result in the surface soil
being reduced to a fine dust or minerals being
concentrated on the surface forming a crust which then
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Overall, farming reduces soil biodiversity and soil
organic content. Different land use activities in urban
and industrial areas also have the capacity to
dramatically affect soil quality. This is evident in
localised sites where pollution from different types of
chemicals, such as oil, polychlorinated biphenyls (PCBs)
and acids associated with industrial activity has resulted
in the need for expensive and careful soil cleaning,
removal and rehabilitation. Domestic chemicals and
garden fertilisers associated with urban residential areas
also adds to the impacts on soil biodiversity and quality
in towns and cities around the world.
Figure 1.14 Farming soils carried away in
massive dust-storms
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Soil loss
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The two major processes that
cause soil loss are soil erosion
and landslides. Water and
wind are the most common
agents of soil erosion. Where
land cover changes result in
temporary or long term
absence of vegetation then
this exposes soils to
accelerated erosion. Crop
farming may involve a cycle
of preparation, planting,
growth and harvesting. If any
of these stages includes
widespread exposure of the
soil then these temporary
periods
increase
the
potential for soil loss.
Across Australia’s agricultural
regions the rate of natureal
soil replacement is very low
and in many areas it is greatly
Figure 1.15 Gully erosion on cleared farming land in Victoria
exceeded by the rate of loss
through erosion. Wind
cultivation of the land, road construction and clearing
erosion results in the removal of large quantities of
for fences, buildings, power lines and other
fertile topsoil containing organic matter, thus reducing
infrastructure.
the productive value of affected lands. Significant
quantities of this dust are deposited off-shore, and on
Activities
many occasions over the past century dust originating
in Australia has been deposited as far away as New
1. Construct a cause and effect chart showing
Zealand. Dust-storms are a clear indication of soil
types of soil degradation. The causes will be land
erosion - see figure 1.14. In the past the frequency and
cover change resulting from land use activities
extent of major dust-storms in Australia has been
and the effects will be the different types of soil
significant. In recent times climate change and an
degradation. Summarise the main causes and
increase in rainfall in the arid and semi-arid regions of
effects using an appropriate chart or model.
the continent has resulted in an increase in vegetation
Examples of these charts can be found by
cover, and a reduction in major dust-storms, though
searching internet sources.
extended hot, dry, drought conditions in areas like
2. Identify and describe different methods that can
Queensland may offset this decrease.
be used to mitigate the negative impacts of land
cover change on soil.
Water erosion includes both sheet and gully erosion.
3.
Study figure 1.13 and describe the spatial
Sheet erosion is the uniform removal of soil from slopes.
pattern
of soil salinity in Australia. With reference
It can occur during intensive rainfall following recent
to
a
land
use map name the types of rural land
cultivation of soil. Gully erosion is one of the most visible
uses
found
in areas of high and low risk. Explain
and severe forms of water erosion as indicated by figure
why
rural
land
use in Australia may be a factor in
1.15. Gullies are steep-sided watercourses which
accounting
for
the variations in salinity risk
experience flows during heavy or extended rainfall.
levels.
Suggest
other
factors that may account
Gullies generally extend down to the underlying rock
for
the
variation.
and depending on the soil depth may be anywhere
4. Identify and describe two ways in which climate
from two to 15 metres in depth. The formation of
change might affect soil degradation and
erosion gullies can be triggered by various human
erosion levels.
activities. These include overgrazing by farm animals,
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Topic two
Changing the
Land
Land cover change also known as land-use and land cover change (LULCC) is a general term for the human modification
of the Earth’s land surface. In some instances the study of land cover change has been expanded to include anthropogenic
impacts on aquatic environments. Humans have been modifying land to obtain food and other resources for thousands
of years. Current rates of land cover change are greater than at any time in history. World population growth, urbanisation,
industrialisation and rising living standards are all driving unprecedented changes in ecosystems and environmental
processes at local, regional and global scales. Climate change and biodiversity loss are two major consequences of land
cover change. Transformations to land cover have changed global climate and biodiversity through anthropogenic
interactions with atmospheric and ecological systems. These interactions are in turn producing further changes to land
cover change. The study of land cover change is the study of processes, interactions, impacts and responses between
humans and the natural environment.
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LAND COVER CHANGE
PROCESSES
Land cover change is the change in the biophysical and
built environment primarily brought about by human
activity. Some of these activities are directly linked to
human actions while other may be natural processes
triggered by these actions. Explaining land cover
change therefore involves the study of land use and
analysing its impact on natural ecosystems. The types
of land cover changes that can be readily observed
include deforestation, ecosystem fragmentation, altered
drainage systems, modification of coastlines, urban and
industrial expansion or contraction, mining and
changing forms of agriculture.
The invention of machinery such as those shown in
figure 1.16 with the capacity to change the environment
has been a recent development in human history. The
agrarian or farming revolution which commenced in
Europe in the 18th century marked the start of
mechanised farming. No longer were people’s capacities
to change their environment limited to animal and
human energy. Farm machines allowed farmers to
modify and expand their farming activities beyond the
limits of their own physical labour. Food production
increased and commercial farming became widespread
throughout large areas of the world. Farm labour needs
declined and workers migrated from the rural areas to
the newly developing industrial cities. In 20th century
Australia the ongoing rural-urban migration produced
a significant decline in rural population and country
towns. In 1911 about 43 per cent of all Australians lived
in rural areas. By 2014 this had declined to 10 per cent,
with the majority of Australians now living in the state
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Figure 1.16 Farm tractors from the start to the
end of the 20th century
capital cities. As farm machinery became larger and
more sophisticated, farms amalgamated with larger
properties being able to be managed by fewer workers.
Farm mechanisation is an important factor contributing
to the ongoing changes of agricultural land cover.
Demands for natural biotic and abiotic resources such
as timber and minerals are also producing significant
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global land cover changes. Forestry includes the loss of
primary or undisturbed forest and its replacement with
secondary forests, scrublands and farmland. In some
instances it is also replaced by plantation forests, which
are managed and harvested as a crop. While the actual
site of a mine may be relatively small when compared
to the total land area of a region, the effects of the
mining activity may have a wider impact. The
construction of transport, power and water systems, the
processing of ore and the stockpiling of processed rock
as well as the development of mining settlements,
extends the mining impacts well beyond the actual site.
Modern large scale mining such as the Kalgoorlie super
pit shown in figure 1.17 illustrates the dramatic land
cover change at a mine site.
Social values including attitudes towards sustainable
development and environmental conservation are
important in influencing the nature of land cover
change. These values may be described as driving forces
and mitigating forces. Values that seek to change the
land are driving forces while those actions that seek to
prevent the negative effects of human actions are the
mitigating forces. Economic development is a driving
force. It often involves changes in land use, which in turn
may lead to social challenges and ecosystem
degradation. The competition for farm land surrounding
large urban centres is linked to the process of urban
sprawl. Farming activities are disrupted as urban areas
expand and land use changes. Urban development has
been linked to many environmental problems,
including air pollution, water pollution, and loss of
wildlife habitat. Urban water runoff often contains
nutrients, sediment and toxic contaminants, these can
not only cause water pollution but also large variations
in stream flows and temperatures. Habitat destruction,
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Remnant natural ecosystems are often a consequence
of urban, industrial and rural land use. These areas of
relatively natural environments are sometimes
protected as parks and reserves. This is illustrated by
figure 1.18, which shows part of Kings Park in Perth
surrounded by urban land uses. While they have some
ecological benefit the fragmented nature of these sites
affects the viability of all species, particularly the tertiary
consumers. In addition the fringes of these remnant
systems are vulnerable to the impacts of the
surrounding anthropogenic ecosystems.
Figure 1.17 Kalgoorlie Super Pit, Western Australia. A major gold producing mine site
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Changing the land
Figure 1.18 Part of the western end of Kings Park with the Swan River in the bottom left hand corner
fragmentation, and alteration associated with urban
development have been identified as a significant cause
of biodiversity decline and species extinction.
Mitigating forces are commonly related to actions to
conserve natural ecosystems or prevent the
replacement of low impact sustainable land uses with
high impact types. This may involve the use of
environmental laws which restrict uncontrolled
development or require certain environmental
objectives to be met by land use developers. Mitigation
also aims to promote the beneficial impacts of land
cover change. Reforestation of hill-slopes to prevent soil
erosion and promote greater biodiversity is one
example of a beneficial impact. Environmental
compensation measures are a further type of
mitigation. This involves offsetting the changes in one
area with beneficial actions in another. Mining
approvals in Australia can include the requirement to
replace the changed environment with an equal
amount of rehabilitation or preservation in another
area.
In summary the processes of land cover change are
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driven by human factors including population growth,
resource demands and exploitation, political systems,
social and cultural values and technological capacity.
Natural processes also change land cover as a result of
interactions between climate, ecosystems and
geomorphology, though the focus of this unit is on the
human impact.
Activities
1. Identify and explain at least two reasons why
land cover changes over time.
2. Identify two ways in which land cover change
has occurred in Australia and the reasons for
these changes.
3. Explain the impact of fragmentation or the loss
of land on natural ecosystems.
4. Identify and discuss two ways in which land
cover change has the potential to result in
conflict between different land use activities.
5. Describe how governments may influence land
cover change.
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TERRESTRIAL
ANTHROPOGENIC
BIOMES – HUMAN
ANTHROMES
Remote forests include forests such as the taiga and
boreal forests of Northern Canada and the Russian
Federation. The core of the Amazon in South America
also qualifies as a remote forest. While these forests are
far from large population centres and largely
untouched, they are affected by human activity. Due to
their high biodiversity and resource potential they are
explored and exploited. Some limited areas of the
northern boreal forests have been clear-cut as the
timber from this biome is removed for human use.
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Human impacts on terrestrial biomes can range from
slight environmental modifications where the
biodiversity remains largely intact through to complete
land cover change. Some indicators of the level of
impact include percentage of vegetation clearing, levels
of genetic and species diversity, degree of ecological
fragmentation, as well as soil and water condition and
quality. Some of these impacts discussed in this section
refer to the state of the Australian environment in terms
of forests/woodlands, rural and urban land cover
change as well as other global examples. Figure 1.19
illustrates a range of anthropogenic changes associated
with a rural landscape. This example is from the
Canterbury Plains on the South Island of New Zealand.
and urban settlements. While they generally have a high
degree of biodiversity, being in close proximity to
human populations has an impact. These forests may
include parks and reserves where structures such as
roads, picnic areas and tourist accommodation are
found. They may also have evidence of past and
ongoing logging. In addition there are often introduced
animals and plants, which affect and modify the natural
ecosystems. Population density in these forests is low
with a global average slightly less than three persons
per square kilometre (km2).
Forests and woodland anthromes
Anthropogenic forest and woodland biomes include
populated forests, remote forests and wild forests. The
populated forests are located near agricultural lands
Wild Forests are characterised by vast tree cover and a
total lack of any civilization and human interaction. The
land in these regions is rarely used in any way and there
are no permanent dwellings. The climate varies greatly
because this anthrome represents both equatorial
forests and the boreal forests of the far north.
Figure 1.19 Rural land cover change
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Changing the land
Prior to European settlement, largely undisturbed native
vegetation covered most of Australia. While most
ecosystems had been modified to some degree during
the 40,000 years or so of Aboriginal and Torres Strait
Islander settlement, the most dramatic changes have
occurred since European colonisation of the continent.
Currently about 85 per cent of Australia is vegetated by
native species, mainly in the arid and semi arid regions.
Most of the land cover change has been associated with
the clearing of forests and woodlands. These biomes
originally covered some 55 per cent of the continent
and this has been reduced to 42 per cent. Their location
corresponds to the most intensively used rural and
urban land use zones. While some further clearing and
modification is expected, large areas of the remaining
forests and woodlands are now protected as national,
state and local parks and reserves.
Throughout Asia one of the most significant cropping
anthromes is the village based, intensive irrigated and
rain-fed farming systems. The villages are densely
populated and the surrounding land is intensively
cropped often producing several crops ( usually rice)
per year from the land. The main focus of food
production is for local consumption. In this way there is
some degree of nutrient recycling within the farming
location. Warm temperatures and moderate to high
rainfall occurs in the village anthromes which also
correspond to tropical temperate forest regions. The
village farming system is typical of India, South East Asia
and China, where it is home to very large rural
populations.
Moderately intensive irrigated and rain-fed mosaic
farming is a cropping anthrome typical of the
agriculture found near large population centres in
Europe, North America and Australia. In Australia
intensive dairying, beef cattle and sheep for meat is
carried on improved pastures combined with the
production of fodder crops such as hay, oats and
lucernes. These types of mosaic farming can be often
found near the major state capital cities. Market
gardening, vineyards and orchards are another type of
intensive cropping found relatively close to the major
population centres in Australia.
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The overall extent of woody vegetation is an important
indicator of the condition of land cover. This includes
trees and shrubs which are mainly permanent types of
vegetation. They are important in maintaining deeper
and more stable soils, preventing water-logging and
salinity, and protecting the quality of surface water
sources – rivers and lakes. Their shade and structure
provide a micro-climate and habitat that is more
suitable for other plants and animals. The nutrient cycles
and energy flows that they help support are also
important in the continuing maintenance of vegetative
land cover.
Croplands
Agricultural anthromes
Land cover associated with agriculture represents the
most extensive form of land use in Australia and is
therefore a significant type of anthropogenic biome.
Agriculture can be either intensive or extensive. In
general, the more intensive the activity, the
greater the changes there are to the natural
environment. Different types of structures,
crops and farm animals produce distinctive
types of farming landscapes. In this way
agricultural land cover changes produce a
variety of rural landscapes.
Agricultural anthropogenic biomes can be
broadly divided into two main types –
cropland and rangelands. Within each of
these there are other distinctive land cover
landscapes. Croplands may include
irrigated and rain-fed farming systems as
well as intensive populated and remote
extensive cropping systems. Rangelands
may be divided into populated and remote
rangeland systems.
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Further away from Australia’s main centres more
extensive broad-acre cropping occurs. This is the mixed
farming mosaic of the wheat-sheep belts located in the
southern regions of Western Australia, South Australia,
Victoria and New South Wales. Figure 1.20 shows the
wheat-sheep belt landscape during late summer on the
western plains of New South Wales.
Figure 1.20 Mixed farming mosaic of the wheat-sheep belt of NSW
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Rangelands
Rangelands mainly rely on natural pastures
to support herds of domesticated grazing
animals including cattle, sheep, goats and
camels. People such as the Maasai and Zulu
in Africa are found in a village rangeland
anthrome. These rangelands generally
have a population density around ten
persons per km2.
Other types of
rangelands include populated and remote
rangelands. The populated rangelands
contain very low population densities of
less than ten persons per km2, while the
remote rangelands are generally wild with
little evidence of human activity.
URBAN ANTHROMES
Urban regions include major cities, regional towns and
urban villages. While there are wide variations in the
population density of these anthropogenic regions they
are the densest of all the different types of anthromes.
Human structures and built land cover dominates the
landscape with little or no agricultural activity. Worldwide about half of the world’s population lives in urban
settlements. They cover some seven per cent of the
Earth’s total ice-free land area.
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Populated rangelands such as that shown in figure 1.21
occur across much of the semi-arid regions of Australia
where it includes the grazing of sheep for wool and
cattle for meat on very large pastoral properties.
Biodiversity in this anthrome depends on the area of the
world and ranges on which it is found but it is typically
low in most areas. Careful management of stocking
rates (number of animals per square kilometre) in
Australia has allowed for the retention of a reasonable
level of biodiversity on pastoral properties. In Western
Australia a number of properties previously leased for
sheep have proved uneconomic and have been left to
return a modified natural state. They have a variety of
introduced and native plant and animal species giving
them some degree of biodiversity.
Figure 1.21 Populated rangeland in Northern Australia
Activities
1. Using the information in the textbook and that
found at the website www.ecotope.org (select
anthromes and education in drop down menu)
compare and contrast land cover change in
populated and remote forests
2. Compare the environmental impacts of
agricultural croplands and rangelands. Produce
a dot point summary of the main effects and the
differences between the two agricultural
anthromes.
3. Using Google Earth write a detailed description
of the rural land use in the area around Wattleup
along Wattleup Road by referring to settlement
density, environmental changes and farming
features and characteristics. Using the same set
of factors compare this type of agriculture to that
found around the settlement of Beverly in the
wheat-belt. Discuss how these examples
demonstrate the differences in land cover
associated with the intensification of agriculture.
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While the location of urban settlements is less
influenced by the natural environment than other types
of anthromes, globally they have been concentrated in
the temperate broadleaf forest biome. This is due to the
historical influence of industrialisation that occurred in
Europe and North America. The North American
megalopolis of Bosnywash (also called Bos-Wash)
contains around 50 million people. It runs down the
northeast coast of the USA as a continuous urban strip
and is made up of the cities of Boston, New York,
Baltimore, Philadelphia and Washington along with
many more, smaller cities and suburban areas. Figure
1.22 shows a small part of New York City, surrounding
its famous Central Park on Manhattan Island. Bosnywash
corresponds to the broadleaf forests of North America.
Figure 1.22 Central Park, Manhattan Island New York
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While this illustrates an association between urban
settlement and this biome it is not a necessary
requirement. There are a variety of reasons for the
location of an urban settlement and they can be found
in many different climatic regions and biomes.
Resources, accessibility, religion, defence, government
and cultural values all influence the location of this land
use type.
One of the most dramatic land cover changes
associated with freshwater anthromes is the
disappearance of the Aral Sea. In the 1960s the Soviet
Union embarked on a major agricultural project to grow
crops including rice and cotton in the desert
surrounding the Aral Sea. Two of the major rivers that
fed this huge inland lake were dammed to provide
irrigation water for this ambitious project. Most of the
sea’s water was diverted and it started to shrink. The
water level dropped by some 20 centimetres per year
during the 1960s and by the 1980s the rate had
increased to some 90 centimetres per year. By 2010 the
sea was only a small fraction of its original size as shown
by figure 1.23 (a), (b). The ecosystems and the river
deltas feeding into the Aral Sea have nearly been
destroyed.
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Australia’s pattern of urban settlement reflects the
history of European occupation of the continent. Sea
travel and exploration of the coastline resulted in the
largest cities occupying coastal locations. Inland
exploration and settlement spread outwards from these
coastal cities producing a radiating pattern of
settlement focussed on the colonial (later state) capitals.
The colonial capitals were built in areas of forest and
woodland, and on coastal areas that provided some
form of natural harbour. They were also areas with
suitable building materials – timber and stone, and
reliable sources of water.
lakes, seasonal flows and movement of sediments as
well as altering natural river ecosystems.
The residents and industries of the urban built
environment consume natural resources, including
water, energy and land. The waste generated by
urban/industrial activities within the urban
environment also has an impact on the natural
environment. Australia’s built environment is diverse
with a variety of land cover characteristics associated
with the different urban land uses. In addition there are
different types of plants and animals found within urban
areas that interact with people and the various landuses to create distinctive anthromes. The plants found
in residential gardens, parks and street-scapes often
have been introduced from many other places around
the world. Animals that thrive in urban environments
may be native species that adapt well to the new habitat
or they may be types that are pest or pet species.
There are significant pressures on the urban
environment driven by population and economic
growth, and climate change. An increasing need for
space and buildings (our urban footprint), increasing
traffic congestion and increasing consumption can
affect the liveability and environmental efficiency of the
built environment.
Freshwater anthromes
Biodiversity in freshwater ecosystems – rivers, lakes and
wetlands – is undergoing rapid global decline. Major
drivers are land use change, eutrophication,
hydrological disturbance, climate change, overexploitation and invasive species. By 2010 there were
around 50,000 dams affecting some 70 per cent of the
world’s rivers. Water diverted for irrigation affects inland
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Figure 1.23 (a) - Extent of the Aral Sea in 1980
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government areas. Each has their own concerns and
requirements. Getting an agreement that achieves a
sustainable social, economic and environmental
outcome has been tried on many occasions but has
failed to date.
Marine anthromes
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With over 50 per cent of the world’s population living
within 100 kilometres of oceanic coastlines the impact
of land based activities and the use of marine resources
have both had an impact on marine ecosystems. The
oceans have long been used as a source of food, as a
method of transport, for waste disposal and for
recreation. Human impacts have increased along with
rapid population growth, substantial developments in
technology and significant changes in land use. Overfishing, pollution and introduced species into different
marine ecosystems are affecting life in the sea. With
developments in large scale fishing technologies,
commercial fish species found on the continental
shelves around the world are either fully or overexploited. Some fishing techniques such as dredging
and trawling can cause widespread damage to marine
habitats and organisms living on the sea floor. These
techniques also often capture non-target species
(known as by-catch) that are then discarded.
Fiure. 1.23 (b) - Extent of the Aral Sea in 2010
Accelerated evaporation and reduced water flow has
increased salinity in the remaining water in the Aral sea,
while the falling water level has left huge plains covered
with salt and toxic chemicals. Some of these chemicals
were the result of weapons testing, industrial projects
and agricultural fertilisers and pesticides. The dry land
is now being eroded and the chemicals are picked up
by the wind and carried away as toxic dust-storms.
Apart from affecting natural ecosystems the spreading
of these chemicals is also affecting the health of the
people who live in the surrounding regions.
In Australia the issue of freshwater use and biodiversity
loss is seen in the Murray-Darling river system in Eastern
Australia. Development of large scale irrigation and
climate change are combining to put stress on the river
and its ecosystems. Attempts to solve the problem and
provide sufficient water for the natural environment –
environmental flows – is in conflict with the demand for
water for urban and rural uses. The Murray-Darling
system runs through four states and many local
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In addition to fishing the use of oceans for the disposal
of waste – including sewage and industrial chemicals –
has the potential to harm marine species and damage
habitats. In this way marine ecosystems are increasingly
being modified by human actions and in most cases
there is a loss of biodiversity.
Eutrophication is caused by the release of excess
nutrients. This is generally due to agricultural fertilisers
being carried in rivers to the ocean. These excess
nutrients can encourage the rapid growth of algae and
phytoplankton producing blooms. When these die they
cover parts of the ocean floor, reducing oxygen levels
during decomposition and damaging seafloor habitats.
The main features of this type of marine degradation are
illustrated in figure 1.24.Eutrophication is also a problem
in freshwater anthromes.
Finally the large scale movement of ocean transport has
spread marine plants and animals to new environments
where, in some instances they have thrived and now
pose a serious pest problem to the ecosystem. Without
natural controls some species have grown unchecked
and have killed or severely affected native species with
an overall loss of biodiversity. It is estimated that some
250 introduced plant and animal species have been
brought to Australia by commercial ships and private
yachts since European settlement. Japanese starfish,
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Asian swimming crab and the New Zealand sea-star are
just a few examples of these introduced animal species.
Over time excess nutrients enter the aquatic ecosystem
encouraging plant growth and
d algae blooms. Water
oxygen levels are depleted by excessive growth and
the decomposition of dead pla
ants. A point is reached
where fish and other organism
ms die. Eutrophication
results in the death of an ecosystem.
sunlig
igh
gh
ht sup
pp
p ts
por
phot
otosyn
y the
thesis
e
1. Nutrient load
5 De-oxygenation and death
5.
3. Phytoplankton and algal growth
2. Accelerated plant growth
How different communities and cultures around the
world view the natural environment and its resources
varies greatly. Cultural beliefs and values including
religious beliefs are important in formation of these
views. In addition, how economic systems operate in
different places as well as technological levels and
scientific understandings also influence these views and
responses. Finally the consideration of the future by
addressing the question of sustainable development is
important in understanding variations in the human
environmental impact.
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4. Dec
D omposition by bacteria
ECONOMICS, CULTURE,
VALUES AND
SUSTAINABILITY –
VARIATIONS IN THE
HUMAN IMPACT
Figure 1.24 - Process of eutrophication in
an aquatic environment
Economic systems and affluence
Activities
1. Outline the land cover changes associated with
Australia’s urban growth.
2. Discuss the significance of urban development
as a global driver of land cover change
3. Identify and describe three ways in which
freshwater ecosystems are altered by human
land use activities.
4. Draw maps of the Aral Sea in 1980 and in 2010.
Estimate the percentage decrease in the water
surface between 1980 and 2010 by placing a grid
over both maps. Explain why these changes have
occurred and the environmental consequences.
5. Investigate the Murray-Darling river system
using the website www.mdba.gov.au.
• Draw a map showing and labelling the major
rivers and streams found within the MurrayDarling basin.
• Briefly describe the environmental features of the
river basin
• Outline the issues affecting the environmental
sustainability of the river basin.
• Identify and describe the different human
impacts and uses of the river basin.
• Describe the process of land cover change
associated with irrigation districts found along
the Murray-Darling river system.
• Outline evidence of biodiversity loss associated
with land cover change in the basin
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Economic systems and organisational structures exist at
the local, national and global scales. From a
geographical point of view the way economic activity
influences land use and therefore land cover change is
important. The use of natural resources such as land,
minerals, plants and animals to meet needs and wants
illustrates the relationship between economic activity,
world biomes and land cover change.
Economic systems may be classified in a number of
ways. Whether a local or national economy is
predominantly commercial or subsistence is one way,
while the degree of government involvement,
especially at the national level is another. Commercial
economies aim at producing surplus products and
specialised services which can be bought and sold.
Continuous economic growth is important in these
economies in order to produce more goods and services
and to increase wealth. While this system uses large
amounts of resources it also has the wealth to be able
to carry out conservation and restoration of selected
ecosystems. Improved farm efficiency, methods and
land management in commercial economies may allow
greater amounts of farming products to be produced
from smaller areas of land, thus increasing productivity.
The use of greenhouses, for example, to grow food in a
controlled environment generates far more produce
than in open fields. In figure 1.25 a greenhouse
constructed on the roof area of a high rise building in
Montreal, Canada produces large quantities of
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and economically developed economy. Similar patterns
can be observed in other European countries including
Germany and France. Overall, forest density and extent
has increased in high income countries and generally
declined in low income countries. Increases in
population and rising affluence do not have to be at the
expense of the natural environment. In many instances
there will be sustainable solutions to meeting
community needs and wants.
Figure 1.25 Urban rooftop greenhouse
vegetables for much of the year. It also illustrates how
food production and urban development can occur
together.
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Tree cover in the United Kingdom declined as land was
cleared for farming, from 15 per cent in 1050 to about
five per cent in 1900. However by 2000 it had increased
to ten per cent even though the country’s population
has grown substantially. This change in land cover
illustrates the capacity to maintain food production
while increasing areas of forest biomes in a commercial
Subsistence economies tend to have low living
standards and little personal wealth. Most of the
population are involved in farming in order to feed
themselves. In these economies there is limited
infrastructure and localised forms of commercial activity
in the form of irregular market places, mainly selling
seasonal crops. Traditional farming methods in some
situations may only be suitable for low population
densities. When a population increases and demand for
food rises then growing demands alter land use and
land cover change. Moving from subsistence to a
commercial economic system also brings many
changes. Over the past half century, countries of South
and Southeast Asia have witnessed a major shift from
predominantly subsistence agriculture to industrialised
Increasing cost of farm land per hectare - land rent
1. Extensive rural land use - e.g. grazing
2. Moderately extensive land use - e.g. wheat growing
3. Intensive land use - e.g. market gardening
is greater than 1 and 2
These points mark the boundary between
one land use and the next. Here the value
of production per hectare between one
land use and the next is equal.
is greater than 1 and 3
is greater than 2 and 3
1
2
3
Market point
Increasing distance and decreasing value of land
Figure 1.26 The economic rent model for rural land use
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Changing the land
economies. These changes have been accompanied by
expanding urban populations and the growth of huge
megacities around the region, often at the expense of
prime farmland. Commercialisation of agriculture has
also led to the expansion of cash crops, including
several tree-based crops such as oil-palm, rubber, coffee,
cashew, and fast-growing trees species for pulp and
paper. In many areas, these have replaced food-crops as
well as encouraging large scale clearing of rainforest
biomes. This economic development has significantly
changed land cover across much of Asia.
Technology
While technology increases the capacity of humans to
change the environment it also allows them to develop
more sustainable practices. The capacity to implement
farming techniques that reduce water requirements
(irrigation systems), mitigate soil degradation, minimise
the negative effects of farm chemicals and reduce the
clearing of natural ecosystems are some ways in which
technology and agricultural science can promote
sustainability.
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International trade and the growth of a globally linked
or world economy has had a dramatic effect on regional
land use and land cover. The open cut mining of iron ore
in the Pilbara or bauxite in the Darling Ranges southeast
of Perth would not have occurred without the demand
for these resources in countries such as China, Japan,
the USA and Germany. Increased trade and the process
of globalisation will continue to produce different land
use patterns and changes as each country develops
resources, products or skills that can be sold in world
markets. Globalisation need not always result in
landscape degradation. Factors such as eco-labelling,
wider and more rapid spread of technologies, better
media coverage putting international pressure on states
that degrade their resources, and the movement of
people across borders to gain better educational and
employment opportunities can all be seen as benefits
of globalisation, which in turn can protect landscapes.
distance from a market point such as a town or city
influenced the type of land use and land cover due to
the cost of transport. In turn the difference in transport
costs associated with moving agricultural products to
the market affected the value of the land. Land close to
the market-place had a high value and was more
intensively used to produce higher value products. Land
in more remote locations was cheaper and contained
more extensive types of land use with lower production
values per hectare. As transport costs and technologies
change however, so too does the land use types and the
corresponding land cover associated with the economic
rent mechanism. Over time there will be ongoing
changes in the types of land uses found around market
points due to changing markets, costs and
technologies.
Changes in transport technology can make regions
more accessible and therefore more able to provide
One important geographical concept within regional or
resources to a wider market. High value products can
local areas in terms of economic impacts on land cover
be moved quickly to any part of the world by air
change is von Thunen’s economic rent mechanism. This
transport, while bulk goods can be carried overseas by
is illustrated by figure 1.26. Von Thunen proposed that
increasingly larger and larger ships as illustrated by the
bulk wheat carrier shown in figure 1.27.
Well developed transport systems and
infrastructure are critical to the success of
a range of land uses. Greater accessibility
brought about by the development of
transport can also have negative
environmental impacts. The extension of
transport into areas previously isolated can
bring biodiversity loss as land is cleared for
roads and as roads provide access to these
untouched areas by new settlers. Road
building was a catalyst for land cover
change in the Amazon rainforest. As they
were
constructed,
the
Brazilian
government encouraged settlement near
these roads. These schemes provided
virtually free land to those who settled and
cleared the land to develop farms. Prior to
the 1970s land clearing in the Brazilian
Figure 1.27 Russian bulk wheat carrier being loaded with
grain from the Rostov region
Amazon was relatively small scale. By the
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Changing the land
1980s it was conservatively estimated that deforestation
was over half a per cent per year or an area of some
50,000 square kilometres annually.
In conclusion it can be stated that, land cover changes
will often reflect the variations in technological capacity
and science in different regions of the world.
Culture
While the technology of Indigenous Australians was
limited to wood, bone and stone tools they did make
changes to the land through the practice of fire-stick
farming or land management. Aboriginal people used
fire as a sophisticated tool to continually manage and
modify the landscape. At certain times of the year, they
set fire to the bush to encourage new growth or ‘green
pick’, which then provided productive feeding grounds
where grazing animals would gather to exploit the fresh
shoots. This higher concentration of animals made
them convenient targets for Aboriginal people to hunt
and kill. A secondary benefit to firing is that it also
increases the productivity of certain varieties of bush
tucker such as fungi and tubers. In some areas of
Australia the forests and coastal heath-lands have
developed a greater amount of undergrowth where
European settlers discouraged this practice. This
resulted in fewer fires but ones which were much more
intense. Land cover in these areas was once again
changed. Aboriginal fires were small-scale ‘cool’ fires,
unlike the wide spread, catastrophic fires caused by
Europeans. The fires frequently set by Aboriginal people
over time formed a ‘mosaic’ effect of differently burnt
landscapes of varying ages. This allowed Aboriginal
people to create a series of diverse environments,
broadening the variety of plants and animals available
to them.
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The motivations, collective memories, personal
histories, attitudes, values, beliefs, and individual
perceptions of land managers can have a significant
influence on land-use decisions. The intended and
unintended ecological consequences of land-use
decisions all depend on the knowledge, information,
and management skills available to land managers. The
cultural values of the wider community also affect the
nature and types of land use and land cover change.
These values include conservation or environmental
values as well as development values. Re-forestation
and rehabilitation of degraded environments illustrates
these value based decisions. In Western Australia, landcare groups are examples of this desire to repair and
protect natural ecosystems. These groups operate in
both rural and urban environments. They are motivated
by a desire to protect the aesthetic and biological
features of natural environments and to repair degraded
environments. Large scale tree planting by land-care
groups in the Western Australian wheat-belt to reduce
salinity and prevent soil erosion is one example of the
application of these values.
sources. At other times they would come together to
socialise and perform sacred ceremonies. The seasons
played a part in this movement and it was also a way of
maintaining sustainable environments and food
sources.
Indigenous land management
practices
Sustainability
Aboriginal and Torres Strait Islander Peoples practised
a variety of land uses that produced distinctive
anthromes and land cover patterns. Indigenous
Australians had lived on the continent for some 50,000
years before the arrival of European settlers. Population
numbers and densities were low, with the people living
in some 700 language or tribal groups. Most lived a
semi-nomadic way of life adapted to the natural
environment in which they found themselves.
Indigenous people lived as hunters and gatherers. The
men hunted the large animals such as kangaroos, emus
and turtles and the women and children hunted smaller
animals and collected fruits, berries and other plants.
On the coast people caught fish and collected many
types of shellfish including mussels and oysters.
A recent report by the United Nations estimates that
humans have affected about 85 per cent of the world’s
terrestrial environments with some 60 per cent of
natural biomes being degraded in the past 50 years. The
UN considers that land cover change and the
development of anthropogenic biomes are posing a
serious threat to the world’s biodiversity. It is estimated
that the loss of biodiversity has already exceeded the
upper limits of rehabilitation with the current rate of
extinction being 100-1,000 times higher than the preindustrial age level. Additionally, freshwater resources
are also overwhelmed by the increasing world
population and climate change. These factors have
increased the variability of water resources and have
reduced their supply in dry areas.
The numbers of people in a group varied, with some
breaking up into smaller family groups at different times
of the year to move across the country to seek new food
The solution to biodiversity loss lies in the development
of sustainable practices. These include achieving a level
of food security through methods that increase yields
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Changing the land
Figure 1.28 A portion of Perth’s rural-urban interface
WORLD POPULATION
GROWTH AND LAND
COVER CHANGE – URBAN
AND RURAL
LANDSCAPES
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while minimising environmental impacts and reducing
consumption and reducing waste of non-renewable
resources including fresh water. Sustainable
development is an objective where all land use
decisions are based on the need to prevent biodiversity
loss and manage resources to consider the needs of
future generations.
land in the world. Policy efforts to avoid this
loss of productive land are being put in
place, but their effectiveness in the face of
economic demand is often limited.
Another threat to biodiversity is the
widespread adoption of automobile
transportation in some developed nations.
This has transformed large areas of
agricultural land and natural ecosystems
into relatively low density residential uses
around cities and along highways (urban
sprawl). This invasion of rural areas by
urban expansion is illustrated by the urban
sprawl on Perth’s northern fringes shown in
figure 1.28. ‘Smart growth’ including
compact cities strategies and other urban
programs have been developed in many
cities to encourage more efficient urban
land use and protect agricultural land.
Protection of productive agricultural land has become
a major priority in many regions of the world. Land
degradation by overgrazing and intensive agriculture
on marginal lands is a major driver of land loss; a
number of national and international programs have
responded with land reforms and incentive programs
to avoid this outcome. In rapidly industrialising nations
with dense populations such as China, and in the past,
Korea, Japan and Western European nations, demand
for land for industry and residential use is driving out of
production some of the most productive agricultural
Logarithmic scale
The growth in population, its spread or distribution and
the increase in population density are important drivers
of land cover change. Population growth, distribution
and density can be observed in both urban and rural
landscapes. For most of human history world
population grew very slowly. Ten thousand years ago
the estimated world population was
five million. Nearly all people lived
as nomadic hunters and gatherers.
Artificial fertilisers
7,000 million
Oil and gas power
The development of agriculture in
World population growth
Electricity
12 000 BP to present
areas such as Mesopotamia in
2,000 million
Steam
present day Iraq ensured a degree of
engines
1,000 million
food security and gave rise to the
Coal power
first cities. The beginning of
Expansion of farming
Globalisation
agriculture was also the beginning
Development of iron tools
and farm equipment
of population growth and
100
million
The first cities
permanent settlement. It was not
Development of agricultural irrigation
until the 1800s, however, that the
Kiln fired pottery
Copper and bronze tools
Independent
first billion was achieved. Since that
10 million
nations
time there has been an acceleration
Beginnings of agriculture
or explosion of world population.
Rise of
Rise of the
Mainly nomadic hunting
From 1800 it took 130 years to 1930
empires
1
million
and gathering
city-states
to reach the second billion, then 30
12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0
years and 15 years to get to the third
billion and fourth billion. By 2015 it
Figure 1.29 Growth in world population and socio-political systems
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Changing the land
had grown to 7.28 billion and it is estimated to increase
further to 11 billion by the end of the 21st century.
Figure 1.29 shows the main features of world population
growth. A global trend towards urbanization also is
taking place.
Global factors including the development of world
trade and world environmental standards have had an
impact on countries such as Australia and the decision
making of governments. This includes issues of foreign
land ownership, bio-security with regards to the import
and export of agricultural products and meeting the
regulations of international environmental agreements.
The establishment of world heritage areas like Shark Bay
in Western Australia or Kakadu in the Northern Territory
are examples of how international environmental
agreements affect land cover.
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The world’s urban population is growing by 60 million
a year, about three times the increase in the rural
population. The movement of people towards cities
has accelerated in the past 40 years, particularly in the
less-developed regions, and the share of the global
population living in urban areas has increased from one
third in 1960 to 50 per cent (3.5 billion people) in 2014.
Overall urban growth results about equally from births
in urban areas and from the continued movement of
people from rural regions. By 2030, it is expected that
nearly 5 billion or 61 per cent of the world’s 8.1 billion
people will live in cities. Globally, the number of cities
with 10 million or more inhabitants is increasing rapidly,
and most of these new “megacities” are in the lessdeveloped nations.
change. One example is the rural land use policy of the
Western Australian government. The state Department
of agriculture and Food works to ensure that sufficient
land and water resources are available to meet future
needs of the state. The department also assists
agricultural businesses develop rural production. The
overall objective of rural land use planning is to have
sufficient suitable land and water resources to support
the production needs of agriculture and food in Western
Australia.
GOVERNMENTS AND
POLICY – REGULATION,
LAND OWNERSHIP AND
POLITICS
Governments affect land use and land cover change
through the establishment of laws, regulations and
policies. Land ownership laws and land use planning
regulations are two aspects of government influence. In
Australia, land ownership includes freehold title,
leasehold and traditional land rights. Each of these
provides certain rights, restrictions and obligations.
Ownership of minerals found beneath the land surface
are also regulated, with state governments approving
mineral leases within their territorial limits, while the
federal government has authority over some
commonwealth lands and certain offshore undersea
areas. Leasehold rights over crown lands in areas away
from the main settled areas mainly relate to pastoral or
rangeland properties. This gives the lessee water and
grazing rights with certain environmental conditions.
Leaseholds are also restricted to a set number of years
before application needs to be made for renewal.
Freehold title provides ownership for all time. Planning
and environmental regulations however can restrict
how the land is used. Freehold farming properties have
regulations that deal with the clearing of vegetation and
the use of water. Government controls therefore
influence land use, land cover patterns and land cover
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Chapter 1 ­ An overview of environmental change
Activities
1. Define affluence and outline the association
between growing affluence and economic
systems.
2. Outline how growing affluence may affect land
cover change.
3. Explain how economic competition for land
influences land cover and land cover change.
4. Explain the impact of economic globalisation on
land cover change.
5. Describe three ways in which advances in
technology influence the nature and rate of land
cover change.
6. Describe two cultural values or viewpoints that
influence the process of land cover change.
7. Summarise the main features of traditional
indigenous land management practices in
Australia.
8. Use the examples found at the following internet
site to identify and evaluate the characteristics
of indigenous peoples’ land management
practices found in different global regions.
www.ourworld.unu.edu/en/land-use-climatechange-adaptation-and-indigenous-peoples
9. Write a detailed explanation of the way that land
cover change has been affected by world
population growth.
10. Describe three ways in which government
policy, regulation and land ownership laws
have influenced Australia’s land cover change
processes.
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Topic three
Spatial technology
and
science
Spatial technologies are any type of technology that refers to place, space or location. They include technologies that
collect and organise data from specific points on the earth’s surface. Some 80 per cent of all information collected today
has a spatial element to it. This means that it is tied to a place. Consider the nature of nightly news reports. Events and
people nearly all have a locational reference. Globalisation is about places and their interconnections, and in a world where
these interconnections are expanding more and more, both in the virtual world of the internet and in the physical world
of land, air and sea transport, spatial technology is an essential field of research.
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The use of spatial technologies forms the basis of many geographers’ work practices. The Global Positioning System (GPS),
Google Earth, geographic information systems (GIS) and the use of satellite images are the most commonly used spatial
technologies to visualise, manipulate, analyse, display and record spatial data. The use of spatial technologies is also
essential to the inquiry and skills process. Spatial technology application links geographic locations to information about
them so you can: find information about places across the globe or locally, analyse relationships between locations, make
decisions on the location of facilities, map the demographics of different population and integrate maps with information
from a variety of sources. Spatial technology relies on direct measurement and observations which are carried out in the
field as well as remote sensing. Both approaches are discussed in this topic.
FIELDWORK – DIRECT
MEASUREMENT AND
OBSERVATION
Fieldwork is research carried out onsite using different
recording tools, observations and measurements.
Mapping,
sampling,
tallying,
interviewing,
photographing and the use of recording and testing
equipment are all ways in which data can be collected
from a fieldwork site. The main objective of fieldwork
that looks at land cover change is to investigate the
nature and extent of changes to biodiversity as well as
changes to anthropogenic biomes. Change over time is
an important element in the study of land cover. Being
able to record these changes is important. They can
include short term changes such as with the seasons
and longer term changes as with human generations intergenerational changes. Looking at the changes from
summer to winter in a landscape to see seasonal
patterns is one example of fieldwork observation.
Comparing current land cover to information provided
by historical data is a way that changes can be
compared from one generation to the next.
Topographic maps provide a range of natural and built
data and these can be used along with fieldwork
observations of the same site to identify the type and
nature of land cover change.
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Interviews conducted with people of different age
groups provides useful information on the perceptions
of land cover change. While recollections of how things
used to be are not always accurate they do give an
insight into the types of changes that people think are
important. These memories may include the types of
animals, plants, settlement characteristics and rates of
change in the past. Perspectives on current patterns of
land cover will also reveal attitudes, beliefs and values
that people have with regards to their immediate
environment.
Random, checkerboard, quadrant, select point and
transect sampling are ways to gain valid fieldwork data
without conducting a complete survey. Sample data
can be extrapolated to provide information on
population numbers, density, diversity and spatial
variations for the total study area. Where a study area
contains obvious examples of certain types of land
cover, stratified sampling can be used. A small area in
each sector may be selected as typical of that zone and
then fieldwork data observations can be made. This
method is useful where distinctive ecosystems exist. For
example a river system may have riverbank, floodplain,
sand-spit, wetland and valley slope environments that
can be individually sampled. In an urban environment
random city blocks can be used as quadrants to sample
urban land use and land cover.
Ground level and ground based oblique photography
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Spatial technology
and science
Observe, identify and classify
Sample, record and measure
Sketch, map and photograph
a
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Discusss, debate and evaluate
Consider and apply geog
graphical concepts
Figure 1.30 Direct observation fieldwork tasks
is an important fieldwork data collection method.
Photographs taken from the same point over time by
the geographer will illustrate land cover change. They
also provide visual information on the variations and
diversity of land cover elements. Seasonal variations in
the landscape are clearly illustrated by photographs
taken at different times of the year. These can also be
compared from one year to the next to illustrate factors
such as climate variability and climate change. The
retreat of valley glaciers around the world has been
accurately documented using ground
photographs taken over a number of years.
information about the earth’s surface, without being in
contact with it as illustrated in figure 1.31. It usually
refers to the technology of acquiring information about
the earth’s surface (land and ocean) and atmosphere
using instruments onboard airborne (aircraft, balloons)
or space-borne (satellites, space shuttles) platforms. In
addition the use of sonar on board ships to map the
ocean floor is a type of marine remote sensing. Remote
sensors or instruments include optical, microwave, radar
and laser technologies.
Types o
Ty
off satellit
e lite remotte sensing
se si g
Field sketching and mapping using
measuring tapes, compasses, inclinometers
and GPS equipment are important spatial
and visual forms of data. The use of a base
map to collect information on different
natural and built features also allows
geographers to analyse and evaluate
interrelationships,
distributions,
frequencies and density patterns. Figure
1.30 illustrates a range of fieldwork
processess.
REMOTE SENSING
Passive reflected
- photographic
Remote sensing is the science of obtaining
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Chapter 1 ­ An overview of environmental change
Passive em
mitted - infrared,
electromaagnetic radiation
Active transmisssion - radarr, laser
radio and microwave
Figure 1.31 Passive and active remote sensing
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Spatial technology
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The types of information collected include aerial and
satellite photographs, infra-red images, and specific
wavelength colour images based on electromagnetic
radiation. This information is sometimes called passive
sensing as it requires energy being given off by features
on the earth or in the atmosphere.
Active remote sensing occurs where an energy pulse is
transmitted from the instrument. This energy can
include sound, radio and microwave transmissions as
well as light and laser beams. Active sensors both detect
features and measure distance or range. Changes in
ocean levels and topography can be measured very
accurately using laser altimeters and LIDAR (light
detection and ranging). LIDAR can also identify and
measure aerosols, clouds and other constituents in the
atmosphere.
Applications of remote sensing
Because of its varied applications and ability to allow
users to collect, interpret, and manipulate data over
large often not easily accessible and sometimes
dangerous areas, remote sensing has become a useful
tool for all geographers and earth scientists. The
following is a brief summary of remote sensing
applications.
Coastal applications: Monitor shoreline changes, track
sediment transport, and map coastal features. Data can
be used for coastal mapping and erosion prevention.
Ocean applications: Monitor ocean circulation and
current systems, measure ocean temperature and wave
heights, and track sea ice. Data can be used to better
understand the oceans and how to best manage ocean
resources.
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The processing and interpretation of remote sensing
images has specific uses within various fields of study.
In geology, for example, remote sensing can be applied
to analyse and map large, remote areas. Remote sensing
interpretation makes it easy for geologists to identify an
area’s rock types, geomorphology, and changes from
natural events such as a flood or landslide.
polygons, which are later put into shape-files to create
maps.
Remote sensing is helpful in studying vegetation types.
Interpretation of remote sensing images allows
geographers, ecologists, those studying agriculture and
foresters to easily detect what type of vegetation is
present in certain areas. Over time any
changes to the vegetation cover can also
be detected.
Hazard assessment: Track hurricanes, earthquakes,
erosion, and flooding. Data can be used to assess the
impacts of a natural disaster and create preparedness
strategies to be used before and after a hazardous
event.
Natural resource management: Monitor land use,
map wetlands, and chart wildlife habitats. Data can be
used to measure and minimize the damage that urban
growth has on the environment and help decide how
to best protect natural resources.
The study of urban, industrial,
infrastructure and rural land uses are also
improved with the use of remote sensing.
It allows planners, geographers and policy
makers to easily identify which land uses
are present in an area. This can then be
used as data in city planning applications,
biodiversity evaluation and the study of
species habitats.
Finally, remote sensing plays a significant
role in GIS. Images are used as the input
data for the raster-based digital elevation
models (abbreviated as DEMs) - a common
type of data used in GIS. Figure 1.32 is an
example of a DEM developed using remote
sensing. The air photos taken during
remote sensing applications are also
converted by GIS digitizing to create
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Figure 1.32 DEM of portion of Zion National Park USA
using a USGS elevation dataset
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Spatial technology
and science
Remote sensing
products
Figure 1.33a True colour image of the world.
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There are many different products
including photographic, map and
digital data information. They are
illustrated by the examples
provided in this and other sections
of the textbook. The first is a true
colour image of the world using a
variety of devices and methods. The
information contained in this image
was gained using spectrometers,
radiometers,
high
resolution
cameras and thermal imaging
equipment. It was combined with
additional elevation data based on
information collected from ground
surveys. Information needed to be collected over a
number of days and then combined to provide the best
possible composite image. See figure 1.33a.
A second example of a product is the use of active
remote sensing instruments to produce various
topographic images. The image of Death Valley in the
United States shown in figure 1.33b, has been taken
from the Space Shuttle using Synthetic-Aperture Radar
(SAR). It is a form of radar which is used to create images
of an object, such as a landscape – these images can be
2D or 3D representations of the object. As the shuttle
passes over the target object a series of pulses are sent
out from the radar at different angles. This builds up
data from the various positions in order to create the
image.
Changes in vegetation cover can be accurately
monitored and illustrated using remote sensing data.
Thermal imaging combined with satellite photography
and imaging using different parts of the colour
spectrum can produce accurate maps of changes in
vegetation cover for large areas of the world. These
illustrate rates of deforestation, changes in the types of
vegetation cover and changes in plant biodiversity.
Maps of vegetation change can be produced from the
data and used to provide evidence of human activity
along with the changes and extent of anthropogenic
biomes.
Rapidly changing events such as weather patterns,
bush-fires and floods can all be monitored from space
by satellite or from the air by planes. The use of GIS and
the data produced by remote sensing aids agencies
including the fire services, police, the armed forces,
search and rescue, and emergency workers in providing
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Figure 1.33b Death Valley USA. A form of active remote
sensing using radar
a more effective service. Several remote sensing data
sources were used to determine the extent of the 2009
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black Saturday bushfires in Victoria including Landsat
and the MODIS (Moderate Resolution Imaging
Spectroradiometer) instrument aboard NASA’s Terra and
Aqua satellites. This information helped the emergency
services plan and respond to the bushfire.
Models are used to study land cover change. Urban
development, forestry, agriculture, mining, and other
land uses can substantially alter the Earth’s surface. Land
use and the resultant change in land cover have
important effects on ecological systems and processes.
Developing models that project/predict future landcover change allows for the mitigation of the potential
consequences of land cover change on numerous
ecosystem elements such as biodiversity, water quality,
and climate. It also allows for greater accuracy in
determining the optimum level of sustainable
development within a region. Data on biogeochemical
cycles, biodiversity, landforms, soils, hydrology, weather
and climate variability are used in land cover change
modelling, in order to develop these sustainable
solutions.
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Aerial photography includes air oblique and ‘bird’s eye’
or vertical photographs. Fixed wing aircraft with
mounted cameras are traditionally used to capture
images along a set path. Where these overlap then three
dimensional views can be obtained by studying a set of
two photographs through a stereoscope. By flying a set
route at a set height it is possible to calculate a scale for
these vertical photographs and to measure distances
and areas. The value of aerial photography was seen as
soon as the first cameras were invented, with one of the
first photographs being taken from a hot air balloon in
1858 over Paris. Fixed wing powered aircraft were also
used in the First World War to take photographs of
enemy positions.
understanding of the climate system and climate
change. Projected changes in temperature and
precipitation patterns at the regional and the global
levels have been developed using these models. Maps
illustrating future climate patterns are only possible
given the power of computers to process large amounts
of data and apply complex spatial modelling.
Aerial photographs have been a valuable historical
source of land change information for use with the more
recent GIS software. They are analysed and then
digitised to allow for comparisons with modern satellite
and aircraft data.
SPATIAL MODELS –
PREDICTING AND
PROJECTING CHANGE
Spatial models are used to explain geographical
processes such as flows, inputs throughputs and
outputs,
connections,
associations
and
interrelationships. The ways in which different
geographical features are connected to each other, their
density, distribution, shape and change over time are all
important in understanding the earth and in particular,
land cover change. Spatial models help to predict
outcomes. Where they explain changes associated with
time and distance, they are a valuable planning and
decision making tool. Spatial models such as Von
thunen’s economic rent model, Christaller’s central place
theory, Weber’s least cost location model and the
gravity model of trade are all useful tools in accounting
for land use patterns and the prediction of future
patterns.
GIS software has allowed spatial scientists to develop
multi-variable models using complex algorithms, to
explain and predict large scale earth systems. The use
of these models has become central to the
O u r
G l o b a l
F u t u r e
Diagrams can be used to illustrate the main elements in
a model. These show the logic or reasoning behind
climate, ecology or land change models. Diagram
models are often used by geographers to help explain
how different elements are linked together and how
they interact. They are a useful visual planning tool
when developing software to process data on spatial
phenomena. A number of diagrammatic models have
been used throughout this textbook to help explain
geographical patterns and processes.
Activities
1. Compare and contrast the methods and
usefulness of direct observation and remote
sensing.
2. Describe three types of remote sensing and
comment on the value of each method.
3. With reference to the following website
http://remotesensing.usgs.gov/gallery/ select
change over time and find examples that show
changes in agricultural, mining and urban land
cover. Using one example of each type of land
cover draw sketch maps to show the change and
briefly describe the change illustrated in each
example.
4. Explain the concept of geographical modelling
and give examples of spatial modelling that
projects changes in land cover.
An overview of environmental change ­ Chapter 1
Page 41