Chapter 6
Humans in the Biosphere
Weekend Homework
• Read Pages 138 – 143
• Do questions 1-4 on pg 143
• This will go into your Logbook (part 2)
Videos for PJ Day!
• We’ll start this unit off with a couple of videos
– Take notes while you watch
• Human Pre-History 101: Agriculture Rocks our
World (7:00)
– https://www.youtube.com/watch?v=IVHD9wGlbho
• Crash Course Ecology: Human Impacts on the
Environment (10:38)
– https://www.youtube.com/watch?v=5eTCZ9L834s&in
dex=10&list=PL8dPuuaLjXtNdTKZkV_GiIYXpV9w4Wxb
X
Unit Exam Coming Up!
• Next Friday will be our Unit Exam on all of
Unit 2: Ecological Organization in the
Biosphere
– Chapters 3-6
• We’ll finish up Chapter 6 (a review chapter) by
Wed, Thursday will be a review period
• Start reviewing now…
Earth as an Island
• Planet Earth is a closed population, similar to
a remote island.
• All humans and other organisms share a
limited resource base that they depend on for
their long-term survival.
• Understanding how humans interact with the
biosphere is important to protect these critical
resources.
Human Activities
• As a species, we depend on food webs and
biogeochemical cycles.
• Ecosystems provide a range of ecosystem
services that provide breathable air, drinkable
water, fertile soil, as well as storage and
recycling nutrients, pollinating our food crops,
and regulating the climate.
Human Activities
• Since we depending on these services for our
survival, it’s important to understand how we
change local and global environments.
• As a species, we use as much energy, and
transport as much material, as all Earth’s other
multicellular species combined! We are the most
important source of environmental change on
the planet.
• Some of the most important activities that affect
the environment are hunting & gathering,
agriculture, industry, and urban development.
Hunting & Gathering
• For must of human history, humans got their
food through hunting and gathering.
• Hunted birds, mammals, and fishing in lakes
and rivers
• Gathering wild seeds, fruits, and nuts.
Hunters & Gatherers
• These early hunters changed their
environment – about 12000 years ago caused
a mass extinction of animals in North
America.
• Among the animals that disappeared from the
continent or became extinct worldwide
include woolly mammoths, giant ground
sloths, sabre tooth tigers, as well as cheetahs,
zebras, and yaks.
Hunters & Gatherers Today
• Some groups of people around the world still
follow a hunter-gatherer lifestyle, at least
some of the time. These hunters have
relatively little impact on the environment,
but today most use some form of technology,
such as manufactured tools, guns, and
snowmobiles.
Agriculture
• Over time hunter-gatherers learned which
plants were useful for food and medicines.
Around the end of the last ice age, about
11000 years ago, humans began planting and
cultivating some of those plants, including
wheat, rice, and potatoes.
Agriculture
• They also started domesticating animals for
food or other uses, such as sheep, goats,
cows, pigs, as well as dogs and horses.
• Agriculture was a major development in
human history – it provided a stable and
predictable food supply, allowing larger, stable
settlements, and the development of
governments, laws, and writing.
Changes in Agriculture
• Farmers acquired tools and basic machinery
such as plows and seed drills
• Exploration of the world caused an exchange
of crops around the world
– Potatoes and squash from the Americas were
brought to Europe
– Rice from Asia was brought to the Americas and
to Europe
Advances in the 1800s & 1900s
– Irrigation in dry areas such as the western US and
Canada made them much more productive
– Improved machinery for plowing, planting, and
harvesting made it more efficient
– Scientists developed new crops with higher yields.
These crops were often planted as monocultures,
where very large fields were planted with a single
crop over and over
– Synthetic fertilizers and pesticides helped increase
yields and reduce losses to pests
Green Revolution
• The Green Revolution – middle of Twentieth
Century
– Despite advances in agriculture, there were food
shortages in many parts of the world
– Governments & scientists worked to increase food
production in these regions:
• Miracle strains of wheat and rice were developed and
shared
• Modern techniques such as monocultures, technology, and
synthetic fertilizers were introduced to these regions
Green Revolution
• These efforts greatly increased the world’s
food supply and nutrition
– Wheat production in Mexico increased by 10
times in 20 years.
– India and China produced enough food to feed
their growing populations
– Global food production doubled over 50 years
Future Challenges
• Modern agriculture has produced ecological
issues
– Large-scale monocultures can lead to problems with
insect pests and disease
– Chemical pesticides can damage beneficial insects,
contaminate water supplies, and accumulate in the
environment
– Irrigation requires a large amount of water, which can
cause issues
• A major portion of food production is dependent on
irrigation
• This irrigation can contribute to drying up natural aquifers
Future Challenges
• We need to find ways to maintain the benefits
of modern agriculture, which reducing these
ecological consequences
Industrial Growth &
Urban Development
• Industrial Revolution - new machines and
factories to increase industrial development
– Lead to most of the conveniences of modern life,
including our homes, clothes, electronic devices, cars,
farm machinery. This has lead to major increases in
our standard of living.
– All of these advances require energy, primarily from
fossil fuels
– Increased pollution: wastes from cities, agriculture,
and industries pollute the air, water, and soil.
Industrial Growth &
Urban Development
• Crowded urban centres lead to people moving
to the suburbs, causing cities to spread and
replace farmland and natural ecosystems,
plus increased pollution from commuters
• How can we control the harmful effects of
human activity, while preserving our standard
of living, and improving the standard of living
in impoverished parts of the world?
Tragedy of the Commons
• Tragedy of the Commons – when a resource
(grazing lands, ground water for irrigation, fish
in the ocean, etc), is unregulated and anyone
can use it, it often becomes destroyed because
no-one is responsible for it.
Classifying Resources
• Environmental goods and services can be
classified as either renewable or non-renewable.
• Renewable resources can regenerate – living
things and non-living resources that are
replenished by biogeochemical cycles. However
they are still not unlimited.
– Examples: Trees, grazing lands, fresh water,
populations of animals
• Nonrenewable resources cannot be replenished
by natural processes.
– Examples: Fossil fuels (coal, oil, natural gas)
Sustainability
“We do not inherit the earth from our ancestors;
we borrow it from our children”
– Moses Henry Cass
A short video to Introduce Sustainability
https://www.youtube.com/watch?v=B5NiTN0ch
j0
2 Definitions of Sustainability
• Improving the quality of human life while
living within the carrying capacity of
supporting ecosystems
• The capacity of our human society to continue
indefinitely within the natural cycles of the
earth.
Seven Generations
• Seven Generations Concept: an ecological
concept that urges the current generation of
humans to live sustainably and work for the
benefit of the seventh generation (about 140
years) into the future.
• This idea comes from Iroquois teachings:
Chief Oren Lyons of the Onondaga Nation has
written that it is a responsibility of chiefs to
“make every decision that we make relate to the
welfare and well-being of the seventh generation
to come”
How can we be sustainable?
4 Basic Care Instructions for our Planet –
developed by scientists in Sweden
– Reduce our dependence on fossil fuels and heavy
metals
– Reduce our dependence on synthetic chemicals
that persist in nature
– Reduce our destruction of nature
– Ensure we are not stopping people globally from
meeting their basic needs
What about Sustainable
Development?
• Sustainable Development:
Development that meets the needs of the
present without compromising the ability of
future generations to meet their own needs
Sustainability
• Sustainability explained with science:
• https://www.youtube.com/watch?v=beidaN3S
NdA
Land Resources
• Arable (farmable) land is required for
agriculture, but plowing and intensively
planting and/or grazing this land can lead to
soil erosion (up to 47 tons of topsoil lost per
hectare, every year) and desertification.
Sustainable Techniques
• contour plowing (using the shape of the land
to reduce erosion), no-till farming (leaving
stems and roots of the previous crop in place
to hold the soil), and planting winter crops like
rye to reduce erosion in the offseason.
Forest Resources
• Living forests act as the lungs of the Earth,
cleaning the air, taking up carbon dioxide, and
producing oxygen. They also store nutrients,
provide habitats, moderate climate, limit soil
erosion, and protect freshwater supplies.
Deforestation, partially or completely
removing these trees from an area, has huge
negative effects on all of these systems.
Forest Resources
• Since trees can be replanted after they are cut
down, forestry products are often considered
renewable. However, harvesting trees also
reduces the biodiversity of the forest
ecosystem, and makes it less resilient to
disturbances.
Negative Affects of Harvesting Trees
• Negatively affects the organisms that depend
on those trees for food and habitat
• Succession takes a long time to replenish
those habitats
• Usually replanting projects only replace 1 or
very few species of trees, regardless of how
many species were harvested from the area
• While the trees are gone, soil is no longer held
in place, so erosion can occur quickly
The Pine Plantation
Community Tree Planting
The Forest Regenerating
Old Growth Forests
• Old growth forests are forests that have never been
cut, they are the most important to preserve in
terms of their ecosystem value and services. They are
often home to a rich diversity of species, which will
be lost if these trees are cut.
Sustainable Practices
• Selective harvesting of a
few mature trees from
throughout the forest can
promote succession and
the growth of younger
trees, while leaving most
of the ecosystem intact.
Sustainable Forestry Practices
• Focussing harvesting on tree farms that have
already been cut and are regularly replanted,
while preserving old growth forests. New fastgrowing varieties of trees can help to make
these tree farms a truly renewable resource.
Fishery Resources
• Fish and other marine species are a source of
food for human communities. However fisheries
(fishing grounds) are often an example of a
tragedy of the commons.
• People from different provinces, states, and
countries often harvest from the same fishery,
viewing it as a renewable resource that could be
harvested indefinitely, but this use has been
largely unregulated, so overfishing (harvesting
fish faster than they can replenish the
population) has been common, leading to major
declines on species like Cod and Haddock.
Quick Video
• https://www.youtube.com/watch?v=pygNPwc
cgGM#t=11 (2:20)
Cod in Newfoundland
• In 1497 English Explorer John Cabot was
amazed at the incredible number of cod off
Newfoundland
– Could lower a basket into the water and it would
fill with fish!
• Until the late 1950s, 250,000 tons of cod were
caught annually.
Cod in Newfoundland
• In the 50s, large factory vessels from other countries
began catching huge about of cod and other fish in
giant nets
– In 1968 the annual catch increased to
800,000 tons
• At this rate the Cod could not renew their numbers
– By 1975 the annual catch declined to 300,000 tons
• Canada increased their jurisdiction farther off the
coast, which decreased the involvement by other
countries
– catches continued to decline to 139,000 tons in 1978
– At this rate the fisheries might have recovered
Cod in Newfoundland
• Canadian factory ships began replacing the
foreign ones, and by 1984 they were bringing in
harvests of 250,000
– This stopped any recovery of the fisheries
• Draggers (bottom trawlers) were used to increase
the catch rate
– Technology which dropped huge nets dragged along
the bottom of the ocean, picking up everything in its
path – lots of “bycatch”
– Destroys the ecosystem, kills young fish, spawning
fish, and the food source for the cod
Bottom Trawling (Dragging)
Cod in Newfoundland
• In 1988 the scientific community
recommended that the allowable catch be cut
in half, but no action was taken
• In 1992 the Canadian Minister of Fisheries and
Oceans has to impose a complete ban on
fishing the Northern Cod
– The cod fishery had completely collapsed
Cod in Newfoundland
• For over 400 years the cod fishery had been
one of the richest in the world
• By 1992 it was almost completely eliminated
• Over 42,000 people in the fishing industry
were put out of work
• Department of Fisheries estimated that it
would take a least 15 years with absolutely no
fishing, before the fishery was at a reasonable
level again
Global Fishery Statistics
• 52% of fish stocks are fully exploited
(max capacity)
• 20% are moderately exploited
• 17% are overexploited
• 7% are depleted
• 1% is recovering from depletion
Aquaculture
• Aquaculture (fish farms for human
consumption) is one option to reduce the
stress on natural fisheries, however it can also
cause water pollution due to the use of
chemicals to improve production, and
antibiotics to reduce disease (remember
antibiotic resistance?)
• Some new forms of aquaculture are being
developed to try to reduce these issues.
Sustainable Fisheries
• Using ecological data on fish populations to
produce regulations and guidelines for
commercial fishing can lead to much more
sustainable fishing industries.
• These guidelines regulate the number and size
(age) of fish that can be caught, and which
regions can be harvested at particular times of
year to allow for mating to occur naturally.
Air Resources
• We require air to breathe every second of our
lives. The quality of this air has major impacts
on our health, and on the health of
ecosystems. Pollutants are any harmful
materials that enter the biosphere through
the land, water, or air.
Air Resources
• Smog is a mixture of chemicals in a greybrown haze in the atmosphere over a city or
industrial centre.
– Largely due to exhaust from vehicles and
industrial emissions
– Has major effects on people with respiratory
problems such as asthma
Smog
Air Resources
• Particulate pollution – fine particles of ash
and dust that are inhaled and cause major
health problems
– Caused by the burning of fossil fuels & wood
– A major problem in regions where people cook
and heat their homes by burning wood or oil in
their home – lots of indoor air pollution
Air Resources
• Nitrates and Sulphates combine with water
vapour in the atmosphere to produce Acid
Rain
– Kills plants by damaging leaves and roots and
changing the pH of the soil
– Changes the pH of standing water ecosystems,
killing aquatic organisms
Sustainable Practices
• Automobile regulations and Clean Air
regulations have lead to reductions in air
pollution in North America and in Europe
– Many of these problems can be reduced through
technology that “scrubs” these particles and
chemicals out of emissions before they leave the
smokestack or tailpipe
• Air pollution from industry and home heating
and cooking is still a major problem in other
parts of the world
Water Resources
• While water is a renewable resource, the total
amount of water is limited, and the quality of
water must be preserved. Humans use water
for consumption, but much larger amounts
are used in agriculture and in industry.
Water Pollution
• Chemicals from industry and agriculture can enter
streams and rivers if not properly disposed of
• Wastes discarded on land (such as in landfills) can
seep into the ground and enter ground water
• Domestic Sewage (water from sinks and toilets)
– contains nitrates and phosphates which can lead to
algal blooms
– contains microorganisms that can spread disease
Sustainable Practices
• Most cities in North America and Europe now
treat their sewage before it enters the water
systems to remove disease-causing microbes
and reduce nitrates and phosphates
– However this does not happen all over the world
– sanitation is still a major issue
India’s Yamuna River
• More than 400 million gallons of sewage enters the
river from Delhi’s drains without passing through the
city’s treatment plants.
Sustainable Practices
• Reducing the use of
industrial and
agricultural chemicals,
and requiring strict
procedures for disposal
of harmful substances
so they don’t get into
the water sources
Sustainable Practices
• Protecting & restoring natural systems in the
water cycle such as wetlands that can help
purify water
Sustainable Practices
• Conserving water in homes, industry, and
agriculture helps reduce pressure on these
systems
– For example: drip irrigation to reduce water loss
through evaporation
Crash Course Pollution Video
• https://www.youtube.com/watch?v=kdDSRRC
KMiI (9:22)