CHAPTER 9
REVIEW QUESTIONS
9.1
Climate and geography.
9.2
Both have tall trees and thus provide a variety of habitats for organisms. The taiga, however, is
found in colder drier locations than temperate deciduous forests, with a rainfall of 35–40 cm
per year. Since evaporation rate is low in these regions, the soil remains very wet and is acidic.
The temperate deciduous forests require annual rainfalls of about 100 cm, with distinct
seasons. These forests show vertical stratification, and ground growth is more limited, due to
the shade of the canopy, than that of the taiga.
9.3
Rainforest. This is a very closed environment, the massive canopy maintaining a high humidity
which allows rapid breakdown of dead material and thus recycling of nutrients. The number
and variety of trees provide a great number of different habitats for other organisms, thus
biodiversity is very high.
9.4
Each stratum of the forest has different environmental conditions which support different life
forms.
9.5
Wind, tides and the rotation of the earth on its axis.
9.6
Western warm temperate, warm temperate, eastern warm temperate, tropical, and cool
temperate. Because of the temperature of the prevailing ocean currents in these areas and the
types and amounts of nutrients they carry, there are some differences in the types of organisms
found in each zone. This is particularly noticeable in the types of algae, molluscs and
echinoderms found in each zone.
9.7
These animals use energy to secrete excess salt from their bodies.
9.8
Sea water is very buoyant, thus supporting the organisms so that they do not need a very large
skeletal system.
9.9
A large amount of light is absorbed by sea water in the upper layers, limiting visual ability.
9.10
In warm regions, surface waters are moved by the prevailing winds, and the deeper water, rich
in nutrients and dissolved oxygen, is ‘pulled’ to the surface to replace it. The upward
movement of this deep water is called an upwelling.
9.11
Plankton are free-floating organisms, nekton are free swimmers (e.g. fish, turtles and seals) and
benthos are bottom-dwellers.
9.12
Littoral is where the land meets the sea, and is an area subject to tidal variation and thus
variation in temperature, water coverage and exposure to prevailing terrestrial conditions. The
neritic zone is the shallow coastal water associated with the continental shelves. Due to the
action of tides, waves and winds this zone is rich in dissolved oxygen and nutrients but is
subject to variations in temperature (shallow) and salinity (freshwater outflow from land and/or
evaporation). The abyssal zone is the deep water zone, which, although more stable than the
other zones, is mostly devoid of light and thus algae.
9.13
With respect to the littoral zone, the horizontal zonation refers to the different types of
organisms found at different distances from the low tide mark. These zones reflect the
adaptations of the organisms found in them to withstand particular degrees of exposure to air.
Vertical zonation can also be found at any point in the horizontal zonation. Because of the
topography of the area, some parts of the habitat a distance from low tide may contain rock
pools and other areas which protect them from the desiccating effect of tidal exposure. Thus
organisms normally found closer to low tide may be found higher up the shore line.
9.14
In some organisms the outer covering is impermeable, or reduces permeability to water (e.g.
cuticle, scales and/or a covering of mucus) and helps conserve body salts; gills may actively
absorb salts in the water; the presence of an excretory system which conserves salts and
releases large amounts of very dilute urine.
9.15
Both are environments with fresh water and thus a low salt concentration and both are subject
to variations in temperature and permanence (dependent on rainfall). In the rapidly flowing
stream, dissolved oxygen is high and the water is usually shallow and thus allows good light
penetration. The movement of the water prevents accumulation of silt and the bottom is firm
and rocky, providing few habitats for organisms. In a large permanent pond, there is little
movement of water and so dissolved oxygen is not as high as in a stream. Light penetration is
limited to the upper zones and edges of the pond and the surface water temperatures are higher
than in deep water. The bottom is usually soft mud or sand.
9.16
Because ponds are isolated from other water systems they are discontinuous and the organisms
living in them can not move from pond to pond. In these systems the inputs and outputs are
balanced.
9.17
Unfavourable factors: very variable temperatures (adaptations to specific temperature ranges);
lack of bouyancy (need for structural support, and animals need a means of locomotion; few
floating forms); scarcity of water (limits range of plants and animals; need for adaptations to
prevent water loss, for internal gas exchange surfaces and fertilisation, and for protection of
the developing young).
Favourable factors: plentiful oxygen supply (animals can maintain high metabolic rate and thus
level of activity); air is transparent (allows good light penetration and high rate of
photosynthesis; visual perception in animals); low viscosity of air (greater variation of shape,
sound production); greater variety of habitats (greater diversity of form and requirements).
9.18
Aridity of the continent with zones of decreasing moisture from the coast to the dry interior;
isolation from other continents; low fertility soils.
9.19
Abiotic: high rainfall with no seasonal drought; humid; soils fertile (or in which there is rapid
decomposition) and water retentive; fire-free.
Biotic: Large number of decomposer (fungi and bacteria) ensure rapid decomposition and thus
nutrient recycling; presence of mycorrhizae; vertical stratification of the forest with high plant
species diversity provides a multitude of habitats for animals with different niches.
9.20
A ‘closed forest’ refers to the fact that the leafy part of the tree (canopy) of each tree merges
with those adjacent to it, limiting the light which penetrates the forest. Thus plants growing on
the forest floor (mosses and ferns, etc.) are adapted to low light intensities. Vines and creepers
have adaptations which allow them to cling to, and ‘climb’ up the trunks of trees to reach the
sunlight and there is a profusion of epiphytes which use the trees as a base instead of the
ground, to procure adequate light.
9.21
Tropical rainforest: found in northern Queensland. Trees tend to be straight stemmed and
slender with plank buttresses on larger trees; leaves large, thin and smooth edged and may
have a ‘drip tip’; cauliflory common; lianes and epiphytes abundant; strangler figs present.
Sub-tropical rainforest: central and southern coastal Queensland; Northern NSW. Compared
with the tropical rainforest, plant species diversity is reduced; smaller leaves; fewer lianes and
epiphytes; cauliflory generally absent; fewer species with buttress and stilt roots.
Temperate rainforest: found in the McPherson Ranges (Queensland) and Tasmania. In these
forests buttressing, cauliflory and lianes are absent; fewer tree species; leaves are smaller and
often have serrated edges; mosses and lichen are prominent.
9.22
Dry sclerophyll forest: trees, mostly eucalypts, tall and widely spaced with few shrubs and
ferns.
Savannah woodland: scattered low trees; grasses cover the ground.
Desert: no trees; scarce covering of bunch grasses such as spinifex; flowering ephemerals
present.
9.23
Community boundaries are not fixed and many species can be found utilising more than one
boundary if they have adaptations to allow this. Thus mangroves, which are facultative
halophytes, can live in both saline, semi-saline and freshwater areas.
9.24
Mangroves are usually found in tropical and sub-tropical coasts (with their associated
temperature and rainfall ranges) where there are quiet tidal waters, areas of silt build-up around
the mouths of fresh water outflows or swampy areas inundated with tides. They live in poorly
drained, anoxic, saline soils which are usually fine grained.
9.25
a.
b.
c.
High salt content: higher internal salt concentration than terrestrial trees; storage of salt in
old leaves; salt exclusion system of roots or salt excretion by glands in the leaf.
Low oxygen soils: aerial roots and pneumatophores.
Unstable soils: extensive, shallow roots; adventitious roots; stilt roots; meandering
buttress roots.
9.26
Random sampling implies that each measurement has an equal chance of being selected as part
of the sample.
9.27
A single measurement could be far from the average value.
9.28
a.
b.
c.
d.
9.29
A belt transect is a strip of the terrain of a particular width and length from which the species
under study are counted, whereas in a line transect only the species which intersect the length
of a single line are recorded.
9.30
a.
b.
9.31
In shrubs and trees: beater net.
In grass: sweep net.
Flying in air: kite net; stun trap.
In litter: pitfall trap or extract using a Tullgren funnel.
Small insects: aspiration bottle.
Soil corer.
pH meter or indicators.
Sample weighed, burnt then reweighed.
Light meter.
p = Mn/R = (55 × 75)/35 = 118
100 × 100 m = 10,000 m2
thus population density = 118/10,000m2
 1/100m2