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Questions may appear in the exam
Why is loam soil the best soil for plant growth?
Loam soil has a good balance of sand and clay without the negative qualities
.
The negative qualities of clay are that it is prone to waterlogging whereas loam has good drainage
Loam is stable and not prone to wind erosion, retains moisture and nutrients unlike sand
Loam allows for easy root penetration and good aeration allowing oxygen to the roots unlike clay.
Define carrying capacity?
Carrying capacity is the maximum number of a species or "load" that can be sustainably supported by a given environment
Why is carrying capacity is difficult to measure?
There are many different potential limiting factors for natural populations
The population's needs may alter over time due to genetic changes and evolution
Environmental conditions may change, e.g climate change, introduced species
It takes extensive and long term studies to identify a precise relationship between a species and given environmental factors
How do you calculate an ecological footprint?
The ecological footprint of the population is the area of land that would be required to provide all of the population’s resources and assimilate all of its wastes. It can be useful as a model to provide a quantitative estimate of human carrying capacity, and is measured in global hectares (gha). It is calculated by dividing the amount of material consumed by a person (tonnes per year) by the yield of the specific area (annual tonnes per hectare) from which it was harvested, or where waste material was absorbed. The number of hectares from the calculation are then converted to global hectares using yield and equivalence factors.
Why is it said that vegetarians have a smaller ecological footprint?
Vegetarians only eat plants/ plants are producers which are at a lower trophic level than animals. This means there is less energy lost and greater efficiency of energy transfer. There is less land and water required to provide food for vegetarians. There is less carbon dioxide and methane from plant production whereas there is from the farming of meat.
Food wastage increases a countries ecological footprint. Outline the reasons for food wastage in wealthy and less-wealthy countries.
In LEDCs, food wastage occurs primarily at the farmer/producer end of the supply chain. This is due to inefficient harvesting, inadequate local transportation and poor infrastructure. Food is often stored in unsuitable conditions, and is destroyed by mould and pets, and food can also be damaged during transportation over poorly maintained roads.
In wealthy countries, food wastage is largely due to excess wealth, consumerism and mass marketing. In MEDCs like the UK, one third of food is simply thrown away. Similarly, in supermarkets, entire crops of fruit and vegetables may be rejected and wasted because they do not meet “consumer expectations” in terms of characteristics like shape and size (not edibility).
Research the stages of succession of an ecosystem that has been disturbed by fire. Describe the difference between a pioneer community and a climax community.
Research the stages of succession of an ecosystem that has been disturbed by fire. Describe the difference between a pioneer community and a climax community.
An ecosystem affected by fire is an example of secondary succession in that the process is started by an event that reduces an established ecosystem to a smaller population of species, and occurs on pre-existing soil.
An area of growth
A disturbance (fire) starts
The fire destroys the vegetation
The fire leaves behind empty, but not destroyed soil
Grasses and other herbaceous plants grow back first
Small bushes and trees begin to colonise the public area
Fast-growing evergreen trees and bamboo trees develop to their fullest, while shade tolerant trees develop underneath
The short-lived and shade-intolerant evergreen trees die as the larger deciduous trees grow overhead. The ecosystem is now at a similar state as to where it began.
Secondary succession occurs in places where organisms had lived before
Outline reasons why species in a pioneer community are more likely to be r-strategists than k-strategists
Species in a pioneer community are more likely to be r-strategists because of their ability to reproduce rapidly and expand their population by having many offspring. These species can get through their lifecycle quickly and are generally small in size. However, r-strategists cannot compete in later stages of succession. Examples of r-strategists are mice, rabbits and bacteria.
Outline reasons why the climax community is more stable than an intermediate community
There is a greater number of species/habitats/ ecological niches and genetic diversity in climax communities
Gross productivity and stored biomass is higher in climax communities
There are more complex and diverse energy pathways and food webs in climax communities
There is more established nutrient cycling
There is more favourable abiotic conditions and soil properties
More established negative feedback mechanisms
What differences in soil quality might there be in a pioneer community compared to a climax community?
In a pioneer community, soil will be extremely simple and in some cases even non-existent, as the first steps of soil formation may begin with a pioneer community. Over time, more complex plants/root systems and organisms will improve the soil by bringing more nutrients and protecting soil from natural elements.
What is the difference between zonation and succession?
SUCCESSION = is the process of changes in a community or ecosystem over time
ZONATION = is the process of changes over an environmental gradient or space.
How might a food web change as a result of succession?
There may be an increasing number of trophic levels and longer food chains.
The food webs may be composed of new or different species.
There may be more branching/greater complexity and different amounts of energy transferred at each trophic level.
More biomass may be stored at each trophic level.
There may be an increased prominence of decomposers present
Describe how the addition of
sand to loam
Positive effects
It will increase drainage and prevent water logging
It will increase infiltration and permeability which will reduce the loss of water due to run off.
It will increase porosity/airspaces and reduce soil compaction providing more oxygen to roots.
It would allow for increase flow and availability of nutrients
It will promote decomposers to survive and multiply increases the availability of nutrients.
It will allow for easier root penetration
Negative effects
It will reduce the water holding capacity so less water for plants
It will increase the possibility of leaching and reduce the amount of minerals available for plants
It will reduce the stability of soil giving less anchorage to plants
Besides hydroelectricity, identify one form of natural income that can be derived from damming rivers
Fishing and irrigation. Many dams that are used for hydroelectricity are also used for these two other reasons to use the dam to its full potential
Outline 3 conservation strategies that could reduce soil erosion
Improved irrigation techniques- for example covering irrigation canals will prevent evaporation before the water reaches the land or trickle flow irrigation, a system consists network of pipes so the water comes out drop wise and can be taken in by the roots before it evaporates.
Wind reduction- by planting trees as wind breaks or by alternating low and high crops
Addition of soil conditioners which will increase pH and counter soil acidification. For example, limestone will help clay particles to stick together and act like sand, which make larger particles created more free draining than raw clay and trap more air, improve the decomposition by soil
If provided with a soil profile diagram state one
Transfer of matter
Infiltration of water
Leaching of nutrients
Transformation process
Nitrogen fixation
Dissolving of inorganic salts
Composition of plant material
Example of one output to the atmosphere
Release of nitrogen gas by denitrifying bacteria
Release of carbon dioxide
Evaporation of water
Provide two reasons
for
and 2 reasons
against
aquaculture
Reason for aquaculture
More economically efficient and profitable
Increased food demand due to increasing population numbers
Reasons against aquaculture
Escaped fish may impact wild stock through genetic degradation/ disease/competition
High density population lead to more disease
What reasons may there be for differences in fish yields from aquaculture and wild fish populations?
Wild yield may be limited due to overfishing or unsustainable harvesting techniques
There may be stricter regulations on wild fishing activity
Farming yield may be increased due to increasing demand from growing human population or improved technological developments such as sonar in fishing ships which can detect schools of fish.
What integrated aquaculture and why this system may have fewer environmental impacts than fish farms only?
Integrated aquaculture is the concurrent or sequential linkage between two or more farm activities of which at least one is aquaculture.
MAIN OBJECTIVE
This system can cause a few environmental issues in the ecosystem as the fragmentation could cause segregation in the ecosystem, there can also be a chance of fishes escaping into the local ecosystem ad becoming an invasive species
Outline two environmental impacts of the growth of aquaculture.
Eutrophication of the water from fish waste
Genetic degradation of wild populations from aquaculture fish ‘escapees’
Depletion of water bodies to construct the aquaculture farms/habitat loss/disturbance of ecosystems
Outline two differences and two similarities regarding how humans exploit terrestrial and aquatic food sources.
Differences
most food grown is taken from producers eg wheat, rice
easier to increase productivity by additions of fertilizers
more extensive range of organisms are farmed
selective breeding is undertaken to improve the yield of both plants and animals. Selective breeding of terrestrial food sources has been undertaken over thousands of years
Similarities
Both systems are exploited at most trophic levels
Both systems can exploit herbivores which can feed on indigestible (to humans) cellulose
eg in grass cannot be digested by humans but can be digested by the bacteria in the gut of herbivores.
Both farmed and ;’wild’ food can be obtained from both systems
When a new dam is proposed an Environmental Impact Statement(EIS) must be prepared. Describe the stages involved in an EIS.
Step 1
Inflation of scoping
Mandatory
Voluntary
Step 2
Information needed for scoping
Location
Technical capacity
Likely impacts
Step 3
Scoping consultant
Other interested parties
General public
Environmental local and regional authorities
Step 4
Scoping outputs: Scoping Opinion/ Report