Outline one climatic and one edaphic (soil) factor which affect the final climax community in an ecosystem.

Explain two examples of soil degradation and the appropriate soil management strategies from a named farming system.

Evaluate the impact of economic development on the ecological footprint of a human population.

Please note: although "quality of expression" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.

Climatic:
amount of precipitation / insolation / (mean) temperature;
limit primary productivity/rate of photosynthesis that will determine the available biomass/food base/on which climax community will depend;

Edaphic:
soil depth / mineral content/amount of N/P/K / soil compaction/aeration / soil particle size / balance between clay, silt and sand / percolation rate / soil pH;
determine the particular vegetation types/plant species adapted to those conditions that support the climax community. 

Award up to [2 max] for climatic factor and up to [2 max] for edaphic factor.

[4 max]

Please note: although "quality of expression" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.

Named farming system: e.g. intensive corn (Zea mais) farming in Mid-West of USA;

Degradation (Deg) + Strategy (Strat): soil compaction managed by addition of organicmatter/manure / reduced tillage;

Deg: compaction leads to reduced drainage/oxygen levels in soil which reduces ability of roots/crop to grow (and support crop);
Strat: organic matter enhances the soil ecosystem which helps aerate soil / reduced tillage allows soil ecosystem to recover and aerate soil;

Deg + Strat: toxification of soil managed by reduced use of inorganic fertilisers/pesticides / bioremediation;

Deg: excess use of liquid ammonia/fertilisers / pesticides can reduce range of soil microorganisms able to live;
Strat: reduced use of chemical additives allows soil ecosystem to recover and provide ecosystem service of nitrogen fixation;

Deg + Strat: acidification of soil managed by addition of lime;

Deg: acid precipitation in areas with soils that are naturally acidic, can quickly acidify the soil beyond normal levels;
Strat: lime neutralises the acid pH of the soil;

Deg + Strat: waterlogging of soil managed by addition of organic matter/sand/drainage systems;

Deg: reduced organic content through over-harvesting / elevated water table through over-irrigation / lack of use of organic fertilisers;
Strat: improve soil drainage through addition of organic matter/drainage ditches/sub-surface pipes;

Deg + Strat: soil runoff/erosion managed by maintained plant cover all year / reduced grazing / wind breaks/stone walls / contour terracing/ploughing;

Deg: caused by soil compaction / overgrazing / leaving land bare means soil may blow away in wind or wash away with rain;
Strat: plant cover/reduced grazing/windbreaks/contour ploughing reduces ability of wind/rain to erode soil. 

For each of two examples award [1 max] for named degradation and appropriately linked strategy; 1 mark for development of degradation i.e. its cause/effect; and 1 mark for development of management strategy i.e. how it works:

Award [5 max] if no named farming system.
Award [3 max] if no explanations.

[6 max]

Please note: although "quality of expression" marking is no longer used in exams, this question from a past syllabus may still be useful for student practice.

Increasing Ecological Footprint (EF):
equation I = PAT (Impact = Population × Affluence × Technology) predicts that increasing economic development (affluence) will increase a population’s impact on the environment/ecological footprint;
economic development (ED) may increase the use of resources/desire for material goods and thus increase the EF of a population;
as demand for power from electricity, if electricity generation is from fossil fuels or nuclear power, EF will increase (due to area needed for waste assimilation);
as population becomes richer meat consumption usually increases, (increasing the area of land needed agriculture), increasing EF;
waste generation increases with increased consumption, increasing EF;

Decreasing EF:
ED may mean a move to renewable energy production (decarbonised society) (reducing need for land to assimilate waste);
ED may increase use of technology to reduce waste production / increase energy efficiency, decreasing EF;
ED may increase education level of population about environmental problems leading to a reduced EF;
ED may slow or decrease population growth and thus reduce impact of population on EF;
ED normally associated with increasing urbanisation which leads to greater efficiency of the population, thus reducing EF;
Countries with strong cultural/religious/ecocentric values may be more likely to regulate their ED to reducing/restricting EF. 

Conclusion should be a clear statement of effect of ED on EF that is supported by evidence given in response.

e.g. generally ED leads to an increase in EF but this can be dependent on geographical location/cultural/religious background e.g. simple lifestyles / predominantly vegetarian diets;
ED has often lead to increasing EF in the short term, but as EVS are shifting / alternative technologies are available there may well be a longer term reduction in EF.

Conclusion should be a clear statement of effect of ED on EF with supporting statements.

Award [7 max] if no clear conclusion regarding relative strengths or weaknesses.
Award [5 max] if only strengths or limitations discussed.
Award [3 max] if EF is not explicitly discussed.

[8 max]

Expression of ideas [2 max]

Was rarely answered well, candidates were able to identify a climatic factor, but usually couldn’t elaborate or identify and edaphic one so clearly. The effect on the final climax community was often missing.

Candidates mostly got four points on this question, they usually identified one degradation example with a strategy, explanation was often lacking.

Candidates who answered this generally identified that increased economic development led to more resource consumption, and sometimes they would link it to consumption of meat. Another marking point they would occasionally earn was that increased economic development could reduce footprint with technology. After these points, very little was clearly identified. Even those candidates who successfully answered the question often missed out a conclusion.