Distinguish, using examples, between the processes of succession and zonation.

Explain the relationship between ecosystem stability, diversity and succession.

Discuss the relationship between social systems and food production systems with the help of named examples.

succession is the (orderly) process of change over time in a community;
changes in the community of organisms frequently cause changes in the physical environment that allow another community to become established and replace the former through competition;
zonation is the arrangement/patterning of communities/ecosystems into zones over distance/space (due to a change in an environmental factor);
in succession biotic changes lead to changes in abiotic conditions while in zonation changes in abiotic conditions lead to changes in biotic composition;
an example of succession is formation of sand dunes / community formation after volcanic eruptions / wildfires and an example of zonation is biomes on a global scale / changes in communities with altitude on a mountain / changes in communities associated with tidelines;

[1] available for example of succession and zonation

[4 max]

ecosystem stability refers to the resilience of the system (and its tendency to avoid tipping points), and its ability to maintain stability;
a complex ecosystem, with the variety of nutrient and energy pathways it provides contributes to its stability;
habitat diversity is associated with high levels of species diversity / high levels of species diversity are associated with high levels of genetic diversity;
a steady state equilibrium allows for the maintenance of a high level of genetic diversity through constant population sizes;
high levels of biodiversity (habitat, species and genetic diversity) are intrinsically linked with ecosystem stability;
during the initial stages of colonisation, biodiversity increases greatly but then stabilizes / a climax community is more diverse and thus stable than the earlier stages of succession;
during earlier stages of succession, the communities can become diverted due to human interference (when the system has less resilience);
ecosystems that have evolved over long periods of time can reach a steady state condition, withstanding disturbances;
an ecosystem’s capacity to survive change may depend on diversity (resilience and inertia);
a climax community (with simple nutrient and energy pathways) in a tundra biome may be less resistant to change (resilient) than a climax community (with complex nutrient and energy pathways) in a tropical rainforest;

[6 max]

Guidance to examiners: Social systems refer to the inter-relationships between individuals, groups and organisations. Reference to social systems may make either implicit or explicit references to economic systems. This is acceptable.

MEDCs
tend to have more intensive food production systems;
rely upon (and build) infrastructure to support intensive food production systems;
centralise processing facilities;
subsidise food production systems;
e.g European common agriculture policy / US subsidised corn production
e.g locked-in production deals between supermarkets and producers in UK
e.g overwintering farm animals indoors to reduce stress on land / to utilise summer production of feed
e.g one abattoir used for most animal slaughter in US

LEDCS
are usually more varied and range from intensive systems (such as rice farming)
to subsistence farming (including slash and burn systems);
some have evolved over thousands of years to integrate local geography;
more likely to remain tied to historic cultural systems;
farmers more vulnerable to economic and meteorological fluctuations;
e.g rice-fish farming in Vietnam evolved to exploit local weather conditions
e.g low scale slash and burn systems in Brazil threatened by encroachment by intensive farming
e.g farmers in north India committing suicide as a result of droughts

General
many farming systems are based on a capitalist model which is not always dependant on the development of the country;
the social system of the country is not always the key determinant of the food production system;
other factors that may influence the food production system include the population density / soil fertility / access to appropriate technology / influence of political and other institutions;

Award [1] for naming at least one food production system. For each food production system identified, award [1] for a description of it, up to a maximum of [3]. Award [1 max] for an explicit and valid conclusion.

Note to examiners: An isolated statement e.g “developed countries have intensive food production systems” or an unjustified opinion e.g “I think developed countries have the best food production” should not be considered as a valid conclusion. The conclusion must be supported/justified by points raised that must have at least addressed both sides of the argument. A valid conclusion may, however, be stated within the body of the response rather than at the end, and may involve some balanced decision.

[8 max]

Candidates could define succession and zonation correctly and most gave a reasonable example of each. Many candidates did not attempt to distinguish between the two concepts.

The candidates found the definitions of each concept fairly easy to write. However explaining the relationship proved to be much harder, many answers interchanged the concepts in repeated sentences without clearly demonstrating an explanation. Diversity and succession seemed to be easier for more candidate to explain, stability caused more confusion.

The concept of a social system seemed to confuse candidates, but most managed to mention some social systems such as LEDC and MEDC. The markscheme allowed for a wide range of interpretations of the term “social system”. Many candidates wrote about contrasting food production systems without really mentioning the social systems involved. This question was poorly answered by many of the candidates.