About Tom Expertise I can answer most questions about ecological theory individuals, communities, and ecocsystems up to and including degree level. unfortunately I do not do maths so i cannot help on the mathematical side of population dynamics or genetics.
I am particularly interested in climate change and it's effects.
Experience Sixth form teacher and researcher.
Education/Credentials Honours degree in biological sciences specialising in ecology.
Question Why does the productivity of an ecosystem increase during the course of ecological succession?
Answer It doesnt necessarily
Thinking about a situation on land. Assume that we start from bare rock.
Initial conditions are harsh, exposed, little shelter, few resources, which are hard to get to. It’s a tough place to live. To begin with much of the efforts (and resources) of bodies are invested in simply staying alive (E.g. Stress Tolerators, Grimes). This is an efficient strategy in terms of survival and reproduction but an inefficient strategy in terms of productivity.
As conditions change through succession there is greater shelter and a greater variety of resources which are more readily available. This allows bodies to gather resources more effectively and to spend less effort and resources on protecting themselves from a harsh world. So productivity goes up.
So broadly speaking productivity increases along a succession.
However as conditions become less harsh and resources become more available the rewards for competing with your neighbour become greater, while at the same time the penalty for not competing becomes harsher. (e.g. if a plant is staved of light by a faster growing neighbour it will die). This forces bodies into a competitive arms race. Each body trying to exploit and own as many resources as it can (e.g. Competitors, Grimes) this is actually a very wasteful way of doing things so productivity falls.
At the end of a succession you have a community.
The composition of a final community is determined by which bodies arrive at the site, which bodies are successful at establishing themselves and which bodies are successful in holding their ground over generations of changing environmental conditions, changing resources and changing relationships with neighbours.
There is no specific mechanism built into this process to drive community productivity in a particular direction. Productivity will be low at the start it will increase over time but it will fluctuate depending on the balance of interactions within the community and there is no guarantee that it will settle on a high
