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Succession occurs in natural ecosystems - AQA - A-Level Biology - Question 1 - 2019 - Paper 2
Question 1
Succession occurs in natural ecosystems. Describe and explain how succession occurs. Figure 1 shows percentages of energy transferred from sunlight to a zebra in a ... show full transcript
Worked Solution & Example Answer:Succession occurs in natural ecosystems - AQA - A-Level Biology - Question 1 - 2019 - Paper 2
Step 1
Describe how succession occurs.
Answer
Succession begins with colonization by pioneer species, which are the first organisms to inhabit a previously barren environment. These pioneering species alter the habitat, making it more suitable for other species. Over time, as these initial organisms die and decompose, they enrich the soil, allowing subsequent species to thrive. This process increases biodiversity as more complex organisms establish themselves, leading to a climax community where the ecosystem reaches a stable state.
Step 2
Explain the role of species in succession.
Answer
Pioneer species play a crucial role by changing the environment, for example, through processes such as soil formation. As these species alter the conditions, they create an environment that becomes less hostile for other species. Thus, other organisms can gradually replace the pioneers, leading to an increase in diversity and the overall productivity of the ecosystem.