Question

11 why does primary succession usually take longer to occur than secondary succession?
12 explain what is meant by climax community.
13 how might an invasive species disturb an ecological community?

Explanation:

• Question 11: Primary succession starts on bare rock with no soil. Pioneer species like lichens must first break down rock to form soil. This soil - building process is time - consuming. In secondary succession, there is already soil present (e.g., after a forest fire in an area that previously had a forest). So, the establishment of new plant and animal communities can happen more quickly as the soil provides nutrients and a medium for seed germination.
• Question 12: A climax community is a stable, mature ecological community that has reached a long - term equilibrium. It is the final stage of ecological succession. The species composition of a climax community changes very little over time (unless there is a major disturbance like a volcanic eruption or human - induced large - scale deforestation). It is in balance with the local climate, soil, and other environmental factors.
• Question 13: Invasive species can out - compete native species for resources such as food, water, and space. For example, they may have no natural predators in the new community, allowing their populations to grow rapidly. They can also alter the physical environment. Some invasive plants may change soil chemistry (e.g., by releasing allelopathic chemicals that inhibit the growth of native plants). This can lead to a decrease in biodiversity as native species are pushed out.

Answer:

• 11. Primary succession begins on bare rock (no soil). Pioneer species build soil slowly. Secondary succession has existing soil. So, primary succession is longer.
• 12. A climax community is a stable, mature ecological community. It is in equilibrium with the environment and has little species - composition change over time (without major disturbances).
• 13. Invasive species out - compete native species for resources (e.g., food, space). They may have no natural predators. Some can alter the physical or chemical environment (e.g., soil chemistry), reducing native biodiversity.