Stability in Ecosystems
- Stable ecosystems have the following features
- Efficient nutrient cycling which allows the system to be self-supporting
- High biodiversity
- Stability, i.e. resistance to change
- E.g. consumer population sizes do not change significantly so resources are not overused
- High levels of photosynthesis
- Some tropical rainforests, e.g. the Amazon rainforest in South America and the Congo rainforest in Africa, have remained in their current state for tens of millions of years; they are
- Highly diverse, e.g. the Amazon rainforest his thought to contain millions of invertebrate species, tens of thousand of plant species, thousands of bird and fish species, and hundreds of mammal species
- High levels of light and moisture mean that photosynthesis rates are high
- Organic matter is cycled by detritivores such as termites, slugs and worms, and by decomposers such as fungi; the nutrients are then taken up again by the trees
- Water is cycled within the ecosystem as it is lost from trees by transpiration before condensing and falling again as rain
- Note that while healthy ecosystems are highly stable, as described above, they are not entirely static; natural selection, leading to evolutionary change, will always be acting on species
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The Amazon rainforest is millions of years old