Biodiversity refers to the number and variety of life forms in a given habitat or region, and is often used as a measure of ecosystem health. Ecosystems with greater biodiversity are generally healthier, more stable, and better able to withstand change or stress.
A diverse ecosystem will be resilient because it contains many species with overlapping ecological functions that can partially replace one another. When a particular species is destroyed by a severe disturbance so that a link in the network is broken, a diverse community will be able to survive and reorganize itself because other links can at least partially fulfill the function of the destroyed species.
On the other hand, in communities lacking diversity, such as monocrop agriculture devoted to a single species of corn or wheat, a pest to which that species is vulnerable can threaten the entire ecosystem.
The Earth’s biodiversity is currently threatened. According to the Millennium Ecosystem Assessment, the last 50 years have seen a substantial and irreversible loss of biodiversity worldwide Some 10 to 30 percent of mammal, bird, and amphibian species are in danger of becoming extinct, and the overall rate of species extinction is also accelerating (Millennium Ecosystem Assessment).
The main cause of diminishing biodiversity in natural ecosystems is habitat loss or degradation as a result of human activity. Deforestation, mining, development, and other practices decrease habitat area. Pesticides, pollution, and other human impacts make habitats less suitable for survival. Invasive species — which people have introduced to new habitats either intentionally or by accident — spread uncontrollably and outcompete native species for food or space.
Ecosystem restoration projects as part of schooling for sustainability often involve monitoring of invasive species or replacement of invasive with native species. School gardens are good places to experience the importance of diverse communities.
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