Our limited resources are threatened by increasing pressure for land to be put to other uses than agricultural growth and wildlife habitate, not least by by fast-growing population levels. Wildlife habitats are lost by physical destruction, pollution and over-exploitation. Perhaps the most profound way that habitats are modified and redistributed, changed and 'lost' is due to the volatile impacts of global temperature change.
For an ecosystem to function naturally, there are certain habitat size and diversity conditions. When habitat within an ecoregion is lost or degraded and the total area of that habitat declines, there is a rapid loss of species and disruption of ecoogical processes. Reduced or degraded habitats threaten biodiversity at gene, species and ecosystems level, hampering the provision of key ecological products and services. Freshwater and marine habitats, especially coral reefs, are also very vulnerable.
In the last 200 years the USA has lost 50% of its wetland habitat, 90% of its north-western old-growth forests and 99% of its tallgrass prairie. Up to 490 species of native plants and animals were lost with another 9,000 now at risk.