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Threats to Biodiversity
Author: From Wikipedia
Threats to Biodiversity
During the last century, erosion of biodiversity has been increasingly observed.
Estimates of extinction rates are controversial, ranging from from very low
to upwards of 200 species a day, but all scientists acknowledge that the rate
of species loss is greater now than at any time in human history, with extinctions
occurring at rates hundreds of times higher than background extinction rates.
Some studies show that about one of eight known plant species is threatened
with extinction. Some estimate put the loss at thousands of species per year,
though these are based on Species-area theory and are controversial. This figure
indicates unsustainable ecological practices, because only a small number of
species come into being each year. All are agreed that the losses are due to
human activities, in particular destruction of plant and animal habitats.
An increasing number of studies indicate that elevated rates of extinction
are being driven by human consumption of organic resources. While most of the
species that are becoming extinct are not food species, their biomass is converted
into human food when their habitat is transformed into pasture, cropland and
orchards. It is estimated that more than 40% of the Earth's biomass is tied
up in only the few species that represent humans, our livestock and crops.
Because an ecosystem decreases in stability as its species are made extinct,
these studies warn that the global ecosystem is destined for collapse if it
further reduced in complexity.
Some justify this situation not so much by a species overuse or ecosystem
degradation than by their conversion in very standardized ecosystems (e.g.,
monoculture following deforestation). Before 1992, others pointed out that
no property rights or no access regulation of resources necessarily lead to
their decrease (degrading costs having to be supported by the community).
Dissenters (notably economist Bjørn Lomborg) argue that there is not
enough data to support the view of mass extinction, and say abusive extrapolations
are being made on the global destruction of rainforests, coral reefs, mangrove
swamps, and other rich habitats.
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