Earth's peeling veneer of life Author: Douglas W. Morris

Mark Jones jones118 at SPAMlineone.net
Tue Jun 6 07:34:36 MDT 2000



Periodical: Nature
Date: 1/5/95
Pages: 25
Keywords: biodiversity, species loss, terrestrial, deforestation, fish,
human population, land use, land cover, agriculture, soil, forest, habitat,
fragmentation, extinction, biological diversity, landscape, degradation
Abstract: In this scientific correspondence, Douglas Morris presents results
of research relevant to large scale loss of biodiversity. He points out that
there is a lag time between environmental degradation and species
extinctions that result from it, and that this highlights the value of more
immediate and more easily estimated indicators of human impact. For example,
he says that more than 11% of the world's terrestrial landscape has been
converted to cropland. A further 25% has been occupied by pastureland. The
proportion of Earth's surface covered by forest and woodland has dropped 90%
since 1700, much of what remains is becoming increasingly fragmented, and
about 40% of what remains is either plantation or secondary forest. The rate
of soil degradation during the last 45 years corresponds to 17% of all
vegetated land. Biotic functions have been completely destroyed in 9 million
hectares and have been largely destroyed in a further 300 million hectares.
World exploitation of marine fishes has increased by 35% since 1979. The
exploitation of freshwater fisheries has expanded 85% during the same
period. About 60% of the world's main fish stocks may be exploited beyond
their ecological or economic optima. Humans use 8% of the world's available
fresh water each year. Tropical deforestation continues at a rate of 0.9%
per year. Human population size is increasing at the rate of 1.7% per year,
with a parallel increase in the number of domestic animals. 'The inescapable
conclusion,' the author says, 'is that much of the planet's surface, and its
veneer of life, has already been destroyed. ... We have embarked on a
trajectory of lost biodiversity whose acceleration and direction can, at
most, be controlled but not reversed.' The piece includes a chart of
statistics and footnotes that reference all sources.






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