Biodiversity (1988) / Chapter Skim
Currently Skimming:
The Current State of Biological Diversity
The Current State of Biological Diversity
Pages 1-18
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 3... ...
THE AMOUNT OF BIOLOGICAL DIVERSITY Many recently published sources, especially the multiauthor volume Synopsis and Classification of Living Organisms, indicate that about 1.4 million living species of all kinds of organisms have been described (Parker, 1982; see also the numerical breakdown according to major taxonomic category of the world insect fauna preparec! by Arnett, 1985~.
|
From page 4... ...
4 / BIODIVERSITY TABLE 1~1 Numbers of Described Species of Living Organismsa Kingdom and Major No. of Described Subdivision Common NameSpecies Totals Virus Viruses1,000 (order of magnitude only)
|
From page 5... ...
Erwin and his associates in the canopy of the Peruvian Amazon rain forest have moved the plausible upper limit much higher. Previously unknown insects proved to be so numerous in these samples that when estimates of local diversity were extrapolatec!
|
From page 6... ...
This biological concept of species is the best ever devised, but it remains less than ideal. It works very well for most animals and some kinds of plants, but for some plant and a few animal populations in which intermediate amounts of hybridization occur, or ordinary sexual reproduction has been replaced by self-fertilization or parthenogenesis, it must be replaced with arbitrary divisions.
|
From page 7... ...
At the generic level, North American elements dominated those from South America: 24 genera invacled to the south whereas only 12 invaded to the north. Hence, although equilibrium was roughly preserved, it resulted in a major shift in the composition of the previously isolated South American fauna (Marshall et al., 1982)
|
From page 8... ...
Tropical rain forests, or more precisely closed tropical forests, are defined as habitats with a relatively tight canopy of mostly broad-leaved evergreen trees Van Valen's original formulation, whose difficulties and implications are revealed by more recent research, has been discussed by Raup (1975) and by Lewin (1985)
|
From page 9... ...
It is not unusual for a square kilometer of forest in Central or South America to contain several hundred species of birds and many thousands of species of butterflies, beetles, and other insects. Despite their extraordinary richness, tropical rain forests are among the most fragile of all habitats.
|
From page 10... ...
World will certainly continue to accelerate deforestation during the coming decades unless heroic measures are taken in conservation and resource management. There is another reason to believe that the figures for forest cover removal present too sanguine a picture of the threat to biological diversity.
|
From page 11... ...
has projected ultimate losses due to the destruction of rain forests in the New World tropical mainland. If present levels of forest removal continue, the stage will be set within a century for the inevitable loss of 12% of the 704 bird species in the Amazon basin and 15% of the 92,000 plant species in South and Central America.
|
From page 12... ...
Several other studies of recently created islands of both tropical and temperatezone woodland have produced similar results, which can be crudely summarized as follows: when the islands range from 1 to 25 square kilometers-the size of many smaller parks and reserves the rate of extinction of bird species during the first 100 years is 10 to 50%. Also as predicted, the extinction rate is highest in the smaller patches, and it rises steeply when the area drops below 1 square kilometer.
|
From page 13... ...
from 0.2 to 14 square kilometers, anti, in reverse order, their resident bird species suffered 14 to 62% extinction rates. What do these first measurements tell us about the rate at which diversity is being reducecI?
|
From page 14... ...
In fact, systematics has one of the lowest cost-tobenefit ratios of all scientific disciplines. It is equally true that knowledge of biological diversity will mean little to the vast bulk of humanity unless the motivation exists to use it.
|
From page 15... ...
gene stocks and special habitats in particular, create plantations to supply industrial and fuel woocl, benefit indigenous tribal forest peoples, settle encroachers, and much else." In another approach, Thomas Lovejoy ~ 1984) has recommended that debtor nations with forest resources and other valuable habitats be given discounts or credits for undertaking conservation programs.
|
From page 16... ...
Most comprehensive of all-and in my opinion the most encouraging in its implications-is the three-part series Tropical Forests: A Call for Action, released by the World Resources Institute, The World Bank, and the United Nations Development Programme (1985~. The report makes an assessment of the problem worI(lwide and reviews case histories in which conservation or restoration have contribute(1 to economic development.
|
From page 17... ...
1985. A comparison of two recent estimates of disturbance in tropical forests.
|
From page 18... ...
1985. Humid Tropical Forests: AID Policy and Guidance.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.