Biodiversity

Your browser may not support display of this image. Biological diversity, or biodiversity for short, refers to the variety of species across Earth as a whole or in a specific place. Biodiversity is an important development concept because it is a way of summing the total value of Earth’s resources available for human use. Sustainable development is promoted when biodiversity of a particular place or Earth as a whole is

Biological and Geographic Biodiversity

Species variety can be understood from several perspectives. Geographers are especially concerned with biogeographic diversity, whereas biologists are especially concerned with genetic diversity. For biologists, biodiversity refers primarily to the maintenance of genetic diversity within populations of plants and animals.

Scientists have classified about 2.5 million species, including 900,000 insects, 41,000 vertebrates, and 250,000 plants, and more than a million invertebrates, fungi, algae, and microorganisms. About 1.4 million species have been given names. Estimates of Earth’s total number of species range from 3 to 100 million, with 10 million as a median “guess”, which means that humans have not yet discovered, classified, and named most of Earth’s species.

Your browser may not support display of this image. New species are constantly being identified- but human actions are exterminating species more rapidly than they are “discovering” new ones. Human actions are responsible for the extinctions by destroying habitats, primarily through pollution of air and water, removal of existing plants and animals, and an introduction to foreign and exotic species.

For geographers, biodiversity is a measurement of the number of species within a specific region or habitat. A community containing a large number of species is said to be species-rich, whereas an area with few species is species poor.

Two communities may have the same number of species and the same total population of individuals, yet one may be more diverse than the other, depending on the distribution of the total population among the various species. A community with a large population of many species is regarded as more diverse than a community that contains a preponderance of one species and a very small number of all others.

Your browser may not support display of this image. Frustrated by the inability to precisely measure environmental impacts, Millennium Ecosystems Assessment has undertaken a multiyear effort to establish systematic data sets. Heavy reliance is placed on remote sensing and satellite mapping to establish data sets.

The Importance of Ecosystems

Ecosystems support a rich diversity of species which interact with their surrounding environments to produce a number of benefits; these include:

* air and water purification
* provision of many of man's necessities such as shelter, food, fuel and building materials
* stabilization of the Earth's climate
* detoxification of waste products
* plant pollination
* weather and environmental control through floods and fire
* control of erosion
* control of disease
* source of many medicines
* nutrient recycling.

Measurement of biodiversity

Distribution of biodiversity

Species diversity varies systematically across the globe with latitude, longitude, and altitude (or its equivalent, depth, in the oceans). The trend toward higher species diversity in the tropics is perhaps the most conspicuous biogeographic pattern in nature, and is sufficiently general to have been considered a "rule". In most marine groups, diversity is maximal in the Indo-West? Pacific.

Superimposed on these large-scale global patterns are local hot spots of diversity generated by geographical features, by quirks of geologic history, or by mixing of biotas from different biogeographic provinces. These biodiversity hot spots have become important (and often controversial) foci for conservation efforts.

Ecological controls on biodiversity

A central question in explaining these patterns of diversity is determining the relative importance of long-term evolutionary processes — the balance between origin and extinction of species — and local ecological processes of species interactions.

The general similarity among diversity patterns of different taxa with latitude and region suggests that prehistorically these patterns have been controlled primarily by factors operating over large spatial and temporal scales. Ultimately, the number of species in a region is set by a balance between origin through speciation, loss through extinction, and migration of species among regions, all of which operate over long (geologic) time scales.

Conversely, on local spatial scales and over ecological time scales on the order of a few generations of organisms, a wealth of evidence shows that diversity often varies systematically with habitat area, habitat heterogeneity, disturbance, and availability of energy (i.e., productivity) and other resources, notably water in terrestrial ecosystems.



Human disturbance factors

For the most recent 10,000 years man has been the greatest factor affecting biodiversity, with adverse impacts occurring at an accelerating pace since approximately the Industrial Revolution. Human intervention in ecosystem function have been expressed through habitat destruction, habitat fragmentation, overexploitation, and pollution. In some locations such as Easter Island and Hawaii the majority of macroscopic species that existed as recently as the mid-Holocene are now extirpated.

Biodiversity is important in development because it is a way of summing up the total value of Earth's resources available for human use.
Biological and Geographic Biodiversity
-Geographers worry about biodiversity while biologist worry about genetic diversity.
-Biologists refer to biodiversity as a way to maintain genetic diversity in a population of plant and animals. Genetic diversity deals with variations in genetic material like genes and chromosomes.
-Geographers use biodiversity as a measurement of the number of species within a specific region or habitat. A community with a large amount of species is known as species-rich, while an area with small amounts of species is known to be species-poor.

Destruction
Humans have a tendency of destroying habitats, through pollution of air and water, removal of existing plants and animals, and introduction of foreign and exotic species, and make it hard for scientists to identify these species. There has been many strategies established to protect genetic diversity. Endangered species are being protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Some countries establish their own strategies to protect biodiversity. For example Luxembourg protects 44% of its land, while Iraq has no land under conservation. People are relying on remote sensing and satellite mapping to create data sets.

About 2.5 million species have been classified.
900,000 insects
41,000 vertebrates
250,000 plants
more then a million invertebrates, fungi, algae, and microorganisms
About 1.4 million species have been named.
About 3- 10 million species have not yet been discovered.

Biodiversity in the Tropics
High temperatures, greater climate predictability, and longer growing seasons are ideal conditions for a diversity of species to grow. Extinction is so high because of cutting down forests. This is occurring because of economic activities: decline in shifting cultivation, logging, cattle ranching, and cultivating cash crops. Governments approve this because it is a way for the economy to develop.

-3 species per hour are extinguished in the tropics
-More than 5,000 species are considered in danger of extinction
-Tropical rainforests occupy 7% of Earth's land area
-They contain ½ of the world's species
-2/3 vascular plants species
-1/3 avian species
-Tropical rain forests are disappearing 10- 20 million hectares (25-50 million acres) per year.