7.3: Conservation of Biodiversity

The core threat to biodiversity on the planet, and therefore a threat to human welfare, is the combination of human population growth and the resources used by that population. The human population requires resources to survive and grow, and those resources are being removed unsustainably from the environment. The three greatest proximate threats to biodiversity are habitat loss, overharvesting, and introduction of exotic species. The first two of these are a direct result of human population growth and resource use. The third results from increased mobility and trade. A fourth major cause of extinction, anthropogenic (human-caused) climate change, has not yet had a large impact, but it is predicted to become significant during this century. Global climate change is also a consequence of human population needs for energy and the use of fossil fuels to meet those needs. Environmental issues, such as toxic pollution, have specific targeted effects on species, but are not generally seen as threats at the magnitude of the others.

Humans rely on technology to modify their environment and replace certain functions that were once performed by the natural ecosystem. Other species cannot do this. Elimination of their habitat—whether it is a forest, coral reef, grassland, or flowing river—will kill the individuals in the species. Remove the entire habitat within the range of a species and, unless they are one of the few species that do well in human-built environments, the species will become extinct. Human destruction of habitats (habitats generally refer to the part of the ecosystem required by a particular species) accelerated in the latter half of the twentieth century.

Estimation of Extinction Rates

Estimates of extinction rates are hampered by the fact that most extinctions are probably happening without being observed. The extinction of a bird or mammal is often noticed by humans, especially if it has been hunted or used in some other way. But there are many organisms that are less noticeable to humans (not necessarily of less value) and many that are undescribed.

The background extinction rate is estimated to be about 1 per million species years (E/MSY). One “species year” is one species in existence for one year. One million species years could be one species persisting for one million years, or a million species persisting for one year. If it is the latter, then one extinction per million species years would be one of those million species becoming extinct in that year. For example, if there are 10 million species in existence, then we would expect 10 of those species to become extinct in a year. This is the background rate.

One contemporary extinction-rate estimate uses the extinctions in the written record since the year 1500. For birds alone, this method yields an estimate of 26 E/MSY, almost three times the background rate. However, this value may be underestimated for three reasons. First, many existing species would not have been described until much later in the time period and so their loss would have gone unnoticed. Second, we know the number is higher than the written record suggests because now extinct species are being described from skeletal remains that were never mentioned in written history. And third, some species are probably already extinct even though conservationists are reluctant to name them as such. Taking these factors into account raises the estimated extinction rate to nearer 100 E/MSY. The predicted rate by the end of the century is 1500 E/MSY.

Many international agencies are working on biodiversity and their conservation. The International Union for Conservation of Nature and Natural Resources (IUCN) is one of these. It was introduced in 1948 and work on conservation of nature and their sustainable uses.

The IUCN maintains the information about the status of plants and animal species. This record of information is known as “Red Data Book” or Red List.

The IUCN mentions the criteria of species categorization in the Red data book. It is based on the following points:

1. The current and previous distribution of species.
2. Decline in the population of species in the period of time.
3. Quantity and quality of natural habitat of the species.
4. The biology and potential value of the species.

Here are the major terms of species category.

1. EXTINCT (EX): The term extinct indicates the species’ last individual has died or no records are present.
2. RARE (R): It indicates species, which are very uncommon or naturally existing in small numbers and decline in their population. A rare species may be an endangered species, which is normally found in small concentrated area.
3. ENDANGERED (EN): Endangered category indicates that the available species have reduced at a critical level due to destruction of habitat and climate change.
4. VULNERABLE (VU): It denotes that the population of species decrease in numbers due to habitat destruction and poaching or species might become endangered in near future if the same factors will be continued.

For sustaining life on the earth, biodiversity conservation is needed. Usually, there are two basic approaches in the world. These are in-situ and ex-situ conservation methods.

1. In-situ conservation approach: This indicates conservation of biological diversity in habitats or ecosystems. Biosphere reserves, National parks and Sanctuaries are the examples of in-situ conservation method.
2. Ex-situ conservation approach: The protection of biodiversity outside their natural habitat or ecosystems is called ex-situ conservation. Botanical garden, zoological parks and seed genes banks are few examples of this conservation approach.

Contributors and Attributions

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