Saturday, March 29, 2014

What is the future of global biodiversity?

A definition of biodiversity is ‘the spatial and temporal variability of the structure and function of living systems’. Biodiversity drives the functioning of ecosystems through countless reciprocal interactions with the physical and chemical components of the environment. Biodiversity is the foundation and mainstay of agriculture, forests and fisheries as well as soil conservation and water quality. Biodiversity is our wealth and a vital means of sustenance.

 Wilson (1993) said “biodiversity is vital to healthy forests, while proper forest management is vital to the maintenance of biodiversity.”  At least 40% of the world’s economy and 80% of the needs of the poor are derived from biological resources. In addition, the richer the diversity of life, the greater the opportunity for the discovery of new medicines, economic development and adaptive responses of species to climate change (The convention about life on earth).

The present biodiversity is the result of 3.5-4.0 billion years of evolution. According to some estimates there could be as many as 30-50 million species on the planet earth. About 1.7 million of earth’s species have been identified and designated with a scientific name. About 6% of the identified live in boreal or polar latitudes, 59% in the temperate zones and the remaining 35% in the tropics. Our biodiversity is under threat globally, nationally and locally.  Biological diversity is diminishing all over the earth. Large scale global extinction of species occurred in the 20th century at a rate that was a thousand times higher than the average rate during the preceding 65 million years. Human beings have been elevated the extinction of 5-20% of the species in many groups of species. All available evidence points to a sixth major extinction event currently underway. Previous five mass extinction events were due to planetary change, natural disasters and biological competition. They have eliminated between 35-96% of all species on earth. The current massive wave of biological extinction is mainly due to human activities.
In the year 2006, large numbers of earth’s species are formally classified as rare or endangered or threatened. About 40% of the 40,177 species assessed using the IUCN Red List Criteria are now listed as threatened species with extinction – a total of 16,119 species. Some 10-30% of the mammal, bird and amphibian species are currently threatened with extinction, all due to human actions. Climate change from carbon dioxide emissions accelerate the demise of many forms of life.

Global loss of biodiversity

Of the approximately 265,000 plant species in the world, more than 60,000 are at risk of extinction. About 6000 plants are known to be used in agriculture, forestry and medicine, while only 150 species are used for intensive cultivation (about 20 species producing 90% of the world’s food)Some studies show that about one-eighth of known plant species is threatened with extinction. About 12.5 % of the world’s plant species to become critically rare. Three-fourths of the world’s bird species are declining in population or threatened with extinction. About 27% of the world’s 330 parrot species are in danger of extinction. Amphibians (frogs, salamanders and related species) declining worldwide. About 20% of all reptiles and a third of the world’s 266 known species of turtles are threatened with extinction. About one-third of all fishes and 90% of all large fishes have disappeared from the world’s oceans. Every year between 17,000 and 100,000 species vanish from our planet. Some people say that up to one-fifths of all living species could disappear within 30 years.

Global loss of ecosystems

The ecosystems of the world are maintained by their biodiversity.  Healthy ecosystems support high biodiversity. Every ecosystem can be characterized by its own species composition. Ecosystems differ in their physical structure, temperature, water availability, food types and richness and complexity of biological communities including the number of niches, trophic levels and ecological processes. These differences make certain ecosystems habitable to some species but not to others and enable a great diversity of species to exist across the globe. The habitat heterogeneity hypothesis states that an increase in habitat heterogeneity leads to an increase in species diversity. The increase in the number of habitats leads to an increase in species diversity in a landscape.  Of all marine habitats, the coastal waters are under greatest pressure. Ninety percent of the world’s fish catch (measured by weight) depend on coastal habitats for at least part of their life cycles.Coral reefs, which rival rain forests in diversity, are being destroyed through siltation, coral mining and pollution. Mangroves, which line one quarter of tropical coastal lines, are being cut down for lumbar, fuel wood and to build aquaculture ponds. Estuaries and wetlands, important sites for migratory species, are threatened in many areas by coastal development. Deeper waters, which are rich in diversity, are threatened by the disposal of toxic chemicals.  Global ocean primary production has declined more than 6%. One fourths of marine fish stocks are currently overexploited or significantly depleted. Tropical rain forests are shrinking by 11 million hectares per year. About 31 million hectares forest cover in industrial countries has been changes apparently by air pollution and acid rain. In many parts of the world, logging, grazing and mining are the major threats to endanger forest ecosystems. An estimated 26 billion tons of top soil are lost in excess of new soil formation annually. Some 6 million hectares of new desert are formed annually by land mismanagement. Thousands of lakes in the industrial towns are now biologically dead, thousands more are dying. Underground water tables are falling as demand for water rises above aquifer recharge rates. Fresh water systems tend to be the first habitat to experience a  huge biodiversity loss due to closer contact with human beings. The biodiversity of freshwater lakes, streams, rivers and wetlands may be the most threatened ecosystems on earth. Fully one fifth of the world’s freshwater fishes are either endangered or extinct.

Root causes of biodiversity loss

The Global Biodiversity Strategy (1992) has identified several of the root causes of biodiversity loss.
Population bomb (Paul Ehrlich) – the world’s population has more than tripled in the 20th century and continued growth is expected over the next 50 years especially in the developing countries. As the number of people increases, crowding generates pollution, destroys more habitats and uses up additional natural resources. In addition human beings have the habit of controlling the nature.
Over exploitation and mass consumption of natural resources – population growth and increasing resource consumption affect biodiversity in two ways: they create pressure to convert wildlife habitats into agricultural and urban land and they produce wastes that pollute habitat and poison wildlife.
Ignorance of people about species and ecosystems – most people are not aware of the ecological and economic value of species and the ‘ecological services’ they provide.
Poorly conceived policies – government policies designed to encourage some sectors such as agriculture or forestry can have the side effect of destroying biodiversity.
Global trading systems -  in developing countries which rely heavily on agricultural commodities for export earnings those pressures have pushed farmers toward large scale plantations  growing a relatively narrow range of crops that are in demand (for e.g., coffee, cocoa and bananas) on world markets.
Inequity of resource distribution – globally, there are inequities between richer countries with the technological and financial capacity to develop and exploit natural resources and the poorer countries without such capacity and technology. The environmental impact person varies greatly among and within countries, largely depending on the nature and degree of industrialization.
Failure to account for the value of biodiversity – markets tend to undervalue biodiversity, thereby promoting (directly or indirectly) its depletion. Ironically biodiversity produces and supports immense benefits to society, but it is totally ignored in national economic accounts because it is difficult to value. When market undervalues biodiversity, policies and subsidies may encourage sustainable or destructive activities.

Significance of biodiversity loss

Biodiversity is an extremely important as well as a fundamental component of life on earth. It creates and maintains ecological systems. It is important to the global economy and is essential for food security. It safeguards human health. Without vegetation or organisms, landscapes would be virtually indistinguishable from one another. Biodiversity creates complex environments that could never be reproduced by human beings. The loss of species diversity is unique among other anthropogenic changes because it is irreversible. The value of biodiversity is immeasurable and thus must be protected. Biodiversity is an important concern of scientists, environmental activists, and society as whole and even politicians. Conservation of biodiversity requires communication and cooperation between all of these parties.

Global initiatives on biodiversity conservation

The World Conservation Union, World Resources Institute and United Nations Environment Programme are the three important agencies, whose mandates center on the conservation of the world’s biodiversity. They have developed the ‘Global Biodiversity Strategy’, an international programme to help to protect biodiversity. The broad objectives are to: 1) preserve biodiversity; 2) maintain earth’s ecological processes and life- support systems and 3) ensure that natural resources will be sustainably used by humans.

“Biodiversity is the strength of the web of life, binding together all living things. It is greatest expression of the truth that diversity holds the key to life. It is also one of the most important and threatened assets left to mankind. The protection, promotion and wise utilization of biodiversity may very well form the cornerstone of our future global survival.”     -Marthinus van Schalkwyk (Biodiversity synthesis report).

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