University mof Port Harcourt,Choba,Port Harcourt,Nigeria

Rapid decline in biodiversity: a threat to survival of humankind

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Courtesy of University mof Port Harcourt,Choba,Port Harcourt,Nigeria

Biodiversity, coined from two words; Biological Diversity simply refers to the variety and variability of life forms (plants, animals and micro-organisms) on earth. In other words, it is the totality of genes, species, and ecosystems in a region. Thus, biodiversity can be divided into genetic diversity within specie, Specie diversity within a community in an ecosystem as well as the more complex ecosystem diversity, regionally and globally. A salient point to note here is that biodiversity is the degree of variety in nature and not nature itself. The beauty of the earth lies in its diversity; diversity in terms of people, plants, animals, and other micro-organisms. Biodiversity could be described as the essence and basis of life itself.

The most important types of habitats for biodiversity include; tropical forests, wetland such as the mangroves, aquatic environment such as the freshwater lakes and coral reefs; and the African Savannah (Oda, 1991). Among these, the tropical rainforest is adjudged the richest in biodiversity with over 90% of the species. In recent years, evolutionary biologists and conservationists have focused increasing attention on tropical rain forests, for two principal reasons. First, although these habitats cover only 7% of the Earth's land surface, they contain more than half the species in the entire world biota. Second, the forests are being destroyed so rapidly that they will mostly disappear within the next century, taking with them hundreds of thousands of species into extinction. Other species-rich biomes are in danger, most notably the tropical coral reefs, geologically ancient lakes, and coastal wetlands. Each deserves special attention on its own, but for the moment the rain forests serve as the ideal paradigm of the larger global crisis.

Tropical rain forests, or more precisely closed tropical forests, are defined as habitats with a relatively tight canopy of mostly broad-leaved evergreen trees sustained by 100 centimeters or more of annual rainfall. Typically two or more other layers of trees and shrubs occur beneath the upper canopy. Because relatively little sunlight reaches the forest floor, the undergrowth is sparse and human beings can walk through it with relative ease. The species diversity of rainforests borders on the legendary. Every tropical biologist has a favorite example to offer. However, despite their extraordinary richness, tropical rain forests are among the most fragile of all habitats. They grow on so-called wet deserts--an unpromising soil base washed by heavy rains.

Two-thirds of the area of the forest surface consists of tropical red and yellow earths, which are typically acidic and poor in nutrients. High concentrations of iron and aluminum form insoluble compounds with phosphorus, thereby decreasing the availability of phosphorus to plants. Calcium and potassium are leached from the soil soon after their compounds are dissolved from the rain. As little as 0.1% of the nutrients filter deeper than 5 centimeters beneath the soil surface (NRC, 1982).One is not actually trying to discuss the ecology of the rainforest as an excellent popular account of rain forest ecology is given by Forsyth and Miyata (1984).

Approximately 40% of the land that can support tropical closed forest now lacks it, primarily because of human action. By the late 1970s, according to estimates from the Food and Agricultural Organization and United Nations Environmental Programme, 7.6 million hectares or nearly 1% of the total cover is being permanently cleared or converted into the shifting-cultivation cycle. The absolute amount is 76,000 square kilometers (27,000 square miles) a year. In effect, most of this land is being permanently cleared, that is, reduced to a state in which natural reforestation will be very difficult if not impossible to achieve.

A straight-line extrapolation from the first of these figures, with identically absolute annual increments of forest-cover removal, leads to 2135 A.D. as the year in which all the remaining rain forest will be either clear-cut or seriously disturbed, mostly the former. By coincidence, this is close to the date (2150) that the World Bank has estimated the human population will plateau at 11 billion people (The World Bank, 1984). In fact, the continuing rise in human population indicates that a straight line estimate is much too conservative. Population pressures in the Third 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. In many local areas with high levels of endemicity, deforestation has proceeded very much faster than the overall average. Madagascar, possessor of one of the most distinctive floras and faunas in the world, has already lost 93% of its forest cover. The Atlantic coastal forest of Brazil, which so enchanted the young Darwin upon his arrival in 1832 ('wonder, astonishment & sublime devotion, fill & elevate the mind'), is 99% gone (Wilson, 1988).

What is the Amount of Biological Diversity & what implications?
Many recently published sources, especially the multi-author 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). Approximately 750,000 are insects, 41,000 are vertebrates, and 250,000 are plants (that is, vascular plants and bryophytes). The remainder consists of a complex array of invertebrates, fungi, algae, and microorganisms.

Most systematists agree that this picture is still very incomplete except in a few well-studied groups such as the vertebrates and flowering plants. If insects, the most species-rich of all major groups, are included, I believe that the absolute number is likely to exceed 5 million. Recent intensive collections made by Terry L. 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 extrapolated to include all rain forests in the world, a figure of 30 million species was obtained (Erwin, 1983). In an even earlier stage is research on the epiphytic plants, lichens, fungi, roundworms, mites, protozoans, bacteria, and other mostly small organisms that abound in the treetops.

Other major habitats that remain poorly explored include the coral reefs, the floor of the deep sea, and the soil of tropical forests and savannas. Thus, remarkably, we do not know the true number of species on Earth, even to the nearest order of magnitude (Wilson, 1985a). However, based on the described fauna and flora and many discussions with entomologists and other specialists, one could guess that the absolute number falls 5 million

What values do biodiversity possess?

An intelligent question that would arise giving the state of our biodiversity would be: What values do biodiversity possess? Or better still, why conserve biodiversity? How useful is biodiversity? Biodiversity could be described as the basis of human existence. This is true insofar as mankind would continue to need food, medicines, raw materials to fashion his material culture. On a general note, it is not easy to classify the values of biodiversity, but economists have been able to do a general classification of biodiversity values into two categories as follows: Use values, Non-use values. The use value further subdivided into: Direct use values, indirect use values, option values and quasi-option use value (see table below).

Type of values of Biodiversity

Value type Subtype Example

Use Values
(a) Direct Consumptive, productive & Non consumptive Variety of home consumed forest fruits, plant breeding & tourism.
(b) Indirect Ecological processes
( c) option Future values of drugs, etc.
(d) Quasi-option Values of being able to ascertain option value
Non-use values Existence value of Elephants.
Culled from ODA (1991)

However, for the purpose of the readership of this article, the values of Biodiversity are broadly listed as follows: Provision of food, drinks, medicine, meat, milk, fabric, raw materials for industries, plant /animal breeding (Genetic Engineering), for recreation/tourism, aesthetics, psychological satisfaction ( pride).

It would be pertinent to note here that over 90% of our food intake is from biodiversity. International Food Policy Research Institute (2004) showed that the diversity of agricultural production—comprising cultivated and gathered products such as fruits, vegetables, and multiple varieties of rice—was important to ensuring food security. Homestead food production focused on a wide variety of fruits and vegetables and integrated with animal husbandry enables households to diversify and increase the quality of their diet. Agro-biodiversity used and conserved in a livelihood context can directly contribute to nutrition, health, and income generation. Health and prosperity linked to robust socio-cultural institutions, in turn, help individuals and populations make healthy behavioural choices, and help institutions develop public policies that maintain the diversity and health of ecosystems (Mmom, 2009). Agro-biodiversity could be more effectively utilized to improve diets and nutrition. Eight hundred million people in the world have diets insufficient in energy and some 2 billion suffer from micronutrient deficiencies. In Ghana, three out of four people look to wildlife for most of their proteins. Improving accessibility to a range of crops would offer nutritional benefits to both the rural and urban poor.

Researches have also shown that over 70% of our antibiotics are from extracts from plants. Traditional medicine that is making wave in Africa is based on plants and animals extracts. Traditional medicine forms the basis of primary health care for about 80% of people in developing countries; one-fourth of all prescriptions dispensed in the United States contain active ingredients extracted from plants, and over 3000 antibiotics are derived from micro-organisms. (Reid and Miller,1989). In fact, man shall continue to depend on plants as a source of both traditional and orthodox medicines.

Man is able to fashion his material culture from biodiversity as they provide raw materials for our clothing, shelter, and industries. Economic benefits from wild species alone make up an estimated 4.5 % of the Gross Domestic Product of United States. Genetic Engineering to produce superior quality of plants and animals to forestall crop failure and famine is made possible with biodiversity. Biodiversity helps to maintain ecological processes; plants act as carbon sink and maintaining Greenhouse Effect through carbon sequestration. Ecotourism is the major stay of several economies. Worldwide nature tourism generates as much as $12billions in reserve each year. In fact, biodiversity offers aesthetics in nature and earns man some psychological satisfaction.

From the foregoing, it becomes obvious that the survival of Humankind depends on the continuous existence and conservation of biodiversity. In other words, a threat to biodiversity is a serious threat to the survival of Human Race. To this end, biological diversity must be treated more seriously as a global resource, to be indexed, used, and above all, preserved. Three circumstances conspire to give this matter an unprecedented urgency. First, exploding human populations are degrading the environment at an accelerating rate, especially in tropical countries. Second, science is discovering new uses for biological diversity in ways that can relieve both human suffering and environmental destruction. Third, much of the diversity is being irreversibly lost through extinction caused by the destruction of natural habitats due to development pressure and oil spillage, especially in the Niger Delta. In fact, Loss of biodiversity is significant in several respects. First, breaking of critical links in the biological chain can disrupt the functioning of an entire ecosystem and its biogeochemical cycles. This disruption may have significant effects on larger scale processes. Second, loss of species can have impacts on the organism pool from which medicines and pharmaceuticals can be derived. Third, loss of species can result in loss of genetic material, which is needed to replenish the genetic diversity of domesticated plants that are the basis of world agriculture (Convention on Biological Diversity). Overall, we are locked into a race. We must hurry to acquire the knowledge on which a wise policy of conservation and development can be based for centuries to come.

How Much Diversity Is Being Lost? And How Fast Is The Decline?

No precise estimate can be made of the numbers of species being extinguished in the rain forests or in other major habitats, for the simple reason that we do not know the numbers of species originally present. However, there can be no doubt that extinction is proceeding far faster than it did prior to 1800. Oda (1991) noted that specie extinction rates are estimated at approximately 10-20,000 per year or between 1,000 -10,000 times faster than the natural rate before human intervention. Approximately 490 species (6%) of freshwater fish are considered to be threatened, with 24 of them considered extinct The basis for this statement is not the direct observation of extinction and most of these are endemic (ODA,1991). To witness the death of the last member of a parrot or orchid species is a near impossibility. With the exception of the showiest birds, mammals, or flowering plants, biologists are reluctant to say with finality when a species has come to an end. There is always the chance (and hope) that a few more individuals will turn up in some remote forest remnant or other. But the vast majority of species are not monitored at all.

Instead, extinction rates are usually estimated indirectly from principles of biogeography. As mentioned above, the number of species of a particular group of organisms in island systems increases approximately as the fourth root of the land area. This has been found to hold true not just on real islands but also on habitat islands, such as lakes in a 'sea' of land, alpine meadows or mountaintops surrounded by evergreen forests, and even in clumps of trees in the midst of grassland (Mac Arthur and Wilson, 1967).

In general, the tropical world is clearly headed toward an extreme reduction and fragmentation of tropical forests, which will be accompanied by a massive extinction of species. At the present time, less than 5% of the forests are protected within parks and reserves, and even these are vulnerable to political and economic pressures. For example, 4% of the forests are protected in Africa, 2% in Latin America, and 6% in Asia (Brown, 1985). Thus in a simple system as envisioned by the basic models of island biogeography, the number of species of all kinds of organisms can be expected to be reduced by at least one-half--in other words, by hundreds of thousands or even (if the insects are as diverse as the canopy studies suggest) by millions of species. The current reduction of diversity seems destined to approach that of the great natural catastrophes at the end of the Paleozoic and Mesozoic eras--in other words, the most extreme in the past 65 million years. In at least one important respect, the modern episode exceeds anything in the geological past. In the earlier mass extinctions, which some scientists believe were caused by large meteorite strikes, most of the plants survived even though animal diversity was severely reduced. Now, for the first time, plant diversity is declining sharply (Knoll, 1984).

Just as there is no clear estimate of the number of species lost, one cannot also say with certainty the rate of extinction of species. However, a measure of specie extinction is the rate of habitat loss. In the tropic rainforest estimates suggest that it is cleared at the rate of 14, per year. In Nigeria, it is estimated that the tropical rainforest is lost at the rate of 3.5 % per annum with the tendency of increase in the foreseeable future. Thus it is estimated that the rate of biodiversity loss equals the rate of forest clearance. However, Studies by Jared Diamond and John Terborgh on bird species have led to the estimation of the decay constants for the bird faunas on naturally occurring islands (Terborgh, 1974 and Diamond, 1984). These investigators took advantage of the fact that rising sea levels 10,000 years ago cut off small land masses that had previously been connected to South America, New Guinea, and the main islands of Indonesia. Thus they are called land-bridge islands. In the study of the South American land-bridge islands, Terborgh found that the smaller the island, the higher the estimated decay constant and hence extinction rate. Applying the natural land-bridge extinction curve to an island of this size (17 square kilometers) and fitting the derived decay constant to the actual period of isolation (50 years), Terborgh predicted an extinction of 17 bird species. The actual number known to have vanished as a probable result of insularization is 13, or 12% of the 108 breeding species originally present.

Several other studies of recently created islands of both tropical and temperate-zone 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. To take one example provided by Willis (1979), three patches of subtropical forest isolated (by agricultural clearing) in Brazil for about a hundred years varied from 0.2 to 14 square kilometers, and, in reverse order, their resident bird species suffered 14 to 62% extinction rates.

What are the causes of this rapid decline?

Biodiversity is being eroded as fast today as at any time since the dinosaurs died out some 65 million years ago. It has also been established in this paper that the crucible of extinction is believed to be the tropical rainforest which houses between 50-90% of the total biodiversity. Scientists estimate that at the decline rate of 17 million hectares annually, roughly 5-10% of the tropical forest species may face extinction in the next 30 years. Thus, one may ask, what are the main causes of biodiversity loss?

Six fundamental causes of biodiversity loss are identified as follows:

• Unsustainable high growth rate of human population, poverty and natural resource consumption.
• The steady narrowing spectrum of traded products from agriculture, forestry and fisheries.

(A) (B)

(C) (D)
A-Biodiversity loss due to pollution (Oil/Gas activities)
B-Land reclamation for development depletes the mangrove forest
C-Road construction / infrastructure development depletes biodiversity
D-Overexploitation of the resources threatens the mangroves.
• Economic systems policies that fail to value the environment and its resources.
• Inequity in the ownership and flow of benefits from both the use and conservation of biological resources.
• Deficiencies in knowledge and application.
• Legal and institutional framework that hinders sustainable exploitation.
The aforementioned six (6) fundamental causes of biodiversity loss operate through the following mechanisms:
• Habitat loss and fragmentation
• Introduction of alien species
• Overexploitation of plant and animal species
• Pollution (land, air & water)
• Global climate change and
• Change in agricultural systems (commercial agriculture & forestry)

Habitat loss and fragmentation are a major factor of biodiversity loss and result from the increasing growth of human population and the need to cultivate more land to feed the teeming population; quest for economic development and rapid urbanization, especially in the developing countries.
Introduction of alien or exotic species is responsible for many recorded specie loss, especially on islands. Most alien species are evasive in nature and become predators, competitor to the indigenous species leading to their extinction.
Overexploitation of plants and animal species is a major consequence of poverty in the developing countries. Numerous forest, fisheries and wildlife resources are overexploited to the point of extinction because of their economic value. A good example of this is the cedar of Lebanon that once blanketed 500,000 hectares now found in only a few scattered remnants of forest. It is pertinent to note that poverty and greed is a major cause of overexploitation ob biological resources.

Environmental pollution (Air, Land & water) strain the ecosystems and may reduce or eliminate populations of sensitive species. The Niger Delta is a very sensitive ecosystem but prone to incessant oil spillage which destroys the fragile ecosystem. The mangrove vegetation and the associated biodiversity are very often destroyed in cause of the oil pollution. Soil microbes have also suffered from pollution as industrial effluents with heavy metals brings on salinization. Acid rain from air pollution has also damaged forests.

Change in agricultural systems, especially commercial agriculture and forestry has led to the erosion of biodiversity. On-farm diversity is shrinking fast. Commercialization of markets potentially limits the opportunities of small-scale farmers to produce and sell minor crops or to compete against the produce of local or foreign commercial farms. The conventional explanation for the loss of crop diversity on the farm is that such losses are demand driven. Farmers no longer want to grow diverse sets of varieties, particularly landraces. As they become integrated into the market and have greater opportunities to access modern varieties, sell surpluses, and purchase products, farmers may prefer to specialize and plant a few high-yielding modern varieties that provide them with higher incomes. Thus, the change in cropping systems is a major contributing factor to biodiversity loss.

Global climate change could be described as a potential cause of biodiversity loss inasmuch as this change is yet be significantly documented and substantiated. It is expected that in coming decades, a massive side-effect of global warming could significantly cause havoc to world living organisms including man. The expected global rise in temperatures with an associated rise in sea level will displace the limit of tolerance of certain species.

Which way forward?

The biological diversity most threatened is also the least explored, and there is no prospect at the moment that the scientific task will be completed before a large fraction of the species vanishes. A deliberate effort at conservation of biodiversity is called for and this starts with research, to determine what number of species is available. It would be a great advantage, in my opinion, to seek such knowledge for the entire biota of the world. Each species is unique and intrinsically valuable. It is necessary to know which species are present (recall that the great majority have not even received a scientific name) as well as their geographical ranges, biological properties, and possible vulnerability to environmental change. At present, there is no way of knowing whether there are 5, 10, or 30 million species on Earth. There is no theory that can predict what this number might turn out to be. Thus effort need to be made to understand all of diversity, else we will fall far short of understanding life in these important respects, and due to the accelerating extinction of species, much of our opportunity will slip away forever.

The problems of human beings in the tropics are primarily biological in origin: overpopulation, poverty, habitat destruction, soil deterioration, malnutrition, disease, and even, for hundreds of millions, the uncertainty of food and shelter from one day to the next. These problems can be solved in part by making biological diversity a source of economic wealth. Wild species are in fact both one of the Earth's most important resources and the least utilized. We have come to depend completely on less than 1% of living species for our existence, the remainder waiting untested and fallow. In the course of history, according to estimates made by Myers (1984), people have utilized about 7,000 kinds of plants for food; predominant among these are wheat, rye, maize, and about a dozen other highly domesticated species. Yet there are at least 75,000 edible plants in existence, and many of these are superior to the crop plants in widest use. Others are potential sources of new pharmaceuticals, fibers, and petroleum substitutes.

In response to the crisis of tropical deforestation and its special threat to biological diversity, proposals are regularly being advanced at the levels of policy and research. For example, Nicholas Guppy (1984), noting the resemblance of the lumbering of rain forests to petroleum extraction as the mining of a nonrenewable resource for short-term profit, has recommended the creation of a cartel, the Organization of Timber-Exporting Countries (OTEC). By controlling production and prices of lumber, the organization could slow production while encouraging member states to 'protect the forest environment in general and gene stocks and special habitats in particular, create plantations to supply industrial and fuel wood, benefit indigenous tribal forest peoples, settle encroachers, and much else.

There is the need for dialogue between the government, industry, non-governmental Agencies, development organizations, women and indigenous people on mechanisms of conservation. Biodiversity conservation must take place at the individual level, global level and in between. The knowledge systems of the indigenous people must not be undermined if conservation efforts are to succeed. The opinions of the local people must be integrated and they must see themselves as stakeholders for conservation efforts to yield positive result.

The issue of environmental ethics--how we value the natural worlds in which we evolved and now, increasingly, how we regard our status as individuals is extolled. We are fundamentally mammals and free spirits who reached this high a level of rationality by the perpetual creation of new options. Natural philosophy and science have brought into clear relief what might be the essential paradox of human existence. The drive toward perpetual expansion--or personal freedom--is basic to the human spirit. But to sustain it we need the most delicate, knowing stewardship of the living world that can be devised. Expansion and stewardship may appear at first to be conflicting goals, but the opposite is true. The depth of the conservation ethic will be measured by the extent to which each of the two approaches to nature is used to reshape and reinforce the other. The paradox can be resolved by changing its premises into forms more suited to ultimate survival, including protection of the human spirit.

The survival of humankind on earth is hinged on the continuous availability of biodiversity through their conservation. This so in the sense that if the present rate of decimation of biodiversity remains unchecked humankind is already doomed. To this end, frantic efforts at biodiversity conservation can ultimately succeed and endure only in the large context of a worldwide transition to sustainable living. Thus, the following ten (10) principles of biodiversity conservation as suggested by the Global Biodiversity Strategy are hereby paraphrased and re-emphasized:

• We must see every life as unique warranting respect from humanity.
• We must see biodiversity conservation as an investment that yields substantial local, regional and global benefits.
• We must be wiling to equitably share among nations and people within a nation the cost and benefit of biodiversity conservation.
• We must change our pattern and practice of economic development to a more sustainable way.
• We need policy and institutional reforms to create the condition through which increased funding for biodiversity conservation can be effective.
• We need to set priorities for biodiversity conservation, but the focus must not be on a few specie-rich ecosystems. It is obvious that priorities differ when viewed from local, national, and global perspective as such all need to be taken into account.
• We must ensure public awareness and concern are substantially heightened and policy makers have access to reliable information upon which to base policy action to sustain biodiversity conservation.
• We must deliberately plan and implement actions to conserve biodiversity at a scale determined by ecological and social criteria.
• We must ensure that our cultural diversity is closely linked to biodiversity. In other words, conserving biodiversity often helps strengthen cultural integrity and values. And finally.
• We must ensure increased public participation, respect for fundamental human right, and improve popular access to education and information and greater institutional accountability as they are essential element of biodiversity conservation.

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