BIODIVERSITY
Introduction :-
The great variety of life on earth has provided for man’s needs over thousands of years. This diversity of living creatures forms a support system which has been used by each civilization for its growth and development. Those that used this “bounty of nature” carefully and sustainably survived. Those that overused or misused it disintegrated.
Science has attempted to classify and categorize the variability in nature for over a century.This has led to an understanding of its organization into communities of plants and animals.This information has helped in utilizing the earth’s biological wealth for the benefit of humanity and has been integral to the process of ‘development’. This includes better health care, better crops and the use of these life forms as raw material for industrial growth which has led to a higher standard of living for the developed world. However this has also produced the modern consumerist society, which has had a negative effect on the diversity of biological resources upon which it is based. The diversity of life on earth is so great that if we use it sustainably we can go on developing new products from biodiversity for many generations. This can only happen if we manage biodiversity as a precious resource and prevent the extinction of species.
Definition:-
‘Biological diversity’ or biodiversity is that part of nature which includes the differences in genes among the individuals of a species, the variety and richness of all the plant and animal species at different scales in space, locally, in a region, in the country and the world, and various types of ecosystems, both terrestrial and aquatic, within a defined area.
What is biodiversity?
1. Genetic diversity
2. Species diversity
3. Ecosystem diversity
Usually three levels of biodiversity are discussed—genetic, species, and ecosystem diversity.Genetic diversity
Each member of any animal or plant species dif- fers widely from other individuals in its genetic makeup because of the large number of com- binations possible in the genes that give every individual specific characteristics. Thus, for ex- ample, each human being is very different from all others. This genetic variability is essential for a healthy breeding population of a species. If the number of breeding individuals is reduced, the dissimilarity of genetic makeup is reduced and in-breeding occurs. Eventually this can lead to the extinction of the species. The diversity in wild species forms the ‘gene pool’ from which our crops and domestic animals have been de- veloped over thousands of years. Today the va- riety of nature’s bounty is being further harnessed by using wild relatives of crop plants to create new varieties of more productive crops and to breed better domestic animals. Modern biotechnology manipulates genes for develop- ing better types of medicines and a variety of industrial products.
Species diversity
The number of species of plants and animals that are present in a region constitutes its spe- cies diversity. This diversity is seen both in natu- ral ecosystems and in agricultural ecosystems. Some areas are more rich in species than oth- ers. Natural undisturbed tropical forests have a much greater species richness than plantations developed by the Forest Department for timberproduction. A natural forest ecosystem provides a large number of non-wood products that lo- cal people depend on such as fruit, fuel wood, fodder, fiber, gum, resin and medicines. Timber plantations do not provide the large variety of goods that are essential for local consumption. In the long-term the economic sustainable re- turns from non-wood forest products is said to be greater than the returns from felling a forest for its timber. Thus the value of a natural forest, with all its species richness is much greater than a plantation. Modern intensive agricultural eco- systems have a relatively lower diversity of crops than traditional agropastoral farming systems where multiple crops were planted.
At present conservation scientists have been able to identify and categorise about 1.8 million spe- cies on earth. However, many new species are being identified, especially in the flowering plants and insects. Areas that are rich in species diversity are called ‘hotspots’ of diversity. India is among the world’s 15 nations that are excep- tionally rich in species diversity.
Ecosystem diversity
There are a large variety of different ecosystems on earth, which have their own complement of distinctive inter linked species based on the dif- ferences in the habitat. Ecosystem diversity can be described for a specific geographical region, or a political entity such as a country, a State or a taluka. Distinctive ecosystems include land- scapes such as forests, grasslands, deserts, mountains, etc., as well as aquatic ecosystems such as rivers, lakes, and the sea. Each region also has man-modified areas such as farmland or grazing pastures. An ecosystem is referred to as ‘natural’ when it is relatively undisturbed by human activities, or ‘modified’ when it is changed to other types of uses, such as farmland or urban areas. Ecosys- tems are most natural in wilderness areas. If natural ecosystems are overused or misused theirproductivity eventually decreases and they are then said to be degraded. India is exceptionally rich in its ecosystem diversity.
HOTSPOTS OF BIODIVERSITY
The earth’s biodiversity is distributed in specific ecological regions. There are over a thousand major ecoregions in the world. Of these, 200 are said to be the richest, rarest and most dis- tinctive natural areas. These areas are referred to as the Global 200. It has been estimated that 50,000 endemic plants which comprise 20% of global plant life, probably occur in only 18 ‘hot spots’ in the world. Countries which have a relatively large proportion of these hot spots of diversity are referred to as ‘megadiversity nations’. The rate at which the extinction of species is occurring throughout our country remains ob scure. It is likely to be extremely high as our wil- derness areas are shrinking rapidly. Our globally accepted national ‘hot spots’ are in the forests of the North-East and the Western Ghats, which are included in the world’s most biorich areas. The Andaman and Nicobar Islands are extremely rich in species and many subspecies of different animals and birds have evolved. Among the endemic species i.e. those species found only in India, a large proportion are con- centrated in these three areas. The Andaman and Nicobar Islands alone have as many as 2200 species of flowering plants and 120 species of ferns. Out of 135 genera of land mammals in India, 85 (63%) are found in the Northeast. The Northeast States have 1,500 endemic plant spe- cies. A major proportion of amphibian and rep- tile species, especially snakes, are concentrated in the Western Ghats, which is also a habitat for 1,500 endemic plant species.
Coral reefs in Indian waters surround the Andaman and Nicobar Islands, Lakshadweep Islands, the Gulf areas of Gujarat and Tamil Nadu. They are nearly as rich in species as tropi- cal evergreen forests!
Hotspots and Biodiversity
As new data enable us to periodically update the hotspots, they also grant us an increasingly complete picture of the natural wealth and human context of these important areas. Here, we examine the current state of our knowledge, building from earlier analyses with updated biodiversity data. The Global Mammal Assess- ment (Schipper et al. 2008), for example, provides substantially revised data on the status and distribution of Earth’s mammals, while recently compiled population (LandScan 2006) and poverty (CIESIN 2005) data sets provide important socio- economic context.
A total of 35 regions now meet the hotspot criteria, each holding at least 1,500 endemic plant species and each having lost 70% or more of its original habitat extent. Combined, the 35 hotspots once covered a land area of 23.7 million km2 , or 15.9% of Earth’s land surface, just less than the land area of Russia and Australia combined. However, as a result of the extreme habitat destruction in these regions over the past century, what remains of the natural vegetation in these areas is down to just 2.3% of the world’s land area (3.4 million km2 ), just greater than the land area of India. More than 85% of the habitat originally present in the hotspots has been destroyed. This means that an irreplaceable wealth of biodiversity is concentrated in what is in fact a very small portion of our planet.
The hotspots hold more than 152,000 plant species, or over 50% of the world’s total, as single-hotspot endemics, and many additional species are surely endemic to combinations of hotspots. While plant numbers are based on specialist estimates, major advances in the reliability of species distribution data allow much more accurate statistics to be compiled for terrestrial vertebrates (birds, amphibians, mammals, and reptiles). Overall, 22,939 terrestrial vertebrates, or 77% of the world’s total, are found in the hotspots. A total of 12,717 vertebrate species (43%) are found only within the biodiversity hotspots, including 10,600 that are endemic to single hotspots and the remainder confined to multiple hotspots. Among individual vertebrate classes, the hotspots harbor as endemics 1,845 mammals (35% of all mammal species), 3,551 birds (35%), 3,608 amphibians (59%), and 3,723 reptiles (46%). If one considers only threatened species – those that are assessed as Critically Endangered, Endangered, or Vulnerable on the IUCN Red List of Threatened Species (IUCN 2008) – we find that 60% of threatened mammals, 63% of threatened birds, and 79% of threatened amphibians are found exclusively within the hotspots. Although reptiles and amphibians show a greater tendency toward hotspot endemism than the generally more wide-ranging birds and mammals, the overall similarity among plant and various vertebrate taxa confirms a general congruence of higher-priority regions across multiple taxa.
Although the concentration of species-level richness and endemism in the hotspots is striking, it is not sufficient to assess the overall biological diversity of the hotspots. It may be that other measures that assess phylogenetic diversity or evolutionary history better represent some aspects of biodiversity – for example, ecological diversity, evolutionary potential, and the range of options for future human use – than does endemism at the species level alone. However, our knowl- edge of phylogenetic information for entire clades is not yet sufficient for detailed analysis of the evolutionary history found within hotspots or other regions (but see Sechrest et al. 2002). Although the delineation of higher taxa (i.e., Linnean categories) is somewhat subjective, taxonomic distinctiveness should be a useful proxy for evolutionary, physiological, and ecological distinctiveness. Overall, the biodiversity hotspots harbor a disproportionate share of higher taxonomic diversity, holding as endemics 1,523 vertebrate genera (23% of all mammal, bird, fish, reptile, and amphibian genera) and 61 families (9%). This is nowhere more striking than in Madagascar and the Indian Ocean Islands Hotspot, which by itself harbors 175 endemic vertebrate genera and 22 endemic vertebrate families, the importance of which cannot be overstated. Other island systems such as the Caribbean, New Zealand, and New Caledonia harbor tremendous endemic diversity at higher taxo- nomic levels, as do mainland systems such as the Tropical Andes and the Eastern Afromontane region.
Although by definition we know little about what future options biodiversity may provide, time and again humanity finds solutions in biodiversity – medicines, foods, engineering prototypes, and other products – that enhance human lives and address our most pressing problems. It is thus difficult to overestimate the impor- tance of maintaining the option value afforded by the vast storehouse of evolution- ary diversity that the biodiversity hotspots represent. This is perhaps nowhere illustrated more clearly than in the case of the gastric-brooding frogs of the genus Rheobatrachus. Discovered in the early 1970s amid the streams and forests of Australia, the two Rheobatrachus species were the only amphibians known to incubate their young internally, in the mother’s stomach. Researchers noted that the compounds secreted to avoid harm to the young might aid the development of treatments for digestive conditions such as ulcers that affect millions of humans worldwide. However, before these possibilities could be explored, the habitats of these unique creatures had become so badly decimated that both species were extinct by the mid-1980s (Hines et al. 1999). As they were endemic to what is now known as the Forests of East Australia Hotspot, failure to conserve them there resulted in their extinction. Redoubled effort is needed in the biodiversity hotspots to ensure that we do not permanently foreclose the opportunity to learn from the evolutionary innovations of other endemic taxa.
Concurrent to the development of the hotspots concept was the recognition of the importance of conserving the least-threatened highly diverse regions of the globe. These high-biodiversity wilderness areas (Mittermeier et al. 2003) are defined on the basis of retaining at least 70% of their original habitat cover, harboring at least 1,500 plant species as endemics, and having a human population density of less than 5 people per km2.
Based on the updated data used in this analysis, the five High-Biodiversity Wilderness Areas (Amazonia, Congo Forests, Miombo- Mopane Woodlands and Savannas, New Guinea, and North American Deserts) hold 28% of the world’s mammals and 20% of the world’s amphibians, including 7% of mammals and 11% of amphibians as endemics, in about 7.9% of the world’s land surface (6.1% including only intact habitats). While the highly threatened hotspots must be conserved to prevent substantial biodiversity loss in the immediate future, there is also strategic advantage in investing in conserving biodiverse wilderness areas, which by virtue of their intactness and comparatively lower costs make good targets for proactive conservation action (Brooks et al. 2006). For this reason, Conservation International has for the past two decades focused on both the biodiversity hotspots and high-biodiversity wilderness areas as part of its two-pronged strategy for global conservation prioritization.
Social and Economic Context importance of biodiversity hotspots:-
The biodiversity extinction crisis is one of several grave challenges facing human- ity today. Climate change and the persistence of poverty pose the prospect of a grim future for Earth and billions of its human inhabitants. These challenges, though, are intimately intertwined. The same environmental degradation that threatens the persistence of species contributes substantially to anthropogenic greenhouse gas emissions and undermines the ecosystem services that support human communities. Climate change will have particularly severe impacts on the poor (Ahmed et al. 2009) and jeopardizes a large portion of Earth’s species (IPCC 2007; Parmesan and Yohe 2003; Thomas et al. 2004). Yet if these problems are inextricably linked, so too are many solutions. Perhaps nowhere is this more evident than in the hotspots.
The hotspots, home to a major portion of the world’s terrestrial biodiversity, are also home to a disproportionate share of its people (Cincotta et al. 2000). Recent population data (LandScan 2006) show that the 35 hotspots contain about 2.08 billion people – 31.8% of all humans – in just 15.9% of Earth’s land area. Populations in hotspots are generally growing faster than the rest of the world. Between the 2002 and 2006 releases of the LandScan population data set, population within hotspots grew an estimated 6.0%, while Earth’s overall popula- tion increased only 4.8%. Hotspots also contain a substantial fraction of the world’s poor. Although spatially explicit estimates of poverty have not been compiled globally, the incidence of child malnutrition provides one measure of the poverty in an area and has been estimated at subnational scales worldwide (CIESIN 2005). These data show that 21% of the world’s malnourished children live in hotspots.
The interactions between biodiversity, extreme habitat loss, other threats, and socioeconomic context are complex. Past habitat loss may have indeed been connected to poverty. For example, the lack of alternative sources for food, fuel, shelter, and income can lead to exploitation of natural habitats to meet these urgent needs. Yet rampant consumption of energy, food, and raw materials by both devel- oped and developing countries has played just as great a role in the degradation of these areas, albeit from regions often geographically distant from hotspots. But even this more complete picture misses a critical point. Regardless of past causes, the more pressing issue is that all of humanity depends on the habitats that remain in biodiversity hotspots. Poor communities are often those most dependent on sustain- ing the clean water, protection from storms, and other ecosystem services they derive from nature. Based on Turner et al. (2007), the estimated value of all services provided by the hotspots’ remaining habitats is $1.59 trillion annually – on a per-area basis more than seven times that provided by the average square kilometer of land worldwide. This calculation is almost certainly an underestimate, as it does not account for the increase in value that may result from the increasing scarcity of these services in hotspots in the face of increasing need for them. Meanwhile, it is not just the poor communities in hotspots that benefit from these services. For example, based on recent data (Reusch and Gibbs 2008), the hotspots store more than 99 Gt of carbon in living plant tissues, and still more in peat and other soils. The greenhouse gas emission reductions that result from slowing high rates of habitat loss in these regions are a critical contribution to slowing global warming.
Hotspots are very important for the survival of human cultural diversity. A study of the distribution of human languages (Gorenflo et al. 2008) used human linguistic diversity as a surrogate for human cultural diversity and found that about 46% of the 6,900 languages still spoken are found within the borders of the hotspots and at least 32% of languages are spoken nowhere else. This concentration very much parallels what we see in terms of endemic species. What is more, it also includes a very high proportion of the languages, and the unique cultures speaking them, most at risk of disappearing over the next few decades.
Hotspots are also notable as centers of violent conflict. Another recent study (Hanson et al. 2009) found that 80% of the world’s violent conflicts since 1950 (i.e., those involving more than 1,000 deaths) took place within the biodiversity hotspots and most hotspots experienced repeated episodes of violence over the 60-year span. This result suggests that, if conservation in hotspots is to succeed, conservation efforts must maintain focus during periods of war and that biodiversity conservation considerations should be factored into military, humanitarian, and reconstruction programs in the world’s war zones.
Securing Hotspots for the Future
Threats to hotspots are similar to, although generally more intense than, threats to biodiversity worldwide. Habitat destruction, projected to remain the dominant threat to terrestrial biodiversity even in an era of climate change (Sala et al. 2000), is pervasive in hotspots and driving extinctions in many (Brooks et al. 2002). The growing impacts of climate change will be felt worldwide, as altered precipitation and temperature, rising oceans, and climate-driven habitat loss threaten a large fraction of species with extinction (Thomas et al. 2004) and drive desperate human populations to further environmental degradation (Turner et al. 2010). Other threats are less widespread, but felt severely in particular regions. Introduced predators have devastated island hotspots, where species evolved in the absence of domestic cats and rats and other invasive predators (Steadman 1995). Introduced plants are having massive impacts on hydrology and biodiversity in some hotspots, particularly those having Mediterranean-type vegetation (Groves and di Castri 1991). Exploitation for protein (e.g., bushmeat), for medicine, and for the pet trade threatens species in all hotspots, particularly the Guinean forests of West Africa (Bakarr et al. 2001), Madagascar, and hotspots in Southeast Asia (van Dijk et al. 2000). Chitridiomycosis, a fungal disease, is recognized as a proximate driver of amphibian declines and extinctions worldwide (Stuart et al. 2004; Wake and Vredenburg 2008). It may prove to be the most destructive infectious disease in recorded history, with a substantial effect on the hotspots, which harbor an astonish- ing 59% of all amphibians as endemics.
The establishment and effective management of protected areas (Bruner et al. 2001) must continue to be the cornerstone of efforts to halt the loss of biodiversity, both in the hotspots and elsewhere. These areas may be in the form of national parks or strict biological reserves or may come in a variety of other forms, depending on local context, including indigenous reserves, private protected areas, and commu- nity conservation agreements of various kinds. An overlay of the hotspots with protected areas with defined boundaries from the World Database on Protected Areas (IUCN and WCMC 2009) reveals that 12% of the original area of the 35 hotspots is under some form of protection, while 6% is classified as IUCN category I–IV protected area (which provides a higher degree of protection in terms of constraints on human occupation or resource use). These numbers are underestimates since boundaries for many protected areas have not been systemati- cally compiled, and they certainly overestimate the land area that is managed effectively. Yet the fraction of hotspots covered is less meaningful than the locations themselves. Efforts to conserve the hotspots must focus on ensuring long-term persistence of the areas already protected and strategically add new protected areas in the highest priority unprotected habitats that remain intact as indicated by systematic efforts to identify gaps in protected areas networks (e.g., Rodrigues et al. 2004).
Maintaining the resilience of hotspots in the face of climate change is another major challenge. Changing temperature and precipitation patterns forces species to move according to movement in their preferred habitat conditions, yet these movements will often be both difficult for species to undertake and complex for researchers to predict. Due to the nature of climatic gradients, the distances species must move are likely to be shorter in mountainous terrain and longer in flatter regions (Loarie et al. 2009). On the other hand, mountains are more likely to have habitat discontinuities that make species dispersal more difficult. Meanwhile, species’ tolerance to climate variability can be low (Tewksbury et al. 2008) and changing climates are likely to produce a complex global mosaic of climates shifted in space, climates which disappear in the future, and entirely novel climates (Williams et al. 2007). To be successful, then, conservation planning must begin to systematically plan actions in both space and time. Protecting the sites where species currently exist is essential, particularly the Key Biodiversity Areas where species are at greatest current risk (Eken et al. 2004). The hotspots, in fact, harbor 81% of the global total 595 Alliance for Zero Extinction sites – locations harboring the sole remaining populations of the most threatened species (Ricketts et al. 2005). If we lose these sites now, we will not be granted another chance to save their species later. However, this is only the beginning. We must also protect habitats where species will be in the future, as well as provide “stepping stones” to facilitate movement to these new ranges. Biologists are increasing their ability to anticipate and plan for these needs (Hannah et al. 2007). To be successful, conservation in a changing climate will require a very strong focus on ending further habitat destruction as quickly as possible.
Conclusion
Based initially on plant endemism, the hotspots have in the past two decades been confirmed as priority regions for the efficient conservation of biodiversity more broadly. Collectively, they harbor more than half of all plant species and 43% of all terrestrial vertebrates as endemics, an even greater proportion of threatened species, and a substantial fraction of higher-taxonomic diversity. More recent information has revealed that this phenomenal concentration of biodiversity into habitats cov- ering a combined 2.3% of the world’s land area coincides with disproportionate concentrations of ecosystem services in many of the regions where local communities directly depend on the natural environment on a daily basis. While conservation in these areas is made difficult by ongoing threats, scarce information, and limited local financial capacity, conservation here is not optional. Indeed, if we fail in the hotspots, we will lose nearly half of all terrestrial species regardless of how successful we are everywhere else, not to mention an almost unthinkably large contribution to greenhouse gas emissions and extensive human suffering resulting from loss of ecosystem services upon which the human populations of the hotspots ultimately depend. Ongoing research reviewed here and in the rest of this volume serves as a rallying cry for greatly augmented funding, research, and political action on behalf of hotspot conservation. The future of life on Earth depends on it.
