This article throws light upon the top eight things to know about Biodiversity. They are:- 1. Introduction to Biodiversity 2. Classification of Biodiversity 3. Global Biodiversity 4. National Biodiversity: India as a Mega-Diversity Nation 5. Local or Regional Biodiversity 6. Measurement 7. Hot Spots of Biodiversity 8. Biodiversity Conservation.
Biodiversity # 1 Introduction:
Biodiversity refers to the wide variety of life forms on earth and the ecosystem complexes in which they occur.
The biosphere comprises of a complex collection of innumerable organisms, known as biodiversity which constitutes the vital life support for the survival of human race.
In the convention of Biological diversity signed at Rio de Janeiro (Brazil) in 1992 by 172 nations, the Biological diversity is defined as the variability among living organisms from all sources including interalia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part. This includes diversity within species, between species and ecosystems.
Biological diversity (or biodiversity) represents the sum total of various life forms such as unicellular fungi, bacteria, protozoa and multicellular organisms such as plants, fishes, birds and mammals at various biological levels including genes, species, habitats and ecosystems. Our biological systems are constantly impoverished by human activities.
Only the man is responsible for the destruction of habitats through intensive agricultural development, urbanisation, industrialisation, over population, deforestation, exploitation of resources and ethical degradation etc. Thus strategies must be developed and implemented for the preservation, maintenance and restoration of forest ecosystems while simultaneously formulating action plan for the sustainable use of forest resources including efficient utilisation, recycling techniques and reforestation.
Biodiversity # 2 Classification:
Units of biodiversity may range from the genetic level within a species to the biota in a specific region and may extend upto the great diversity found in different biomes.
1. Genetic Diversity (Diversity of Genetic Organisation within a Species):
There exist several varieties within any given species which slightly differ from each other in one or more characteristics such as shape, size, resistance against insects, pests, diseases and resilience to survive under adverse environmental conditions. Such a diversity in the genetic make-up of a species is known as genetic diversity. When the genes within the same species show different versions due to new combinations, it is called genetic variability. A species having large number of varieties, strains or races is considered as rich and more diverse in its genetic organisation.
2. Species Diversity (Diversity of Species within a Community):
The richness of species in an ecosystem is called species diversity. The biotic component of an ecosystem may be composed of a number of species of plants, animals and microbes which interact with each other and also interact with the abiotic factors of the environment.
Estimates of 2010 indicate that about 10 to 80 million species exist on earth. However, only 1.5 million living species have been assessed and enlisted so far. We have been losing this accumulated heritage by our own activities, thereby undermining the very basis of our own existence.
3. Biotic Community and Ecosystem Diversity:
This is the diversity of ecological complexity showing variations in ecological niches, trophic structures, functions, food webs and nutrient cycling etc. An ecosystem develops its own characteristic community of living organisms depending upon the availability of abiotic resources, environmental conditions like moisture, temperature, altitude and precipitation etc. Different types of forests, grass lands, meadows, rivers, lakes, ponds etc. represent diverse ecosystem with their own characteristic biotic community. For example, a pond may possess different sets of flora and fauna as compared to another ecosystem such as a river.
4. Landscape Diversity:
It refers to the placement, size and distribution of various ecosystems and their interactions across a given land surface.
Biodiversity # 3 Global Biodiversity:
Globally, about 1.5 million species are known till date which is perhaps 2% of the actual number. We have roughly 170,000 flowering plants, 30,000 vertebrates, about 250,000 other groups of species and the remaining species may range from 8 million to 100 million. Table 4 illustrates the estimated number of some known living species (1,400,000) in different taxonomic groups.
Terrestrial biodiversity of earth is best described as biomes. Biomes are the largest ecological units present in different geographic areas and are named after the dominant vegetation, e.g., the tropical rain forests, coniferous, deciduous forests, savannas, desert, tundra etc.
The tropical rain forests constitute about 50% to 80% of global biodiversity and are inhabited by teeming millions of species of plants, birds, insects, amphibians and mammals. They are the earth’s largest store house of biodiversity. More than one-third of the world’s therapeutic drugs are extracted from plants growing in tropical forests.
Out of the 3,000 plants identified by National Cancer Research Institute as sources of cancer fighting drugs 70% come from tropical rain forests. Very recently, extract from one of the creeping vines in the rain forest at Cameroon has proved effective in the inhibition of replication of AIDS virus.
The wonderful Neem tree known for its medicinal properties in tropical India, has now come into lime light even in the western temperate countries. Euphorbia lathyris (Grophar or gasoline tree), the most suitable energy plant, contains more than 5% oil and polymeric hydrocarbons.
Tropical forests having 1,25,000 flowering plants are the treasure house of food, medicines and commerce. Tropical deforestation alone is reducing the biodiversity by half a percent every year. Several species are becoming extinct before they have been discovered. The Silent Valley in Kerala is the only place in India where tropical rain forests occur.
Needless to say, we must protect our precious forests. The case of Silent Valley Hydroelectric Project was abandoned mainly because it had exposed to risk our tropical rain forest biodiversity. Temperate forests have much less biodiversity but there is much better documentation of species.
Marine diversity is even much higher than terrestrial biodiversity and ironically, they are still less known. Estuaries, coastal waters and oceans are biologically diverse and the diversity is just dazzling. Sea is the cradle of every known animal phylum. Out of the 35 existing phyla of multicellular animals, 34 are marine and 16 of these are exclusively marine.
Mapping the biodiversity has, therefore, been rightly recognized as an emergency matter in order to plan its conservation and practical utilization in a judicious manner.
Biodiversity # 4 National Biodiversity: India as a Mega-Diversity Nation:
India is one of the 12 mega-diversity countries in the world. It ranks 10th among the plant rich countries, 11th in terms of endemic species of higher vertebrates and 6th among centres of diversity and origin of agricultural crops. The Ministry of Environment and Forests, Government of India currently recorded 47,000 species of plants and 81,000 species of animals which is about 7% and 6.5% of global flora and fauna.
1. India is unique in having immense natural beauty in its different biomes and in possessing a diverse flora and fauna.
2. Indian wildlife is incomparable in its variety. The tiger, lion, leopard, elephant, rhinoceros, snakes and minks are found here in abundance. India has more graceful deers, peacocks and cats than any other country in the world.
3. India includes more than 150 families of terrestrial vertebrates and more than 7,50,000 species of insects.
4. The animals like black buck, Nilgiri tahr, pigmy hog, golden langur, lion-tailed macaque etc., are unique wild animals of India. India is gifted with a wide variety of deers such as musk deer (Kastura), barking deer, spotted deer (Cheetal), swamp deer (Bara singha), hog deer, mouse deer and dancing deer (Sambhar).
5. The typical wild Indian birds include peafowl, jungle fowl, quail, duck, pigeon, sand grouse, eagle, pelican, hornbill etc.
6. Indian reptiles include crocodiles, lizards, gharials and more than 125 varieties of snakes.
Many wild animals have disappeared due to natural and human activities. About 600 species of animals and birds have become extinct because of climatic and geographical changes and also by over-hunting by man for food, fur, recreation and monetary benefits.
Endemism (species restricted only to a particular area):
About 62% of amphibians and 50% of lizards are endemic to India. Western ghats exhibit the site of maximum endemism. [Also refer to Endemic species of India in the same Unit].
Centre of origin:
India has been the centre of origin of 5000 species of flowering plants, 166 species of crop plants and 320 species of wild varieties of cultivated crops, thereby providing a broad spectrum of diversity of traits for crop plants.
In India, marine diversity is rich in molluscs, crustaceans, corals, polychaetes, mangrove plants and sea grasses. More than 350 species of corals of the world are found here. India has two hot spots of biodiversity (out of 25) in north-east region and western ghats. However, a large proportion of biodiversity (93 major wetlands, coral reefs and mangroves) is still to be fully explored.
Biodiversity # 5 Local or Regional Biodiversity:
Biodiversity at regional level can be categorized into three types based upon their spatial distribution:
1. Alpha Diversity.
Alpha diversity indicates diversity within the community. It refers to the diversity of organisms sharing the same community or habitat in a small homogeneous area. Alpha diversity is strongly correlated with physical environmental variables. For example, there are 100 species of tunicates in arctic waters, 400 species in temperate waters and 600 species in tropical seas. Thus, temperature seems to be the most important factor affecting alpha richness of tunicates.
2. Beta Diversity:
Beta diversity indicates diversity between communities across different habitats and environmental gradients. Beta richness means that the cumulative number of species increases as more heterogeneous habitats are taken into consideration. For example, the ant species found in the local regions of north pole is merely 10. As we keep on moving towards the equator and add more and more habitats, the number of ant species reaches as high as 2000 on the equatorial region.
3. Gamma Diversity:
Gamma diversity refers to the diversity of habitats over the total landscape gradients or geographical area. The diverse communities are functionally more productive and stable even under environmental stresses.
Biodiversity # 6 Measurement:
The most common measures of biodiversity are given below:
1. Species Richness (S):
Species richness is the simplest of all the measures of subspecies diversity where we have just to count the number of subspecies present in a community. However, this does not indicate how the diversity of population is distributed or organized among those particular subspecies. For example, if there are 4 different subspecies observed in zone 1 and zone 2, the richness would be equal. But this does not take into account the percentage of the abundance of each subspecies.
2. Simpson Index (D):
Simpson index measurement accounts for both the richness and percentage of each subspecies within a zone.
3. Shannon-Wiener or Shannon-Weaver Index (H):
It measures the order (or disorder) observed within a particular system. Similar to Simpson’s index, this measurement takes into account subspecies richness and proportion within a zone.
Note that diversity indices are mathematical functions that combine richness and even-ness in a single measure, although usually not explicitly. If species i comprises proportion pi of the total individuals in a community of S species, the Shannon diversity is
and Simpson diversity is
Both Shannon and Simpson diversities increase with increase in richness and even-ness for a given pattern but they do not always rank communities in the same order. Simpson diversity is less sensitive to richness and more sensitive to even-ness than Shannon diversity, which in turn, is more sensitive to even-ness than is a simple count of species (richness, S).
4. Berger-Parker Index:
It depends exclusively on even-ness. It is simply the inverse of the proportion of individuals in the community that belong to the single most common species, 1/pi (max).
5. Fisher’s α:
Fisher’s α, proposed by R.A. Fisher, is derived from the log series distribution as a general model for relative abundance:
where successive terms represent the number of species with 1, 2, 3, … n individuals and a is treated as an index of species diversity. Estimating a from relative abundance distribution, however, depends only on S (total number of species) and N (total number of individuals) but nevertheless requires substantial computation. Fisher’s α is relatively insensitive to rare species.
Which measure of diversity should be used?
It depends on what one wishes to focus on (pure richness or a combination of richness and even-ness), the relative abundance pattern of the data, comparability to previous studies and the interpretability of the results.
Biodiversity # 7 Hot Spots of Biodiversity:
Hot spots of biodiversity are the areas which exhibit high species richness and exceptional concentration of species endemism. Hot spots are the most threatened reservoir of plant and animal life on earth. The term was first introduced by Norman Myers in 1988. There are 25 such hot spots on a global level out of which two are present in India, namely the Eastern Himalayas and Western Ghats (Table 6).
Fifteen hot spots occur in tropical forests, five are Mediterranean type and five are islands. These hot spots covering 1.4% of the total world’s land area are found to exhibit 40% of terrestrial plants and 25% of vertebrate species. After the tropical rain forests, the second highest number of endemic plant species is found in the Mediterranean (Mittermeier).
Broadly, these hot spots are in Western Amazon, Madagascar, Borneo, North-Eastern Australia, West Africa, Brazil’s Atlantic forests, Arctic Tundra, Alaska, Mauritius and Alps. About l/6th of the world’s population, most of whom are desperately poor people, live in these areas. Any measure of protecting these hot spots needs to be planned keeping in view the human settlements and tribal issues.
Hot Spots of India:
Hot spots of India are not only rich in floral wealth and endemic species of plants but also exhibit diversity among amphibians, reptiles, tailed butterflies and some mammals. Two out of 25 hot spots lie in India extending into neighbouring countries namely, Indo-Burma region (covering Eastern Himalayas) and Western Ghats—Sri Lanka region.
(A) Eastern Himalayas:
Eastern Himalayas display an ultra-varied topography that fosters species diversity and endemism. There are numerous deep valleys in Sikkim which are extremely rich in endemic species. In an area of 7298 km2 of Sikkim, about 4300 plant species are found of which 60% are endemic.
The North-East India along with its contiguous regions of Burma and Chinese provinces of Yunnan and Schezwan is considered as the cradle of flowering plants. Out of the world’s recorded flora, 33% are endemic to India of which 35,100 are in the Himalayas.
Now forest cover of Eastern Himalayas has dwindled to 1/3 of its original arena. Certain species like Sapria himalayana, a parasitic angiosperm was seen rarely during the last 50 years.
(B) Western Ghats:
Western Ghats extend along a 17,000 km2 strip of forests in Tamil Nadu, Kerala, Karnataka and Maharashtra and have 40% of the total endemic plant species. About 50% lizards and 62% amphibians are endemic to Western Ghats. The major centres of evergreen diversity are Agastyamalai Hills and Silent Valley—the new Amambalam Reserve Basin. It is reported that only 6.8% of the original forests are existing today while the rest have been deforested.
Although the hot spots are characterized by endemism, yet a few species are common to both the hot spots in India. Common plants include Hypericum, Rhododendron, Ternstroemia japonica while the common fauna include Fairy blue bird, laughing thrush and lizard hawk etc.
Other hot spots of India facing threat to endemic species include Silent Valley (Kerala), Palni and Nilgiri hills (Tamil Nadu), Kodai and Ooti lake (Tamil Nadu), Doon Valley (Uttaranchal), Chilka lake (Orissa), Narayan Sarovar (Gujarat), Sunderbans (West Bengal), Thar desert (Rajasthan), Dal lake (Kashmir), Gir forest and little Rann of Kachch (Gujarat), wet land and Sariska (Rajasthan).
The hot spot approach has been valuable in enabling nations to better target their conservation investments. Efforts are underway to identify hot spot areas of other ecosystems, including wetlands, deserts and large lakes.
Biodiversity # 8 Biodiversity Conservation:
Biodiversity is the most valuable gift of nature and it is an insurance for our food and ecological security.
It represents the very essence of life on the earth and maximum efforts should be done:
(i) To preserve the biological diversity.
(ii) To maintain essential ecological processes and life support systems.
(iii) To ensure that any utilisation of species and ecosystem is sustainable.
Following steps may go a long way in conserving biodiversity:
1. Biodiversity Inventories:
Better inventories and assessments are needed of current conditions, abundance, distribution and management direction for genetic resources, species populations, biological communities and ecological systems. For this purpose, the following activities may be supported.
a. Survey to map out the distribution of earth’s ecosystems.
b. Rapid assessment programmes to provide a Snap-Shot of richness of species,
c. Extensive inventory efforts should be focused on poorly known habitats, degraded and multiple-use habitats as well as on vertebrates and vascular plants that can be used as benchmarks for habitat quality.
d. Intensive inventories, to determine all the species present, from microbes to vertebrates, should be prepared at selected sites.
These efforts will lead to significant improvement in inventory processes, methodologies and technologies such as given below:
a. Enable the best use of existing information and new technologies such as remote sensing and geographical information system (GIS).
b. Provide estimates of resources in specific geographical units and evaluate their reliability.
c. Eliminate redundant data collection, develop common terminology and promote data sharing through corporate data bases.
d. Provide a base-line for monitoring changes in the condition of the resources.
e. Provide up-to-date data base using modelling techniques, accounting procedures and re-inventories.
f. Ensure optimum utilisation of information management systems to provide maximum flexibility for data integration and manipulation.
2. Conserving Biodiversity in Protected Habitats:
The two basic approaches to the wildlife conservation are as follows:
(A) In-situ Conservation (within habitat in nature):
In-situ conservation involves protection of a group of typical ecosystems through a network of protected areas like biosphere reserves, national parks, sanctuaries, sacred lakes and reserve forests.
(i) Biosphere Reserves:
Biosphere reserves conserve some representative ecosystems containing unique biological communities. They also ensure conservation of landscapes, species and genetic resources. At present, India has 13 Biosphere reserves viz. Nanda devi (UP), Nokrek (Meghalaya), Manas (Assam), Sunderbans (West Bengal), Gulf of Mannar (Tamil Nadu), Nilgiri (Karnataka, Kerala, Tamil Nadu), Great Nicobars and Similipal (Orissa), Dibru saikhowa, Dehan debang, Pachmarhi, Agasthyamalai and Khanghendzonga.
(ii) Protected areas (National parks and sanctuaries):
Protected areas of land or sea are specially dedicated to the protection of biodiversity and associated cultural resources. The World Conservation Monitoring Centre (WCMC) has recognised 37000 protected areas around the world. As on September 2002, India had 581 protected areas (89 National parks and 492 wildlife sanctuaries).
A national park is an area which is strictly reserved for the welfare of wildlife and where activities such as forestry, grazing, cultivation, habitat manipulation and private rights are prohibited.
Major national parks with important wildlife are listed in Table 7:
Sanctuaries are protected areas where killing, hunting, shooting or capturing of wildlife are prohibited. However, private ownership rights and forestry operations are permitted to the extent that they do not affect wildlife adversely.
Some sanctuaries with major wildlife are given in Table 8:
Gene pool is defined as the total number of genes of every individual in an interbreeding population possessed by a specific species at a particular time. A large gene pool indicates high genetic diversity, increased chances of biological fitness and survival. A small gene pool shows low genetic diversity, reduced chances of acquiring fitness and increased possibility of extinction. Gene pool increases when mutation occurs and survives. It decreases when population size is significantly reduced by genetic diseases and deformities.
Gene pool gives an idea of the number of varieties and types of genes existing in a population. It can be used to determine gene frequencies or the ratio between different types of genes in a population.
For plants, there is one gene sanctuary for citrus (Lemon family) and one for pitcher plant (an insect eating plant) in North east, India.
(B) Ex-situ Conservation (Outside habitats):
Ex-situ conservation is achieved by establishment of gene banks, germ plasm banks, seed banks, zoos, botanical gardens, genetic resource centres, pollen grains, tissue culture and DNA banks. Here endangered plants and animals are collected and bred under controlled conditions in captivity under human care.
The International Board for Plant Genetic Resources was framed in 1974 with its Head quarters in Rome. By 1985, a chain of 43 gene banks was set up in different countries. In India, we have following important gene bank/seed bank facilities.
(i) National Bureau of Plant Genetic Resources (NBPGR), New Delhi. Here agricultural and horticultural crops and their wild varieties are preserved by cryo-preservation of seeds, pollens etc. by using liquid nitrogen at a very low temperature of -196°C. Varieties of rice, tomato, onion, chilli, turnip, radish, carrot, tobacco, poppy etc., have been preserved for several years without losing seed viability.
(ii) National Bureau of Animal Genetic Resources (NBAGR), Karnal, Haryana. It preserves semen of domesticated bovine animals.
(iii) National Facility for Plant Tissue Culture Repository for the conservation of varieties of crop plants or trees by tissue culture. This facility has been created within the NBPGR. The G-15 countries have also resolved to set up a net work of gene banks to facilitate the conservation of varieties of aromatic and medicinal plants for which India is the networking coordinator country.
3. Restoration of Biodiversity:
Biodiversity is threatened not only by reduction of habitat area but also by degradation of quality of the remaining habitats. By restoring both the extent and quality of important habitats, restoration programmes provide refuge for species and genetic resources that might be lost otherwise.
Several techniques are used in India to restore ecosystems depending upon the nature of the ecosystem and the impact of type being addressed. These techniques include vegetation, planting to control erosion, fertilization of existing vegetation to encourage growth, removal of contaminated soils, fencing to prevent cattle, reintroduction of extirpated species, restoration of hydrologic connections to wetlands, etc.
Rapid reforestation to reinstate green plant cover on barren lands, hill slopes, highways, roads etc. taking care to ensure that the species planted are ecologically compatible to the region and useful to the local people, will go a long way in restoring biodiversity. However, restoration is not a substitute for the preservation or good management as it is both expensive and time consuming.
4. Imparting Environment Related Education:
People at large should be motivated to conserve resources, to avoid extravagance and educated properly regarding ecological issues. All efforts should be made to conserve indigenous knowledge, traditions and environment friendly practices.
5. Population Control:
Effective population control measures have to be adopted as a top-priority issue in the national agenda by involving people of all political parties, religious faiths and social organisations. Suitable incentives and disincentives should be in-built into the strategies specially formulated for this purpose.
6. Enacting, Strengthening and Enforcing Environment Related Legislations:
Existing environment laws against unsound ecological practices should be strengthened and enforced ruthlessly. Simultaneously, voluntary organisations should be motivated to include protection of biodiversity as a major and priority issue in their agenda.
7. Controlling Urbanization:
Ever-increasing urbanization and expansion of urban settlements should be controlled. Biological diversity should be infused into the urban localities.
8. Reviewing Agricultural Practices:
We should refrain from temptation of high yield and making a fast buck at the cost of sustainable development. So try to infuse diversity in our agricultural practices by restoring to mixed cropping poly-culture and tolerance to wild plants and other life forms around agricultural fields. A healthy soil should be maintained by using natural manures and less synthetic fertilizers and pesticides. All our efforts should be made to maintain a balanced prey-predator relationship in agro-ecosystems.