You have already learnt about the geomorphic processes particularly weathering and depth of weathering mantle in different climatic zones. See the Figure 6.2 in Chapter 6 in order to recapitulate. You should know that this weathering mantle is the basis for the diversity of vegetation and hence, the biodiversity. The basic cause for such weathering variations and resultant biodiversity is the input of solar energy and water. No wonder that the areas that are rich in these inputs are the areas of wide spectrum of biodiversity.
Biodiversity is a system in constant evolution, from a view point of species, as well as from view point of an individual organism. The average half-life of a species is estimated at between one and four million years, and 99 per cent of the species that have ever lived on the earth are today extinct. Biodiversity is not found evenly on the earth. It is consistently richer in the tropics. As one approaches the polar regions, one finds larger and larger populations of fewer and fewer species. Biodiversity itself is a combination of two words, Bio (life) and diversity (variety). In simple terms, biodiversity is the number and variety of organisms found within a specified geographic region. It refers to the varieties of plants, animals and micro-organisms, the genes they contain and the ecosystems they form. It relates to the variability among living organisms on the earth, including the variability within and between the species and that within and between the ecosystems. Biodiversity is our living wealth. It is a result of hundreds of millions of years of evolutionary history.
Biodiversity can be discussed at three levels :
(i) Genetic diversity; (ii) Species diversity;
(iii) Ecosystem diversity.
Genetic Diversity
Genes are the basic building blocks of various life forms. Genetic biodiversity refers to the variation of genes within species. Groups of individual organisms having certain similarities in their physical characteristics are called species. Human beings genetically belong to the homo sapiens group and also differ in their characteristics such as height, colour, physical appearance, etc., considerably. This is due to genetic diversity. This genetic diversity is essential for a healthy breeding of population of species.
Species Diversity
This refers to the variety of species. It relates to the number of species in a defined area. The diversity of species can be measured through its richness, abundance and types. Some areas are more rich in species than others. Areas rich in species diversity are called hotspots of diversity (Figure 16.5). Ecosystem Diversity You have studied about the ecosystem in the earlier chapter. The broad differences between ecosystem types and the diversity of habitats and ecological processes occurring within each ecosystem type constitute the ecosystem diversity. The ‘boundaries’ of communities (associations of species) and ecosystems are not very rigidly defined. Thus, the demarcation of ecosystem boundaries is difficult and complex.
Importance of Biodiversity
Biodiversity has contributed in many ways to the development of human culture and, in turn, human communities have played a major role in shaping the diversity of nature at the genetic, species and ecological levels.
Biodiversity plays the following roles: ecological, economic and scientific. Ecological Role of Biodiversity Species of many kinds perform some function or the other in an ecosystem. Nothing in an ecosystem evolves and sustains without any reason. That means, every organism, besides extracting its needs, also contributes something of useful to other organisms. Can you think of the way we, humans contribute to the sustenance of ecosystems. Species capture and store energy, produce and decompose organic materials, help to cycle water and nutrients throughout the ecosystem, fix atmospheric gases and help regulate the climate. These functions are important for ecosystem function and human survival. The more diverse an ecosystem, better are the chances for the species to survive through adversities and attacks, and consequently, is more productive. Hence, the loss of species would decrease the ability of the system to maintain itself. Just like a species with a high genetic diversity, an ecosystem with high biodiversity may have a greater chance of adapting to environmental change. In other words, the more the variety of species in an ecosystem, the more stable the ecosystem is likely to be.
Economic Role of Biodiversity
For all humans, biodiversity is an important resource in their day-to-day life. One important part of biodiversity is ‘crop diversity’, which is also called agro-biodiversity. Biodiversity is seen as a reservoir of resources to be drawn upon for the manufacture of food, pharmaceutical, and cosmetic products. This concept of biological resources is responsible for the deterioration of biodiversity. At the same time, it is also the origin of new conflicts dealing with rules of division and appropriation of natural resources. Some of the important economic commodities that biodiversity supplies to humankind are: food crops, livestock, forestry, fish, medicinal resources, etc. Scientific Role of Biodiversity Biodiversity is important because each species can give us some clue as to how life evolved and will continue to evolve. Biodiversity also helps in understanding how life functions and the role of each species in sustaining ecosystems of which we are also a species. This fact must be drawn upon every one of us so that we live and let other species also live their lives.
It is our ethical responsibility to consider that each and every species along with us have an intrinsic right to exist. Hence, it is morally wrong to voluntarily cause the extinction of any species. The level of biodiversity is a good indicator of the state of our relationships with other living species. In fact, the concept of biodiversity is an integral part of many human cultures.
Excercise
1. Multiple choice questions.
(i) Conservation of biodiversity is important for :
(a) Animals (c) Plants
(b) Animals and plants (d) All organisms
(ii) Threatened species are those which :
(a) threaten others
(b) Lion and tiger
(c) are abundant in number
(d) are suffering from the danger of extinction
(iii) National parks and sanctuaries are established for the purpose of :
(a) Recreation (c) Pets
(b) Hunting (d) Conservation
(iv) Biodiversity is richer in :
(a) Tropical Regions (c) Temperate Regions
(b) Polar Regions (d) Oceans
(v) In which one of the following countries, the ‘Earth Summit’ was held?
(a) the UK (c) Brazil
(b) Mexico (d) China
2. Answer the following questions in about 30 words.
(i) What is biodiversity?
(ii) What are the different levels of biodiversity?
(iii) What do you understand by ‘hotspots’?
(iv) Discuss briefly the importance of animals to human kind.
(v) What do you understand by ‘exotic species’?
3. Answer the following questions in about 150 words.
(i) What are the roles played by biodiversity in the shaping of nature?
(ii) What are the major factors that are responsible for the loss of biodiversity?
What steps are needed to prevent them?
Please refer to attached file for NCERT Class 11 Geography BioDiversity And Conservation
