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बेसिक इंग्लिश का दूसरा सत्र (कक्षा प्रारंभ : 22 अक्तूबर, शाम 3:30 से 5:30)
May 22, 2014

What is biodiversity?

  • Biological diversity - or biodiversity - is a term use to describe the variety of life on Earth. It refers to the wide variety of ecosystems and living organisms: animals, plants, their habitats and their genes.

  • Biodiversity is the foundation of life on Earth. It is crucial for the functioning of ecosystems which provide us with products and services without which we couldn’t live. Oxygen, food, fresh water, fertile soil, medicines, shelter, protection from storms and floods, stable climate and recreation - all have their source in nature and healthy ecosystems. 

  • But biodiversity gives us much more than this. We depend on it for our security and health; it strongly affects our social relations and gives us freedom and choice.

  • Biodiversity is extremely complex, dynamic and varied like no other feature of the Earth. 

  • Biodiversity is the variation in living organisms, viewed within a given habitat, ecosystem or in the world as a whole. All living organisms & the environment in which they live-in are mutually reactive. They tend to affect each other in various ways 

  • In one line, it can be called as co-actions & reactions .The biodiversity we see today, is the fruit of billions of years of evolution, shaped by natural processes and increasingly affected by the influence of humans. It forms the web of life of which we are an integral part and upon which we so fully depend 

  • The species react to environmental changes & adapt them structurally & physiologically.

  • The environment, in turn, is also affected in accordance with species specific activities not only their growth but dispersal, reproduction, pollination, decay & even their death affects environment

  • Under similar temperature & climatic conditions, there may simultaneously develop more than one colony of different communities. Some of these species might just be off taking from a starting stage while others might have reached their climax stage , rest being in their different stages of succession  

Biodiversity can be discussed at three levels

1. Genetic Diversity :

  • May be defined as variation in genes with a particular species. It refers to the heritable variation. Sexual reproduction plays an important role genetic diversity. A species having more genetic diversity can adapt better to the changed environmental conditions.

  • Genetic diversity is the variety in the genetic make-up among individuals  within a species. Many plants and some animal species have as many as  400,000 genes. These can give rise to enormous genetic variations in the individuals, in the species. 

  • The amount of diversity at the genetic level is important because it represents the raw material for evolution and adaptation. 

  • More genetic diversity in a species or population means greater ability for some of the individuals in it to adapt to changes in the environment.

  • Less diversity leads to uniformity, which is a problem in the long term. It is unlikely that any individual in such a population would be able to adapt to changing conditions.

  • Domesticated species often have low levels of genetic diversity. This is caused by the artificial selection, or preferential breeding. of crops and animals for traits that humans find preferable. While this can have positive short-term results, such as a richer harvest, low diversity among domesticated species poses risks. A newly-evolved virus or bacteria strand can invade a population of nearly identical organisms very rapidly. The protection that diversity generally offers in wild population is lost in this scenario. 

    The Irish Potato Famine between 1845 and 1852 was caused by a parasite invading a large population of nearly identical potatoes. The parasite was a water mold named Phytophthora infestans. This famine caused Ireland’s population, which was widely dependent on potatoes for food, to decrease by 20 to 25 percent.

2. Species diversity :

  • It is the number of different species in a particular area (species richness) weighted by some measure of abundance such as number of individuals or biomass. 

  • Other measure of species diversity is the species evenness, which is the relative abundance with which each species is represented in an area. An ecosystem where all the species are represented by the same number of individuals has high species evenness. An ecosystem where some species are represented by many individuals, and other species are represented by very few individuals has a low species evenness.

  • It is very difficult to estimate the different species in a given area. Most of the species are found near the equator and a few at the poles. Species diversity varies a great deal from one ecosystem to another.

  1. The farther we move from the equator towards the pole the lesser is the species diversity.

  2. However in deserts where there is a direct heating owing to direct solar insolation there is again a lesser species diversity implicating that presence of water also plays an important role.

  3. The third most important thing is presence of atmosphere. Life is present on earth where all 3 spheres viz atmosphere, lithosphere, & hydrosphere are present & are in continuous interaction with each other. The intensity with which they  interact with each other determine the intensity or magnitude of life & degree of  variations in it.

  4. A Rainforest like a western ghats is however an exceptional example of biodiversity the reason being again the same because all the three spheres here meet with exceptional intensity.

The following factors determine the degree of species diversity in an ecosystem or community:

a. Habitat stress: Species diversity is low in habitats under any stress such as harsh climate or pollution.  

b. Geographical isolation: Species diversity is less in isolated regions like an island. if a species in an island disappears due to random events, it cannot be  easily replaced. Organisms from the mainland have difficulties in reaching and colonizing the island.

c. Dominance by one species: The dominant species consumes a disproportionate share of the resources. This does not allow many species to evolve and flourish.

d. Edge effect: There is always greater species diversity in transition area, where two or more ecosystem overlap.

e. Geological history: Old and stable ecosystems such as rain forests that have not experienced many changes have high species diversity. An ecosystem like the arctic has undergone many changes and this does not allow any species to establish themselves.

3. Ecosystem diversity :

  • An ecosystem is a community plus the physical environment that it occupies at a given time. An ecosystem can exist at any scale, for example, from the size of a small tide pool up to the size of the entire biosphere. There are several kinds of habitats or ecosystems around the world such as those that occur in deserts, forests, wetlands, mountains, lakes, rivers, and agricultural landscapes

  • Ecosystem is a unit of the biosphere in which there is an interaction between the living and non-living factors so as to maintain a continuous flow of energy. It is a structural and functional unit of a biosphere.

  • Ecosystem diversity refers to the diversity of a place at the level of ecosystems.

  • Diversity of an ecosystem is dependent on the physical characteristics of the environment, the diversity of species present, and the interactions that the species have with each other and with the environment. Therefore, the functional complexity of an ecosystem can be expected to increase with the number and taxonomic diversity of the species present, and the vertical and horizontal complexity of the physical environment.

  • The term differs from biodiversity, which refers to variation in species rather t han ecosystems. Ecosystem diversity can also refer to the variety of ecosystems present in a biosphere, the variety of species and ecological processes that occur in different physical settings.

Some Examples :

  • Savanna grasslands is the biggest grassland ecosystem in the biosphere.    

  • Sundarban forest of India is the biggest mangrove forest of the world and a big ecosystem as well as it supports a large variety of life.

  • Examples of ecosystems: Grassland, wetland, desert, aquatic ecosystem etc.

Importance of Biodiversity :

At least 40 per cent of the world’s economy and 80 per cent of the needs of the poor are derived from biological resources. In addition, the richer the diversity of life, the greater the opportunity for medical discoveries, economic development, and adaptive responses to such new challenges as climate change. 

Services offered by Biodiversity/Ecosystem:

A healthy biodiversity provides a number of natural services for everyone:

a) Provisioning Services : These are the products obtained from ecosystems. They include food, water and other resources.

Food: Ecosystems provide the conditions for growing food. Food comes principally from managed agro-ecosystems but marine and freshwater systems or forests also provide food for human consumption. But wild foods from forests are often underestimated.

Ornamental resources: Animal products, such as skins and shells, and flowers are used as ornaments, although the value of these resources is often culturally determined. This is an example of linkages between the categories of ecosystem services.

Raw materials:
Ecosystems provide a great diversity of materials for construction and fuel including wood, biofuels and plant oils that are directly derived from wild and cultivated plant species.

Fresh water: Ecosystems play a vital role in the global hydrological cycle, as they regulate the flow and purification of water. Vegetation and forests influence the quantity of water available locally.

Medicinal resources: Ecosystems and biodiversity provide many plants used as traditional medicines as well as providing the raw materials for the pharmaceutical industry. All ecosystems are a potential source of medicinal resources.

Fuel :
Wood, dung, and other biological materials serve as sources of energy.

Genetic resources :
This includes the genes and genetic information used for animal and plant breeding and biotechnology.

b) Regulating Services are the services that ecosystems provide by acting as regulators eg. regulating the quality of air and soil or by providing flood and disease control.

Local climate and air quality: Trees provide shade whilst forests influence rainfall and water availability both locally and regionally. Trees or other plants also play an important role in regulating air quality by removing pollutants from the atmosphere.

Carbon sequestration and storage: Ecosystems regulate the global climate by storing and sequestering greenhouse gases. As trees and plants grow, they remove carbon dioxide from the atmosphere and effectively lock it away in their tissues. In this way forest ecosystems are carbon stores. Biodiversity also plays an important role by improving the capacity of ecosystems to adapt to the effects of climate change.

Moderation of extreme events: Extreme weather events or natural hazards include floods, storms, tsunamis, avalanches and landslides. Ecosystems and living organisms create buffers against natural disasters, thereby preventing possible damage. For example, wetlands can soak up flood water whilst trees can stabilize slopes. Coral reefs and mangroves help protect coastlines from storm damage.

Waste-water treatment: Ecosystems such as wetlands filter both human and animal waste and act as a natural buffer to the surrounding environment. Through the biological activity of microorganisms in the soil, most waste is broken down. Thereby pathogens (disease causing microbes) are eliminated, and the level of nutrients and pollution is reduced.

Erosion prevention and maintenance of soil fertility:
Soil erosion is a key factor in the process of land degradation and desertification. Vegetation cover provides a vital regulating service by preventing soil erosion. Soil fertility is essential for plant growth and agriculture and well functioning ecosystems supply the soil with nutrients required to support plant growth.

Storm Protection:
Presence of coastal ecosystem such as mangroves and coral reef can dramatically reduce effect of hurricane/Tsunami.

Pollination: Insects and wind pollinate plants and trees which is essential for the development of fruits, vegetables and seeds. Animal pollination is an ecosystem service mainly provided by insects but also by some birds and bats. Some 87 out of the 115 leading global food crops depend upon animal pollination including important cash crops such as cocoa and coffee (Klein et al. 2007).

Regulating Human Disease: Ecosystems are important for regulating pests and vector borne diseases that attack plants, animals and people. Ecosystems regulate pests and diseases through the activities of predators and parasites. Birds, bats, flies, wasps, frogs and fungi all act as natural controls.

c) Habitat or Supporting Services: Supporting services are those that are necessary for the production of all other ecosystem services. They differ from provisioning, regulating, and cultural services in that their impacts on people are either indirect or occur over a very long time, whereas changes in the other categories have relatively direct and short-term impacts on people.

Habitats for species: Habitats provide everything that an individual plant or animal needs to survive: food; water; and shelter. Each ecosystem provides different habitats that can be essential for a species’ lifecycle. Migratory species including birds, fish, mammals and insects all depend upon different ecosystems during their movements.

Maintenance of genetic diversity: Genetic diversity is the variety of genes between and within species populations. Genetic diversity distinguishes different breeds or races from each other thus providing the basis for locally well-adapted cultivars and a gene pool for further developing commercial crops and livestock. Some habitats have an exceptionally high number of species which makes them more genetically diverse than others and are known as ‘biodiversity hotspots’.

d) Cultural Services : These are the non-material benefits people obtain from ecosystems through spiritual enrichment, cognitive development, reflection, recreation, and aesthetic experiences, including:

Tourism: Ecosystems and biodiversity play an important role for many kinds of tourism which in turn provides considerable economic benefits and is a vital source of income for many countries. In 2008 global earnings from tourism summed up to US$ 944 billion. Cultural and eco-tourism can also educate people about the importance of biological diversity.

Aesthetic appreciation and inspiration for culture, art and design: Language, knowledge and the natural environment have been intimately related throughout human history. Biodiversity, ecosystems and natural landscapes have been the source of inspiration for much of our art, culture and increasingly for science.

Spiritual experience and sense of place: In many parts of the world natural features such as specific forests, caves or mountains are considered sacred or have a religious meaning. Nature is a common element of all major religions and traditional knowledge, and associated customs are important for creating a sense of belonging.

Cultural diversity:The diversity of ecosystems is one factor influencing the diversity of cultures.

Knowledge systems(traditional and formal): Ecosystems influence the types of knowledge systems developed by different cultures.

Social relations : Ecosystems influence the types of social relations that are established in particular cultures. Fishing societies, for example, differ in many respects in their social relations from nomadic herding or agricultural societies.

Sense of place : Many people value the “sense of place” that is associated with recognized features of their environment, including aspects of the ecosystem.

Cultural services are tightly bound to human values and behavior, as well as to human institutions and patterns of social, economic, and political organization. Thus perceptions of cultural services are more likely to differ among individuals and communities than, say, perceptions of the importance of food production.



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