AN EXCERPT FROM THE BOOK
Our planet Earth is a lovely beautiful white and blue ball when seen from space. It is the third planet from the Sun and it is the largest of the inner planets. It is the only planet known to support life and to contain liquid water at the surface. Our environment includes the biotic (living beings) and abiotic factors (like soil, water, temperature and light). The various segments of the environment consist of the atmosphere, lithosphere, biosphere and the hydrosphere. The surface of the Earth (air, water and land) is called the biosphere. It is composed of smaller units called the ecosystems. An ecosystem includes all the organisms and the non-living environment found in a particular place. They can be large or small. Our Earth hosts a variety of living organisms and the surface of the Earth, as a whole is an ecosystem. Each organism depends in some way on other living and nonliving things in its environment. The study of natural ecosystems will help us to understand the interrelations between living beings and the environment and how the impact of human beings is influencing the natural world.
Ecological case studies
1. Dwindling biodiversity in the Sariska Tiger Reserve, Rajasthan:
Poaching of the wild animals like leopards, tigers and other animals for skin, fur, natural resources, etc. in Sariska coupled with high amount of mining related problems, as the area is rich in dolomite, limestone, schist, marble and quartzite have led to severe ecological problems. There are over 200 mines in the protected forest area and more than 40 mines in the partly protected areas. The Sariska reserve, amidst the Aravallis, covers over 800 sq km of dry tropical forests. â€˜Dhokâ€™ is the principal tree species that covers 90% of the entire area and there are a variety of grasses and shrubs. This reserve supports over 100 species of birds and has the largest population of peafowl in the entire country. Leopards, Caracals, Sambar, Nilgai, Chital, Wild boar are found in this sanctuary. A rare feature of the fauna is the four horned antelope. Eco-development programs have just been implemented in Sariska with the formation of forest protection societies in villages and NGOâ€™s. The future of Sariska reserve lies directly in protecting and reducing the high biotic pressure that affects this unique Aravalli habitat of the Indian tigers.
2. Declining biodiversity in the wonderful Australian Woodlands:
It is predicted that over the next 50 to 100 years there will be a wave of bird extinctions paralleling the loss of many Australian mammal species witnessed earlier this century. The reason for bird species decline is due to practices such as hunting, predation or competition from introduced species and due to loss of habitat. The present case study is related to temperate woodland ecosystems and the birds dependent on them for habitat. Impacts on bird populations provide typical examples of the indirect pressures on biodiversity. Woodlands are distinguished from coastal forests and semi-arid lands by less marked seasonal variations in temperature, lower extremes of rainfall and a longer growing season. Woodland birds have evolved in response to the year-round availability of food and the variety of habitat features such as tree hollows, peeling bark, nectar and other carbohydrates provided by the predominant eucalyptus plant species. The year-round supply of food also means the forests are linked to surrounding habitats, as they are suitable for migratory birds, breeding or when food is scarce elsewhere in times of drought. More than 25% of land bird species found in woodlands are in decline or threatened. The paradise parrot and star finch are extinct. Endangered species include Regent honeyeaters, bush stone-curlew, squatter pigeon, superb parrot, swift parrot, turquoise parrot, grey-crown babbler, painted honey-eater and black-throated finch. In total, 16 woodland-dependent or woodland-associated species are threatened and many more are in decline, as concepts of conservation of ecosystems have not been scientifically followed.
Components of ecology
The term ecology is derived from two Greek words, oikos meaning dwelling place and logos meaning study. So ecology means the study of organisms in their home. The term ecology was termed by the German biologist Ernst Haeckel (1868). He defined ecology as the â€˜surrounding outer worldâ€™, now called the environment. E.P.Odum (1969) defined the term ecology as the study of interrelationships between organisms and environment. Ecology is the study of interactions between organisms (biotic part) and their nonliving environment (abiotic factors). Ecology involves collecting information about organisms and their environment, looking for patterns, and seeking to explain these patterns. Habitat is the place a plant or animal lives, while its niche is the specific place it occupies in an ecosystem. Thus, an ecosystem is the living organisms and the chemical and physical environment and ecology is the study of ecosystems. Living things are organized in an ecosystem by how they secure their food: autotrophs or heterotrophs. A very important factor determining the number and type of organisms living in an ecosystem is the amount of energy available. The amount of energy an ecosystem receives and the amount that is transferred from organism to organism has an important effect on the ecosystemâ€™s structure. All organisms need energy to carry out essential functions, such as growth, movement, maintenance and repair, and reproduction. Energy in an ecosystem flows from the sun to autotrophs (producers) then to organisms that eat the autotrophs, then to organisms that feed on other organisms. The primary source of energy for an ecosystem is the sun.
Ecosystems are ecological units that include all the biotic factors and abiotic factors in an area. E. P. Odum defined ecosystem as the basic functional unit of organisms and their environment, interacting with each other and within their own components. Nearly all ecosystems are dependent upon the flow of solar energy and finite pools of nutrients. Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur make up nearly all life on earth. The diversity of an ecosystem is a measure of the number of different species there, and how common each species is. Ecosystems are very complex and they can contain hundreds or even thousands of interacting species.
Environment and eco-factors
The structural and functional features, their size and composition are important characteristics of any ecosystem. The structural features include the biotic and abiotic components and the functional features include the functions performed i.e. food chains, webs, trophic levels, the flow of energy in the ecosystem, productivity, biogeochemical cycles and ecosystem regulation.