OUR ENVIRONMENT
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INTRODUCTION
Earth is the only planet known for supporting life. Despite the vastness of earth, life exists only in a very narrow zone of the earth called biosphere. Sun is the only source of energy which enables continuous interaction among various life forms. This unit, being the first in the course, brings out the holistic meaning of the word 'environmenť. In broad terms, environment includes everything external to an organism that affects it, including physical as well as living factors. The action and interactionof the physical and living factors makes a system of relationships called ecosystem. This unit will also focus on how we as living beings interact with other living and non-living components of the ecosystem. The concept of sustainable development came into existence that explains symbiotic relationship between human being and environment.
For centuries humans have considered the earth and environment as virtually unlimited resources, but subtle and gradual changes have altered our environment in many different ways. Special mention has been made of human population within the changing scenario over the years, particularly since the industrial revolution. We hope that this unit will give you a better understanding of the environment and its various components. This unit would also enable you to use your intelligence and skills for managing our environment and keeping it healthy for future generations. This unit will further explain the multi-discipilinary nature and scope of environmental studies.
CONCEPT OF ENVIRONMENT
Each and every living organism has a specific surrounding or medium with which is continuously interacts derives its substence and to which it is fully adapted. This surrounding is the natural environment. The word 'natural environment brings to mind broad aspects of landscape, such as soil,water,desert or mountains which can be more exactly described in terms of physical or abiotic influences such as differences in moisture, temperature, texture of soil, and air quality. It also includes the biological or biotic influences in the form of microbes and animals. Thus, environment is defined as, "the sum total of living and non-living components; influences and events surrounding an organism".
Let us begin by asking what is environment? Environment is derived from French word environ which means to encircle or surround while ment means auctioning, i.e., environment is the interaction between organism and the nature. For humans, there are several kinds of environment such as home environment, business environment, political environment and so on. But we are going to discuss only about natural environment: air, water, land. plants, animals and other organisms. Any individual in nature interacts with its environment, influences it and in turn is influenced by it. Thus environment is the sum total of air, water and land interrelationship among themselves and also with the human beings, plants, animals and other organisms. The most significant attribute of the effect of environment on life of an organism is the interaction of environmental elements. These abiotic and biotic factors are dynamic in nature and interact with each other in every moment of life.
No organism can live alone without interacting with other organisms, so each organism has other organisms as a part of its environment. You must be aware that all animals are directly or indirectly dependent upon plants, basically the green plants that manufacture their own food. Plants also depend on animals for a few things such as pollination of flowers and dispersal of fruits and seeds.
Let us try to understand the concept of environment with an example (Refer Fig. 1.1.). Can you identify the environment of a carp fish in the pond? Its environment consists of abiotic components such as light, temperature, and water in which nutrients, oxygen, other gases and organic matter are dissolved. The biotic environment consists of microscopic organisms called planktons as well as aquatic plants and animals and decomposers. The plants are of different kinds such as floating, submerged and partly submerged plants, and trees growing around the edge of the pond. The animals consist of insects, worms, molluscs, tadpoles, frogs, birds and various kinds of fishes. The decomposers are the saprotrophs like bacteria and fungi.
