Environment

• The environment is defined as ‘the sum total of living, non-living components; influences and events, surrounding an organism’. All organisms (from virus to man) are obligatorily dependent on the other organism and environment for food, energy, water, oxygen, shelter and for other needs.
• The relationship and interaction between organism and environment are highly complex. It comprises both living (biotic) and non-living (abiotic) components.

LEVELS OF ORGANISATIONS IN ECOLOGY

1. Individual

•  Organism is an individual living being that has the ability to act or function independently. It may be plant, animal, bacterium, fungi, etc.

2. Population

• Population is a group of organisms usually of the same species, occupying a defined area during a specific time.
• The main factors that make population increase are birth and immigration.
• The main factors that make population decrease are death and emigration.

3. Community

• In order to survive, individuals of any one species depend on individuals of different species with which they actively interact in several ways.
• Ex: Animals require plants for food and trees for shelter. Plants require animals for pollination, seed dispersal, and soil microorganism to facilitate nutrient supply.
• Communities in most instances are named after the dominant plant form (species).
• For example: A grassland community is dominated by grasses, though it may contain herbs, shrubs, and trees, along with associated animals of different species.

Ecosystem

• An ecosystem is defined as a structural and functional unit of biosphere consisting of community of living beings and the physical environment, both interacting and exchanging materials between them.

Components of Ecosystem

1. Abiotic Components

• Energy
• Rainfall
• Temperature
• Atmosphere
• Substratum
• Latitude and altitude

2. Biotic Components

• Primary producers - Autotrophs (self- nourishing). Primary producers are basically green plants (and certain bacteria and algae).
• Consumers – Heterotrophs or phagotrophs (other nourishing). Consumers are incapable of producing their own food (photosynthesis). They depend on organic food derived from plants, animals or both.

Classification of Ecosystem:

 1. Terrestrial

• Forests
• Grasslands
• Deserts

 2.  Aquatic

• Fresh Water
• Saline Water
• Marine Water

Ecotone

• It is a zone of junction between two or more diverse ecosystems.
• For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem. Other examples are – grassland, estuary and river bank.
• It may be very narrow or quite wide.
• It has the conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension.

Niche

• A niche is the unique functional role or place of a species in an ecosystem.
• It is a description of all the biological, physical and chemical factors that a species needs to survive, stay healthy and reproduce.
• A niche is unique for a species, which means no two species have exact identical niches. Niche plays an important role in conservation of organisms.

(a) Types of Niche

1. Habitat niche – where it lives
2. Food niche – what is eats or decomposes & what species it competes with.
3. Reproductive niche – how and when it reproduces.
4. Physical & chemical niche – temperature, land shape, land slope, humidity & other requirement.

Biosphere

• Biosphere is a part of the earth where life can exist.
• Bio- sphere represents a highly integrated and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land).
• Biosphere is absent at extremes of the North and South poles, the highest mountains and the deepest oceans since existing hostile conditions there do not support life. Occasionally spores of fungi and bacteria do occur at a great height beyond 8,000 metres, but they are not metabolically active, and hence represent only dormant life.

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