WHAT IS ECOLOGY?
The term Ecology was coined by Earnst Haeckel in 1869. It is derived from the Greek words Oikos- home + logos- study. So ecology deals with the study of organisms in their natural home interacting with their surroundings. The surroundings or environment consists of other living organisms (biotic) and physical (abiotic) components. Modern ecologists believe that an adequate definition of ecology must specify some unit of study and one such basic unit described by Tansley (1935) was ecosystem.
What is Ecosystem?
An ecosystem is a self-regulating group of biotic communities of species interacting with one another and with their non-living environment exchanging energy and matter.
Composition and organization of biological communities and Abiotic components constitute the structure of an ecosystem. (From K&K)
BIOTIC COMPONENTS
    1.Producers: These are photo-autotrophic and chemoautotrophic plants and microorganisms, serving as a base for an ecological food chain by producing bio mass for Herbivores from raw materials like sunlight, water, CO2 etc.
e.g. Green plants, photo-chemical bacteria and algae etc.
    2. Consumers: The organisms feeding on producers (i.e. green plants) are known as Consumers.   Â
Consumers can further be classified as follows:
- Herbivores: These feed on green plants (producers)
- Carnivores: These feed on consumers.
- Secondary carnivores– feeding on herbivores (e.g. frog, small fish)
- Tertiary carnivores– feeding on another consumer (e.g., snake, eagle)
- Omnivores: These feed on both plants and animals (e.g., humans, rats, many birds)
- Detritivores: These feed on the dead and decaying organisms (e.g., earth worm, crab, ants)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
    3.Decomposers: These organisms derive their nutrition by breaking complex organic compounds into simpler inorganic compounds (e.g., bacteria, fungi)
ABIOTIC COMPONENTS
Various physio-chemical components of the ecosystem constitute the abiotic structure:
Functions of Ecosystem
- It contains different food chains and food webs: It is the sequence of eating and being eaten. Food webs contain inter linkage of food chains. e.g.
Grass → Grasshopper → Frog → Snake → Hawk            Â
Phytoplanktons (water-algae) → water fleas → small fish → large fish (Tuna)
- It contains different food chains and food webs: It is the sequence of eating and being eaten. Food webs contain inter linkage of food chains. g.,
Grass → Grasshopper → Frog → Snake → Hawk                Â
Phytoplanktons (water-algae) → water fleas → small fish → large fish (Tuna)
- It contains different food chains and food webs: It is the sequence of eating and being eaten. Food webs contain inter linkage of food chains. g.,
Grass → Grasshopper → Frog → Snake → HawkÂ
Phytoplanktons (water-algae) → water fleas → small fish → large fish (Tuna)                    Â
- Grazing food chains: It starts with green plants and culminate with carnivores. e.g. Grass –> deer–> lion
- Detritus food chains: It starts with dead organic matter. e.g. Leaf litter in a forest → Fungi → bacteria
      NOTE: Food webs are more stable as they are aggregation of inter-woven food chains.
- There is uni-directional flow of energy in an ecosystem: There is a continuous flow of energy at every successive step in the food chain starting from producers to the top carnivore. It follows the 10% law according to which there is a loss of 90% (respiration, excretion, locomotion etc.) of total energy and only 10% of it is transferred to the next level.
      (NOTE: The flow of energy is always unidirectional.)
- Nutrients (Materials) in an ecosystem move in a cyclic manner: There is always a cycle going between biotic and abiotic component known as biogeochemical cycles.
- Every ecosystem functions to produce and sustain some primary production (plant biomass) and secondary production (animal biomass).
- Every ecosystem regulates and maintains itself and resists any stresses or disturbances up to a certain limit. This self regulation or control system is known as cybernetic system
ECOSYSTEM DEGRADATION
However, ecosystems are often destroyed by human disturbance, leading to the extinction of animal and plant species that can only live in different natural ecosystems. Some species will severely affect the ecosystem after being removed. They are called key stone species. Extinction occurred due to changes in land use. Forests are cut down for firewood and wetlands are drained Create more agricultural land and semi-arid pastures for grazing land and turn them into irrigated fields. Industrial pollution and municipal waste may also lead to the extinction of several species.
The cause for the depletion of herbal sources is twofold – our swiftly exploding population that wishes to preserve itself on sources, and the increase of prosperous societies, which consume and waste a completely huge share of sources and energy. Increasing extraction of sources is on the fee of herbal ecosystems, main to a derangement in their critical functions. Each folks in our everyday lives use a number of sources. If tracked again to their source, one unearths that the sources have been firstly acquired from nature and herbal ecosystems. Our insensitivity to the usage of sources cautiously has produced societies that nature can now not preserve. If one thinks earlier than using sources inclusive of water, reusing and recycling paper, the usage of much less plastics which might be non-degradable, culminative this could have effective implications at the integrity of our herbal useful resource base and preserve the sources that nature provides.