The ecosystem functions through several biogeochemical cycles and energy transfer mechanisms. Observe and document the components of the ecosystem which consists of its non-living or Abiotic features such as air, water, climate and soil. Its Biotic components are the various plants and animals. Both these aspects of the ecosystem interact with each other through several functional aspects to form Nature’s ecosystems. Plants, herbivores and carnivores can be seen to form food chains. All these chains are joined together to form a ‘web of life’ on which man depends. Each of these uses energy that comes from the sun and powers the ecosystem.
Structural and Functional aspect of an Ecosystem:
Components that make up the structural aspects of an ecosystem include:
1) Inorganic aspects – C, N, CO2, H2O.
2) Organic compounds – Protein, Carbohydrates, and Lipids – link abiotic to biotic aspects.
3) Climatic regimes – Temperature, Moisture, Light & Topography.
4) Producers – Plants.
5) Macro consumers – Phagotrophs – Large animals.
6) Micro consumers – Saprotrophs, absorbers – Fungi.
1) Energy cycles.
2) Food chains.
3) Diversity - inter linkages between organisms.
4) Nutrient cycles - biogeochemical cycles.
Types of Ecosystems
Terrestrial Ecosystems Aquatic Ecosystems
Semi arid areas Wetland
Processes of Ecosystems: This figure with the plants, zebra, lion, and so forth illustrates the two main ideas about how ecosystems function: ecosystems have energy flows and ecosystems cycle materials. These two processes are linked, but they are not quite the same.
Energy enters the biological system as light energy, or photons, is transformed into chemical energy in organic molecules by cellular processes including photosynthesis and respiration, and ultimately is converted to heat energy. This energy is dissipated, meaning it is lost to the system as heat; once it is lost it cannot be recycled. Without the continued input of solar energy, biological systems would quickly shut down. Thus the earth is an open system with respect to energy.
Elements such as carbon, nitrogen, or phosphorus enter living organisms in a variety of ways. Plants obtain elements from the surrounding atmosphere, water, or soils. Animals may also obtain elements directly from the physical environment, but usually they obtain these mainly as a consequence of consuming other organisms. These materials are transformed biochemically within the bodies of organisms, but sooner or later, due to excretion or decomposition, they are returned to an inorganic state. Often bacteria complete this process, through the process called decomposition or mineralization.
During decomposition these materials are not destroyed or lost, so the earth is a closed system with respect to elements (with the exception of a meteorite entering the system now and then). The elements are cycled endlessly between their biotic and Abiotic states within ecosystems. Those elements whose supply tends to limit biological activity are called nutrients.
Producer, Consumer and Decomposers:
Every living organism is in some way dependent on other organisms. Plants are food for herbivorous animals which are in turn food for carnivorous animals. Thus there are different tropic levels in the ecosystem.
Plants are the ‘producers’ in the ecosystem as they manufacture their food by using energy from the sun. In the forest these form communities of plant life. In the sea these include tiny algal forms to large seaweed.
The herbivores animals are primary consumers as they live on the producers. In a forest, these are the Insects, Amphibia, Reptiles, Birds and Mammals. The herbivorous animals include for example Hare, Deer and Elephants that live on plant life. In grasslands, there are herbivores such as the blackbuck that feed on grass. In the semi-arid areas, there are species such as the Chinkara or Indian gazelle.
At a higher tropic level, there are carnivores animals, or secondary consumers, which live on herbivorous animals.
In our forests, the Carnivores animals are Tigers, Leopards, Jackals, Foxes and Small Wild Cats.
Decomposers or Detrivores are a group of organisms consisting of small animals like worms, insects, bacteria and fungi, which break down dead organic material into smaller particles and finally into simpler substances that are used by plants as nutrition. Decomposition thus is a vital function in nature, as without this, all the nutrients would be tied up in dead matter and no new life could be produced.
A constant input of solar energy is the basic requirement for any ecosystem to function and sustain. Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight (gm–2) or energy (kcal m–2). The rate of biomass production is called productivity. It is expressed in terms of gm–2yr–1 or (kcal m–2) yr-1 to compare the productivity of different ecosystems. It can be divided into Gross Primary Productivity (GPP) and Net Primary Productivity (NPP). Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilised by plants in respiration. Gross Primary Productivity minus respiration losses (R) is the Net Primary Productivity (NPP). Secondary Productivity is defined as the rate of formation of new organic matter by consumers. The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of organic matter.
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