Life processes have a common biochemical basis. There is a certain range of environmental conditions under which life processes are carried out with ease. An important consequence of increased complexity of tropic structure is the comparative stability of the ecosystem.
Simple tropic structures are more vulnerable to flow of energy and materials. Elimination of one or a few species does not matter such as some other alternative is available above to the tropic level to meet its requirement. The diversity species composition of the biotic community within an ecosystem enhances its stability.
On the other hand, the increased diversity and complexity, the energy requirement for the maintenance of the system usually goes up and results are decrease in productivity. The productivity of an ecosystem is of following types:
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It refers to the rate at which radiant energy is stored by photosynthetic and chemosynthetic activity of producers. It is of two types.
(a) Gross Primary Productivity (GPP):
It is the total rate of total photosynthesis used up in respiration during the measurement period. The rate of primary productivity is estimated in terms of either chlorophyll content or amount of CO2 fixed.
(b) Net Primary Productivity (NPP):
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It refers to the rate of storage of organic matter in plant tissues in excess of the respiratory utilization by plants.
It refers to the rate of energy storage in the herbivores, carnivores, and decomposers. These consumers lend to utilize already produced food-materials in their respiration and convert the food matter to different tissues. It is because of this fact secondary productivity is not divided into ‘gross’ and ‘net’ amounts.
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It refers to the storage of organic matter not used by the heterotrophy or consumers.
Production efficiency is universally related to system complexity and diversity. Simpler and tropic structures have greater production efficiency.