Rainfed rice - IRRI books - International Rice Research Institute

Natural Ecosystems and
Agro-Ecosystems in
Eastern India
Natural ecosystems
A
n ecosystem is a functional unit consisting of both living and nonliving
components. Ecosystems have a number of structured interrelationships
between soil, water, nutrition and climate on one side
and producers, consumers and decomposers on the other. Ecosystems, when
not modified by human activities, are called natural ecosystems.
Agro-ecosystems
Natural ecosystems managed for
agricultural purposes are called
ago-ecosystems. The two
ecosystems differ in function. For
example, in agro-ecosystems, the
produce is always directly for
human use, whereas, in natural
ecosystems, the produce is only
sometimes for direct human use.
Ecosystem efficiency
Ecosystem efficiency is measured in
output/input ratios. If the ratio is
1, it is not sustainable.
Ecologists measure efficiency as an
‘energy balance’ while planners and
economists view it as a ‘monetary
balance’.
Ecosystem health
The health of ecosystems should be
maintained for sustainable
productivity. Ecosystem health can
also be used as a measure of
Distinguishing features of agro-ecosystems
Less diversified species and individuals.
Relatively homogeneous in their genetic
characteristics and physiological cycles.
The biological process is discontinuous and
concentrated on a specific period.
More uniform than natural ecosystems.
More dependent on external inputs for their operation
and high level of production.
Conceptual framework of ecosystem health
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