Environmental Science

ENVIRONMENTAL SCIENCE : ECOSYSTEM 125

for ecosystem. The solar radiation, which originates from sun is the source of energy for life
and is what sets the ecosystem, besides other natural system.

Energy Flow

Due to unidirectional flow of energy, the behaviour of energy in ecosystem is called
Energy Flow. From the energetics point of view, energy flow is explained as under:

(i) The efficiency of the producers in absorption and conversion of solar energy.

(ii) The use of the above said converted chemical form of energy by the consumers.

(iii) The total input of energy in form of food and its efficiency of assimilation.

(iv) The loss caused through respiration, heat, excretion etc.

(v) The gross, net production.

Single Channel Energy Model

Lindemann (1942) was the first to propose the community energetics approach or the
trophic-dynamic model) to ecology, which enables an investigator to compare the relative
rates at which different kinds concerning energy flow through forest ecosystems by the
application of this kind of approach, e.g. by comparing ratios of leaf fall to litter deposition
on the forest floor. His conclusion was that the rates of leaf production are higher and those
of litter accumulation lower, in the tropics than at higher latitudes.

Solar radiation

118, 872

Decomposition

3.0 Decomposition

0.5

Decomposition

(trace)

N o t u tilised

1.2

Respiration

1.8

N o t u tilised

7.0

Respiration

4.5

N o t u tilised

70.0

Respiration

23.0

HERBI-

VORES

(G .P.)

15.0

CARNI-

VORES

(G.P.)

3.0

AUTOTROPHS

Gross production

(G .P.)

111 .0

Fig. 3.2 Single channel energy model.

The following conclusion can be drawn from the above figure:

(1) Out of the total incoming solar radiation (118,872 g cal/cm^2 /yr), 118,761 gcal/cm^2 /yr

remain unutilized. In this way, the gross production (net production plus respiration)

by autotrophs comes to be 111 gcal/cm^2 /yr with an efficiency of energy capture of

0.10 per sent.