ADVERTISEMENTS:
The achievement of a measure of stability or homeostasis, rather than a mere increase in productivity, in a fluctuating physical environment may well be the primary purpose of ecological succession when viewed from the evolutionary viewpoint.
A mature community with its greater diversity, larger organic structure, and balanced energy flows is often able to buffer the physical environment to a greater extent than the young community.
The principles of ecological succession are of the greatest importance to mankind. Man must have early successional stages as a source of food, since he must have a large net primary production to harvest. In the climax community, because production is mostly consumed by animal and plant respiration, net community production in an annual cycle may be zero. On the other hand, the stability of the climax species and its ability to buffer and control physical forces such as water and temperature are desirable characteristics from the viewpoint of the human population.
ADVERTISEMENTS:
The only way man can have both a productive and a stable environment is to ensure that a good mixture of early and mature successional stages are maintained, with interchanges of energy and materials. Excess food produced in young communities helps feed older stages that in return supply regenerated nutrients and help buffer the extremes of weather, such as storms and floods.
In the most stable and productive natural situation there is usually such a combination of successional stages. A favourable situation exists in many terrestrial landscapes where productive croplands on the plains are intermingled with diverse forests and orchards on the hills and mountains. Ecologically speaking, the crop fields are young communities because they are maintained as such by die constant labour of the farmer, while forests represent older, more diverse, and self-sustaining communities that have lower rates of net production but do not require the constant attention of man.
It is important that both types of ecosystems be considered together in proper relation. If the forests are destroyed merely for the temporary gain of wood, water and soil may wash down from the slopes and reduce the productivity of plains.
However, succession is not always predictable and unidirectional. For example, cyclic succession occurs in most communities on a small scale. In nature, even an old, seemingly stable community is in a state of flux and is a shifting mosaic rather than a steady state. Although succession is undoubtedly an important and widespread process, other influences and processes may dominate the physical and biological structure of many communities.
ADVERTISEMENTS:
According to Elton, succession of communities plays an important part in the slow dispersal of animals. The intricate problems of competition between different species of animals can be studied in series of changing communities. Thus, it becomes clear that succession has a very significant role in shaping the destiny of animal and plant communities.
