Question

1. What is the difference between primary and secondary succession? Explain in detail.

2. How does the Biomass Accumulation Model describe succession of ecosystems following disturbances?

Answer 1

1)

Ecological succession is the natural process of development due to which changes may occur in biological community over a period of time. Succession is the part of changes in community and it can be of two types Primary succession and secondary succession.

Primary succession is the process of growth in an area where there was no vegetation, habitat are initially present. Example - newly formed bare rock, desert, pond.

Secondary succession is the growth of the community in such area where vegetation, habitat is already present but got destroyed due to some internal or external factors. Example - area affected due to deforestation, flood, earthquake etc.

Primary succession occurs in lifeless area whereas secondary succession occurs where life was present previously but got destroyed due to some factors. Primary succession will take 1000 years or more than that to take place while secondary succession will occur in 50 to 200 years. Initially in case of primary succession soil is absent and weathering of rocks will takes place. The environmental conditions are not favorable. In these conditions the pioneer plant or species will develop and further process will occur. In case of secondary succession no such pioneer species will form as environmental conditions are favorable and already soil and some organism may be present.

2)

Bormann and Likens proposed the biomass accumulation model in which there are four phases are present.

Reorganization, Aggradation, Transition and Steady state.

According to the biomass accumulation model disturbing a ecosystem will induce a series of recovery or reorganization process. After disturbance the ecosystem will face loss of nutrients and biomass. During reorganization accumulation of biomass will start. Due to aggredation biomass will increase as deposition of biomass occurs. In transition biomass will decrease from peak and it will get maintained in steady state.