Q. Which of the following is/are trend(s) in from ecological succession ?
(i) An increase in complexity of species.
(ii) An increase in productivity.
(iii) An increase in community stability and species diversity.
(iv) A decrease in non-living organic materials.

 186  216 Ecosystem Report Error

Solution:

Ecological succession is the process by which the structure of a biological community changes and evolves over time. Two different types of succession (primary and secondary) have been distinguished. Primary succession occurs in essentially lifeless areas-regions in which the soil is incapable of sustaining life as a result of factors such as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.