Question

1. Explain the process of succession in ecosystems and distinguish between primary and secondary succession. ( Please type your answer

Answer 1

Ecological succession is the phenomenon of gradual change in the species structure of an ecological community over time. These changes are usually predictable and occurs in an orderly fashion. In nature the species composition of an ecological community changes over time leading to prominence of certain species while others may fade out of existence. Over time the community develops with increased vegetation leading to a more established community.

The key points of an ecological succession are as follows:

The changes in the physical and chemical nature of an environment brings changes in the species richness and diversity of that area. Succession takes place as a result of the processes of living, growing and reproducing. The interaction among organisms affect the environment within an area and changes it. Every species tries to adapted and compete against other species under a very specific set of environmental conditions. If these conditions change, then the existing species will be eliminated by some other species adopting better to that condition. For example, the plant succession. It should be noted that changes in plant communities changes the associated micro-organism, fungus and animal species depending on those plant species. So succession works better in  whole community. The change in the plant species of an area is one of the major driving forces behind changes in animal species. This is because each plant species is somehow associated with certain animal species which feed on it. Similarly the presence of these herbivores will decide the carnivores of that area and this forms a chain of related organisms leading to the establishment of an ecological succession. Succession is a directional process so different stages in a particular habitat succession can usually be accurately predicted by looking into the current status of the organism diversity. These differenr stages established by the presence of different communities are known as 'seres'. Communities change gradually from one sere to another. The seres are not very distinct from each other and one will tend to merge gradually into another, finally ending up with a 'climax' community and the succession will not proceed further. This does not mean that there will be no further change. When large organisms in the climax community, such as trees, die and fall down, then new openings are created in which secondary succession will occur. Many thousands of different species might be involved in the community due to changes over the course of a succession. For example, in the succession from freshwater to climax woodland.

Those succession that begins in new habitats which has never been occupied by any other community is called as primary succession. For example, the development of a community from a barren land or bare rock.

Secondary succession refers to the occurance of new community and changes within it from an area which has been colonized before or from a damaged and disturbed habitat. For example, the occurance of new community in an area destroyed by forest fire or landslides which disrupts the previous community but helps in the establishment of a new community.