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CHAPTER 2 FUNCTIONS OF AN ECOSYSTEM (Part-3)
SUCCESSION Succession is a universal process of directional change in vegetation, on an ecological time scale. Succession is a progressive series of changes Which leads to the establishment of a relatively stable climax community. Types of Ecological Succession Ecological succession is mainly of two types- Primary succession and secondary succession. The primary succession is a slow process that initiates in areas where there are no living organisms. . Secondary succession begins in areas that were once inhabited but destroyed due to environmental disturbances. This is generally faster, as most of the other factors are already present.
Primary Ecological Successiorn am fir, k pine, paper birch black spruce, spruce forest community Heath mat malherbs Lichens and and shrubs and aspen Exposed mosses rocks Time
The differences between primary and secondary succession, the secondary succession starts on a well developed soil already formed at the site. Thus secondary succession is relatively faster as compared to primary succession which may often require hundreds of years. ALLOGENIC SUCCESSION AND AUTOGENIC SUCCESSION . In ecology, allogenic succession is succession driven by the abiotic components of an ecosystem. In contrast, autogenic succession is driven by the biotic components of the ecosystem. An allogenic succession can be brought about in a number of ways which can include: Volcanic eruptions 1. 2. 3. 4. Meteor or comet strike Flooding Drought Earthquakes Non-anthropogenic climate change
Secondary Succession Mature oak and hickory forest ung pine forest shrubs andw small pine with developing understory of oak Annual weeds and Seediings and hickory trees weeds grasses Tim
Allogenic succession can happen on a time scale that is proportionate with the disturbance. For example, allogenic succession that is the result of climate change can happen over thousands of years. AUTO TROPHIC AND HETEROTROPHIC SUCCESSION Succession in which, initially the green plants are much greater is quantity is known as autotrophic succession; and the ones in which the heterotrophs are greater in quantity is known as heterotrophic succession Succession would occur faster in area existing in the middle of the large continent.