Succession. Ecological. Ecological Succession Defined. Ecological succession is a process of change in the species that make up a community.

Transcription

1 Ecological Succession By Danilo Villar Rogayan Jr. Instructor I, Natural Sciences Ecological Succession Defined Ecological succession is a process of change in the species that make up a community. 1

2 Ecological Succession Defined Succession is to create a community in a previously uninhabited area (nothing was living there before) Is the sequence of biotic changes that regenerate (repair) a damaged community Ecological Succession Defined Succession is a sequential change in the relative abundances of the dominant species in a community following a disturbance (Huston & Smith, 1987) 2

3 Ecological Succession Defined Primary Succession the development of an ecosystem in a previously uninhabited area (nothing lived there before, it was only rock!). 3

4 Primary Succession the community develops from an essentially abiotic situation following a cataclysmic disturbance May involve soil formation, potentially a very slow process Ex.: Development of communities ff glaciation, volcanic eruption or receding waters that expose new substrate to colonization Pioneer species- the first organisms that live in a new area Ex: lichen and some mosses break down rock into soil over time Bare rock is exposed and lichen and moss break it down to dirt 0-15 yrs 2-Seeds are blown into the area and small shrubs grow yrs 3-As soil grows thicker, small trees take root yrs 4-Different tree species take root, and replace the old trees yrs 4

5 Secondary succession started after a disaster by the remaining species (soil was left intact) There is already soil! 0-2 yrs Secondary Succession the community develops in a habitat that has been disturbed, but not so severely as to destroy all life Ex. Community development after a fire or hurricane 5

6 Learning Checkpoint Why do you think secondary succession takes less time than primary succession? Secondary succession starts with soil instead of bare rock. Sere the entire sequence of stages in succession Seral stage any particular phase in ecological succession Disturbance any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resource or substrate availability or the abiotic environment. 6

7 Nature of Climax Community Climax the final stage of community change Climax communities are characterized by slow rates of change, compared with more dynamic, earlier stages. They are dominated by species tolerant of competition for resources. Nature of Climax Community An Influential ecologist named F.E. Clements argued that communities work like an integrated machine. These closed communities had a predictable composition. According to Clements, there was only one true climax in any given climatic region, which was the endpoint of all successions. Other influential ecologists, including Gleason, hypothesized that random events determined the composition of communities. He recognized that a single climatic area could contain a variety of specific climax types. 7

8 Nature of Climax Community Evidence suggests that for many habitats, Gleason was right, many habitats never return to their original state after being disturbed beyond a certain point. For example; very severe forest fires have reduced spruce woodlands to a terrain of rocks, shrubs and forbs. Nature of Climax Community Succession can take a long time. For example, old-field succession may require years to reach climax community. But in this time frame, the probability that a physical disturbance (fire, hurricane, flood) will occur becomes so high, the process of succession may never reach completion. 8

9 References: Krohne, David T General Ecology, 2 nd Edition. Cengage Learning Asia Pte Ltd: Singapore. Miller, Kenneth R. and Joseph S. Levine Prentice Hall Biology. Pearson Prentice Hall: Boston, Massachusetts. Nowicki, Stephen Biology. McDougal Littell: Evanston, Illinois. ` Lakô hãsalamát! Maraming salamat! 9