Ecology: Community & Biome | Biology for SSS 3 PDF Download

Community

Groups of organisms of different species that live in common area, which are interrelated and interdependent form a community.

It is a natural aggregation of plants and animals in the same environment.

Biotic Community = Animal community + Plant community + Microbial community

Characteristics of a Community

1. Species Diversity

There are  different types of population (species) found in community, this is called species diversity. It depends on size of the area, type of area, type of soil , altitude, climate.

2. Dominance

The highest number of organism of a species present in community, is called as the dominant species.
Whole community is known by the name of that particular dominant species. e.g. Prosopis community at Aravali hills, Pinus community at Himalaya

3. Stratification 

The different growth form (trees, shrubs, under shrubs, herbs) determines the structure of a plant community.
Stratification is based on mode of arrangement of various growth forms.

• Stratification in lake– In deep lake, zonation or stratification may be according to the need of light. There are three types of zones differentiated in a deep lake.

A. Littoral Zone – This zone is found at bank of lake where very shallow water or marshy land is present. Rooted vegetation is found in this zone.

B. Limnetic Zone – This is the zone of lake water, where light reaches in sufficient amount to the entire surface area. It means this is not too deep. In this region different types of floating plants (phytoplanktons), suspended and submerged plants are present.

C. Profundal Zone – It is very deep area of the lake where light does not reach up to the bottom. Only heterotrophs are present in this zone.

• Stratification in Forest – The clear stratification (vertical arrangement) in various growth forms of plants according to the need of light in any dense forest.
  Surface dwellers → Herbs → Under shrubs → Shrubs →Trees.

Note :

• The clear stratification is found in tropical rain forest. So it is known as multi-storied forest.

• Another example of stratification is mountain.