(e) Ecotone and edge effect:-

It is transistional zone between two adjacent community.

EDGE EFFECT:-

Organism have tendency to increase their population and diversity in transistional zone or Border of community or ecotone.

EDGE SPECIES:-

Organism which spend their max. of time in border of community or ecotone.

Ecological Succession:- It is successful replacement of one community by another community over the long period of time. Direction of succession is always unidirectional.

(a) Sere:- Entire sequence of succession from pioneer  to climax community.

(b) Pionur species:- Species with first to invade bared land area usually lichen and mosses               .

(c) Pioneer community:- First form community on bared area.

(d) Climax community:- Form community at last on bared. Usually trees make climax community.

(e) Seral stage or serol community:- It is community sequence from pioneer to climax community.  

Primary succession (Prisere):- Succession on primary bared (previously sterile area).

Secondary succession (Sale sere):-

Succession on 2 Bared area or destroyed community.

Imp:- 1^° succession take much more time with respect to 2^° succession because  1^° succession mainly involve in formation of soil.

• Autogenic succession:- When environmental factors do not play any role in replacement of community i.e. Biotic community is replaced by itself.
• Allogenic succession (Rare):-

Here environmental factor play a major role in replacement of community.

• Xerosere (Xerach):- Succession on dry habitat:-

(1) Lithosphere:- Succession on rock.

(2) Psamosere:- Succession on sandy soil.

(3) Hydrosphere:- Succession in water