Xerosere

1. xerosere Ecological succession on a bare rock elk

2. Sere and seral community an intermediate stage found in an ecosystem advancing towards its climax community in many cases more than one seral stage evolves until climax conditions are attained   Screen clipping taken: 20-02-2013, 22:54    

3. Bare rocks The first form of life originates at such places which do not had life such as an island formed after a volcanic activity or a retreating glacier   Screen clipping taken: 20-02-2013, 23:45    

4. c rustose lichen stage A lichen is an important pioneer in primary succession composed of a photosynthesizing algae, and a fungi absorbing nutrients from rock and holds water. Together they break down rock Soil accumulates as dust particles trapped in cracks in rock Lichens decompose providing food for mosses

5. Foliose lichen stage They can absorb more water and are able to accumulate more dust particles. The shallow depressions in the rocks become filled with sold and topsoil layer increases further . These autogenic changes favor growth and establishment of mosses .

6. Moss stage As mosses develop in patches they catch soil particles from the air and help increase the amount of substratum. The changing environment leads to migration of lichens and helps invasion of herbaceous vegetation that can out-compete mosses.

7. Herbaceous weeds, mostly annuals such as asters , evening primroses , and milk weeds , invade the rock. Their roots penetrate deep down, secrete acids and enhance the process of weathering. Leaf litter and death of herbs add humus to the soil Herb stage

8. Shrub stage The herb and grass mixture is invaded by shrub species, such as Rhus and Phytocarpus . Early invasion of shrub is slow, but once a few bushes have become established, birds invade the area and help disperse scrub seeds .

9. Climax stage The succession culminates in a climax community, the forest. Many intermediate tree stages develop prior to establishment of a climax community The forest

10. thank you Made by:- Khursheed alam khan