The plants requiring high humidity for proper growth are known as hygrophytes. Orchids, mosses, lichens need high humidity. The rate of transpiration increases with a decrease in humidity.

If number of organisms increased at a specific place, intra species competition will be increased as members of same species compete for limited resources which leads to a reduction in fitness for both individuals. Increase of number of organisms will also increase Inter species competition which occurs when members of different species compete for a shared resource. 

Mortality is state of being mortal, or susceptible to death; opposite of immortality. Reproduction and mortality will balance a population, alteration in both will lead to several situations like exponential population growth, declining populations growth, etc.

About 25-30% of insect population is known to be herbivore but still green plants are persistent. The reason is that population of herbivorous insects is maintained constant by predators. This prevents complete utilization of plants by insects for food.

1. Crustose lichen stage : Crustose are forms an external protective layer on surface of rock. Special types of lichens can grow on ,se rocks. The lichens are called crustose lichens. Examples: Licanora, Rhinodina, etc.

2. Foliage lichen stage: Crustose lichens helps in formation of foliage lichens. THey are leaf like structures which retains water and maintains moisture on rock. Examples: Parmelia, Dermaticarpo, etc.

3. Moss stage :The soil becomes more porous leading to growth of mosses.They penetrate more in to soil and helps for growth of herbaceous plants. Examples: Polyerichum, Tornda, etc.

4. Herbaceous (plant) stage: Due to increases water and hummus, herbaceous plants are grown. Evaporation or transpiration starts taking place. Now bacteria, fungi and or animalscan be found here. Examples: perennial herbs and grass. 

5. Shrub stage: Soil is now favourable for shrubs. They grow and become dense. Examples: Rhus, etc.

6. Climax stage:  Now soil allows growth and establishment of woody plants with dense roots. Later, y are changed into woody forests.