Air in motion is called wind. It can circulate gases, water vapours and small soil particles. The action of wind is an ecological factor. Its affect may be direct or indirect. The direct effects of wind are seen in regions with continuous action of high wind velocities. There are following affect of wind:
- Direct effect of wind
It has following direct effects:
(a) Plants may be uprooted and blown away by storm winds in Coastal
regions or exposed mountain tops. Therefore, the vegetation of these areas is largely composed of species with prostrate or stunted growth. They have well developed underground roots or rhizome system.
(b) There is a continuous and unidirectional wind pressure in coastal regions. Therefore, the trees and their branches direct themselves towards the lowered side.
(c) The branches of large trees are broken or entire trees are uprooted in strong winds or hurricane.
(d) Violent winds cause flattening of the herbaceous plants to the ground. It is called lodging. It takes place in herbaceous and weak stemmed plants like grasses, maize, wheat, corn, sugar-cane etc.
(e) Strong wind also carries sand particles. These particles have abrasive action on the leaves and tender branches. Crops grown near sandy tracts suffer from abrasive action of the wind.
- Direct effects
Indirect effects of wind are physiological. These are:
(al Transpiration: Wind influences the rate of transpiration of plants. Air currents take away the air saturated with water vapour. It increases the transpiration. Wind velocity increases with height above the surface of the soil. Therefore, large plants are more affected by high rates of transpiration than the smaller ones.
(b)Stunted growth: Strong winds increase transpiration rapidly. The plants can not maintain an internal water balance. Therefore, these plants suffer from dehydration. They losses turgidity. Therefore. their organs become dwarfed. This is common in trees on sea coast, arctic, or alpine timberline.
(c)Soil erosion: Wind also causes erosion of soil by carrying out soil particles.
(d) Dispersal of pollen grain, seed and fruit. Wind is also important for dispersal of pollen grains, seeds and fruits.