(4) Human Interfer ice: It is the major biotic factor since human activity influence the rest of biosphere. For example, excessive hunting of carnivorous animals as increased the population of herbivorous animals in
the forests of Madhya Pradesh. They have not only damaged the forests
but have also spoiled crops in the nearby villages.
Scraping and removing of litter from the forest floor are two human activities which lay the ground bare and expose it to agencies of erosion. Lopping and felling of trees in excess of natural regeneration destroy forest structure. Forests have been cleared in the past for producing
agricultural land and bulding of new industrial and residential complex.
Forest clearing through felling and buning has been carried out since the
beginning of agriculture by man. Mahabharata mentions the clearing of
Khandav forest situated between Jamuna and Gangas. Shifting or swidden
agriculture (slash and burn method) consisted of clearing forest and sowing
crops in the cleared areas for a few years. The practice is still in vogue in
parts of Assam (Pathak et.al, 1978). The cradles of the past civilization
have turned into modern day deserts because of over exploitation of natural resources and imigation channels they built for obtained water. The modem Iraq (then Mesopotamia) contains remains of several ancient
canals. Two of them are the largest of all time (Willcocks, 1911). Indus Valley Civilization and Sahara Civilizatiof had well irigated lands. However, irigation systems could not be maintained with the change of politfcal power. The system which was buill up lor increasing the productivity of the land, turmed the same into the most unproductive area.