The extent of man's utilization of natural resources varies with time, place and local economic, social and cultural development. Since available land for agriculture is already diminishing, this increase will result in the impairment of natural resources. Several signs of such impairment are already visible. Erosion is accelerating. Rivers are accumulating silt and pollutants.
Flooding is on the increase.
Soil fertility is declining. The air is getting more polluted. One of the main causes of such processes is the destruction of forests and other vegetation, which had previously provided important soil cover. Efforts to conserve forests, as well as land and water, have been going on for some time. They are aimed at averting floods, reducing erosion and rejuvenating water production through reforestation and afforestation.