kept birth rates high. Efforts at family planning have met with limited success, particularly in rural areas. Pakistan now has a population pyramid with an extremely wide base. About 45 percent of the population is under 15, while 55 percent is under 20 years of age. 50 This demographic structure results in steadily rising demands for social services, especially schools, housing, and jobs. The impacts of rapid population growth are pervasive. They include the sub division of rural agricultural holdings, which decreases the amount of cultivated land per rural inhabitant; the denudation of well-forested hillsides; the migration of villages en masse from high mountain pastures to valleys; and the migration of large numbers of young people to cities. 51 Demand and Supply-Induced Scarcity Land . Pakistan comprises 88.2 million hectares of land, of which 61.8 million has been surveyed. Approximately 20 million hectares is used for agriculture, while some 31 million hectares is forest, rangeland, unutilized, or unutilizable ( Figure 3: Map of Agroecological Regions ). 52 Since independence, the area of land under cultivation has increased by approximately 40 percent. 53 Yet today the country is approaching its physical limits. Of the total surveyed land area, less than 20 percent retains the potential for intensive agricultural use, while 62 percent is classified as having low potential for crop, livestock, and forestry production. Overall, land categorized as cultivable represents less than one-quarter of the country's total area. Today, nearly all of this land is already under cultivation. Very little additional