HISTORICAL LAND-USE EVOLUTION IN A TROPICAL ACID UPLAND AGROECOSYSTEM

Understanding the historical evolution of land use in humid tropical a groecosystems may assist in developing more appropriate farming system s-better able to sustain dense human populations, alleviate deforestat ion and regenerate degraded land resources. We analyzed land use chang e over a 40 year period for a key acid upland farming systems research site (8 km X 10 km) undergoing rapid transformation in Claveria, Mind anao, Philippines. The landscape is dominated by small-scale cereal cr opping on gently to steeply rolling volcanic Oxisols. The six slope cl asses identified (ranging from 0-3% to more than 60%) each occupied be tween 9 and 19% of the study area. Aerial photographs (1:15000) taken in 1949 and 1967, and a ground survey in 1988, were used to map land u se patterns at three points in time. Settlement by in-migration began early in the twentieth century. By 1949 9% of the land was cultivated, but grassland (59%) and forest (14%) were the dominant land uses. Fro m 1949 to 1967 the cultivated area doubled to 20%, and the proportion of grassland decreased to less than 50% of the land. The forested area remained unchanged. Subsequently, settlement by small-scale farmers a ccelerated. Between 1967 and 1988 the area cropped annually doubled ag ain to 41%. Forest land declined drastically during this period to 1%, while perennial cropland (mainly coffee) increased to 30%. Land use o n the steeply sloping lands (more than 15%) was particularly affected during the 21 year period: 27% was converted to field crop production, and 43% to perennial crops. More than 33% of the food crop area is no w on steep slopes. The analysis of the historical evolution of land us e may guide research priorities for developing sustainable technologie s on sloping land based on agroforestry.