Understanding the historical evolution of land use in humid tropical agroecosystems may assist in developing more appropriate farming systems better able to sustain dense human populations, alleviate deforestation and regenerate degraded land resources. We analyzed land use change over a 40 year period for a key acid upland farming systems research site (8 km × 10 km) undergoing rapid transformation in Claveria, Mindanao, Philippines. The landscape is dominated by small-scale cereal cropping on gently to steeply rolling volcanic Oxisols. The six slope classes identified (ranging from 0–3% to more than 60%) each occupied between 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 use 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. From 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 accelerated. Between 1967 and 1988 the area cropped annually doubled again to 41%. Forest land declined drastically during this period to 1%, while perennial cropland (mainly coffee) increased to 30%. Land use on 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 now on steep slopes. The analysis of the historical evolution of land use may guide research priorities for developing sustainable technologies on sloping land based on agroforestry.
Tag: humid tropics
Alley farming as a potential agricultural production system for the humid and sub-humid tropics
It is widely recognized that the biggest challenge facing agricultural research in the Tropics is the development of farming systems capable of ensuring increased and sustained productivity with minimum degradation of the soil resource base. Reversing the trend of declining per capita food production in sub-Saharan Africa, therefore, does not depend solely on the development of improved and high-yielding crop varieties. Development of sustainable production systems is necessary to foster and maintain advantages derived from such improved varieties. The issue of sustainability has received considerable attention in recent years in agricultural research and development (CGIAR, 1990). The nature of much of the upland soils in the Tropics is such that over exposure and over cultivation can easily lead to their degradation. According to the Soil Management Support Services (1986), agricultural land in most humid and subhumid tropical regions is dominated by low activity clay (LAC) soils whose inherent characteristics and limitations make large upland areas dominated by these soils less suitable for conventional mechanized and high-chemical input farming methods. These soils have inherently low fertility, and are highly erodible when left unprotected. Nutrient loss through run off and erosion can, however, be kept to a minimum by using appropriate production systems that minimize disturbance and ensure a protective cover of the surface soil through live or dead mulches (Lai, 1986). Management of vegetation within the cropping system also could contribute to maintenance of soil fertility and enhance the stability of the cropping system (Juo & Lai, 1977; Lal et al., 1978). In the Tropics, trees have long been recognized as essential both for the stability of the environment and for maintenance of soil fertility for crop production. Trees have been recognized as major elements in soil fertility regeneration and conservation as reflected by their prominence in tradition.
Biodiversity: issues relevant to integrated natural resource management in humid tropics
Humanity stands at a defining moment in history. We are confronted with a perpetuation of disparities between and within nations, a worsening of poverty, hunger, ill health and illiteracy, and the continuing deterioration of the ecosystems on which we depend for our well-being. However, integration of environment and development concerns and greater attention to them will lead to the fulfillment of basic needs, improved living standards for all, better protected and managed ecosystems and a safer, more prosperous future.
Agroforestry systems: some definitions and contribution to forests dynamics
Agroforestry is probably one of the most controversial word for the definition of a combination, or intergration of trees (foresty components) and crops or fodder (agricultural components) into various types of cropping systems. Agroforestry systems varies from the most simple (SAF), a crop associated with a tree, to the most complex in terms of structure, the CAF (Complex agroforestry system) with multistrata components, a large biodiversity in terms of species and frequencies, where several perennial crops and trees are associated. After describing rapidly the concept of agroforestry, we will focus on a particular typology and provide two examples of simple agrofest (SAF), parkland in Africa, and complex agroforest (CAF) in Indonesia.