Global distribution of agroforestry systems

Abstract

In land-use parlance, the terms tropical and temperate are used loosely as approximate synonyms for developing countries and industrialized regions, respectively. From the agroforestry perspective, the arid and semiarid lands, and the subhumid and humid lowlands and highlands recognized in the FAO reports are considered as tropical developing regions and the temperate and Mediterranean regions as industrialized. The types of agroforestry systems (AFS) in these two major regions are different because of their climatic and socioeconomic characteristics. The common systems in the humid and subhumid tropics include forms of shifting cultivation and tree intercropping, homegardens, and shaded perennial associations, whereas various forms of silvopastoral systems, extensive tree intercropping, and windbreaks dominate the agroforestry scene in the semiarid and arid tropics. The major AF practices in the temperate regions include alley cropping, forest farming, silvopasture, riparian buffer, and windbreaks. While a substantial knowledge base and steady markets are available for tree species used in temperate agroforestry, most of the trees and other species used in tropical AFS are underexploited and of unknown nature. The global area under AFS is estimated as 1.6 billion hectares, with roughly 78% in the tropics and 22% in the temperate regions; but these are guestimates considering the lack of proper procedures for delineating the extent of areas under irregular stands of trees mixed with understory crops.