Deprived land-use intensification in shifting cultivation: the population pressure hypothesis revisited

This article provides a theoretical framework, based on optimal control theory, to analyze farm households' land-use intensification decisions in forest-based shifting cultivation (slash-and-burn) agroecosystems. The main results from the analysis generally coincide with the "Population Pressure Hypothesis" (PPH) as an important driver of soil degradation due to the so-called "fallow crisis" or "deprived land-use intensification" in shifting cultivation. However, the model also shows, from a supply perspective, that such a vicious circle of lower yields and greater forest land clearing may be avoided when the production elasticity of on-farm labor outweighs the elasticity of substitution between farm labor and soil fertility. Furthermore, using data from shifting cultivating households from Yucatán, Mexico, we calibrate the effect of changes in population density. The numerical analysis suggests that by contrast to better-off households, when population density increases, poorer shifting cultivating households' optimal labor allocation strategy is to further extensify land use by clearing more forest in the village common property land, or "ejido" land. Copyright 2006 International Association of Agricultural Economics.