Land Degradation and Fertility in sub-Saharan West Africa: Disaggregating the Demographic Response

Demographic responses to environmental pressures have long been hypothesized in classic population theory, though empirical analyses remain scarce and traditionally focus on aggregate units of analysis. In this paper we test the hypothesis that land degradation since the 1980s led to marriage postponement and fertility reduction in eight sub-Saharan West African countries in the early 2000s. Using georeferenced data from multiple Demographic and Health Surveys, combined with remotely sensed data on land degradation, we examine proximate determinants of fertility among rural women in response to decline or fluctuation in net primary productivity (NPP) over time. Results consistently show little to no effect of environmental determinants, particularly long-term land degradation, on a set of fertility related outcomes. This is in sharp contrast to the negative association between land degradation and fertility found at the aggregate level. However, recent fluctuations in NPP are negatively associated with age at first marriage, suggesting that early marriage among women may reflect household decisions to diversify and reduce risk. These results call into question the spatial and temporal scales at which demographic responses to environmental pressures occur, and the extent to which these are confounded by economic development.