This represents a significant potential loss of carbon storage capacity and of biodiversity resources. FAO also projects an expansion of 6 million hectares in dry land areas, which are mostly rangeland. Land conversion for aquaculture, although involving a small amount of land, still may threaten unique areas such as mangrove swamps. In some areas, wetlands also are being converted to croplands. Soil erosion presents another potentially significant constraint, particularly in the tropics, where soil fertility is concentrated near the surface.
Erosion also has important downstream effects, such as the siltation of reservoirs.
References and Notes 1. Nikos Alexandratos, ed. Pacific Institute for Studies in Development, Environment and Security and the Stockholm Environment Institute, Water in Crisis , Peter H. Gleick, ed.