Ecosystem recovery in Amazon caatinga forest after cutting, cutting and burning, and bulldozer clearing treatments.

In caatinga forest in the upper Rio Negro Region of southern Venezuela, as disturbance increased in intensity, early successional vegetation changed from primary forest trees (cut treatment) to successional woody species (cut and burned treatment) to forbs and grasses (bulldozed treatment). Soil nutrient levels were greater in both the cut and the cut and burned treatment plots than in the control forest 3 yr after the disturbances, presumably because of steady transfers of nutrients from the forest slash to the soil. Soil nutrient levels in the bulldozed plot were much lower than in the control because of top soil removal. Aboveground biomass at 3 yr was 1291 g m^-2 in the cut site, 870 g m^-2 in the cut and burned site, and 77 g m^-2 in the bulldozed site. Given these rates of biomass accumulation, c.100 yr will be required for both the cut and the cut and burned sites to reach biomass levels characteristic of mature caatinga forest, while over 1000 yr will be necessary in the case of the bulldozed site.-from Authors