Soil erosion and nutrient dynamics in tropical mahogany (Swietenia macrophylla) and acacia (Acacia mangium) forest plantations of the Caratal Watershed, St. Vincent, West Indies

A soil erosion/nutrient dynamics study was conducted in the Perseverance sub-basin of the Caratel Watershed, located on St.Vincent, West Indies. The goal of the study was to quantify the amount of runoff, sediment and nutrients lost in a mahogany and acacia plantation (both eight years of age). From this, conclusions regarding the effectiveness of the plantations at stabilizing former agricultural land can be drawn. Farmers are relocated. The effect of under story clearing on runoff, sediment loss and nutrient loss also was determined.;Erosion plots and modified Gerlach Troughs were used to demonstrate that sediment loss was 2.8 greater in the acacia plantation and runoff was 0.66 times greater in the mahogany plantation. Nutrient loss with sediment was greater in the acacia plantation while nutrient loss as runoff was greater in the mahogany plantation. It also was determined that the nutrient balance of both plantations may be in a degrading state. Understory clearing resulted in a 6.1 times increase in runoff, a 3.7 times increase in sediment loss and an increase in nutrient loss of 60%.;Rainsplash erosion was the dominant erosive force in the acacia plantation and overland flow erosion in the mahogany plantation. Controlling the types of erosion were the differences in vegetation, namely tree heights and grasses and the soils aggregate stability.