Tree diversity, carbon stocks, and soil nutrients in cocoa-dominated and mixed food crops agroforestry systems compared to natural forest in southeast Ghana

摘要

The importance of different agroforestry systems in conservation of biodiversity and ecosystem services is poorly understood. In this study, we investigated tree diversity, carbon stocks, and major soil nutrients in cocoa-dominated and mixed food crops agroforests compared to a natural forest in southern Ghana. Significant decreases in tree species diversity and dominance and carbon stocks in the agroforestry systems compared to natural forest were recorded. The magnitude of carbon stocks declined from natural forest through cocoa-dominated agroforest to mixed food crops agroforest. Soil nitrogen content was greatest in cocoa-dominated agroforest and least in natural forest whereas phosphorus was greatest in natural forest and least in cocoa-dominated agroforest. However, potassium in soil did not vary significantly with land use. The results suggest that, though a poor substitute for natural forest, both cocoa-dominated agroforest and mixed food crops agroforest contained significant levels of tree diversity, carbon stocks and soil nutrients but their value as potential replacements for the natural forest differ. There are implications of the findings of the study for sustainable management of tropical agricultural production landscapes as well as planning carbon projects for mitigation of global climate change.