부산대학교 도서관

Aims: In West Africa, savannas are changing to either forest islands or arable lands arising from anthropogenic interference with the natural ecosystem. This study aimed at quantifying the trade-offs of this land use conversion on major soil quality indicators.Methods: We evaluated soil organic matter (SOM) and other soil quality indicators such as macro- and micronutrients (including the absence of some hazardous trace metals) using standard methodologies across 11 settlements in Burkina Faso, Ghana, and Nigeria. The degree of soil quality improvement/degradation and soil quality were assessed using empirical models.Results: The effects of savanna conversion were manifold and varied depending on the type of land use change, soil depth, and soil quality indicator. In savanna-forests, there was a substantial rise in SOM (37%—794%) and exchangeable cations (15% to 800%) and changes in SOM in the topsoil quadrupled that of the subsoil. A general loss in SOM (1% -74%) and soil macro-and micronutrients occurred under savanna-arable lands. Potassium, calcium and magnesium increased by ≥ 12%, ≥ 15% and 27% respectively while increases in Mn and Zn were 37% and ≥ 250% in the forests over the savannas. Trace quantities of Pb were detected which were below the contamination threshold. About 63% forest islands, 18% arable land, and 9% savannas had SQI % ≥ 50.Conclusion: In marginal lands, land use conversion to forest islands presents great potential for improving soil fertility and overall ecosystem health as shown in the high organic matter and improved soil quality.