Modelling Landscape Effects of Agroforestry on Watershed- and Ecosystem Functions in a Small Watershed in Nicaragua
Alex Pohl, Carsten Marohn, Benjamin Warth, Georg Cadisch
University of Hohenheim, Inst. of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), Germany
Slash and burn agriculture without fallow in maize-bean systems of Northwest Nicaragua has led to severe soil degradation through soil organic matter (SOM) mining and erosion. SOM loss is aggravated through cattle grazing on harvested fields. Improved maize-bean rotation systems have been developed, namely Slashing & Mulching of Crop Residues (CR), which is current farmers' practice, and the Quesungual Slash & Mulch Agroforestry System (QSMAS), an agroforestry system based on permanent soil cover, absence of burning, minimal soil disturbance and efficient fertiliser use. Native trees conserved in cropping fields are heavily pruned twice a year, before maize and bean sowing to provide light, soil cover and litter. While CR and QSMAS do not differ in maize and bean yields, QSMAS is known for its potential to create important ecosystem functions (ground cover, nutrient cycling and soil moisture) through the provision of a mulch layer. However, fodder scarcity during dry seasons compels farmers to expand livestock grazing on QSMAS and CR plots, potentially counteracting systems benefits. Thus, a study using the spatially explicit and dynamic process based Land Use Change Impact Assessment model (LUCIA) was implemented to compare two QSMAS designs, which differed in species composition and pruning intensities, as well as the CR system regarding their effects on watershed functions under different management options.
Keywords: Agroforestry, dynamic modelling, ecosystem services, Nicaragua, Quesungual
Contact Address: Alex Pohl, University of Hohenheim, Inst. of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), 70593 Stuttgart, Germany, e-mail: pohlalexuni-hohenheim.de