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Elevation and cropping system as drivers of microclimate and abundance of soil macrofauna in coffee farmlands in mountainous ecologies

Karungi, J., Cherukut, S., Ijala, A.R., Tumuhairwe, J.B., Bonabana-Wabbi, J., Nuppenau, E.A., Hoeher, M., Domptail, S., Otte, A.
Applied soil ecology 2018 v.132 pp. 126-134
Coffea arabica, Formicidae, agricultural land, agroecosystems, altitude, ambient temperature, annuals, bananas, biotic factors, companion crops, earthworms, ecosystem services, light intensity, microclimate, mineral fertilizers, mountains, shade trees, soil electrical conductivity, Uganda
Unravelling how earthworms and ants are deterministically structured by abiotic and biotic factors is of utmost relevance in fostering favourable environments for their increased abundance and action, more so in the increasingly degraded agricultural ecosystems of mountainous regions in sub-Saharan Africa. The Mount Elgon region (MER) of Uganda is characterised by mosaics of farmlands dominated by Arabica coffee with variability in inclusion of companion crops and shade trees, and in use of organic and inorganic fertilizers; and elevation. In this paper we explored abundance of soil macrofauna and microclimate patterns in different cropping systems at varying mountain elevations. The study covered 72 coffee fields delineated by 3 elevation categories: low, mid and high; and 4 cropping systems: Coffee monocrop (C), Coffee + annual crop (C + A), coffee + banana (C + B), and coffee + banana + shade trees (C + B + T). Results indicated that ant abundance at high elevation was thrice that of low and was same order of magnitude in unshaded than in banana- and tree-shaded systems. Earthworm abundance followed a different trend, decreasing with altitude except in C + B and C + A systems. Some of these relationships could be explained by ambient temperature, light intensity and soil electrical conductivity in the systems. Earthworms preferred less-illuminated shaded coffee systems at warmer low-mid elevations and soils with relatively high electrical conductivity whereas ants’ counts were depressed by such systems, and mostly driven by cooler higher elevations. These results show that agricultural practices at the field scale have notable impact on abundance of macrofauna that provide ecosystem services and need consideration when working towards sustainability.