Land-use diversity within an agricultural landscape promotes termite nutrient cycling services in a southern African savanna

Abstract

Soil macrofauna provide key supporting ecosystem services by transporting nutrients against physical and chemical gradients. In the semi-arid savannas of southern Africa, termites are the dominant macrofauna whose foraging activities increase nutrient availability, soil aeration and water infiltration. With increasing land-use conversion, savanna landscapes are becoming surrounded by a matrix of agricultural landscapes. We tested how compositional and configurational landscape heterogeneity influenced the presence of soil sheetings, a termite foraging activity, within savanna habitat patches embedded in a heterogeneous agricultural landscape in north-east Eswatini. We found that landscape heterogeneity most strongly influenced termite foraging activity at smaller spatial scales (1- to 2-km surrounding the savanna patch). Within this spatial scale, high compositional heterogeneity, which was indicative of diverse habitat patches, promoted termite foraging activity, yet high configurational heterogeneity, indicative of a fragmented landscape, reduced termite foraging activity. At larger landscape scales (5-km), the heterogeneity of the landscape no longer influenced termite foraging activity, yet low to moderate proportions of sugarcane surrounding savanna patches promoted termite foraging activity within those patches. Our results provide novel insights in how the structure of the landscape affects termite foraging activity, demonstrating that diverse, intact landscapes are a critical buffer in maintaining positive nutrient cycling services within an agricultural landscape. Keywords: Ecosystem services, Nutrient cycling, Landscape heterogeneity, Land-use change, Termite foraging activity, Savannas