The contribution of termite mounds to landscape‐scale variation in vegetation in a West African national park

Abstract

AbstractQuestionsTermite mounds are important sources of local‐scale soil heterogeneity and thereby affect savanna vegetation. Studies contrasting mound and savanna vegetation usually neglect variation between savanna types. We aim to answer the following questions: (1) is mound vegetation consistently different from the surrounding savanna vegetation at landscape scale; (2) is mound vegetation homogeneous across different savanna types; and (3) are differences between mound and savanna vegetation influenced more by nutrient accumulation or clay enrichment in mounds?LocationPendjari National Park, northern Benin.MethodsWe analysed the vegetation in 59 pairs of mound and savanna plots in four savanna types. We examined if mounds differed in community composition between savanna types, and from savanna plots using ordinations, and tested for correlations between community composition and soil parameters. We identified characteristic plant species for mounds in each savanna type using the IndVal method. Finally, we evaluated the relative importance of different soil parameters for differences in vegetation between mound and savanna plots using projection to latent structures regression (PLSR).ResultsThere were clear differences between savanna types for both savanna and mound plant communities, and in each savanna type, clear differences emerged between mound and savanna vegetation. Community differences correlated with differences in soil parameters in all cases. We identified ten characteristic plant species for mounds, with little overlap between characteristic species from different savanna types. Across savanna types, 63% of the variation in mound – savanna vegetation contrast was explained by variation in nine soil parameters, most importantly clay content.ConclusionEven at the landscape scale, the influence of mounds on vegetation depends on habitat context. Thus, local mound vegetation patterns can only be understood considering the influence of different soil parameters in each savanna type. However, enrichment of clay and macronutrients together explain the largest part of the differences between mound and savanna vegetation. Further variation in vegetation composition among mounds is likely driven by biotic interactions and spatial distribution of mounds.