The influence of termite-induced heterogeneity on savanna vegetation along a climatic gradient in West Africa

Abstract

Abstract:Termites are renowned ecosystem engineers. Their mounds have been described as an important element of savanna vegetation dynamics, but little is known about their large-scale impact on vegetation composition. To investigate the influence of termite-induced heterogeneity in savannas along a climatic gradient in West Africa termite mound vegetation was compared with adjacent savanna vegetation using 256 paired plots (size of the termite mound and a corresponding savanna area) in five protected areas from northern Burkina Faso to northern Benin. On each plot vegetation and soil sampling was performed. Additionally bioclimatic variables from the WORLDCLIM database were used. The vegetation on the mounds and the surrounding savanna differed within all study sites (DCA length of gradient 3.85 SD) and showed complete turnover along the climatic gradient (DCA length of gradient 5.99 SD). Differences between mounds and savanna were significantly related to termite-induced changes in soil parameters, specifically clay enrichment and increased cation concentrations (base saturation). On a local scale, termite-induced differences in soil conditions were found to be the most important factor affecting mound vegetation, while on a regional scale, annual precipitation showed the strongest significant correlations. However, with increasing precipitation, differences between mounds and the surrounding matrix became more pronounced, and the contribution of mounds to local phytodiversity increased. Eleven plant species were identified as characteristic termite mound species. In the more humid parts of the gradient, more characteristic plant species were found that may benefit from favourable soil conditions, good water availability, and a low fire impact in the mound microhabitat.

Edaphic specialization in relation to termite mounds in Katanga (DR Congo): A reciprocal transplant experiment with congeneric tree species

“…Macrotermes termite mounds in the savanna and dry woodlands of tropical Africa host a distinctive flora and original plant communities (Boaler, ; Burtt et al., ; Davies et al., ; Erpenbach et al., , ; Fanshawe, , ; Joseph, Seymour, Cumming, Cumming, & Mahlangu, ; Muvengwi et al., , ; Seymour et al., ; Traoré et al., ; Van der Plas et al., ; Wild, ). However, up to now, the mechanisms underlying habitat specialization have never been investigated experimentally.…”

“…In the last decade, much progress has been made in the analysis of plant community patterns and functional traits of plant species associated with termite mounds in tropical Africa, and their underlying edaphic determinism (Davies et al., , ; Erpenbach, Bernhardt‐Römermann, Wittig, & Hahn, ; Erpenbach, Bernhardt‐Romermann, Wittig, Thiombiano, & Hahn, ; Erpenbach & Wittig, ; Joseph et al., , ; Muvengwi, Witkowski, Davies, & Parrini, ; Muvengwi et al., ; Van der Plas, Howison, Reinders, Fokkema, & Olff, ). However, the processes accounting for the narrow realized niche of edaphically specialized “termitophilous species” are not well understood.…”

Variable effects of termite mounds on African savanna grass communities across a rainfall gradient

“…) and moisture availability (Steinke & Nel ; Erpenbach et al. ), as well as increased fire protection (Joseph et al. ; Van der Plas et al.…”

“…Once distinct communities have been established, positive feedback loops resulting from increased shading (Erpenbach et al. ; Van der Plas et al. ) and herbivory (Okullo & Moe ) further enhance and maintain differences.…”

Importance of bird seed dispersal in the development of characteristic vegetation on termite mounds in north-eastern Namibia

“…Termite mounds support more diverse woody plant assemblages (Loveridge andMoe 2004, Traore et al 2008) and herbaceous layers (Moe et al 2009, Okullo andMoe 2012a, b) than surrounding tracts of savanna. Termite-induced resource heterogeneity, such as soil composition (Sileshi et al 2010, Erpenbach et al 2013) and soil moisture , Konate et al 1999, induces this vegetation pattern. Spatial heterogeneity is also a factor, in that termite mounds act as refugia for plants from fire (Moe et al 2009, Joseph et al 2013) and flooding , Bloesch 2008.…”