Termite mounds vary in their importance as sources of vegetation heterogeneity across savanna landscapes. (16th July 2017)

• Record Type: Journal Article
• Authors: Muvengwi, Justice; Witkowski, Edward T. F.; Davies, Andrew B.; Parrini, Francesca
• Editors: Overbeck, Gerhard
• Is Part Of: Journal of vegetation science. Volume 28:Number 5(2017:Sep.)
• Page Start: 1008
• Page End: 1017
• Publication Date: 2017-07-16
• Subjects: Basalt -- Biomass production -- Granite -- Macrotermes -- Savanna -- Soil nutrition -- Spatial extent -- Species richness; Plant ecology -- Periodicals; Plant communities -- Periodicals; Plant populations -- Periodicals; 581.7
• DOI: 10.1111/jvs.12560
• Languages: English
• ISSNs: 1100-9233

Abstract

Abstract: Questions: Termite mounds are known to host a suite of unique plants compared with the surrounding savanna matrix. However, most studies testing the significance of mounds for ecosystem heterogeneity have been conducted at single sites. Mound effects on savanna heterogeneity across varying landscapes are less well understood, and how effects might vary across geological types and mounds of different sizes is as yet unknown. Location: Gonarezhou National Park, Zimbabwe. Methods: We studied effects of termite mounds on vegetation spatial heterogeneity across two geologies (granite and basalt), including effects of mound size and the spatial extent of termite influence. Herbaceous vegetation was sampled on mounds and savanna matrix plots, and along distance transects away from mounds. Soil nutrients on mounds and in the matrix were also compared between geologies. Results: Soil nutrients were more concentrated in large mounds compared with the matrix on granite, but not on basalt, with mounds therefore acting as nutrient hotspots only on nutrient‐poor granite. Large‐ and medium‐sized mounds hosted compositionally different grass species to the matrix on granite, but not on basalt. Large mounds on granite also had significantly lower grass and forb species richness compared with the matrix. However, small mounds on granite, and all mound size categories on basalt, did not have an effect on grass and forb species richness or assemblage composition, an observation attributed to a lack of difference in soil nutrients between the mounds and matrix. Conclusion: Our study shows that the significance of termite mounds to ecosystem spatial heterogeneity is strongly influenced by geology and mound size, with mound effects on herbaceous plant species heterogeneity more pronounced in dystrophic geologies and around large mounds. Future studies should take greater cognisance of landscape context and mound size when seeking to understand the contribution of termite mounds to ecosystem structure and function. Abstract : Our results demonstrate that Macrotermes mounds alter the spatial distribution of the savanna herbaceous community, increasing ecosystem heterogeneity, but that effects vary across the landscape, being stronger on nutrient‐poor geologies. Our findings further highlight the growing understanding that termite mound effects are dependent on environmental context and that they are of less consequence in nutrient‐rich areas.