Mound building termites contribute to savanna vegetation heterogeneity

Abstract

With biomass densities comparable to large ungulates and megaherbivores, termites play a key functional role in many tropical savanna ecosystems. This study focuses on vegetated termite mounds (termitaria) constructed by the Termitidae species Macrotermes herus. We studied how resource rich termitaria affect graminoid herbs (Poaceae and Cyperaceae), forbs and woody species composition and diversity. The density of termitaria explained 89% of the variation in dense thickets in the area. Fire tolerant Acacia species dominated the open savanna while fire sensitive species like Grewia spp. and the succulent Euphorbia candelabrum were restricted to termite mounds. Termitaria plots had four times the mean number of woody species and supported three times as many forb species as the adjacent savanna. For woody species, both the Shannon-Wiener index and the Shannon evenness index were higher on temitaria than on the savanna. There were no differences for graminoid herbs, except for the Shannon evenness index which was higher on termitaria. Our results indicate that graminoid herb richness peaks at lower productivity levels than trees and forbs in savanna ecosystems, as also recently found in temperate areas.

Termites create spatial structure and govern ecosystem function by affecting N2 fixation in an East African savanna

“…While many ecologists may quibble about these exact labels, our goal was to understand these species' roles in controlling a key ecosystem process, biological nitrogen (N) fixation. In particular, although the importance of termites in biogeochemical cycling and, in some cases, the creation of heterogeneous habitat, is well recognized (e.g., Arshad 1981, Jouquet et al 2005, Moe et al 2009; see review in Jones 1990), the range of mechanisms by which they exert their effects have remained unclear, as has the spatial extent and patterning of their influences.…”

Modeling Vegetation Lifeforms Abundance based on <i>Epigeal Termitaria</i> Physiography and Altitude in Tropical Savannah of Katolo Sub-Location, Kisumu County

“…Trees growing on-mound were regarded as woody vegetation lifeforms with diameter at the base (10 cm above the mound) greater than 6 cm as determined [28]. These were counted by two observers and actual population obtained following [29] sampling approach by two observers.…”

“…Shrubs growing on and off-mound plots were woody plants below 3 m in height (determined by inclinometer) and have diameter less than 6 cm at 10 cm above the ground as determined by sliding Vernier caliper [28]. (transect).…”

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

“…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. Okullo et al (2012a) suggested that large herbivores maintain termite-induced differences in savanna vegetation.…”