Termite mound as nutrient hot-spots in savannah with emphasis in P cycling and the potential use of mounds as soil amendment

Abstract

Termites are an important component of pedofauna and are mainly distributed in subtropical and tropical areas. Their main effect on ecosystems is linked to the construction of tunnels, galleries, mounds, and nests. Termites induce strong changes in the physical-chemical and biological properties of the soil, after and through the processes of decomposition of the organic matter and formation of biogenic structures. At sites with abundant termite populations, galleries and foraging holes enhance soil porosity and infiltration rates, thus reducing soil bulk density. Termite activities result in nutrient accumulation in mounds; therefore, abundant termite populations could play an important role in controlling nutrient cycling in savannahs, where nutrients, particularly phosphorus (P), can often be a limiting factor. Regarding the high nutrient concentration accumulated in termite mounds, authors have claimed that parts of termite mounds could have potential as fertilisers for cultivated soils, and indeed, the use of termite materials for soil improvement is an extended practice in rural, poor, indigenous communities of Africa and Asia. This paper reviews the published data on the accumulation of the nutrients, mainly P in the soil of termite mounds in comparison with the none modified soil, and evaluates the potential use of termite biostructures in soil improvement. While it is true that in greenhouse experiments and in home orchards it is possible to observe the benefit of termite mound treatments, the implementation of such practices on a larger scale is prevented by the low ratio (by weight) of termite nests with respect to the total weight of the soil, as well as by the relatively long rate of renewal of termite mounds once destroyed. However, the use of large structure of Macrotermes, appears to be justified in a low-input agro-ecological scheme to promote the enhancement of termite-mediated ecosystem services.