Soil‐texture affects the influence of termite macropores on soil water infiltration in a semi‐arid savanna

Abstract

Subterranean termites create tunnels (macropores) for foraging that can influence water infiltration and may lead to preferential flow to deeper soil layers. This is particularly important in water limited ecosystems such as semi-arid, agriculturally utilized savannas, which are particularly prone to land degradation and shrubencroachment. Using termite activity has been suggested as a restoration measure, but their impact on hydrology is neither universal nor yet fully understood. Here, we used highly replicated, small-scale (50 × 50 cm) rain-simulation experiments to analyse the interacting effects of either vegetation (grass dominated vs. shrub dominated sites) or soil texture (sand vs. loamy sand) and termite foraging macropores on infiltration patterns. We used Brilliant Blue FCF as colour tracer to make the flow pathways in paired experiments visible, on either termite-disturbed soil or controls without surface macropores in two semi-arid Namibian savannas (with either heterogeneous soil texture or shrub cover). On highly shrub-encroached plots in the savanna site with heterogeneous soil texture, termite macropores increased maximum infiltration depth and total amount of infiltrated water on loamy sand, but not on sandy soil. In the sandy savanna with heterogeneous shrub cover, neither termite activity nor shrub density affected the infiltration. Termite's effect on infiltration depends on the soil's hydraulic conductivity and occurs mostly under ponded conditions, intercepting runoff. In semi-arid savanna soils with a considerable fraction of fine particles, termites are likely an important factor for soil water dynamics.

The study of soil infiltration in west part of Semarang City, Indonesia

“…It can be seen from the negative trend, indicating that the lower the infiltration rate, the finer the resulting soil type. These results supported the existing theory and previous study, which shows that the higher the fine material in the soil, the infiltration rate will decrease due to the smaller void size [12]. The soil texture parameter had the smallest effect on the infiltration rate, and this is because, in the field conditions, other parameters also affected the infiltration rate.…”