Subterranean Effects of the Termite Constrictotermes cyphergaster on Soil Fungal Abundance in the Brazilian Caatinga

Termites are key ecosystem engineers whose nesting activities influence soil structure, nutrient dynamics, and microbial communities, particularly in resource-limited environments. In semiarid ecosystems, where soils are typically low in organic carbon, termite-induced modifications may help sustain belowground biological activity. Constrictotermes cyphergaster is a widespread arboreal termite in the Brazilian Caatinga whose nests maintain consistent subterranean connections with the soil, yet the microbial implications of these structures remain poorly understood. In this study, we assessed fungal abundance in soils associated with the nesting system of C. cyphergaster at two semiarid sites with contrasting precipitation regimes and soil classes. Soil samples were collected from beneath arboreal nests, from termite-built hypogeous constructions, and from surrounding soils, and fungal density was quantified using colony-forming units. Fungal abundance differed significantly among sampling points at both sites, with higher densities consistently observed in soils influenced by termite structures compared to surrounding soils. These results suggest that the nesting system of C. cyphergaster creates localized conditions that favor fungal proliferation. Our findings highlight the ecological importance of arboreal termites with subterranean connections in structuring soil microbial communities and emphasize their potential role in maintaining soil functioning in semiarid landscapes.