Effect of termite mounds on soil microbial communities and microbial processes: Implications for soil carbon and nitrogen cycling

Fungus-feeding termites are considered to be ecosystem engineers because of their ability to construct massive and complex mounds with different soil physicochemical and biological properties in tropical ecosystems. However, the impact of the termite nesting process on soil microbial communities and microbial functions related to nutrient cycling is poorly understood. In this study, we investigated termite-induced changes in soil microbial communities and their nutrient cycling functions within termite mounds (i.e. live mounds and abandoned mounds) in the humid tropical region of Southwest China. We found that the live mounds harbour intermediate microbial community richness (i.e. PLFAs, fungi, bacteria, G+, and G-bacteria) between sur-rounding topsoils and deep soils, with the ratio of fungi to bacteria (F:B) in mounds being significantly higher than in surrounding soils. However, the microbial communities gradually transformed to resemble the sur-rounding soils after the mounds were abandoned because of natural weathering and plant invasion. A relatively more uniform distribution of microbial communities was found within live mounds than in abandoned mounds and surrounding soils, suggesting that termites shaped the environment within the mounds, leading to the ho-mogenisation of microbial communities. In addition, the termite-induced changes of soil physicochemical properties (e.g. water content, pH, organic matter, total N and P) were closely linked to microbial communities. We also observed a reduction in microbial processes associated with nutrient cycling, including microbial respiration, and extracellular enzymatic activities, in mounds relative to the surrounding topsoils. These findings have important implications for exploring microbial communities within termite mounds, which is critical to understand the potential role of termites in regulating soil carbon and nitrogen cycling in tropical ecosystems.