Effects of ant colonization on spatiotemporal variation of organic carbon mineralization in Xishuangbanna tropical forest soils

Ants as ecosystem engineers can increase the input of soil organic matter, change soil physicochemical properties, and stimulate microbial activities through their colonization, thus affecting the spatiotemporal dynamics of soil organic carbon mineralization. We explored the spatiotemporal characteristics of carbon mineralization rates in ant nests and the adjacent soils in Syzygium oblatum community of Xishuangbanna, Yunnan. We analyzed the association of the variation in carbon mineralization rates with soil physicochemical properties. We found that ant colonization had a significant effect on soil organic carbon mineralization. The mean carbon mineralization rate was 19.2% higher in nest soils than that in the surrounding soils. The monthly carbon mineralization rate in nest soils and the reference soils was ranked as June September March December. The highest increase of carbon mineralization rate in ant nests was observed in 10-15 cm soil layer, while that in the reference soils was in 0-5 cm soil depth. Ant colonization had a significant effect on soil physicochemical properties. Compared with reference soils, soil temperature, soil water, soil organic carbon,soil microbial carbon, total nitrogen, hydrolytic nitrogen, nitrate, and ammonium increased by 7.6%, 5.4%, 9.9%, 14.8%, 13.4%, 9.9%, 24.1%, 6.6% and 19.4%, respectively. In contrast, soil bulk density and soil pH were decreased by 1.4% and 2.5%, respectively. Results from correlation coefficients and principal component analysis (PCA) showed that soil organic carbon and soil microbial carbon were the key factors controlling the mineralization of soil organic carbon, followed by total nitrogen, hydrolyzed nitrogen, ammonium, nitrate, temperature, and soil moisture. We conclude that ant colonization mainly alter the substrate components (i.e., soil organic carbon and microbial biomass carbon) of soil organic carbon mineralization and thus affect its spatio-temporal dynamics in Xishuangbanna tropical forests.