USF St. Petersburg campus Faculty Publications


Warming Affects Soil Nitrogen Mineralization via Changes in Root Exudation and Associated Soil Microbial Communities in a Subalpine Tree Species Abies fabri

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Joseph M. Smoak

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The objective of this study was to quantify the responses of root exudates and nitrogen (N) mineralization of Abies fabri to warming and to identify links between root exudation and microbial N mineralization via interactions with the soil microbial characteristics. We conducted a 2-year study to assess the effects of warming on root traits, root exudation, soil microbial community, net N mineralization, and soil N availability within the rhizosphere of A. fabri. Results showed that warming enhanced the exudation rate of total organic carbon (REC) in both years, while warming tended to increase the exudation rate of total N (REN) in the first year, but decrease it in the second year. At the end of the second year, the C/N ratio of root exudates was higher under elevated temperature than under ambient (control) conditions. Warming increased the net N mineralization and net nitrification rates during the first year, but these effects were not observed in the second year. Although warming showed no significant effect on the content of bacteria and fungi in the first year, warming significantly increased the fungi, Gram-positive bacteria, and fungi/bacteria ratio in the second year. Warming effects on rhizosphere soil N mineralization were mainly positively correlated with the REC and REN. These results suggest that net N mineralization rates may be controlled by the quantity and C/N ratio of root exudates, rather than by the simple enhancement in root exudation rates. Our results suggest that warming could promote soil N cycling in cold regions via increased quality and quantity of root exudates.




Springer Nature