Various seasonal pattern and mechanisms of soil nitrogen transformation along elevations in the Hengduan Mountains

<p><span>Soil nitrogen (N) transformation, a key microbial process in global N cycling, is thought to alter soil N availability and subsequently regulate ecosystem functioning. In particular, the gross rates of N transformation can provide a deeper understanding of internal N dynamics and mechanisms, but questions of whether gross N transformation processes and their underlying drivers change with seasons and elevations remain large uncertain.</span></p> <p><span>Based on field collection along an elevational gradient and laboratory incubation experiments, we investigated the seasonal processes of soil N mineralization and nitrification with 15N isotope dilution technique, and also explored the potential mechanisms involved in the Hengduan Mountains.</span></p> <p><span>Unimodal soil gross/net mineralization rates were higher in the wet season (61.32 mg kg^-1 d^-1; 1.01 mg kg^-1 d^-1; respectively) than in the dry season (10.88 mg kg^-1 d^-1; 0.55 mg kg^-1 d^-1; respectively) (P &lt; 0.001), with a peak at medium elevation. Soil gross/net nitrification rates were lower in the wet season (1.43 mg kg^-1 d^-1; -0.017 mg kg^-1 d^-1) than in the dry season (2.49 mg kg^-1 d^-1; 0.004 mg kg^-1 d^-1; respectively) (P &lt; 0.001), which increased with increasing elevation. The results detected the dominant drivers of the gross transformation rates, specifically microbial attributes occupied crucial roles in controlling the gross mineralization/nitrification</span> <span>in the wet season, and soil physicochemical properties were dominant controllers on the gross mineralization/nitrification</span> <span>during the dry season.</span></p> <p><span>This study revealed the divergent patterns and drivers of N transformation, suggesting that seasonal N cycling should no longer be overlooked if we are to predict N biogeochemical cycles in response to environmental change accurately.</span></p>