Alpine wetland degradation reshapes the balance between hydrolytic and reductive soil nitrogen cycling enzyme potentials on the Qinghai–Tibetan Plateau
- 1College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
Abstract
Alpine wetlands on the Qinghai-Tibet Plateau are increasingly degraded, with potentially important consequences for soil nitrogen (N) cycling and ecosystem functioning. However, how degradation restructures enzyme-mediated soil N cycling and its functional potential remains poorly understood. To address this gap, we conducted a three-year field investigation across 2019 to 2021 four degradation stages (i.e.non-degraded (ND), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD)) in the Gahai Wetland. We quantified four key soil N-cycling enzymes, including urease, protease, nitrate reductase, and nitrite reductase, and developed a nitrogen cycling functional potential (NCFP) index to characterize shifts in the relative balance between hydrolytic and reductive N-cycling functions potentials. Our results showing that degradation-induced drying and nutrient depletion reduced soil water content, soil organic carbon, total nitrogen, ammonium availability, and microbial biomass N, while increasing soil temperature and nitrate accumulation. Enzyme responses were strongly pathway specific: urease and nitrate reductase activities increased with degradation, whereas protease and nitrite reductase activities declined. Consequently, NCFP index shifting from slightly positive values in ND and LD to negative values in MD and HD, indicating a reorganization of N-cycling functional potential from a relative hydrolytic bias toward a relative reductive bias. Interannual hydroclimatic variability further modified this pattern; notably, exceptionally wet conditions in 2021 shifted NCFP index toward negative values across all degradation stages. Redundancy analysis and piecewise structural equation modeling showed that soil water content, and organic carbon were the primary regulators of NCFP index. Alpine wetland degradation reorganized the relative configuration of hydrolytic and reductive N-cycling potentials rather than uniformly suppressing N cycling, and this functional balance was jointly regulated by long-term degradation and short-term hydrological variability. Overall, the study provides new insight into mechanisms of soil N-cycling destabilization in degraded alpine wetlands and informs wetland restoration under a drier future climate.
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BibTeX
@article{chang2026alpine,
title = {{Alpine wetland degradation reshapes the balance between hydrolytic and reductive soil nitrogen cycling enzyme potentials on the Qinghai–Tibetan Plateau}},
author = {W. Chang and W. Ma and J. Wang and L. Song and J. Du and W. He and G. Li},
journal = {SOIL},
year = {2026},
month = nov,
doi = {10.5194/soil-12-1121-2026},
url = {https://doi.org/10.5194/soil-12-1121-2026},
note = {CC BY},
}
RIS
TY - JOUR
TI - Alpine wetland degradation reshapes the balance between hydrolytic and reductive soil nitrogen cycling enzyme potentials on the Qinghai–Tibetan Plateau
AU - W. Chang
AU - W. Ma
AU - J. Wang
AU - L. Song
AU - J. Du
AU - W. He
AU - G. Li
PY - 2026
DA - 2026/11/06
JO - SOIL
DO - 10.5194/soil-12-1121-2026
UR - https://doi.org/10.5194/soil-12-1121-2026
AB - Alpine wetlands on the Qinghai-Tibet Plateau are increasingly degraded, with potentially important consequences for soil nitrogen (N) cycling and ecosystem functioning. However, how degradation restructures enzyme-mediated soil N cycling and its functional potential remains poorly understood. To address this gap, we conducted a three-year field investigation across 2019 to 2021 four degradation stages (i.e.non-degraded (ND), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD)) in the Gahai Wetland. We quantified four key soil N-cycling enzymes, including urease, protease, nitrate reductase, and nitrite reductase, and developed a nitrogen cycling functional potential (NCFP) index to characterize shifts in the relative balance between hydrolytic and reductive N-cycling functions potentials. Our results showing that degradation-induced drying and nutrient depletion reduced soil water content, soil organic carbon, total nitrogen, ammonium availability, and microbial biomass N, while increasing soil temperature and nitrate accumulation. Enzyme responses were strongly pathway specific: urease and nitrate reductase activities increased with degradation, whereas protease and nitrite reductase activities declined. Consequently, NCFP index shifting from slightly positive values in ND and LD to negative values in MD and HD, indicating a reorganization of N-cycling functional potential from a relative hydrolytic bias toward a relative reductive bias. Interannual hydroclimatic variability further modified this pattern; notably, exceptionally wet conditions in 2021 shifted NCFP index toward negative values across all degradation stages. Redundancy analysis and piecewise structural equation modeling showed that soil water content, and organic carbon were the primary regulators of NCFP index. Alpine wetland degradation reorganized the relative configuration of hydrolytic and reductive N-cycling potentials rather than uniformly suppressing N cycling, and this functional balance was jointly regulated by long-term degradation and short-term hydrological variability. Overall, the study provides new insight into mechanisms of soil N-cycling destabilization in degraded alpine wetlands and informs wetland restoration under a drier future climate.
SN - 2199-3971
SN - 2199-398X
ER -