尕海湿地退化过程中土壤氮矿化变化特征及驱动因素

[Objective]To investigate the spatial and temporal variations of soil nitrogen mineralization rate,soil temperature and humidity,and related enzyme activities in degraded wetland ecosystems.To analyze the spatial and temporal changes of soil nitrogen mineralization rate,soil temperature and humidity,related enzyme activities in degraded wetlands,and the characteristics and internal driving factors of soil nitrogen mineralization change.[Methods]The non-degraded,slightly degraded,moderately degraded,and heavily degraded marsh meadows in Gahai wetland served as the research object,and in-situ cultivation of resin cores in the field was used to examine soil nitrogen mineralization in the early growth stage(June-July),peak growth stage(July-September),and wilting stage(September-October)in 2020.During the degradation of wetland marsh and meadow,examine the temporal and spatial changes of soil nitrogen mineralization and its relationship with soil enzyme activity and environmental factors.[Results]1)Temperature,nitrate reductase,and urease activities increased proportionally with the degree of soil deterioration,whereas soil water content,nitrite reductase,and protease activities decreased.July and August are the prime months for soil temperature,urease,nitrite reductase,and protease.Nitrate reductase levels increased progressively and peaked in October.2)Before and after cultivation,the soil's ammonium nitrogen content decreased by 12.9%-52.4%and 13.8%-55.5%,respectively,compared to its non-degraded state.The net ammoniation rate decreased between 18.6%and 61.1%.Each degradation stage's ammonia nitrogen content and net ammoniation rate peaked in July and August,while the wilt stage shrank over time.3)Before and after cultivation,the soil's nitrate nitrogen content increased by 40.2%to 53.5%and 32.7%to 69.5%,respectively,compared to when no degradation occurred.The nitrification rate increased by 26.73 to 80.0%.Each peaked between July and August.4)slightly,moderately,and heavily degradation inhibited soil nitrogen mineralization by 12.4%,17.4%,and 17.4%,respectively,compared to the non-degraded stage.In July and August,respectively,the utmost values for the three categories were recorded.5)Net nitration rate was significantly positively correlated with nitrate nitrogen,nitrate reductase activity,urease activity,and temperature,and significantly negatively correlated with ammonium nitrogen,protease,nitrite reductase,and water content.The rates of net ammoniation and net nitrogen mineralization were opposites.The ammonium nitrogen content of the soil was the most influential factor in soil nitrogen mineralization,with a contribution rate of 66.5%.[Conclusion]The degradation of Gahai marsh meadow significantly decreased the net ammoniation rate,increased the net nitrogen mineralization rate,and decreased the net nitrification rate.The growth season significantly affected soil nitrogen mineralization rate,enzyme activity,temperature,and humidity.Soil ammonium nitrogen is a key factor influencing soil nitrogen mineralization,and the research findings provide fundamental data for the development of nitrogen process mechanism models in alpine wetlands against a climate change backdrop.