模拟降雨量变化对高寒湖滨湿地土壤呼吸的影响

Effects of Simulated Changes in Precipitation on Soil Respiration in Alpine Lakeshore Wetlands

[目的]探究降水变化对青海湖高寒湖滨湿地土壤呼吸速率的影响,阐明驱动土壤呼吸变化的主控因素,为高寒湿地生态系统碳库变化及区域碳预算提供技术支撑。[方法]以地处青海湖西岸的鸟岛高寒湖滨湿地为研究对象,建立9个投影面积为3 m×3 m的小区,通过原位减水50%、自然对照、增水50%试验处理,解析降雨量变化对湿地土壤呼吸速率的影响强度及过程。[结果]模拟减雨和增雨处理促使土壤温度分别增加0.79,0.68℃。减雨显著提高湿地植被地下根系生物量,增雨显著提高土壤含水量,增幅分别为10.3%和13.2%(p<0.05)。增雨和减雨处理均降低土壤呼吸速率,且增雨处理抑制效果更明显。2020年不同处理下降水量变化对土壤呼吸速率影响不显著。减雨处理土壤呼吸速率与0—10 cm土壤温度、湿度、pH、土壤全氮以及地下生物量呈二次项正相关关系,与土壤全碳呈二次项负相关关系;增雨处理下土壤呼吸与0—10 cm土壤湿度、pH、地下生物量二次项负相关,与0—10 cm土壤温度、土壤全碳、全氮二次项正相关。[结论]降水格局改变降低青海湖鸟岛湿地土壤呼吸速率,且其速率受多重因素影响,其中土壤温度贡献最大。

[Objective]This study aims to investigate the effects of precipitation changes on soil respiration rate in alpine lakeshore wetlands of Qinghai Lake,to elucidate the main controlling factors driving the changes of soil respiration rate,and to provide technical support for the changes of carbon pool in alpine wetland ecosystem and regional carbon budget.[Methods]Nine plots with projection area of 3 m×3 m were established in the alpine lakeshore wetland of Bird Island,located on the west bank of Qinghai Lake,and the intensity and process of rainfall variation on soil respiration rate in the wetland were analyzed by in situ water reduction of 50%,natural control and water increase of 50%experimental treatments.[Results]The simulated rainfall reduction and rainfall increase treatments induced the increase in soil temperature by 0.79 and 0.68℃,respectively,compared with the control.Rainfall reduction significantly increased the below-ground root biomass of wetland vegetation,and rainfall increase significantly increased soil water content by 10.3%and 13.2%,respectively(p<0.05).Both rainfall increase and rainfall reduction treatments reduced soil respiration rate,and the inhibition effect was more pronounced in the rainfall increase treatment.Precipitation changes under different treatments in 2020 did not have significant effects on soil respiration rate.Soil respiration rate under rainfall reduction treatment was positively correlated with 0—10 cm soil temperature,moisture,pH,total soil nitrogen and below-ground biomass in quadratic terms and negatively correlated with total soil carbon in quadratic terms;soil respiration under rainfall increase treatment was negatively correlated with 0—10 cm soil moisture,pH and below-ground biomass in quadratic terms and positively correlated with 0—10 cm soil temperature,total soil carbon and total nitrogen in quadratic terms.[Conclusion]Altered precipitation patterns reduced soil respiration rates in Bird Island Wetlands of Qinghai Lake,and the rates were influenced by multiple factors,with soil temperature contributing the most.