模拟降雨对新疆天山北坡山地草地碳水通量的影响

Effects of Simulated Rainfall on Carbon and Water Fluxes in Alpine Meadow on the Northern Slope of Tianshan Mountain

为探究降雨对山地草地生态系统碳水通量的影响,以新疆天山北坡山地草地为研究对象,通过模拟0(对照)、5、18和38mm 4个降雨梯度,利用CO_(2)/H_(2)O非色散红外气体分析仪(LI-840A,LI-COR,USA)对模拟降雨后的净生态系统碳交换(Net ecosystem exchange,NEE)、生态系统呼吸(Ecosystem respiration,ER)和蒸散量(Evapotranspiration,ET)进行观测,研究不同降雨量及环境因子对山地草地碳水通量的影响,结果表明,NEE和ER在18mm降雨量处理下均显著高于对照(P<0.05);NEE在38mm降雨量处理下显著高于对照(P<0.05);5mm降雨量处理下NEE、ER和ET与对照均无显著差异。相关分析结果表明,碳水通量在昼夜均与大气温度、大气湿度和土壤温度存在极显著相关性(P<0.01);在昼间时段,土壤湿度对碳水通量有显著的影响(P<0.05);土壤湿度在夜间时段与碳水通量无显著的相关关系,温度是影响山地草地生态系统碳水通量的主要环境因子。以上结果加深了不同降雨量对山地草地生态系统影响的认识,为气候变化预测研究提供了数据支撑。

To explore the impact of different rainfall and environmental factors on the carbon and water fluxes of alpine meadow ecosystem on the northern slope of Tianshan Mountain,Xinjiang,the net ecosystem exchange(NEE),ecosystem respiration(ER),and evapotranspiration(ET)were monitored by setting four simulated precipitation gradients(0 as control,5,18 and 38 mm).The results showed that NEE and ER under the 18 mm precipitation treatment were significantly higher than those of the control(P<0.05).NEE under the 38 mm precipitation treatment was significantly higher than that of the control(P<0.05).There was no significant difference between NEE,ER,ET under the 5 mm precipitation treatment and the control.The correlation analysis revealed that carbon and water fluxes were correlated with atmospheric temperature,atmospheric humidity,and soil temperature during the day and night(P<0.01).Soil moisture had a significant import on carbon and water fluxes during the daytime(P<0.05)instead of nighttime,indicating that temperature was the main environmental factor affecting the carbon and water fluxes of alpine meadow ecosystem.In summary,this study improved the understanding of the effects of different precipitations on alpine meadow ecosystem,which provided a data-driven basis for climate change prediction research.