裸斑对青藏高原多年冻土区高寒草甸生态系统呼吸和甲烷吸收的影响

研究裸斑对青藏高原多年冻土区高寒草甸生态系统呼吸和甲烷通量的影响,对准确评估多年冻土区小流域和区域尺度碳交换具有重要意义。本文以青藏高原风火山高寒草甸中裸斑和高植被覆盖斑块为研究对象,通过对比不同地形条件下(不同坡向和海拔)二者生态系统呼吸和甲烷通量的差异来研究裸斑对高寒草甸生态系统呼吸和甲烷通量的影响。结果表明:(1)裸斑显著减少了高寒草甸的生态系统呼吸,裸斑和高植被覆盖斑块生长季生态系统呼吸的平均速率分别为2.26和6.17 g CO2 m-2 d-1,这主要是二者微生物量碳和蔗糖酶活性差异造成的;(2)裸斑和高植被覆盖斑块在生长季内均表现为甲烷的汇,二者生长季甲烷吸收的平均速率分别为25.4和6.61μg CH4 m-2 h-1;在坡中和坡顶,裸斑的甲烷吸收速率显著大于高植被覆盖斑块,而在坡底,二者的甲烷吸收速率相近;土壤湿度是调控高寒草甸甲烷吸收空间变异的主要因素。研究结果深化了裸斑对青藏高原多年冻土区高寒草甸碳交换影响的认识,可为小流域以及区域尺度碳交换的准确评估提供科学依据。

Effects of Bare Patches on Ecosystem Respiration and Methane Uptake of Alpine Meadow in a Permafrost Region of the Qinghai-Tibet Plateau

It is of great significance to study the effects of bare patches on ecosystem respiration(Re)and methane(CH4)flux of alpine meadow in the Qinghai-Tibet Plateau for accurate assessment of small watershed and regional scale carbon exchange.In this paper,the bare patches and high vegetation coverage patches in an alpine meadow on the Mountain Fenghuo were studied,and the effect of bare patches on the Re and CH4 flux in alpine meadow by comparing the difference in Re and CH4 flux between bare patches and high vegetation coverage patches different terrain conditions(different slope aspects and elevations).The results showed that:(1)The bare patches significantly reduced Re in alpine meadow,and the average Re rates of bare patches and high vegetation coverage patches were 2.26 and 6.17 g CO2 m-2 d-1 during the growing seasons,which was mainly caused the difference in their microbial biomass carbon and saccharase activity.(2)During the growing season,both the bare patches and high vegetation coverage patches functioned as CH4 sinks,and the average CH4 uptake rates of two were 25.4 and 6.61μg m-2 h-1,respectively.The CH4 uptake rate of bare patches was significantly greater than that of high vegetation coverage patches at the middle and upper of the slopes,but their CH4 uptake rate were similar at the bottom of the slopes.Soil moisture was the main factor regulating the spatial variation of CH4 uptake in alpine meadow.These results deepened the understanding of the impact of bare patches on carbon exchange in alpine meadow on the region,and provided scientific basis for accurate assessment of carbon exchange in small watershed and regional scale.