东祁连山北坡高寒灌丛草地围栏与放牧干扰下CO_2释放速率的比较研究

采用原位静态密闭暗箱+便携式红外气体分析仪法对东祁连山高寒灌丛草地围栏与放牧干扰下金露梅(Potentilla fruticosa)灌丛CO2释放速率进行了监测.结果表明:围栏与放牧样地,土壤-植被系统CO2释放速率均呈单峰型曲线,高峰值均出现在下午13∶00~16∶00,最小释放速率在凌晨4∶00~6∶00;白天CO2释放速率大于夜间.围栏灌丛CO2释放速率日最大值为368.64μmol.m-2.min-1,最小值为36.28μmol.m-2.min-1;放牧灌丛CO2释放速率日最大值为296.21μmol.m-2.min-1,最小值为18.43μmol.m-2.min-1;在植物生产高峰季节(7、8月)CO2释放速率亦达到高峰状态,最大月(8月)围栏内灌丛平均释放速率为288.25μmol.m-2.min-1,放牧灌丛平均释放速率为219.81μmol.m-2.min-1;9至11月份,灌丛CO2释放速率逐渐回落.围栏内灌丛CO2释放速率高于放牧灌丛,围栏与放牧干扰在7至10月份差异极显著(P0.01),11月差异不显著(P0.05).围栏灌丛与放牧灌丛CO2释放速率的日变化与月动态与5cm土壤温度均呈正相关.

A study of CO_2 emission rate from alpine shrub grassland under fencing and grazing disturbance in the northern slope of Eastern Qilian Mountains

The CO_2 emission rate of alpine Potentilla fruticosa shrub under fencing and grazing disturbance was monitored by insitu enclosed chamber-NDIR method. The results showed that the dynamic characteristics of CO_2 emission rate in soil vegetation system under two treatments were both expressed a single peak curve. The peak appeared from 13∶00 to 16∶00 with the value of 368.64 μmol·m~(-2)·min-1 and 296.21 μmol·m~(-2)·min~(-1) under fencing and grazing disturbance treatments, respectively.The minmum CO_2 emission rates were 36.28 μmol·m~(-2)·min-1 and 18.43 μmol·m~(-2)·min-1 under fencing and grazing treatments,respectively, which appeared from 4∶00 to 6∶00 in the early morning.The CO_2 emission rate was higher in daytime than that at night under both treatments. Beside, the CO_2 emission rate also showed a seasonal variation during the experimental period.The highest CO_2 emission fluxes was found in August, which was 288.25 μmol·m~(-2)·min-1 in fence plot, and 219.81 μmol·m~(-2)·min-1 in grazed area, this due to the high temperature and humid from July to August. Accordingly the CO_2 emission rate was gradually decreased from September to November with the decrease of air temperature and humidity. And the CO_2 emission rate in fenced area was higher than in grazed area, the differences were extremly significant(P<0.01) in July, August, September and October, but is not significant (P>0.05) in November. A positive correlation was showed between diurnal and seasonal dynamics of CO_2 emission rate and soil surface temperature within 0 and 5 cm.