Study On The CO₂ Emission Rate Of Alpine Shrub And Meadow Ecosystem In Eastern Qilian Mountain

Using insitu enclosed dark chamber-NDIR method method,start a primary study on CO₂ emission emission rate from Soil-Plant Systems of alpine shrubland meadow under fencing and grazing conditions and the relevant analysis of CO₂ emission rate with 5 cm depth soil temperature,soil water content The results showed that:1 The diurnal variation of CO₂ emission rate of Soil-Plant Systems of alpine shrubland meadow underfencing and grazing conditions-the fenced shrubland(WG), grazed shrubland(FG),fenced meadow(WC)and grazed meadow(FC) were similar.They all had the evident characteristics of"unimodal curve".The peak of CO₂ emission rate appeared between 13:00and 16:00,the valley appeared from 4:00 to 6:00. The CO₂ emission rate presented the ascending tendency from 6:00 to 16:00 and it dropped from 16:00 to 6:00 of the next day.The maximum rate of all treatment plots apperaed around14:00,and the minimum rate appeared around 4:00,in growing periods of plant;in non plant growing season,The maximum rate of all treatment plots apperaed around 16:00,and the minimum rate appeared around 6:00.2 Monthly dynamic changes of the CO₂ emission rate was pretty remarkable,and the trend of four different treatments were consistent.The CO₂ emission rate increased gradually from thebeginning of July to August,and then it dropped down,and the minimum appeared in February.The maximum CO₂ emission rate of WG,FG,WC, FC was 368.62±3.12,296.24±3.58,298.13±2.87,142.16±1.43μmol/(m²Â·min), respectively;the minimum was 9.28±2.14,9.75±0.96,8.62±1.43,6.97±1.76μmol/(m²Â·min),respectively.The value of CO₂ emission rate in growing periods of plant was obviously higher than the value in non plant growing season(P＜0.01)3 In the period of observation,the phenological phase difference of CO₂ emission rate was also significant,the difference was very significant(p＜0.01)in grass exuberance period,wiltting period and returning green stage,but it's not significant(p＞0.05) in initial wiltting period and earlygreen stage,the CO₂ emission rate of all treatments varied with different phenological phase showing an order of grass exuberance period＞initial wiltting period＞earlygreen stage＞later wiltting period.4 There was a extreme significant correlation between soil temperature at 5cm depth and the CO₂ emission rate of fencing shrubland(WG),grazed shrubland(FG),fenced meadow(WC)and grazed meadow(FC);in growing periods of plant,the correlation coefficients were 0.935,0.9056,0.8784 and 0.8671,respectively;in non plant growing season,the correlation coefficients were 0.9167,0.8099,0.9294 and 0.9345, respectively.5 In growing periods of plant,there existed linear positive correlation between the CO₂ emission rate of fencing alpine shrubland ecosystem and 0～10cm soil water content,linear equation was y=21.338x-57.778(r²=0.8843,r=0.94,p＜0.01 );but there was power function relationship between the CO₂ emission rate of grazing alpine shrubland ecosystem and 0～10cm soil water content,the equation was y=11.06x^0.9437(r²=0.7642,r=0.87,p＜0.01)...