Study On The Carbon Flux Observation Over Poplar Plantation Ecosystem Of Xiping City In Henan Province Of China

Poplar plantation distributes widely in China because of its fast growth and strongly adaptive ability to ecological enviromnen, therefore, it's impact on carbon sequestration is very important for forest carbon sink in China, which has been paid more and more attention in the field of corbon flux research recently. Based on the analysis of eddy covariance measured CO2 fluxes data at the Poplar plantation ecosystem in Xiping City of Henan Province, we discussed the effect of variables on net ecosystem CO2 exchange (NEE), gross primary productivity (GPP) and ecosystem respiration (Re) at diffeRent time scales, analysis the daily and seasonal variation of the Poplar plantationn ecoystem. The main Results include:(1) The Result of partial Correlation analysis showed that the PAR and the Soil_VWC are the key environmental factors in regulating the daily GPP of Poplar plantation ecosystem in Xiping City of Henan Province with Correlation coefficient 0.67 and 0.37, respectively, and those higher than others obviously.The daily GPP of Poplar plantation ecosystem accord with normal distribution in every month, and the peak of the daily GPP at 1:00 pm. The daily total value of GPP reached the peak on May, and it decreased somewhat in June and July because of the Poplar plantation diseases and insect pests, then increased in August dued to the regerminate of the Poplar plantation.The GPP total value of Poplar plantation ecosystem in Xiping City of Henan Province is 1288.1gC/m2 in 2010, that is in a low level than others because of the Poplar plantation diseases and insect pests.(2) The result of partial correlation analysis showed that the maximum correlation coefficient is about VPD and daily Re which is 0.426, the second Correlation coefficient is about PAR and the daily Re. Otherwise, the Soil_VWC and Soil_T's Correlation is significant with the daily Re. The trend of the daily Re is similar with Soil_T'daily mean value. The growth peak of Re appears at March and August Respectively. The Re total value of Poplar plantation ecosystem in Xiping City of Henan Province is 964.7gC/m2 in 2010.(3) In daily scale, the Result of partial Correlation analysis showed that the PAR, RHand the Soil_VWC are the key environmental factors in Regulating the daily NEE of Poplar plantation ecosystem in Xiping City of Henan Province with Correlation coefficient-0.579,-0.193 and-0.135. and the ergression model is:NEE=3.558-0.101 PAR-0.015RH-3.804 Soil_VWC. The PAR is the key environmental factors in regulating the NEE of Poplar plantation ecosystem in Xiping City of Henan Province in hour scale. The next is WS and RH. Soil_T and SoilVWC have little influence to NEE, but theRe is great difference in different seasons.(4) In non-growing season, carbon sequsstration of Poplar plantation ecosystem can enhance after raining and sleeting, and after snowwing and fogging, the carbon emission of the Poplar plantation ecosystem could enhance.(5) The variation of diurnal NEE is characterized by daytime carbon uptake and carbon release at night,and we can see the CO2 flux appears rinforzando at morning in June, July and October. The daily NEE total value of the Poplar plantation ecosystem was approximately zero in non-growing season,and it is negative mostly in grow season. The daily and monthly NEE total value appear decreasing obviously in July beacause of the Poplar plantation diseases and insect pests. The NEE total value of Poplar plantation ecosystem in Xiping City of Henan Province is-343.4gC/m2 in 2010, and it is on the low side than else Poplar plantations in the other state.