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China Agricultural University (2014)

Carbon Flux Analysis and Modeling of Vineyard in the Arid Region of Northwest China

郭维华; Guo Wei Hua

Titre : Carbon Flux Analysis and Modeling of Vineyard in the Arid Region of Northwest China

Auteur : 郭维华; Guo Wei Hua

Grade : Doctoral Dissertation 2014

Université : Université de l’agriculture de Chine

Résumé
On the premise of global change, carbon flux cycle of terrestrial ecosystem has become a research focus. Green vegetation is the most important part of carbon cycle ; it has important effect on atmospheric carbon pool. Moreover, it is a fragile ecosystem in arid regions of Northwest China, and wind grapes are widely grown there, so the vineyard plays an important role for the local atmospheric, research on it has significance means for understading the whole carbon cycle of terrestrial ecosystem.Based on above reasons, carbon flux was measured using eddy covariance system in a wine vineyard in arid northwest China during2008to2013, and analysis the dynamic changes of vineyard’s carbon flux under different time scales, and it’s carbon source/sink properties ; then distinguish the main factor of the carbon flux under different time scales ; by comparing the different types of model, getting the proper model for simulation local soil carbon flux ; and based on the above, by comparing different types of carbon flux model, establishes a sutable model for simulation the frame vegetation ecosystem carbon variation. The main results are as follows :(1) The net ecosystem CO2exchange were-820,-824,-961, and-992gC-m-2-y-1form2008to2011respectively, and showed a significant carbon sink. And vineyard NEE was positive value at the early growth stage, higher negative value at the mid-growth stage, and low negative value at the later growth stage. Diurnal variation of NEE was "W" shaped curve in sunny day, but "U" shaped curve in cloudy day.(2) The main factors affecting hourly NEE were canopy conductance (gc) and net radiation (Rn). The main factors affecting daily NEE were gc, air temperature (Ta) and vapour pressure deficit (VPD). The main factors affecting month NEE were gc, air temperature (Ta) and atmospheric CO2density.(3) The effect of temperature and Q10soil carbon models in the simulation are not good, with R2of0.10and0.32respectively, because they only consider the influence of temperature on soil carbon flux. In this study, we established an improved water-temperature integration model (W-T model) by considering both temperature and moisture factors, and the simulation results have been improved obviously, R2reached to0.78.(4) When using the mainly ecosystem scale carbon flux model to simulate the vineyard carborn flux variation, such as SMPT-SB and Crop-C model, the results are not as expcted, the simulation are overvalued by60%and30%. This is due to not considering the plant and soil have different carbon flux varation in the frame vegetation ecosystem. After considering this situation,, we establishes a new ecosystem carbon model called SMPT-SW combined with the SMPT-SB model and W-T soil carbon model, to simulate the vineyard’s NEE. The simulation result has a significant increase compared with above two models, the simulation is overvalued about8%, and R2is0.85.(5) According to the two kinds of carbon emission scenarios proposed by IPCC5th working report, using the SPMT-SW modle to predicte the net primary productivity of vineyard in arid regions of Northwest China from2015to2065. The results showed that in low carbon emission scenario, the vineyard’s NPP will be1299gC-m-2-y-1at the year of2065,1.25times that of2015. From 2015to2020among them, the NPP growth is rapid. Meantime, under the high carbon emission scenario, it will be a rapid growth stage for vineyard’s NPP from2015to2030, the NPP increased by24%over15years, but after2030, the NPP will begin to decline, untill the year of2065, the NPP will fell to1213gC-m-2·y-1

Présentation (CNKI)

Page publiée le 2 septembre 2014, mise à jour le 26 septembre 2017