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Titre : Dynamic Simulation of Ecosystem Carbon Cycle in Arid Area of Xinjiang Based on BIOME-BGC Model

Auteur : 李晓星；

Grade : Master’s Theses 2017

Université : Ludong University

Résumé
Xinjiang region is vast,rich in resources,accounting for about one-sixth of the national territory area,affected by climate change significantly.In order to study the carbon cycle dynamics of Xinjiang in recent 35 years(1980-1944),based on the previous research,this paper used the BIOME-BGC model to carry out the numerical simulation analysis,and studied the net primary productivity(NPP)in Xinjiang region from 1980 to 2014,and evaluated the relative contribution rates and their interaction effects of different environmental factors(precipitation,temperature,CO2).The results showed that the total annual NPP of Xinjiang was 219.48 gC / ㎡,the total amount of GPP was 382.96 gC / ㎡,and the total amount of RA was 196.95 gC / ㎡ in the past 35years(1980-1944).The spatial distribution of productivity(NPP and GPP)in Xinjiang was closely related to the spatial pattern of precipitation.The high productivity areas were mainly distributed in areas with favorable water conditions such as Tianshan Mountains and Yili River Valley,while the low productivity areas were located in extreme arid area of southern Xinjiang and northern part of the desert,mainly due to lack of precipitation,high temperatures,and poor ecological environment.The response of NPP to climate change in different vegetation types in Xinjiang were very different.The vegetation density of evergreen coniferous forest(ENF)was 8960.85 gC/㎡,and the vegetation density of grassland(MEW)was 879.71 gC/㎡.The NPP values of evergreen coniferous forest and farmland were significantly higher than those of other vegetation types.The NPP values of grassland,deep-rooted vegetation and non-deep-rooted vegetation are relatively low.Compared with the averageNPP value in1980 1984,the NPP of Xinjiang was reduced from 0.6976 gC/(㎡ ·a)in 1985 to2014,and the interannual fluctuation was significant.The CO2 fertilization effect increased the NPP by 16%,and the positive effect of the temperature increased the NPP by 5%,while the decrease of precipitation resulted in a 27% decrease in NPP.In the different regions of Xinjiang,NPP control factors were different,and about 83% of the study areas were mainly controlled by precipitation,which covered most of Xinjiang’s ecological systems.The main control area of CO2 fertilization accounted for10% of the study area,mainly distributed in the Tianshan Mountains and the low altitude oasis farmland and other areas of good hydrothermal conditions.Temperaturecontrol area accounted for 5% of thestudy area,mainly in the Kunlun Mountains and other high altitude cold areas.There were a small number of regions(2% of the Xinjiang region)scattered in the Kunlun Mountains,where the influence of the above three climatic factors was affected by their interactions(CO2 ?CLIM).This study showed that the southern Xinjiang was a key ecological fragile area,and its ecological security was facing the challenge of climate change.However,the warming of the 21 st century was unlikely to have a significant effect on the NPP in Central Asia due to the stimulation of autotrophic respiration.

Mots clés : Xinjiang； BIOME-BGC model； carbon cycle； NPP； climate change；

Présentation (CNKI)