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Beijing Forestry University (2020)

Water Use Efficiency of Vegetation in the Mu Us Desert

王姣月;

Titre : Water Use Efficiency of Vegetation in the Mu Us Desert

Auteur : 王姣月;

Grade : Master’s Theses 2020

Université : Beijing Forestry University

Résumé partiel
Water use efficiency(WUE)is a key proxy to characterize the coupling process between carbon and water cycle in terrestrial ecosystems.Understanding how WUE varies with its impact factors helps to evaluate the adaptability on vegetation to local environmental conditions.Based on remote-sensing data and meteorological observations,the vegetation WUE in the Mu Us Desert from 2001 to 2016 was estimated by model calculation and data fitting.We implemented this study in the following aspects :(1)analyzing the spatial-temporal variations in WUE,(2)investigating the relationship between WUE and meteorological factors,and(3)probing the seasonal WUE responses to variability of land surface phenology parameters.The results are as follows :(1)Annual average WUE showed strong spatial heterogeneity in the Mu Us Desert,in which it was higher in the east but lower in the middle and west.The spatial distribution of WUE was determined by the hydrothermal conditions and the plant’s own physiological characteristics.Owing to revegetation programme,significant increases were observed in WUE during the study period.On an annual scale,both net primary production(NPP)and WUE had increased in most areas since 2001,which contributed to the improvement on local ecological environment.However,in the central and western part of the Mu Us Desert with poor condition of water and heat,WUE showed a decrease trend due to faster increases in evapotranspiration(ET)as compared to NPP.This phenomenon was particularly evident in spring and summer,which determined the critical period of annual WUE level,and might be harmful to the sustainable development of local ecosystems over time.(2)Correlations between WUE and meteorological factors were totally different by contributing to non-codirectional changes or asymmetric co-directional changes of NPP and ET.Annual precipitation was generally positively correlated to WUE,while the decreasing spring precipitation in recent years was detrimental to the annual WUE.There were relatively insignificant relationship between WUE and air temperature.T

Mots clés : water use efficiency; meteorological factors; land surface phenology parameters; revegetation; Mu Us Desert;

Présentation (CNKI)

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