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Jiangxi Normal University 江西师范大学 (2020)

Assessing the Dynamic of Aridity-humidity and Its Impacts on Vegetation Greenness on the Qinghai-Tibetan Plateau


Titre : Assessing the Dynamic of Aridity-humidity and Its Impacts on Vegetation Greenness on the Qinghai-Tibetan Plateau

Auteur : 张华敏;

Grade : Master’s Theses 2020

Université : 江西师范大学

As“the driving force”and“the amplifier”for global climate change,the Qinghai-Tibetan Plateau(QTP)plays an essential role in ecosystem security of China and even Asia with the properties of sensitive and fragile to climate change.Accurately assessing aridity-humidity change of the QTP and its influence on vegetation greenness is beneficial to regional animal husbandry development,and it would provide the referenced significance for the construction of ecological safety barrier in China.Based on remote sensing data and meteorological observation data,this study aims to quantify spatio-temporal change of aridity-humidity during 1970-2017 and vegetation greenness since 2003 on the QTP by using Sen’s slope estimator,mutation model,correlation analysis and other approach.Then explored the responses of vegetation greenness to aridity-humidity change.The main conclusions are as follows :(1)Continuous wetting on the Qinghai-Tibetan Plateau during 1970-2017.The SPEI of growing season(SPEIgs)on the QTP exhibited a significant increasing trend at the rate of 0.01/yr(p<0.05),indicating that the QTP tended to undergo continuous wetting during 1970–2017.In contrast,its surrounding area underwent a significant trend shift from an increase to a decrease in SPEIgs around 1984(p<0.05).Spatially,most of the stations on the QTP were characterized by an increasing trend in SPEIgs,except a small number of stations on the eastern fringe of QTP.Its surrounding area showed strongly different patterns of distribution,most of the stations presented decreasing trend,especially in the southern Gansu,the western Sichuan,and the northwest of Yunnan.The results of the intensity analysis showed that the rate of wet changes was relatively fast in the 1970s–1980s on the QTP,followed by a maintenance phase during 1980s–1990s and 1990s–2000s,and the transition from 2000s to 2010s was associated with wetting.Whether at the regional or site scale,the wetting trend on the QTP is likely to continue in the future,the surrounding area were characterized by a decreasing trend.There were significant difference between ecosystem zones and altitudes in SPEIgs on the QTP,the Qaidam mountain desert area(IID2)and 2000-2500m wetting obviously.(2)Compared MOD-NDVI,MOD-EVI,MYD-NDVI,MYD-EVI vegetation greenness data on the QTP from 2003 to 2018,it can be found that the spatial distribution and spatio-temporal changes of multi-year averages were consistent.Overall,MOD-NDVI is the best one to characterized the vegetation greenness on the QTP.The analysis result depend on MOD-NDVI were shown that monotonic greening trends of the vegetation on the QTP,with local degradation,and the spatial mutation phenomenon is obvious

Mots clés : SPEI; Vegetation greenness(NDVI); Responses; Spatio-temporal change pattern; Qinghai-Tibetan Plateau;

Présentation (CNKI)

Page publiée le 24 octobre 2020, mise à jour le 6 mars 2022