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Lanzhou University (2020)

Global Desertification Vulnerability Impacted by Human Activity and Climate Change

张国龙;

Titre : Global Desertification Vulnerability Impacted by Human Activity and Climate Change

Auteur : 张国龙;

Grade : Doctoral Dissertation 2020

Université : Lanzhou University

Résumé partiel
According to the United Nations Convention to Combat Desertification(UNCCD),desertification is the impoverishment of arid,semi-arid,and some sub-humid ecosystems due to the combined impact of human activities and climate change.Desertification not only threats the global ecological security,but also affects the economic and social development.Study the growth status of vegetation and the impact of climate change to the vegetation dynamics,which is in favor of taking action to protect and promote restoration of the ecosystems and making policy to combat climate change and desertification.The assessment of global scale desertification vulnerability to climate change and human activities is an important step to help decision makers to formulate the best strategies for land rehabilitation and the fight against global desertification in sensitive areas.However,there is no global desertification vulnerability map that considers both climate change and human activities.In this study,we first analyzed the spatial-temporal character of global leaf area index(LAI)and the impact of temperature and precipitation to vegetation dynamics.Farther,we assessed global desertification vulnerability using a global desertification vulnerability index(GDVI),which was defined by human activities and climate change indicators,to obtain a global overview of desertification vulnerability.Finally,we projected future global desertification vulnerability by the end of this century under different scenarios,the conclusion as follows:1.At global scale,the LAI increased from 1982 to 2014.The increasing trend of LAI in the spring and autumn is further lager than that in the summer,which indicated that the extension of growth length may be the dominant factor in the increasing annual LAI in the northern hemisphere.The regions with the most significant contributions to the global LAI change trend are South Asia,East Asia,Europe and South America.Although humid region dominated the increasing tendency of global LAI,the increase of relative LAI is significant in the drylands.Precipitation is the key factor influencing vegetation growth in the drylands,however,the human activities is an important contribution to global greening.2.The contribution of seasonal trend to annual LAI change shown obviously spatial heterogeneity.The fraction of spring LAI to annual LAI increased in the Central Asia,Europe,East China,Australia and Southern South America.

Mots clés : desertification; drylands; leaf area index; human activities; climate change; vulnerability index; future projection;

Présentation (CNKI)

Page publiée le 5 juin 2021