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sur le développement des zones arides et semi-arides

Titre : Effects of Introducing Caragana Korshinskii on Spatiotemporal Variation of NDVI-ET in Desert Steppe

Auteur : 刘春虹

Grade : Master 2022

Université : Ningxia University

Résumé partiel
Land surface vegetation change is an important representation of land use/cover change,which affects land surface energy balance and water cycle mainly by changing geophysical properties such as land surface albedo,vegetation coverage and soil moisture.Since the 1970 s,the central Ningxia desert savanes is given priority to with bean Caragana is a perennial deciduous shrub Caragana Korshinskii large-scale plantation cultivation,in the area,degradation of grassland restoration of soil and water conservation and desertification control plays an important role in such aspects,but at the same time it appeared in the local different levels of water-born dysfunctional relationship,destroy the secondary problems,such as hydrological cycle.The improvement of ecosystem quality and function is the core goal of current and future ecological construction in desert steppe region,especially the reconstruction of regional ecological construction route around artificial vegetation construction and regional hydrological cycle rebalancing.Therefore,it is necessary to accurately evaluate the effects of Caragana Korshinskii introduction on regional vegetation and hydrological processes,and provide scientific basis for regional ecological construction planning and artificial vegetation management.NDVI and ET are important indicators reflecting vegetation status and water consumption at regional scale,and are often used for overall identification and analysis of regional carbon-water balance changes.In view of this,the temporal and spatial distribution characteristics of NDVI and ET in desert steppe area of central Ningxia were studied by using unary linear regression analysis,pixels-by-pixel correlation analysis and multiple regression residual analysis,and the effects of climate change and human activities on regional vegetation change were quantified.At the same time,based on medium and high resolution multi-source satellite remote sensing image data,combined with field survey data,the temporal and spatial distribution and coverage characteristics of artificial Caragana Korshinskii forest in the region were explored,and the relative contribution of Caragana Korshinskii plantation to regional NDVI-ET was identified by analyzing the contribution of different vegetation types to NDVI-ET in the region.The main results and conclusions are as follows :（1）The overall vegetation coverage of desert steppe in the middle of Ningxia is relatively low.The annual NDVI average is 0.06-0.82,and the regional average is only 0.30.The average annual evapotranspiration ranges from 75-383mm,with an average of 106mm.The high ET value region is consistent with the high NDVI value region.Regional NDVI and ET showed an overall trend of continuous growth,with an average increase of 0.073/10 years in NDVI.The increasing trend of regional evapotranspiration was mainly distributed in the southeast region,while the decreasing area was mainly distributed in the northwest region.There was a strong correlation between REGIONAL NDVI,ET and precipitation from 2001 to 2020,and there was an obvious spatial difference.

Mots clés : desert steppe ;artificial Caragana korshinskii forest ;NDVI-ET ;temporal and spatial changes ;

Présentation (CNKI)