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China University (2010)

Analysis And Reconfiguration Of Degraded Desert-oasis Ecotone In The Lower Reaches Of Tarim River

Wang Z X

Titre : Analysis And Reconfiguration Of Degraded Desert-oasis Ecotone In The Lower Reaches Of Tarim River

Auteur : Wang Z X

Grade : Doctoral Dissertation 2010

Université : China University

Résumé partiel
Ecological restoration and reconstruction of damaged ecosystem becomes more and more concerned issue of the society on continental river basin in arid zone. The results of analysis and reconfiguration of degraded ecosystem provide scientific basis for planning and design of regional ecological restoration and reconstruction project and has important directive significance in desert-oasis ecotone in the lower reaches of Tarim River. On the basis of the theory of restoration ecology, this study took "history-of- degradation→analysis-of-status-quo→reconfiguration-of-vegetation-community" as the main line, explored the regional water environmental change and history of degradation of the lower reaches of Tarim river about 50-year, the change of shallow water table depths about 50-Year and history of degradation in desert-oasis ecotone, described the characteristics of habitat and vegetation community and the relationships between habitat and vegetation community in desert-oasis ecotone, and put forward the strategy of vegetation community reconfiguration for desert-oasis ecotone on the basis of status quo. The methods and technologies of this study included dendroecology, geostatistics, quantitative ecology, remote sensing and geographic information system. The main results showed :(1) The regional water environmental change were various and complicated about 50-year. The water environmental condition did not display completely that the nearer to the upper reaches(Daxihaizi reservoir) the site was, the better its water environmental condition was, reflecting degree of ecology degeneration of different regions in the downstream were not same ; The worst periods of water environmental conditions occurred mainly in the 1990s. This phenomenon was attributed to the breaking flow of river downstream for more than 30 years. The best periods of water environmental conditions appeared in the 1960s and at the beginning of this century, and this phenomenon was attributed to perennial water period and eco-water period. The abrupt change examination indicated that the regional water environmental change had the obvious sudden change effect. The regional water environmental change in the lower reaches of Tarim River was determined by quantity of surface flow, distance to the upper reaches (Daxihaizi reservoir), distance to ancient watercourses, distance to the waterring watercourse, micro-topography and pattern of regional shallow water table determined by regional geological structure et al. jointly.(2) The analysis of regional shallow water table depths about 50-year reconstructed by Tamarix hispida Willd. Tree-ring width data and NDVI change classification between 1972 and 2005 both showed that degree of ecology degeneration become gradually serious from 1950 to 1990s, but regional ecology is on the way to preliminary restoration after 2000 because of eco-water transfer in desert-oasis ecotone. There was an obvious relationship between tree-ring widths of Tamarix hispida Willd. and regional shallow water table depths. The analysis result showed that there was the evident negative correlation(-0.917) between the STD tree-ring index and the 3-6 Month shallow water table depths in desert-oasis ecotone in the lower reaches of Tarim River, indicating obvious tree physiology significance. Using the stepwise linear regression models, the 3-6 Month shallow water table depths about 50-year in desert-oasis ecotone was reconstructed.

Mots clés : lower reaches of Tarim River, desert-oasis ecotone, tree ring, change of water environment, habitat heterogeneity, vegetation community, DCCA, reconfiguration of vegetation community

Présentation (Globethesis)

Page publiée le 8 mai 2013, mise à jour le 4 mai 2018