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Tarim University (2021)

Study on the Spatial Pattern Dynamics and Construction Assembly of Populus Euphratica Communities in the Upper Reaches of Tarim River

康佳鹏

Titre : Study on the Spatial Pattern Dynamics and Construction Assembly of Populus Euphratica Communities in the Upper Reaches of Tarim River

Auteur : 康佳鹏

Grade : Master 2021

Université : Tarim University

Résumé partiel
With climate change and unreasonable exploitation of soil and water resources,natural Populus euphratica communities have been seriously degraded,which endangers the sustainable development of the desert oasis seriously.Therefore,investigating the spatial pattern dynamics and construction mechanism of riparian Populus euphratica forest communities in the upper reaches of Tarim River desert is important to curb ecological degradation,build vegetation protection and restoration system,and promote sustainable economic and ecological development.In this study,three fixed monitoring samples of 11 ha are established in the upper Tarim River,and the species composition and community structure of the Populus euphratica forest communities are analyzed based on the plant species survey data.Spatial point pattern analysis based on a completely stochastic model,eight species multi-degree distribution models,and species richness distribution pattern are used in combination with different habitats and sampling scales in order to explore the spatial pattern dynamics and construction mechanisms of Populus euphratica forest communities.The main findings of this study are as follows.(1)The vegetation structure of the desert riverine Populus euphratica community was simple and the species were relatively rare,including 2 species of arbor,3 species of shrubs and 10 species of herbs ;The species hierarchy within the habitat was clear and the arbor layer and shrub layer were dominant in the vertical structure.The tree diameter structures in different habitats were bell-shaped and inverted pyramidal shaped,respectively,and lacking the complement of young trees.The community was poorly regenerated and belonged to the declining population(2)Species richness was the highest in riverine habitats,and decreased in terrace and sandy habitats with habitat deterioration,where diversity index and richness index were significantly and positively correlated with soil moisture content,and evenness index was significantly and positively correlated with soil salinity.The total diversity index of Populus euphratica forest communities was negatively correlated with the difference of soil water content,and the species diversity decreased with the increase of water content difference between the two sections.(3)The overall spatial pattern of the dominant species was aggregated.The species in the riverine habitat were mainly aggregated,and the intensity of aggregation decreased with the deterioration of the habitat.Seedlings were aggregated in both the floodplain and the sandy land habitats,and the aggregation intensity decreased with the increase of species age,and the old trees were randomly distributed.The spatial distribution was scale-dependent,and the aggregation intensity decreased with the increase of the scale,which tended to be randomly distributed or even uniformly distributed at larger scales.Species interactions dominated at small scales,while habitat heterogeneity dominated at large scales(4)The spatial correlations of species at different developmental stages showed strong scale dependence,and both intraspecie and interspecific correlations(positive and negative)all decreased with the increase of scale,and eventually they all tended to be unrelated.

Mots clés : Populus euphratica ;community structure ;point pattern analysis ;abundance pattern ;scale;community assembly ;

Présentation (CNKI)

Page publiée le 7 novembre 2021