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sur le développement des zones arides et semi-arides

Titre : Study on Plant Community and Soil Stoichiometry Characteristics of Desert Grassland in Urumqi

Auteur : 袁小强

Grade : Master 2022

Université : Xinjiang Agricultural University

Résumé partiel
The desert grassland in Urumqi City is a component of the temperate desert in northern Xinjiang,and the ecosystem is fragile.In-depth research on the ecological stoichiometric characteristics of desert grassland vegetation,litter and soil,and understanding of the changes of each component is of great significance for revealing community characteristics and stability.In this study,different communities in the Urumqi desert grassland（Haloxylon ammodendron community,Haloxylon ammodendron+Ephedra przewalskii community,Ephedra przewalskii+Sarcozygium xanthoxylon community,Seriphidium transiliense community,Nanophyton erinaceum community）were used as the research objects to analyze the species diversity of different communities,plant species,litter and soil ecological stoichiometric characteristics,to clarify the general laws of the stoichiometric characteristics of each component and its internal correlation,in order to provide data support and theoretical basis for the stoichiometric characteristics and restoration mechanisms of Xinjiang desert grassland ecosystems.The main results are as follows :（1）The species composition of the desert grassland community in Urumqi is relatively simple.There are significant differences in vegetation coverage,height and density among the communities.The biomass is in the order of below-ground＞above-ground＞litter.The below-ground biomass of Ephedra przewalskii+Sarcozygium xanthoxylon community was the highest at 0-5 cm,and the below-ground biomass decreased with the increase of soil depth ;the above-ground biomass and the below-ground biomass were in an exponential function relationship,and the litter biomass and the underground biomass showed a significant relationship.Linear relationship ;species diversity has a unimodal curve relationship with above-ground biomass,and an exponential function relationship with below-ground biomass.（2）The average plant organic carbon,total nitrogen and total phosphorus in the desert grassland community in Urumqi area were 227.47 g·kg-1,4.24 g·kg-1and 0.43 g·kg-1,which were lower than the average level of 394.00 g·kg-1,18.4 g·kg-1,1.14 g·kg-1in Xinjiang,lower than the national average of438.00 g·kg-1,20.20 g·kg-1,1.46 g·kg-1,and lower than the global terrestrial plants.The average levels of plants were 461.60 g·kg-1,20.60 g·kg-1,1.99 g·kg-1,and the C:N,C:P,N:P of plants were between43.59-62.45,335.16-693.64,7.69-12.97,respectively ;The contents of organic carbon,total nitrogen and total phosphorus in the litter were 195.41-216.03 g·kg-1,3.04-4.92 g·kg-1,0.13-0.51 g·kg-1,which were lower than those of plants and higher than those of soil.C:N,C:P,N:P are respectively between 43.88～70.40,423.62～1625.01,117.47～530.60.（3）In the 0-50 cm soil layer,the contents of soil SOC,TN,and TP varied between 1.06-11.81 g·kg-1,0.14-0.81 g·kg-1,and 0.15-0.49 g·kg-1,respectively,all of which were low.Compared with the national average level of 11.12 g·kg-1,1.06 g·kg-1,and 0.65 g·kg-1,it shows that the soil carbon,nitrogen,and phosphorus content in the study area is relatively low,and nutrients are relatively poor ;with the deepening of soil depth,the soil carbon,nitrogen and phosphorus in each community showed a gradual decreasing trend,and the"surface aggregation"was more obvious

Mots clés : Desert grassland ;Plant Community ;Species diversity ;Biomass;Soil ;Stoichiometric characteristics ;

Présentation (CNKI)