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sur le développement des zones arides et semi-arides

Titre : Characteristics of Soil Physical and Chemical Properties among Xinjiang Temperate Desert Steppe

Auteur : 张慧

Grade : Master 2022

Université : Xinjiang Agricultural University

Résumé partiel
Grassland is one of the largest terrestrial ecosystems.As an important parameter of soil quality and a major indicator of nutrients in grassland ecosystems,the study of its variability and influencing factors can help to gain a deeper understanding of the relationship between soil and grassland.As one of the major grassland types in Xinjiang,a lot of research has been conducted on the physical and chemical properties of the surface layer of the desert grassland,but relatively little research has been conducted on the variation of the physical and chemical properties of the deeper layers of the soil and their differences from the surface layer.This study have examined variations of soil bulk density（SBD）,ratio of rock to soil（RRS）,total nitrogen（TN）and p H under wind erosion,water erosion,standing litter,litter,sand covering,gravel and saline spots conditions and explored their trends with mean annual temperature（MAT）,mean annual precipitation（MAP）,elevation,slope gradient and slope aspect on basis of these variables collected at 0-5cm,5-10 cm,10-20 cm,20-30 cm,30-50 cm,50-70 cm and 70-100 cm among 92 sites.The results found that :（1）In the Xinjiang temperate desert steppe,TN and p H show a gradual decrease and increase respectively with increasing soil depth.The variability of SBD,RRS and TN was moderate in all soil layers,while p H showed weak variability.In addition,there was a good correlation between SBD,RRS,TN and p H in different soil layers.（2）RRS showed an overall decreasing trend with increasing MAT,while p H gradually increased.As the MAP increases,the overall trend of SBD and p H decreases,while the TN gradually increases.（3）With increasing elevation,SBD only gradually decreased in the 5-10 cm soil layer,while the p H gradually increased.TN increased only in the 50-70 cm soil layer with increasing slope gradient.SBD was significantly lower on shady slopes than on other slopes.SSR was mainly higher on the sunny slope than on the semi-shady slope,while TN was significantly lower on the sunny slope than on the semi-sunny and shady slopes.（4）SBD increased significantly under the influence of wind erosion,water erosion,standing litter,litter and gravel,and decreased significantly under the influence of saline spots.RRS was significantly reduced only under the influence of standing litter.Wind erosion and saline spots significantly increased TN,while water erosion,standing litter and sand covering significantly decreased TN.In addition,wind and water erosion significantly increased p H

Mots clés : Soil physical and chemical properties ;climatic factors ;topographic factors ;surface microenvironment ;Xinjiang temperate desert steppe ;

Présentation (CNKI)