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Ningxia University (2022)

Study on the Spatial and Temporal Characteristics of Soil Moisture and Its Influencing Factors in Desert Grassland under the Background of Vegetation Restoration

王启学

Titre : Study on the Spatial and Temporal Characteristics of Soil Moisture and Its Influencing Factors in Desert Grassland under the Background of Vegetation Restoration

Auteur : 王启学

Grade : Master 2022

Université : Ningxia University

Résumé partiel
During the long-term uplift of the Ordos Plateau,many closed shallow dish-shaped depressions were formed,which ecologists concluded as the "three circles" model.That is to say,the beach is centered on the low depression,and the slope surrounding the beach is outward,and the outermost is the raised hard beam land.This "three circles" structure is repeated in the Ordos Plateau,forming a spatial structure of mosaic distribution.The desert steppe area crosses the central and northern parts of the Ordos Plateau from northeast to southwest.Historically,grassland desertification was caused by unreasonable human reclamation and overgrazing,since the 1990s,the implementation of ecological projects such as plantation construction,grassland replanting,and fencing has restored the vegetation coverage,diversity,and productivity of degraded grasslands,and desertification has shown a reversal trend.However,the current large-scale single plant restoration still faces sustainable restoration problems such as the decline of dominant plant populations and the depletion of soil water resources.Therefore,at a larger spatial scale,studying the annual change process of grassland soil moisture and its influencing factors including lake and wetland subsystems can provide a scientific basis for revealing the vegetation restoration and maintenance mechanism of the Ordos Plateau desert grassland and its associated systems.This study takes the complete landscape natural system including the desert wetland of the Haba Lake Nature Reserve in Yanchi County as the research object.The landscape scale includes beam land-slope land-beach land-lake,with an area of 12 km × 12 km.The construction of nature reserves promotes the natural and artificial restoration of vegetation in the study area,and some areas are even overloaded.Based on the spatial resolution of 1 km,the 12 km2 landscape unit is divided into 152 vegetation and soil survey and monitoring sample points.The specific research contents are as follows:First,based on the vegetation and soil background survey and sampling data of 152 sample points at the landscape scale in 2019,using multiple regression trees,redundancy analysis and other methods to clarify the research area after vegetation restoration and construction(including nearly 30 The natural restoration of the past 13 years and the restoration of artificial vegetation in the past 13 years),the spatial variation pattern and influencing factors of plant community types,species composition,and the influencing factors,laid the foundation for the interpretation and cognition of the annual dynamic changes of soil moisture in the study area.Secondly,around the soil moisture monitoring data of the 0-120 cm profile at the beginning and middle of each month from April to November 2020,combined with the continuous monitoring and survey data of vegetation,topography,soil texture and other biotic and abiotic factors,Kriging interpolation analysis,set pair analysis,redundancy analysis,hierarchical segmentation and other methods are used.Comprehensively analyze the characteristics of annual temporal and spatial changes of soil moisture and its identity and opposition with the above-mentioned biotic and abiotic factors,explore the relationship between different biotic and abiotic factors and annual changes in soil moisture,and reveal the main controlling factors affecting soil water pools

Mots clés : desert wetlands ;community classification ;soil moisture characteristics ;influencing factors ;

Présentation (CNKI)

Page publiée le 13 mai 2023