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Ningxia University (2017)

Water Source of Shrubs and Herbs Vegetation of Artificial Caragana Intermedia Shrublands in Desert Steppe

赵伟;

Titre : Water Source of Shrubs and Herbs Vegetation of Artificial Caragana Intermedia Shrublands in Desert Steppe

Auteur : 赵伟;

Grade : Master’s Theses 2017

Université : Ningxia University

Résumé partiel
Soil drought is the main problem of maintain ecosystem stability of artificial Caragana intermedia shrublands in desert steppe area.It is important to clarify the water source of dominant shrubs and herbs of Caragana intermedia shrublands,which has important theoretical and application research value for adaptive management and innovation of degraded Caragana intermedia shrublands.BSC is a typical habitat characteristic of the aging Caragana intermedia shrublands(Planted in 1975a),and it tend to have a significant effect on the water circulation of system.In order to explore the water source of the shrubs and herbs vegetation,especially the water use of the aging Caragana intermedia shrublands,and the effects of the biological soil crust on the water source and correlation of the shrubs and herbs,we take three different age stages include 1975a,1987a and 1996a of Caragana intermedia as the object of study in Yanchi County.Based on the analysis of evolution pattern of soil and vegetation of artificial Caragana intermedia shrublands,we analyze and compare the differences of the water sources of the aging Caragana intermedia shrublands and other age stages Caragana intermedia.Then we focus on the role of biological soil crust in the water source of aging Caragana intermedia shrublands of shrubs and herbs.The main conclusions are as follows :(1)Evolution Patterns and driving of soil and vegetation of artificial Caragana intermedia shrublands:Compared with natural grassland,after the number of species of Caragana intermedia shrublands of 1996a reached the peak value,and the number of species decreased gradually with the increase of age,perennial gramineae grass began to appear.However,the dominant species was the annual vegetation still.The species diversity index showed a trend of decreasing after increasing first.The main indexes of soil nutrient was significantly restored after introduction artificial Caragana intermedia shrublands to the grassland of degraded grassland,and maintained a positive recovery trend in the study period.But the natural decay of Caragana intermedia shrublands and the sudden increase of some soil indexes occur simultaneously.The full development of biological soil crust promoted the improvement of soil quality in the aging Caragana intermedia shrublands,and also changed the soil hydrological process and hydrological environment characteristics of Caragana intermedia shrublands.For the internal succession of artificial Caragana intermedia shrublands,the evolution of desertification environment dominated by early Caragana intermedia shrublands was gradually transitioned to the succession stage of ecological and hydrological mutual feedback driven by later biological soil crust.(2)Comparison of water source of Caragana intermedia shrublands in different ages:The soil water use efficiency of internal of Caragana intermedia shrublands on the surface soil layer decreased gradually with the increase of age,and the water use efficiency of deep soil was gradually increased.There was no significant difference between the water use efficiency of 1996a and 1987a Caragana intermedia shrublands on the inside and outside of soil layer.The rate of water use efficiency at external of 1975a Caragana intermedia shrublands,in the 0-5cm soil layer was higher than 0-10cm soil layer of external of 1996a and 1987a,and higher than 0-10cm soil layer at internal of 1975a Caragana intermedia shrublands,but the rate of water use efficiency below 10cm soil layer was less than 1987a.With the increase of age,the rate of water use efficiency of deep soil moisture increased,and the rate of water use efficiency was 1996a(16.0%)<1987a(30%)<1975a(33.6%).In general,with the increase of age,Caragana intermedia shrublands tend to use the deep soil moisture.Internal of Caragana intermedia was higher than external of Caragana intermedia,in addition to the surface layer,which reveals the potential role of biological soil crust in the water source of aging Caragana intermedia shrublands.(3)The change of water source and competitive relationship of dominant shrubs and herbs with growing age:the water source of the annual herbaceous in different age was mainly concentrated in the surface layer of 0-l0cm,which is represented by Artemisia scoparia and Bassia dasyphylla ;With the increasing of age,the rate of water use efficiency of Artemisia scoparia further improved,and from internal of Caragana intermedia>external of Caragana intermedia to internal of Caragana intermedia

Mots clés : desert steppe; artificial Caragana intermedia shrublands; water sources; biological soil crusts; stable isotope;

Présentation (CNKI)

Page publiée le 1er février 2018