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Northwest A & F University (2018)

Study on Characteristics of Soil Nutrients and Carbon Storage in Biocrusts and Underlying Soil of Mu Us Sandland

李宜坪;

Titre : Study on Characteristics of Soil Nutrients and Carbon Storage in Biocrusts and Underlying Soil of Mu Us Sandland

Auteur : 李宜坪;

Grade : Master’s Theses 2018

Université : Northwest A & F University

Résumé
Biological soil crusts have important contributions to the maintenance of the ecological functions of desert ecosystems and the stability of soil organic carbon pools,To ascertain how much carbon reserves can be fixed by biocrusts on a regional scale,The study focused on moss and algae crusts widely distributed in the Mu Us Sandland.Selected representative plots for collecting crusts and underlying 0-5cm deep soil and determined their pH,total nitrogen,total phosphorus,and organic matter to explore the spatial differentiation characteristics of soil nutrients in biocrusts at the regional scale.To investigate the effect of vegetation on the distribution of nutrients in biocrusts,the typical vegetation plots of Artemisia ordosica,Salix psammophila,Caragana intermedia,and meadow were selected to measure the content of total nitrogen,total phosphorus,and organic matter in crusts and soil under 10 cm depth.Finally we estimated the carbon storage of the entire Mu Us Sandy Land based on the organic carbon content of the sampling plots,and the potential for carbon enrichment of biocrusts was analyzed.The main conclusions are as follows :(1)The spatial variability of nutrients in biocrusts and underlying soil(0-5cm)is great.The semi-variance function fitting models of p H,total nitrogen and organic matter are all spherical models,and total phosphorus is a linear model ;Total nitrogen and organic matter have a strong spatial autocorrelation,and the spatial correlation of total phosphorus is weak.The distribution patterns of total nitrogen,total phosphorus,and organic matter all showed obvious spatial regularities,and their contents were decreasing from east to west.The three nutrient contents were low on the entire regional scale and were lack of nutrients.The pH showed an increasing trend from east to west and the soil alkalinity gradually increased.This trend is also consistent with the zonal distribution law of soil types in the sand area.Topography had different influences on soil nutrient distribution of biocrusts.Among them(altitude,slope,aspect),Altitude had a very significant effect on total phosphorus(F=11.764,P=0.001),The effect of slope on total phosphorus also reached a very significant level(F=10.28,P=0.002),The aspect had no influences on total nitrogen,total phosphorus,and organic matter of biocrusts,but it showed:shady slope,semi-sunny slope>sunny slope,semi-shady slope.(2)The nutrient content of biocrusts developed in different parts of the vegetation community showed:total nitrogen,total phosphorus,and organic matter between the shrubs were higher than that under the shrubs(while the algae crusts of the Artemisia ordosica community showed that nutrient contents under the shrubs was higher than that between the shrubs).Nutrients in biocrusts and underlying soil of different vegetation types are different significantly.The total nitrogen and organic matter of moss crusts showed:Caragana intermedia>meadow>Salix psammophila>Artemisia ordosica,total phosphorus of moss and total nitrogen,total phosphorus,organic matter of algae all showed:meadow>Caragana intermedia>Artemisia ordosica>Salix psammophila.(3)The distribution pattern of organic carbon density in biocrusts and underlying soil(0-5cm)is consistent with the distribution of soil types in Mu Us sandland.

Mots clés : Mu Us sandland; biocrusts; soil nutrients; spatial variation; carbon storage;

Présentation (CNKI)

Page publiée le 15 mai 2019