祁连山南坡不同生态系统土壤粒径分布与分形特征

Soil particle size distribution and fractal characteristics of different ecosystems on the southern slope of Qilian Mountains

摘要:

【目的】 探究祁连山南坡不同生态系统土壤粒径分布与分形特征，揭示不同生态系统的水土保持效果。【方法】 选择青海云杉、高山灌丛、高山草地生态系统为研究对象，利用激光衍射技术测定土壤粒度组成，拟合各生态系统土壤粒径和体积分形维数的回归关系，分析土壤粒径分布与分形特征，土壤蓄水性能与其关系。【结果】 1）各生态系统土壤质地主要是粉砂-砂壤土，伴有黏粒组分；青海云杉和高山草地粒度频率曲线呈双峰态，但高山灌丛呈多峰态，其粒度组成复杂；2）各生态系统土壤粒径与体积分形维数的相关性均表现为黏粒＞砂粒＞粉粒，其中高山灌丛表现为高度相关；3）不同蓄水指标对不同生态系统影响不同，但土壤容重和总孔隙度的影响作用具有普遍性。【结论】 不同生态系统水土保持功能差异明显，高山灌丛比青海云杉和高山草地黏粒含量高、抗蚀能力强，具有更好的水土保持效果。但高山灌丛质地复杂，受外界扰动大，呈退化趋势。

Abstract:

【Objective】 In order to explore the soil particle size distribution and fractal characteristics of different ecological system on the southern slope of Qilian Mountains，and to provide scientific basis for regional soil and water conservation.【Method】 Picea crassifolia，alpine shrub and alpine grassland ecosystems were selected as the research objects. The laser diffraction technology was used to determine the soil particle size composition. The regression relationship between soil particle size and volume fractal dimension was fitted. The soil particle size distribution and fractal characteristics were analyzed，and the effect of soil water storage performance on it was explored.【Result】 1）The soil texture of each ecological system was mainly silty-sandy loam with clay components. The grain size frequency curves of picea crassifolia and alpine grassland were bimodal，but the alpine shrub was multimodal，among which grain size composition was complex. 2）The correlation between soil particle size and volume fractal dimension of each ecological system was clay ＞ sand ＞ silt，and high correlation was found in alpine shrub. 3）Different ecological system were affected by different water storage indexes，but the influence of soil bulk density and total porosity was universal. 【Conclusion】 The alpine shrub ecological system in the study area has a better soil and water conservation effect，but shows a trend of degradation，so the protection should be strengthened.