宁夏荒漠草原沙漠化过程中土壤粒径分形特征  

Fractal features of soil particle size in the process of desertification in desert grassland of Ningxia,China

作　　者：阎欣[1] 安慧[1] YAN Xin AN Hui(Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China/Ministry of Education Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China, Ningxia University, Yinchuan 750021, China）.)

机构地区：[1]宁夏大学西北土地退化与生态恢复省部共建国家重点实验室培育基地/西北退化生态系统恢复与重建教育部重点实验室,银川750021

出　　处：《应用生态学报》2017年第10期3243-3250,共8页Chinese Journal of Applied Ecology

基　　金：宁夏高等学校科学研究项目(NGY2017006)资助~~

摘　　要：研究宁夏荒漠草原沙漠化过程中土壤性状、土壤粒径分形维数的变化特征,以及分形维数与土壤性状的关系.结果表明:草地沙漠化对土壤分形维数(D)影响显著,D值为1.69~2.62.除在10~20 cm土层出现较小波动外,随着沙漠化程度加剧,0~30 cm土层D值整体呈减小趋势.在荒漠草原沙漠化过程中,荒漠草地D值最大,黏粒和粉粒体积百分含量最高,极细砂粒和细砂粒体积百分含量最低;流动沙地D值最小,黏粒和粉粒体积百分含量最小,极细砂粒和细砂粒体积百分含量最高.D与<50μm和>50μm粒径的土壤颗粒存在显著正相关和负相关,表明50μm粒径是决定草地沙漠化过程中土壤分形维数与土壤粒径关系的临界粒径.随着荒漠草原沙漠化加剧,土壤有机质和全氮含量逐渐降低,土壤容重逐渐升高,固定沙地至半固定沙地是荒漠草原沙漠化的质变过程,其中土壤粘粒体积百分含量、粉粒体积百分含量、土壤有机质含量、土壤全氮含量骤减,极细砂粒体积百分含量、细砂粒体积百分含量和土壤容重骤增.分形维数与土壤有机质、土壤全氮和土壤容重显著相关,固定沙地与半固定沙地分形维数的临界值为2.58,因此分形维数2.58可作为荒漠草原沙漠化的退化指标.The variation of soil properties,the fractal dimension of soil particle size,and the relationships between fractal dimension of soil particle size and soil properties in the process of desertification in desert grassland of Ningxia were discussed. The results showed that the fractal dimension（ D） at different desertification stages in desert grassland varied greatly,the value of D was between1.69 and 2.62. Except for the 10-20 cm soil layer,the value of D gradually declined with increasing desertification of desert grassland at 0-30 cm soil layer. In the process of desertification in desert grassland,the grassland had the highest values of D,the volume percentage of clay and silt,and the lowest values of the volume percentage of very fine sand and fine sand. However,the mobile dunes had the lowest value of D,the volume percentage of clay and silt,and the highest value of the volume percentage of very fine sand and fine sand. There was a significant positive correlation between the soil fractal dimension value and the volume percentage of soil particles 〈50 μm,and a significant negative correlation between the soil fractal dimension value and the volume percentage of soil particles 〉50 μm. The grain size of 50 μm was the critical value for deciding the relationship between the soil particle fractal dimension and the volume percentage. Soil organic matter（ SOM）and total nitrogen（ TN） decreased gradually with increasing desertification of desert grassland,but soil bulk density increased gradually. Qualitative change from fixed dunes to semi-fixed dunes with the rapid decrease of the volume percentage of clay and silt,SOM,TN and the rapid increase of volume percentage of very fine sand and fine sand,soil bulk density. Fractal dimension was significantly correlated to SOM,TN and soil bulk density. Fractal dimension 2.58 was a critical value of fixed dunes and semi-fixed dunes. So,the fractal dimension of 2.58 could be taken as the desertification indicator of desert grassland.

关 键 词：土壤粒径分布 土壤分形维数 土壤理化性质 沙漠化 荒漠草地 

分 类 号：S812.2[农业科学—草业科学]