干旱荒漠区不同演替阶段白刺灌丛沙堆土壤粒度特征

Soil Grain-size Characteristics of Nitraria tangutorum at Different Succession Stages in Desert Area

为探讨干旱荒漠区白刺灌丛沙堆土壤粒度特征,以民勤不同演替阶段(发育、稳定、衰退、严重衰退)白刺灌丛沙堆为对象,分别采集0~100 cm土层土壤样本,测定土壤粒度组成,计算并分析粒度参数。结果表明:1)干旱荒漠区发育阶段白刺灌丛沙堆土壤以细砂(50.04%~57.10%)和中砂(16.05%~22.03%)为主,稳定、衰退、严重衰退演替阶段白刺灌丛沙堆土壤以细砂(46.71%~64.06%)和极细砂(17.14%~29.06%)为主。2)平均粒径介于极细砂、细砂和中砂(1.92~3.17ф),分选系数介于较好和较差之间(0.69~1.41),偏度负偏至正偏(-0.141~0.299),峰度中等至很尖锐(1.01~1.99),分形维数(1.665~2.242)。随着白刺灌丛沙堆的演替发展,平均粒径变细、细粒物质所占比重增大,分选系数从中等、较好-中等之间、较差、中等-较差,粒度频率曲线变窄。3)从垂直分布来看,4个演替阶段不同土层粒度参数差异不显著。在0~10 cm土层中,不同演替阶段白刺灌丛沙堆土壤粒度参数存在极显著差异(P<0.01)。

In order to understand the soil grain-size characteristics of Nitraria tangutorum shrub in the desert area,soil samples were collected from six depths(0-100 cm) under the shrubs at different succession stages(developmental stage,stable stage,recession stage,severe recession stage) in Minqin,Gansu Province,from which the physical components of the soil grains and relative parameters were measured and analyzed.The results showed that 1) in developmental stage,the soil was mainly occupied by fine(accounted for 50.04%-57.10% of the total)and middle sized(16.05%-22.03%)sands,and in stable,recession and severe recession stages,the soils were mainly occupied by fine(46.71%-64.06%)and very fine sands(17.14%-29.06%).2) The mean grain size of the soil ranged from those of very fine,fine and middle sands(1.92-3.17ф);the sorting coefficient ranged from better sorting to worse sorting(0.69-1.41);the skewness ranged from negative to positive bias(-0.141-0.299);the kurtosis ranged from medium to very sharp(1.01-1.99);and the fractal dimension ranged from 1.665-2.242.With the development of the shrubs,the mean diameter of the soil grain became smaller,and the proportion of fine particles increased;the sorting coefficient underwent mdium-good,medium-poor-poor;the particle size frequency curve became narrow.3) From the perspective of vertical distribution,there was no significant difference in the parameters of soil particle size at the four stages.In the 0-10 cm soil layer,there were extremely significant differences in soil particle size parameters in different succession stages of N.tangutorum shrubs(P<0.01).