环县典型草原试验践踏和土壤水分因子控制试验的表土颗粒分布分维及其相互关系
首发时间:2007-03-22
摘要:采用试验模拟滩羊践踏与降水控制试验,对不同试验组合样区表土(0-15cm)质地的机械组成进行分析,结果表明:土壤粒径分布的差异可能存在空间异质性,但在立地条件基本一致的情况下,践踏和模拟降水是造成土壤粒径分布差异的主要原因。持续高强度的放牧家畜践踏,是干旱化草地沙化的主要原因。降水具有双向调节的作用,适度降水有阻挡地表粗化的功能。但高降水条件在低践踏强度下可致地表粗化,随着践踏强度的提高地表粗化被部分地抑制。利用分形模型计算了土壤粒径分形维数,计算结果表明:分维数值均表现为重度践踏区<中度践踏区<轻度践踏区<对照区,说明分维数指标对践踏强度呈一定的负相关,即践踏强度越大土壤的分维数值越小,空间异质性程度越高。但分形维数递减幅度与模拟降水处理水平相关,在模拟降水处理水平依次为干旱、自然降水、平水、丰水时,粒径分形维数递减幅度依次为4.33%、2.61%、1.34%和1.23%。降水与践踏的匹配关系,对形成确定的分形维数具有决定性作用,可用二元回归式表达: 。土壤侵蚀过程在土壤颗粒分形维数上亦可表现为分形维数降低,因此,在此种意义上来说,土壤分维数的测算对土壤侵蚀程度的评估具有一定的指示意义,对进一步研究放牧草地土壤侵蚀机理可能具有推动作用
关键词: 土壤颗粒分布 分形 分维 试验践踏 模拟降水 放牧生态学
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Experimental tramping on steppe of Huanxian County and particle size distributions and fractal dimension of the surface layer of soil by soil humidity controlling experiment factors and their mutual relation
Abstract:We analyzed the surface soil (0-15cm) structure of different trial sample zone by stimulant precipitation and experimental tramping experiment. Its findings indicated that the different soil particle size distributions may cause by space heterogeneity. However, in the by and large same site, tramping and stimulant precipitation was the main reason for different soil particle size distributions. The lasting high intensity tramping was the leading cause of aridity and grassland desertification. Precipitation has two-way regulating effects. Moderate precipitation can prevent earth surface from roughness effectively, but high precipitation with low tramping intensity can lead to earth surface roughness. As tramping intensity increased, earth surface roughness was restrained partly. Fractal dimension can be calculated by using fractal model. The result shows that fractal dimension value characterized by heavy tramping zone Keywords:
particle size distributions
fractal dimension
experimental tramping
stimulant precipitation
grazing ecosystem
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环县典型草原试验践踏和土壤水分因子控制试验的表土颗粒分布分维及其相互关系
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