南亚热带不同林分土壤颗粒分形与水分物理特征

以广西国有高峰林场的6种不同林分(马尾松林Pinus massoniana、杉木林Cunninghamia lanceolata、尾巨桉林Eucalyptus urophylla×E. grandis、米老排林Mytilaria laosensis、红锥林Castanopsis hystrix和天然次生林)为对象,运用分形学和森林水文学的理论和方法,研究了不同林分类型土壤的颗粒组成以及水分物理特征。结果表明:研究区不同林分类型的土壤颗粒组成以黏粒为主,其次为粉粒和细砂粒,粗砂粒的含量相对较低,土壤颗粒分形维数从大到小依次表现为天然次生林、杉木林、米老排林、红锥林、马尾松林和尾巨桉林;不同林分类型土壤的水分物理特征存在差异,蓄水性能大小依次表现为天然次生林、米老排林、杉木林、红锥林、马尾松林和尾巨桉林,且土壤表层(0~10 cm)的蓄水能力要好于下层(20~50 cm);土壤颗粒分形维数主要受黏粒含量的影响,分形维数与黏粒含量呈极显著正相关,与总孔隙度、饱和蓄水量显著正相关,与土壤密度显著负相关,而与非毛管孔隙度、非毛管蓄水量和有机质含量相关性不显著。土壤颗粒分布的分形维数可作为反映南亚热带赤红壤地区人工林土壤水文物理性质的综合性指标。

Fractal and hydrophysical characteristics of soil particles in different forest stands in south subtropical China

Based on the theories and methods of soil fractal and forest hydrology,we examined soil particle composition and hydrophysical characteristics of six different forest types(Pinus massoniana forest,Cunninghamia lanceolata forest,Eucalyptus urophylla×E.grandis forest,Mytilaria laosensis forest,Castanopsis hystrix forest and natural secondary forest)in Nanning Stateowned Gaofeng Forest Farm of Guangxi.Clay was the main component of soil particles in the study area,followed by silt and fine sand particles,while the content of coarse sand particles was relatively low.The fractal dimension of soil particles ranked with following order:natural secondary forest,C.lanceolata forest,M.laosensis forest,C.hystrix forest,P.massoniana forest and E.urophylla×E.grandis forest.There were significant differences in soil hydrophysical characteristics across different forest types.Water storage capacity was following the order of natural secondary forest,M.laosensis forest,C.lanceolata forest,C.hystrix forest,P.massoniana forest,and E.urophylla×E.grandis forest.Moreover,water storage capacity of surface soil layer(0-10 cm)was better than that of lower layer(20-50 cm).The fractal dimension of soil particles was mainly affected by clay content.Fractal dimension had a significant positive correlation with clay content,total porosity and saturated water storage,and a significant negative correlation with soil density.There was no significant relationship between fractal dimension and non-capillary porosity,non-capillary water storage,and organic matter content.The fractal dimension of soil particle distribution can be used as a comprehensive index to reflect the soil hydrophysical properties of forest plantations in the subtropical red soil area.