晋西黄土丘陵区不同植物群落的土壤分形特征

Soil fractal characteristics of different vegetation communities in Loess Hilly Region,Western Shanxi Province

为研究晋西黄土丘陵区不同植物群落与土壤结构特性和入渗特性的关系,探索土壤结构的定量化描述,运用分形学原理和方法,研究晋西黄土丘陵区油松纯林、刺槐纯林、油松＋刺槐混交林、侧柏纯林、黄刺玫灌丛、柠条灌丛及荒地7种植物群落的土壤分形维数与土壤质地、密度、孔隙度、含水量及饱和导水率的关系.结果表明：1）植物群落具有改善土壤颗粒结构的作用,其改善作用以针阔混交林（油松＋刺槐混交林）最好,阔叶林（刺槐纯林、黄刺玫纯林）次之,针叶林（油松纯林、侧柏纯林）最低.2）研究区土壤颗粒分形维数在2.799 ～ 2.805之间,黏粒（＜0.002mm）质量分数偏高.3）土壤颗粒分形维数与土壤黏粒质量分数呈显著正相关关系,与土壤砂粒（2.00～0.02 mm）质量分数、土壤总孔隙度、含水量及饱和导水率呈显著负相关关系.因此,土壤颗粒分形维数可以表征土壤结构特性和入渗特性的好坏.不同的植物群落对土壤的改良效果不同,研究结果可为研究区域植树造林提供参考依据.

In order to study the relationship among different vegetation communities,soil structure and infiltration characteristics in loess hilly region,and to quantitatively explore the soil structure,fractal theory and methods were used to study the relationship between soil fractal dimension and soil texture,bulk density,porosity,moisture content and saturated hydraulic conductivity of seven vegetation communities,i.e.,Pinus tabuliformis pure forest,Robinia pseudoacacia pure forest,P.tabuliformis ＋ R.pseudoacacia mixed forest,Platycladus orientalis pure forest,Rosa xanthina shrubbery pure forest,Caragana microphylla shrubbery pure forest,and wasteland in Loess Hilly Region,Western Shanxi Province.The results showed that：1） All kinds of vegetation communities were beneficial to improving the structure of the soil particles.The improvement of coniferous and broad-leaved mixed forest （P.tabuliformis ＋ R.pseudoacacia mixed forest） is the best,followed by broad-leaved forest （R.pseudoacacia pure forest and Rosa xanthina shrubbery pure forest）,and coniferous forest （P.tabuliformis pure forest and Platycladus orientalis pure forest） is the lowest.2） The soil fractal dimension in the study area was between 2.799 and 2.805,and the mass fraction of clay （＜ 0.002 mm） was in high level.3） The soil fractal dimension had a significantly positive correlation with the mass fraction of soil clay,while a significantly positive correlation with the mass fraction of soil sand,total soil porosity,moisture content,and saturated hydraulic conductivity.Therefore,the soil structure and infiltration characteristics can be characterized by the fractal dimension of soil particles.The improvement effects of different vegetation communities on soil varied,and the results could provide a reference for the afforestation in the study area.