小流域尺度土壤容重及其影响因素的空间变异

Spatial heterogeneity of bulk density and its influencing factors at small watershed scale

揭示土壤容重及其影响因素的空间变异能够为容重制图以及土地质量评价服务。选择黄土丘陵沟壑区典型小流域,测定土壤容重与环境因子。在分析土壤容重与环境因子空间变异的基础上,建立二者之间关系。结果表明:土壤容重表现为弱变异性。土地利用、坡位与坡形对土壤容重产生显著影响;不同土地利用方式土壤容重表现为乔木林地<园地<灌木林地<荒草地<耕地的总体趋势;坡位之间土壤容重表现为上坡<山顶<中坡<下坡;坡形之间土壤容重表现为凹形坡<凸形坡<线形坡<梯田。根系密度、枯落物蓄积量、植被盖度与生物结皮盖度在不同土地利用方式之间差异显著。不同坡位之间只有生物结皮盖度差异显著。不同坡形之间只有根系密度差异显著。相关分析表明表层土壤容重与生物结皮盖度及坡向相关不显著,容重与植被盖度、枯落物蓄积量、根系密度及坡度显著负相关。逐步回归分析表明土地利用、坡度与植被盖度是影响土壤容重的主要因素,能够解释58.15%的土壤容重变异,本研究建立的拟合关系为土壤容重空间制图提供了便捷途径。

Revealing spatial heterogeneity of bulk density（BD）and its influencing factors were important,which can provide theory basis for BD mapping and land resource evaluating.The study was conducted in a typical small watershed in the loess hilly areas,soil surface bulk density and its influencing factors were measured.Spatial heterogeneity of bulk density and its influencing factors were analyzed,the relationship between them was revealed.The results were as follows：BD demonstrated weak spatial variation.Land use,slope position,and slope shape effected BD significantly.The general trend for BD was WoodlandOrchardShrublandGrasslandCropland,Upper slopeSlope topMiddle slopeLower slope,and Concave slopeConvex slopeStraight slopeTerrace.Root density,mass of litter,coverage of vegetation and biological soil crust were significantly effected by land use.Only biological soil crust coverage was significantly affected by slope position.Only root density was significantly affected by slope shape.The correlation coefficients between BD and biological soil crust coverage and slope aspect were not significant,but there were significant negative correlation between BD and vegetation coverage,mass of litter,root density and slope gradient.The results of stepwise regression analysis showed that land use,slope gradient and vegetation coverage were the main factors to effect BD,and they can explain 58.15% of BD variation.The fitting relationship provided a simple way for BD mapping.