晋西黄土区不同植被类型土壤抗冲性及表层根系分布特征

采用原状土冲刷水槽法,以油松林、刺槐林、山杏林、荆条地及荒草地土壤为研究对象,研究了晋西黄土残塬沟壑区蔡家川流域不同植被类型土壤抗冲性能及植物根系对土壤抗冲性的影响。结果表明:(1)在原状土冲刷试验过程中,各植被类型径流量随冲刷时间的变化趋势不明显,含沙量随时间延长先减少后趋于平稳,土壤抗冲指数呈逐渐增加的趋势。(2)各植被类型总根长密度、根表面积密度、根体积密度及根生物量密度均表现为刺槐、油松林地较大,山杏、荆条、荒草地较小且相差不大,总根系参数之间均存在正相关关系。各植被类型不同根径范围(0～0.5,0.5～1.0,1.0～2.0,2.0～5.0,5.0 mm)的根系指标中,0～0.5 mm径级的根长密度均最大,根体积密度总体表现为细根比粗根小。(3)不同植被类型植物根系均能增强土壤的抗冲性,增强效应表现为刺槐林地和油松林地较强,山杏、荆条、荒草地较弱。植物根系指标中1 mm径级的根长密度、根表面积密度、根体积密度与土壤抗冲性增强值呈显著或极显著正相关关系。其他径级根系参数与土壤抗冲性增强值相关性不显著。

Soil Anti-scourability and Root Distribution Characteristics in Surface Soil Under Different Vegetation Types in the Loess Region of Western Shanxi Province

Soil anti-scourability of different vegetation types and the effects of plant roots on soil anti-scourability in Caijiachuan watershed of Loess Gully-Hilly Area in Western Shanxi Province were studied by using undisturbed soil scouring experiment, taking the soil of Pinus tabulaeformis forest, Robinia pseudoacacia forest, Armeniaca sibirica forest, Vitex negundo land and wasteland as research objects. The results showed that:(1) In the undisturbed soil scouring experiment, the trend of runoff of all vegetation types with the scouring time was not obvious, and the sediment concentration decreased at the beginning and then tended to be stable with time, while the index of soil anti-scourability showed a trend of increasing gradually. (2) The total root length density, root surface area density, root volume density and root biomass density of all vegetation types showed that Robinia pseudoacacia and Armeniaca sibirica forest land were larger, while Prunus armeniaca, Vitex negundo and wasteland were smaller and similar. There was a positive correlation between the total root parameters. Among the root indexes of different vegetation types with different root diameter ranges (0~0.5, 0.5~1.0, 1.0~2.0, 2.0~5.0, >5.0 mm), the root length density of 0~0.5 mm diameter root was the largest, and the root volume density of the fine roots was generally smaller than that of coarse roots. (3) Plant roots of different vegetation types can enhance soil anti-scourability. The enhancement effect was stronger in Robinia pseudoacacia and Armeniaca sibirica forestland, weaker in Armeniaca sibirica, Vitex negundo and wasteland. There were significant or extremely significant positive correlations between the root length density, root surface area density and root volume density of<1 mm diameter root and soil anti-scourability enhancement value among all plant root system indexes. There was no significant correlation between other diameter root parameters and soil anti-scourability enhancement value.