植被恢复对侵蚀坡地表层土壤性质的影响

为了评价表层土壤有机碳和养分对放牧和不同植被类型互作的反应,选择四川省西昌市西溪乡牛郎村马家松坡放牧丘陵坡地,分别在坡顶、上、中、下部各层采集有乔木(桉树)、灌木(米油枝)、草本3种类型植被覆盖以及无植被覆盖的0—5 cm表层土壤,测定分析了土壤容重、土壤有机碳、速效氮含量。结果表明,植被对改善表层土壤有机碳和速效氮含量的作用大小顺序为:米油枝>草本植物>桉树。米油枝、草本植物能显著提高土壤有机碳和速效氮含量,桉树改善表层土壤有机碳和速效氮含量的作用则比较小。不同坡位对土壤有机碳、速效氮含量无显著影响。不同植被类型下表层土壤容重变化为:米油枝下土壤<桉树下土壤<草地<裸地。米油枝能显著降低表层土壤容重,而在不同坡位间无显著差异。不同植被类型下表层土壤对放牧的反应不同。放牧显著降低了桉树林下表层土壤有机碳和速效氮的含量,对米油枝和草本植物覆被下表层土壤性质的影响不显著。

Effect of Combining Actions of Grazing and Vegetation Rehibilitation on Surface Soil Property of an Eroded Hillslope Land

The purpose of this research was to estimate the response of surface soil organic carbon and soil nutrition to the combining actions of grazing and vegetation restoration.A grazed hillslope with four types of vegetation in the Majiasongpo catchment,Xichang,Sichuan Province was investigated to understand the effects of grazing on surface soil organic carbon(SOC),available nitrogen(N) and bulk density.The 0-5 cm surface soil samples at top,upper,middle and lower positions of the eroded hillslope were collected respectively.There were four treatments of tree-growth area,shrub-growth area,natural-grass re-growth area, and bareland at each slope position.Results show that surface SOC and available N are enhanced with restoration of vegetation.The improving effect of the vegetation ranks in the ascendant order of tree,grass and shrub.Grass and shrub can significantly improve the content of available N,while there is no significant difference found between tree and bare land.Differences in SOC and available N between slope positions are not significant.Treatments,in terms of increased soil bulk density,are shrub,tree,grass and bare land in turn.Significant difference exists between shrub and bare land,and there are no significant differences among other treatments.The response of surface soil to the combining actions is different.Surface SOC and available N are significantly decreased by grazing under the tree,while there are no significant influences under the shrub and grass.