地震灾区生态治理初期土壤抗蚀性特征——以汶川地震典型区为例

摘要

土壤抗蚀性可客观表征土壤结构对各类侵蚀的抵御能力,生态恢复可引起土壤抗蚀性变化.研究地震灾区生态治理初期土壤抗蚀性,有利于了解震后生态恢复对土壤抗蚀性的影响效应.本文通过野外调查与室内分析,运用主成分分析法对汶川和绵竹地震灾区土壤抗蚀性进行综合研究.结果表明:(1)地震灾区生态治理初期,汶川和绵竹植被受损区经过生态恢复,土壤理化性质均发生不同程度的变化,进而影响土壤抗蚀性.两受灾区在土壤有机质含量、机械组成及抗蚀性指数方面存在差异;(2)单一指标不能全面反映该地区土壤抗蚀性的强弱;(3)受灾区植被受损治理区土壤抗蚀性综合指数显著低于未受损区,但与受损未治理区差异不显著,特别是绵竹植被受损治理区土壤抗蚀性综合指数较受损未治理区出现了降低趋势.绵竹植被受损治理区和受损未治理区的土壤抗蚀性综合指数高于汶川;(4)表征研究区土壤抗蚀性的11个指标可简化为:土壤最大持水量、总孔隙度、有机质、全氮、粉粒含量、砂粒含量6个指标,并与土壤抗蚀性综合指数进行拟合,获得土壤抗蚀性评价模型:Y=0.096X1 +0.332X2 +0.198X3-0.040X4-0.062X5-0.398X6 +20.499,R2=0.9977,拟合程度较好.以上研究结果可为地震灾区土壤抗蚀性的后续研究及评价指标体系的构建提供参考.%Soil anti-erodibility is one of the significant parameters for evaluating the ability of soil resistance to erosion.Aiming to understand the effect of ecological restoration on soil erosion durability at the initial stage after earthquake,soil anti-erodibility was studied by using principal component analysis.The results showed that:(1) After ecological restoration,soil physical and chemical properties of the disturbed areas in Wenchuan and Mianzhu exhibited distinct changes,and soil anti-erodibility was considerably affected;The soil organic matter,soil mechanical composition and anti-erodibility index between the two shock-affected regions were different.(2) Single indicator could not reflect the soil anti-erodibility comprehensively in this region.(3) The soil anti-erodibility comprehensive index (SAECI) of the recovered areas in Wenchuan and Mianzhu was respectively significantly lower than those of the undisturbed area.Compared with the disturbed areas,the SAECI of the recovered areas not significantly increased;instead,it declined in Mianzhu.However,in the two affected regions of earthquake,the SAECI of the recovered areas and destroyed without restoration in Mianzhu was higher than those in Wenchuan.(4) All the eleven anti-erodibility indicators could be simplified by six coefficients,maximum water-holding capacity,total porosity,organic matter,total nitrogen,silt content and sand content.Soil ant-erodibility model was obtained by linear regression,where X =independent variables (the six soil indices) and Y =dependent variables (SAECI).The value of R2 was 0.9977.This result could provide a reference for the building of soil anti-erodibility assessment index system and support follow-up research on the shock-affected areas.