三峡水库消落带草本植物对若干土壤物理性质的影响

Impacts of Several Grasses on Soil Physical Properties in the Riparian Zone of Three Gorges Reservoir

为明确三峡水库消落带典型草本植物对土壤物理性质的影响,在三峡腹地忠县石宝镇消落带选取牛鞭草(Hemarthria altissima(Poir.)Stapf et C.E.Hubb.)、扁穗牛鞭草(Hemarthria compressa(L.f.)R.Br.)、双穗雀稗(Paspalum paspaeoides(Michx.)Scribn.)和自然恢复草地狗牙根(Cynodon dactylon(L.)Pers.),以裸地为对照,对比研究了4种典型草地土壤容重(Bulk density,BD)、颗粒组成(Soil particle composition,SPC)、磁化率(Soil magnetic susceptibility,SMS)和抗剪强度(Soil shear strength,SSS)等土壤物理性质的差异。结果表明:三峡水库消落带植物及其根系的存在对土壤容重、土壤体积磁化率、颗粒组成和抗剪强度有重要影响。裸地的土壤容重要显著高于4种草地,但表层土壤体积磁化率要弱于草地;草地与裸地的土壤颗粒组成无明显差异;植物根系可以显著增强土壤抗剪强度,其中牛鞭草地0—10cm和10—20cm层土壤粘聚力分别比裸地增加319.81%和46.89%,而狗牙根草地的增加幅度分别为17.69%(0—10cm)和43.13%(10—20cm)。研究结果可以为三峡水库消落带植被恢复和水土保持提供一定依据。

To understand the impacts of herbaceous plants on soil physical properties,soils in the riparian zone of Three Gorges Reservoir(TGR)with different plant covers(Hemarthria altissima,Hemarthria compressa,Paspalum paspaeoides and Cynodon dactylon)were investigated.With bare area as the control,bulk density(BD),soil particle composition(SPC),soil magnetic susceptibility(SMS)and soil shear strength(SSS)were determined.The results showed that grasses and their roots had significantly influence on soil physical properties.In this investigation,the BD in bare land was significantly higher(p<0.01)than the grasslands while the SMS of 0-20 cm layer in bare area(mean 1.272×10-7 m^3/kg)was weaker than grasslands(mean 1.765×10-7 m^3/kg).Soil grain size in bare area and grasslands is different but not significant.Plant roots can significantly enhance soil shear strength.The soil cohesion in 0-10 cm and 10-20 cm soil layer of H.altissima land increased by 319.81%and 46.89%,respectively,compare to the bare ground.And the rate of soil cohesion increment in C.dactylon land was 17.69%in 0-10 cm layer and 43.13%in 10-20 cm layer correspondingly.The results will be useful for revegetation and soil conservation in the riparian zone of TGR.