Effects Of Fine Roots On Soil Anti-erodibility Of Soil And Water Conservation Vegetation In Black Soil Region Of Northeast China

The soil was studied under different soil and water conservation vegetation and cultivated land in typical black soil region of Northeast China.Root weight density,root length density and root surface area density of fine roots were measured and calculated by root drilling and using Win RHIZO Pro LA2004 root analysis system.Based on the evaluation of water stability index and anti-scouribility coefficient,the soil anti-erodibility and unti-scouribility were studied by using the method of dispersion of soil partical in water and scouring of undisturbed soil.The factors affecting soil unti-erosion charcateristics were studied by physical and chemical analysis.On this basis,the relationship between soil anti-erodibility and unti-scouribility and influencing factors was comprehensively and systematically analyzed,and the soil anti-erosion capability was comprehensively evaluated by using the index system evaluation method.The main conclusions are as follows:(1)In the six types of soil and water conservation vegetation studied,0?1mm diameter root system is the main part of fine roots,and 0?1mm diameter fine roots are mainly distributed in the surface soil;The root weight density(RWD),root length density(RLD)and root surface area density(RSD)of the fine roots of 1?2 mm diameter of the five arbor vegetations were significantly higher than that of the grassland vegetations,and the difference was more significant in the subsoil(P<0.05).In general,broadleaf plantation and mixed broadleaf-conifer plantation have higher RWD,RLD and RSD.(2)Vegetation restoration significantly improved the black soil soil anti-erodibility and unti-scouribility(P<0.05).The impact of arbor vegetation on black soil anti-erodibility was significantly greater than that of grassland vegetation(P<0.05).Broadleaf plantation and mixed broadleaf-conifer plantation had the largest impact on black soil unti-scouribility,while coniferous plantation had the smallest impact.Soil anti-erodibility and unti-scouribility change dynamically.With the accumulation of time,soil anti-erodibility first decreases rapidly,then slows down and finally becomes stable,while the unti-scouribility gradually increases.(3)Correlation analysis showed that fine roots could improve the anti-erodibility and unti-scouribility of black soil,and the contribution of RLD to the anti-erodibility of soil was greater than that of other root system characteristic parameters.In addition,among the six types of soil and water conservation vegetation studied,the fine root characteristics of Fraxinus mandshurica plantation and Fraxinus mandshurica and Larix gmelini mixed plantation had a great influence on the erosion resistance and erosion resistance of black soil,while the fine root characteristics of Fraxinus mandshurica and Pinus syvestris var mongolica mixed plantation only had a great influence on the soil anti-erodibility.(4)Soil and water conservation vegetation fine roots by increasing the soil organic matter,promote<1 mm small particle size of water stable macro-aggregate to>2 mm large particle size of water stable macro-aggregate and at the same time also can promote the<0.02 mm small particle size of micro-aggregate to 0.25?0.05 mm large particle size of micro-aggregate together,The total amount of water-stable aggregates is increased,the composition of water-stable aggregates and micro-aggregates is improved,and the stability of macro-aggregates and micro-aggregates is improved,the stable soil structure is formed.In additionand,the anti-erodibility and unti-scouribility of black soil are enhanced.(5)Soil anti-erodibility has a close realationship with anti-scouribility and the relationship between different plots is different.Vegetation soil shows a positive correlation,while cultivated land soil shows a negative correlation.The multi-index comprehensive evaluation shows that the studied soil and water conservation vegetation has significantly improved the anti-erosion ability of black soil(P<0.05),and the influence degree of Fraxinus mandshurica plantation,Fraxinus mandshurica and Larix gmelini mixed plantation and Fraxinus mandshurica and Pinus syvestris var mongolica mixed plantation is the largest,and the influence degree of arbor vegetation on the subsoil is significantly greater than that of grassland vegetation(P<0.05).Therefore,it can be concluded that the depth of influence of arboreous vegetation on the anti-erosion capability of black soil is significantly greater than that of grassland vegetation(P<0.05),and that the Fraxinus mandshurica plantation and Fraxinus mandshurica and Larix gmelini mixed plantation,Fraxinus mandshurica and Pinus syvestris var mongolica mixed plantation are efficient types of soil and water conservation vegetation in the black soil area.Therefore,that more attention should be paid to broadleaf plantation and mixed broadleaf-conifer plantation in the future vegetation restoration and construction in the black soil region of Northeast China.