| Pinus massoniana is the pioneer tree species for vegetation restoration and soil erosion control in red soil erosion region of southern China.Affected by the natural factors and human activities,the Pinus massoniana pure forest with single stand structure was formed,which reduced the biodiversity,weakened the ability of water and soil storage,and deteriorated the ecological environment.Reasonable under-story vegetation restoration is one of the important measures to reduce soil erosion,improve soil quality and improve the ecological environment.Therefore,this paper took the typical red soil area of granite development in Hetian Town,Changting County,Fujian Province as the research area,and took the contour grass filling belt(M1),small hole sowing grass(M2),strip ditch sowing grass + replanting broad-leaved trees(M3),arbor-shrub-grass mixture(M4),fish scale pit(M5)and serious erosion of ungoverned land(CK)as the research objects.Combining with field investigation,monitoring and laboratory experiment analysis method,and analyzed the characteristics of vegetation growth community,soil physical and chemical properties,soil permeability,litter water holding capacity and the the runoff and sediment yield on runoff plot under different governance modes.Different governance modes were comprehensively evaluated to reveal the regulation of soil and water conservation effect from three aspects:vegetation regulation effect,soil regulation effect and water storage and soil conservation effect.Which can provide scientific reference and guiding practice for the restoration of soil erosion and degraded ecosystem as well as the suitability of typical governance modes.The main conclusions were as follows:(1)Different governance modes can effectively improve vegetation growth.The vegetation coverage reached more than 80% in the sample plots after governance.Compared with CK plot,the vegetation growth characteristics such as tree height,crown width and DBH of arbor and shrub under different governance modes were significantly improved.The plant species diversity,richness and evenness index were M3>M5>M4>M2>M1>CK,while the dominance degree was higher in the degraded plots.which was negatively related to the stability.The dominance of CK sample was the highest,which showed CK>M2>M1>M4>M3>M5.(2)Soil physical properties were significantly improved by different governance modes.Compared with CK plot,different governance modes significantly reduced the soil bulk density,soil hardness and disintegration coefficient.The improvement degree is higher in0-10 cm,and there was an increasing regulation of change with the deepening of soil layer.There were significant differences in soil bulk density and disintegration coefficient among different governance modes,but no significant differences in hardness.The soil moisture content,soil porosity,shear strength and root biomass of M1,M2,M3,M4 and M5 modes were significantly higher than those of CK plot.(3)Different governance modes significantly improved the chemical properties of soil.The contents of soil organic matter,total nitrogen,total phosphorus,available phosphorus and available potassium in different governance modes had obvious "surface aggregation phenomenon".Except for M2 and M5,the change trend of total potassium content in other plots was not obvious.Compared with CK sample plot,the improvement effect of total phosphorus content in M2 is not obvious.The p H had no obvious improvement compared with CK,and M2 and M4 plots were significantly higher than that of other governance modes.There was no obvious variation of soil p H with soil layer,and there was no significant difference in M1,M2 and M3 among soil layers.(4)Different governance modes can effectively improve the soil and water conservation benefits.The litter reserve and water holding capacity increased after the governance,which could absorb 1.76-2.60 times of its dry weight.The water absorption rate reached the maximum in the first 0.25 h,and the litters' water holding capacity accounted for more than80% of the saturated water holding capacity after 2 h immersion.There was a significant difference in litter retention capacity among different governance modes,and much higher than that of CK plot.The soil permeability of governance was significantly higher than that of CK,and the infiltration effect of M5 and M3 were better.With the deepening of soil layer,the soil permeability was weakened,and showed the initial infiltration rate > average infiltration rate > stable infiltration rate.The soil infiltration rate showed the highest value in the initial stage,and declined the most from 0 to 3 min.After 3 min,the decreasing trend slowed down and finally reached a stable infiltration rate.There was a significant positive correlation between rainfall and runoff and sediment yield in different governance modes,and the runoff and sediment yield were much lower than those in CK plot.The best runoff and sediment reduction benefits were 75.87% and 85.17% in the M5 plot,and the sediment reduction benefits of all plots were greater than runoff reduction benefits.(5)Assessment of soil and water conservation effects.Based on the principal com ponent analysis method,the soil and water conservation effects of different governancemodes were comprehensively assessed.The results showed that the comprehensive sc ores of soil and water conservation effects of different governance modes were M3>M5>M4>M1>M2>CK.The comprehensive scores of M3 and M5 were higher,indicating t hat the effect of soil and water conservation were better.The results show that the ve getation reconstruction and restoration measures based on biological measures and supp lemented by engineering measures can have a better effect on soil erosion control. |
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