| The red soil hilly area in the southern Jiangxi is a typical area of soil erosion in the red soil area of southern China.There are large areas of forestlands with sparse vegetation and erosion-degraded in the red soil hilly area,which seriously restricts the social and economic development and ecological environment quality of the area.Therefore,exploring the impact of different restoration measures on the fertility and ecological function of erosion-degraded forestlands is of great significance to the restoration and management of erosiondegraded forestlands.A typical Pinus massoniana erosion-degraded forestland was selected in this study,which located in Ningdu County,Ganzhou City.7 treatments of vegetation with soil conservation engineering practices were set up in first trial: No restoration measures(CT),tree and grass + fish scale pit(FG),tree and shrub + fish scale pit(FS),tree,shrub and grass + fish scale pit(FGS),tree and grass + small horizontal ditch(FGP),tree and shrub + small horizontal ditch(FSP),tree,shrub and grass + small horizontal ditch(FGSP).3 treatments of arbuscular mycorrhizal fungi were set up in second trial: No measures in erosion-degraded forestland(DZ),shrub planting(S),shrub planting with arbuscular mycorrhizal fungi(S+AMF).The effects of different treatments of vegetation with soil conservation engineering practices and arbuscular mycorrhizal fungi measures on the vegetation coverage,soil physics,chemical and biological properties of Pinus massoniana erosion-degraded forestland were studied in order to provide technical support for the restoration and management of the Pinus massoniana erosion-degraded forestland.The main findings and results are as follows:1.One and a half years after taking vegetation restoration measures,vegetation coverage,especially the grass and shrub coverage,was significantly improved compared with those before the experiment,and vegetation restoration promoted the improvement of soil physical,chemical,biological properties and ecological function of the Pinus massoniana erosion-degraded forestland.The values of soil water-stable macroaggregates,mean weight diameter,and geometric mean diameter increased compared with those before the experiment,FG,FGS,FGP and FGSP treatments contributed significantly to the increase in soil water-stable macroaggregates content.When compared with those before the experiment,soil p H decreased slightly in each treatment;the increase ranges of soil organic carbon,total nitrogen and available nitrogen content under each restoration measure were 0.10 to 2.08 g/kg,0.02 to 0.13 g/kg and 8.54 to 25.06 mg/kg,and the ranges of net increment of soil organic carbon,total nitrogen and available nitrogen were 34% to 101%,35% to 83% and 14% to 82%;and the ranges of increase of soil microbial biomass carbon and soil microbial biomass nitrogen under each restoration measure were 15% to 29% and 12% to 27%,while the ranges of increase of easy extractive glomalin-related soil protein and total glomalin-related soil protein under each restoration measure were 6% to 14% and 9% to 14%.The results of correlation analysis and redundancy analysis show that the increase of vegetation coverage,especially the rapid increase of near-surface grass and shrub coverage,is a key factor for promoting the increase of soil carbon and nitrogen.2.After 10 months inoculation of arbuscular mycorrhizal fungi on the roots of Lespedeza bicolor Turcz and Amorpha fruticosa Linn,mycorrhizal colonization rate of vegetation,soil organic carbon,total nitrogen,soil microbial biomass carbon,soil microbial biomass nitrogen and glomalin-related soil protein increased,but soil p H and the content of available nitrogen decreased.After inoculation of arbuscular mycorrhizal fungi,soil p H of S+AMF treatment had a further downward trend compare with those of DZ and S treatment.The ranges of increase of soil organic carbon,total nitrogen and easy extractive glomalin-related soil protein on the upper slope and middle slope showed as S+AMF>S>DZ.The ranges of increase of mycorrhizal colonization rate,soil microbial biomass carbon,soil microbial biomass nitrogen and total glomalin-related soil protein on the same slope showed as S+AMF>S>DZ.While the ranges of decrease of available nitrogen on the same slope showed as S+AMF>S>DZ.The results of mycorrhizal contribution rate,correlation analysis and principal component analysis show that inoculation of arbuscular mycorrhizal fungi has the greatest effect on mycorrhizal colonization rate,soil microbial biomass carbon and soil microbial biomass nitrogen;and improves the mycorrhizal colonization rate of roots of Lespedeza bicolor Turcz and Amorpha fruticosa Linn and the capacity of plant root to absorb nutrients,and indirectly promotes the increase of soil organic carbon,nitrogen and glomalin-related soil protein on the whole slope,especially on the upper slope and middle slope;and total nitrogen,glomalin-related soil protein and soil p H are the main environmental factors to affect the differences of soil properties. |
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