| The degradation of Pinus massoniana is characterized by weak habitat and soil conditions,poor plant site conditions,and low self-healing ability of ecosystem.Therefore,it is very important to improve the ecological regulation benefits of Pinus massoniana degraded and inefficient forest land.In order to reveal the soil physical and chemical characteristics of different vegetation restoration measures,community plant diversity structure characteristics,plant root and leaf characteristics,soil and water conservation characteristics,obtain the comprehensive control benefits of different vegetation restoration measures,select better vegetation measures,and provide scientific reference for the vegetation restoration of Pinus massoniana inefficient forest land.Based this study area on Hetian Town,Changting County,a typical low efficiency forest of Pinus massoniana,with five typical vegetation restoration measures were taken in the standard runoff plot,which were closed and forbidden Management(M1),furrow grass and shrub belt(M2),whole slope grass planting(M3),low efficiency forest transformation(M4),arbor shrub grass mixture(M5)and control plot severely eroded and degraded land(CK)as research objects.Through field plant investigation,sampling and soil properties、plant samples analysis in laboratory,characteristics of soil physical and chemical properties,community plant diversity structure,plant roots and leaf characteristics,soil and water conservation characteristics of different measures were determinated.Combined with principal component analysis,comprehensive evaluation index method and other methods,the comprehensive regulation benefits of different vegetation restoration measures were obtained.Thus to provide theoretical and technical basis for vegetation restoration,stand allocation and forest type layout,and selection of dominant species of soil and water conservation in the red soil area of southern China.The main research results are as follows:(1)Soil physical and chemical characteristics of different measures: The contents of organic carbon,nitrogen,total phosphorus,available phosphorus,total potassium and available potassium in the soil under M5 and M2 measures were significantly higher than those under other measures.With the increase of soil depth,the coefficient of soil disintegration increased significantly.In terms of reducing the rate of soil disintegration,the improvement effect of each treatment measure was M5 > M2 > M3 > M4 > M1 > CK.M5,M3 and M2 have higher soil moisture content,followed by M1 and M4.The fractal dimension of aggregate,> 0.25 mm aggregate failure rate,and < 0.25 mm aggregate content are smaller in M5 and M2 measures,while serious erosion degradation area CK is the opposite.The geometric average diameter and the average weight diameter of soil aggregates in different measures were from large to small,followed by CK < M1 < M4 <M3 < M2 < M5.With the deepening of soil layer,the water content showed a downward trend,while the disintegration coefficient showed an upward trend.(2)Community structure of different measures: species diversity index,richness index,evenness index,average tree height,tree trunk cross-section diameter and vegetation coverage of Pinus massoniana and its understory shrubs are higher in measures M5 and M2,lower in measures M1,M3 and M4,while dominance index is opposite.The species diversity index,richness index and evenness index in M5 were2.55,1.67 and 1.98 times of CK respectively.M5,M2 and M3’s important value index and dominance index of Pinus massoniana were lower.In addition,the crown diameter of Pinus massoniana and Schima superba were the largest.The community evenness,diversity index and richness index were extremly positively correlated with soil organic carbon content(P < 0.01),and positively correlated with soil available potassium and total phosphorus content(P < 0.05).(3)Characteristics of roots and leaves of plants with different measures: under different vegetation restoration measures,roots are mainly distributed in 0-20 cm layer of soil,and with the increase of soil depth,root content was significantly reduced.And the root length,surface area,volume and biomass,root weight density and root length density were M5 > M2 > M3 > M4 > M1 > CK from large to small.The content of carbon,nitrogen and phosphorus in Pinus massoniana leaves were higher in measures M5 and M2,M3,followed by M1 and M4.The specific leaf area of M5 and M2 were higher than that of other measures,while the dry matter content of leaves were lower.Compared with leaf area,the content of soil carbon and nitrogen had a significant positive correlation(P<0.05),and had a significant negative correlation with the content of leaf dry matter(P<0.01).(4)Water and soil conservation and comprehensive benefits of different measures: the overall water absorption rate of litter under different measures was M5 > M2 > M3 > M4 > M1 > CK.The water absorption rate was mainly in the absorption stage,increase stage and conservation stage,and the enhancement value of litter water holding capacity was the highest in M5 and M2,thus water and soil conservation effect were better,while M3,M4,M1 were the second.Comprehensive evaluation index: 31 factors affecting vegetation restoration were selected from the measured indexes.The weight of each evaluation index was determined by principal component analysis,and then the control benefits under different vegetation measures were scored by the calculation of comprehensive evaluation index.The results of evaluation were: M5 > M2 > M3 > M4 > M1 > CK.Comparing the soil and water conservation and comprehensive benefits of different vegetation restoration measures,M5(mixed tree,shrub and grass)and M2(ditch,grass and shrub belt)have not only the best regulation benefits,but also the best soil and water conservation effect,which were suitable vegetation restoration measures to be popularized. |
PDF Full Text Request