Collaborative Mechanisms Otvegetation And Soil Succession Under Different Vegetation Restoration Measures

The relationship between vegetation and environment is extremelycomplex, which has been one of the focus of ecological research. The plantcommunity succession is not only reflected in the species composition and structure,is also reflected in the soil environmental change. The process of Vegetationsuccession process is the process of soil adaptation and transformation by plants. Soiland vegetation are two interdependent factors in soil-vegetation System. Thevegetation formed by tree planting and seeding afforestation has different successionprocess, and its collaborative mechanism of vegetation-soil system should has somedifferent rules. Exploring the relationship of plant succession and soil development,revealing the evolution mechanisms of soil development on community successionprocess, recognizing the role of vegetation on soil development in the differentvegetation restoration measures, are great significant to explore the vegetationsuccession mechanism and forestry ecological construction.The paper made the vegetation succession and roots and litter and soildevelopment of different vegetation recovery as a starting point, quantitative analysisand modeling methods as the main analytical tools to clarify vegetation successionfeature, litters and roots dynamic characteristics of ground surface and the couplingrelations with soil development synergies, and carry out a comprehensive evaluationof different successional stages of vegetation-soil system by building collaborativesuccession degree evaluation model.Through research, the paper has made the main results:(1) With vegetation positive succession, important value of Platycladus orienalisdominant plantation gradually increases, important value of Quercus variabilis andlocust decline; vitex negundo var. is the indicator species in shrub mid-stage and latesuccession, Ziziphus jujuba var. is indicator species of the shrub early succession,which has large niche breadth; in tree successional stages, with the positive succession,the number that had niche overlap gradually increased.(2) With vegetation positive succession, the important values of shrubs species of different vegetation restoration measures first increased and then decreased, theShannon-Wiener index of shrubs in tree layer of tree planting vegetation restorationmeasures were significantly lower than the Shannon-Wiener index of seedingafforestation measure in the same successional stage of mid-stage and late succession,herbaceous Shannon-Wiener index was the opposite.(3) With vegetation positive succession, the seedlings regeneration of coniferousstands formed by tree planting succession was more intense than that of seedingafforestation, the important values of Platycladus orienalis fall sharply, but theimportant values of seedlings of Quercus variabilis, locust and broussonetiapapyrifera gradually increased; the Simpson index of seedlings regeneration of treeplanting measures in various successional stages was lower than that of the seedingafforestation vegetation restoration measures, the Shannon-Wiener index was theopposite.(4) The biomass and nutrient elements per unit area of tree of the vegetationformed by tree planting are siginificant greater than that of the vegetation formed byseeding afforestation at the same successional stage. Compared with the vegetationrecovery measures of seeding afforestation, the root biomass of the tree in treeplanting vegetation recovery measures had a high proportion in total biomass, but farbelow in absolute terms than that of seeding afforestation vegetation restorationmeasures.(5)Taking into account the species diversity, important value and species life, theamendment succession index (Dj) has been built which can describe thecharacterization of vegetation succession. Different vegetation restoration measures,amendments to the succession index with positive vegetation succession. Successionalstages from the bush to tree successional stages, there is a clear upward trend.Afforestation of the same successional stages of vegetation succession index recoverymeasures were significantly succession index than tree planting vegetation restorationmeasures(6) The soil bulk density and soil porosity were gradually reduced of differentvegetation restoration measures with positive succession, the minimum of thatappeared in the late successional stage, and the soil saturated water capacity,non-capillary water holding capacity and capillary water holding capacityincreased;the Kostiakov, Philip and Horton infiltration model can well describe thesoil infiltrationprocess; the soil characteristics and root structure indicators closely related to the soil infiltration capacity were respectively non-capillary porosity androot surface area density.(7) With vegetation positive succession, soil pH value showed a graduallydecreasing trend and soil organic matter content tended to increase in differentvegetation restoration; soil organic matter content of tree planting vegetationrestoration measures was slightly higher than that of seeding reforestation vegetationrecovery measures in the mid-stage and late succession, but in the early stage was theopposite. Soil total N content showed a gradual upward trend with the positivevegetation succession.(8) In tree planting recovery measures, the shrub Shannon-Wiener index had asignificant relation with soil organic matter, total N and total P; the herbal Pielouindex can create a linear regression model with the pH, organic matter, soil bulkdensity, soil wool pipe holding water rates, soil field hold water rates andnon-capillary porosity. In seeding afforestation vegetation recovery mode, the shrubsShannon-Wiener index had a significant correlation with soil total N, total K, and soilbulk density, and can creat linear regression equation with organic matter, total K andsoil field water holding rate; herbal Pielou index had a significant relationship withsoil total N, total P and total K.(9) Based on correlation analysis, PCA and a comprehensive index method, thepaper selected eight indicators of soil physical and chemical properties as theevaluation index system of soil development as evaluation index system, andestablished the comprehensive evaluation index (SDI) that described soil developmentcharacteristics; SDI values increased with positive vegetation succession in differentvegetation restoration measures.(10) Litter biomass of vegetation in seeding afforestation restoration measureswas significantly higher than that of vegetation of tree planting restoration measuresin the same successional stage; the size relation of litter biomass of decompositionlayer was decomposed layer> half-decomposed layer> undecomposed layer.(11) Aboveground biomass of vegetation surface, surface root biomass and litterbiomass had positively conic relattion with soil organic matter content and total Ncontent; total nitrogen of aboveground plant part, underground plant part and litterbiomass had quadratic regression relationship with soil organic matter and soil totalnitrogen respectively.(12) The maximum index values of root length density, root surface area density and root volume density appeared in the mid-stage succession in differentsuccessional stages of different vegetation recovery measures, followed by earlysuccession and late succession; the root system is mainly composed by fine roots(D<2mm), root length of that had a proportion of93.64%to97.52%of total length.(13) In planting vegetation restoration measures, soil organic matter showedsignificant positive correlation with root biomass, root volume density, root surfacearea density and root average diameter; the soil physical and chemical characteristicsthat greater affected root structure parameter values indicators were organic matter,total N and soil bulk density; the root structure of indicators that most sensitive to theresponse of soil physical and chemical characteristics were root length density,specific root length and root average diameter. In seeding afforestation vegetationrestoration measures, soil organic matter was a significant positive correlation withroot biomass, root surface area density, root volume density and root average diameter;the soil development features that greater affected root structure were soil total N, soilsaturated water rates and soil organic matter; root structural characteristics indicatorsthat sensitive to soil development characteristics were root bulk density, average rootdiameter and root length density.(14) In tree planting vegetation restoration measures, soil organic matter and soilmoisture had greater direct positive effect on seedling density, but soil bulk densityhad a greater negative effect on seedlings; litter biomass had total indirect positiveeffect on seedings, and soil bulk density had biggest indirect negative effect impactfactors on seeding density. In the seeding afforestation vegetation restorationmeasures, soil organic matter and soil total N has a larger direct positive effect onseedling density, soil PH value had a greater negative effect on seedings, but soilorganic matter produce the total indirect positive effect on seedings.(15) The collaborative degree model was defined,whic described vegetation-soilsystem co-existing evaluation model, on parameter determine, the specific object ofthe vegetation biomass, Shannon-Wiener index can be selected as indicators of thecharacterization of vegetation succession, soil bulk density, soil organic matter andsoil moisture can be selected as indicators to characterize soil development,succession variables in the index system load percentage of the total load can be usedas a weighting coefficient; in the tree planting vegetation restoration measures, withthe positive succession, vegetation succession distance index showed the trend ofsteady growth, vegetation succession distance index and soil development distance index values gradually approaches are equal. In the seeding afforestation vegetationrestoration measures, with the positive succession, collaborative process of vegetationsuccession and soil development were a gradual process, the collaborative degreeindex steadily increased.