Study On Characteristic Of Artificial Vegetation On Rocky Side-slope In Karst Area Of Mid-Guizhou Province

To understand the vegetation characteristics and variation of matrixnutrients in the initial vegetation planting of side slope ecologicalprotection and the naturalizing law of artificial vegetation of the rocky sideslope. Based on the actual project, this paper selected3rocky slopes withdifferent slope aspect and different gradient as sample slopes, and takingpositioning method and conventional community survey method, testedcommunity characteristics (Species, cover, height, etc.) and soil nutrientfactors monthly (available nutrient elements) within2years of the artificialvegetation planting. Besides, using typical plot method, the researchselected the good retention vegetation of rocky slopes with differentplanting years(2a,4a,7a and10a) in Guizhou province, investigated andanalyzed the species composition, population characteristics, communitycomposition structure features, composition and abundance of soil seedbank species, and compared the similarity between artificial vegetationcommunity on the ground and soil seed bank. The main research resultswere as follows:1. At the initial planting of plant community, the initial seeding specieswas growth rapidly due to the rich sunny and soil nutrient, and the speciescomposition, coverage and height were in the ascendancy, but speciesnumber were fewer. With the planting of artificial vegetation, the habitatconditions of highway slope had a certain extent improvements, whichprovided the possible conditions for native species to invade. Some1-yearpioneer plants began invasion in the2nd year, and the species number wasincreased from4~5initial germination species to more than20at the end ofthe2nd anniversary. In the first early2months of vegetation planting, therewas significant difference in the species composition and coverage betweenslopes with different slope aspect and slope gradient. With the area of the slope vegetation expanded, the effect of slope aspect and gradient tocommunity characteristics was not obvious.2. In the initial artificial planting of slope vegetation, communityspecies were mainly herbs, and showed seasonal changed in terms ofspecies, coverage and height with the time passing. Slope vegetation hadtwo periods of brown during one year, and the coverage of surviving partsuddenly reduced in August, September and winter. Overall, the coverageof slope vegetation in growing season (November) maintained a relativelyhigh level (above80%), and the second year was larger than the first year.The first year after the establishment, spray species was in the ascendancy,however, community height was overall lower in the process of seasonalchanges. Compared with the1st year, community height of the second yearincreased obviously. Within2years of artificial vegetation planting,community maintained a strong growth and the effect of recovery wasgood.3. With the time passing, richness of species increased, communityalpha diversity improved generally, and community composition andstructure were transformed from the simple to complex in the earlyartificial seeding. The dynamic changes of community species betadiversity visually displayed the process of community species turnover andnaturalizing.4. Soil available phosphorus and alkaline nitrogen mass fractiondeclined in two years after the planting of vegetation, and were lower thanthe early establishment. Available potassium mass fractions of No.1andNo.2slopes were declined after wave changes, yet the No.3slope increasedslightly. Mass fraction of organic matter increased significantly in the firstyear, and declined obviously in the first three months of the second yearand then basically stabilized. The correlation between related indices ofplant characteristics and soil nutrient was not significant after the initial vegetation planting (within2years). It indicated that the plant growth,slope soil structure, soil physical and chemical properties and soil microbeeffected more complex interactions during this period.5. The community types of all slope plots with the same recoveryperiod were consolidated. Vegetation coverage expressed the decreasetrends with the time passing. The vegetation coverage of the10years slopewas least, only50%, and that of the remaining recovery periods basicallyremained at a higher level. The soil coverage of slope artificial vegetationwas100%at the early stage. It was fragmentary soil peeling off from7years, but soil coverage was still high (≥85%). The average thickness ofsoil was gradually declined with the extended recovery time.6. After the establishment of artificial vegetation, the number ofspecies was increased over time. And then native species were becomingdominance gradually and then replaced the early planting species, andformed mass-dominant species in the transition stage which was from thedominant species of artificial vegetation community to the invasion ofnatural species, number of species was the largest. Then native gramineousplants had a dominant position gradually and formed single-dominancecommunity, number of species declined, and the early planting specieswere replaced by native species, native woody plants went into thecommunity, and declined the dependence of artificial spray soil for its rootswere outspreading downward, and could formed karst rocky vegetation.7. Gramineae, legume and compositae plants played a significant rolein early natural succession of artificial vegetation. Gramineous plants couldcover stark slope in the near future rapidly for its seeding emergence andrapid growth, and formed the main constructive species in early sowingspecies due to its better tillering ability and barren tolerance. Massiveintrusion of native compositae and Gramineae plants changed thecommunity composition and structure, replaced the early planting species gradually, and increased the naturalizing degree of rocky side slope plant.However, legumes plants did not show special advantages on type andquantity though it had nitrogen fixation. After10years of succession,woody plants began to occupy a larger community space. Vegetationcommunities expressed transition characteristics from the herbaceous to thegrass-shrub stage. The native invasive species played an important roleduring the process of artificial vegetation community changed to thenatural succession of vegetation communities, and ensured continuity andsustainability of slope vegetation recovery.8. The soil seed banks in artificial vegetation-soil system of thehighway rocky slope in karst area of central Guizhou Province had richplant seeds. It was a certain degree similarity in species compositionbetween soil seed bank and aboveground vegetation with the differentrecovery years of slopes, but the similarity index was less than0.5. Andthere was obvious similarity in dominant species, living composition andfunctional composition between aboveground and underground parts ofplant community, which indicated that it had synchronicity in the growthon the ground and underground parts during the herbaceous stage of rockyslope artificial vegetation restoration in karst area.9. The naturalizing processes within10years after the establishmentof the artificial vegetation on highway rocky slope in karst area of centralGuizhou province was: artificial planting grass community stage (1-4a),coexistence and competition of early artificial planting plants and nativeplant grass community stage (4-7a), natural grass-shrub community stage(7-10a).