Reserch On Degraded Vegetation Characters, Restoration And Reconstruction At Limestone Hills Of Xuzhou

1.There are different amoung the numbers of species and the soil factor at different layers in different plantations.They show following order: undergrown layer> shurb layer> tree layer,and the number of species are 14 plant families,18 plant generas in tree layer;18 plant families,22 plant generas in shurb layer;22 plant families,33 plant generas in undergrown layer respectively. The species of plant in tree and shurb layers of plantations are almost light tree species,the species numbers between tree layer and shurb layer was proximately inverse proportion.And with the decrease of the density of plantations,the number of plants and species of undergrowth increase.Based on the data collected from different forest vegetation plantations,species richness, evenness and species diversity of plantations were discussed by patrick index, menhinick index,simpson index,Shannon-Wiener index and Pielou index.The results showed that:the richness is higher in shurb layer than tree layer in the same plantation;and the richness in different plantations are big different,but the same trend appeared in tree and shurb layer of different plantations.Species diversity investigation demonstrates that the species diversity indexes of the same plantations have same change rule,which is higher of shurber layer than tree layer;and the indexes are big different in different plantations.Change of sorenson indices in the same forest vegetation plantations are big,indices of the range from 0 to 0.7826;the result showed that difference of plantations is big.Such as the index between Morus alba+ Robinia pseudoacacia and Platycladus orientalis at FuShan hill is 0.1429; the index between Platycladus orientalis and Robinia pseudoacacia+ Ulmus pumila at QuanShan hill is 0.1333; the index betwteen Platycladus orientalis+ Pistacia chinensis + Robinia pseudoacacia and Platycladus orientalis+ Acer buergerianum + Acer mono is 0.7619; the index between Robinia pseudoacacia+ Platycladus orientalis + Robinia pseudoacacia+ Ulmus pumila is 0.7826.2.Based on the investigation on 7 types of main woody species of plantations in Xuzhou,the niche breath and niche overlap of the main species are studied.The results showed that the niche breaths of Robinia pseudoacacia,Platycladus orientalis,Pistacia chinensis in the tree layer are 0.7625,0.4935,0.4184 respectively,which are higher.The niche breaths of Robinia pseudoacacia,Broussonetia papyrifera in the shrub layer are 0.7358,0.5271 respectively, which are higher.The niche overlaps that Pistacia chinensis with Acer buergerianum and Platycladus orientalis are high. And there are no seedling of Platycladus orientalis at the shrub layer, but the niche overlaps of Platycladus orientalis with other species are much less, so Platycladus orientalis,Robinia pseudoacacia,Broussonetia papyrifera are the main species for the restoration in the limestone low mountains and hills of Xuzhou city.3.The drought resistance and physiological characters under drought stress of 5 plant species(Platycladus orientalis,Melia azedarach,Koelreuteria paniculata,Pistacia chinensis, Sapium sebiferum) are investigated in the potted plant experiment.On the basis of the relationship between physiological standards[malondialdehyde (MDA),leaf relative conductivity, chlorophyll(Chl.),proline content(Pro),peroxidase(POD)]and drought resistance, the comprehensive evaluation of the 5 plant species is handled by subordinative function method. The results indicate that their drought resistance in the order from strong to weak was Platycladus orientalis,Koelreuteria paniculata,Pistacia chinensis,Sapium sebiferum,Melia azedarach , according to their practical performance.4. Based on field investigation and study,site sub-areas are classified by grade, site type groups by the continutiy of the soil and site type by thickness of the soil the limestone low mountains and hills in Xuzhou city. Thus,the area is divided into 3 site sub-areas ,12 site type groups and 30 site types. The results provides the theoretical guidance for the work of vegetation restoration and for the construction of water and soil conservation projects.Based on the analysis of site types of the 16 stone hills of Xuzhou, the experiment summed up systematically the afforestation techniques of limestone mountain from the aspects of afforestation planning and designing,soil preparation,selection of planting stock,nursery stock specification,planting density,soil improvement,soil humidity,root fasten growth.In the experiment,using 15 tree species,afforestation 470hm2.The results show that:The afforesting survival rate is up to 85.6%, among them,Platycladus orientalis is 85.8%,Sabina chinensis is 87.5%,Ligustrum lucidum is 93.7%,Cedrus deoda ra is 82.0%,Sabina chinensis is 63.9%,Robinia pseudoacacia is 84.2%,Acer mono is 85.3%,Pistacia chinensis is 65.7%,Rhus typhina is 97.1%,Sapium sebiferum is 67.7%,Melia azedarach is 78.1%,Diospyros KakI is 84.7%,Punica granatum is 58.6%,Zizyphus jujuba is 61.3%,Prunus cerasifera is 40.0%.5. Based on the data collected from different plantation plots,species richness, evenness and species diversities of plantations are discussed by patrick index, menhinick index, Simpson index , Shannon-Wiener index and Pielou index. The results showed that:(1) Species diversities in different layer in the same plantation shows an order:shrub layer < herb layer. But in Platycladus orientalis plantation,because they grow in an exceptional habitat,species diversities in different layer is in an different order:shrub layer > herb layer.(2) The species diversities of shrub layer in different plantations shows an order:Platycladus orientalis> Koelreuteria paniculata+Platycladus orientalis(downslope)>Platycladus orientalis(2a)>Platycladus orientalis+Pistacia chinensis>Platycladus orientalis+Celtis tetrandrassp +Firmiana simplex+Robinia pseudoacacia>Ligustrum lucidum+Cedrus deodara ( 2a ) >Platycladus orientalis +Koelreuteria paniculata(upslope)> Ligustrum lucidum(2a), and the order in herb layer is Platycladus orientalis +Celtis tetrandrassp +Firmiana simplex +Robinia pseudoacacia>Ligustrum lucidum(2a)>Ligustrum lucidum +Cedrus deodara(2a)> Koelreuteria paniculata +Platycladus orientalis(downslope)> Platycladus orientalis + Pistacia chinensis >Platycladus orientalis + Koelreuteria paniculata(upslope)>Platycladus orientalis(2a)> Platycladus orientali;(3)Sorenson indices in plantations are 0.0560～0.5854.They have less common species, and the largest biodiversities between plantations.