Study On Ecological Function Evaluation And Biodiversity Of Typical Forest Stands In Jinxi Of The Loess Plateau

Taking7kinds of different typical forest stands in CaiJiaChuan, including Robinia pseudoacacia L., Pinus tabulaeformis, Platycladus orientalis (L.) Franco, Robinia pseudoacacia L.+Platycladus orientalis (L.). Franco mixed forest, Robinia pseudoacacia L.+Pinus tabulaeformis mixed forest, Populus davidiana, Quercus liaotungensis,as study subject. Through research on the indexes of maintaining Ecosystem stability function, Hydrological function and Soil characteristic ecological function, using the Analytical Hierarchy Process to determine the Weight of each assessment indicator, and utilizing the mathematical model of the Synthetic Evaluation to evaluate the ecological function of the different kinds of abandoned cropland forests, obtained the ecological function condition of each forest type, and proposed the working and regulative measures with were good for improving each forests’ecology function.(1) there were102kinds of vascular plant, including73kinds of herbaceous,31kinds of shrub and12kinds of arbors, in different forest types. And the species number:mixed forest>pure forest>secondary forest. Species number in secondary forest is lower than other forest type.(2)The a biodiversity of the species biodiversity among different forest types shows that the herbaceous layer is higher than the shrub layer. In shrub layer, the biodiversity appears increase in the order of Pinus tabulaeformis, Platycladus orientalis (L.) Franco, Robinia pseudoacacia L.+Pinus tabulaeformis mixed forest, Robinia pseudoacacia L.+Platycladus orientalis (L.). Franco mixed forest, Quercus liaotungensis and Populus davidiana, while in herbaceous layer the order is increase in that Populus davidiana, Quercus liaotungensis, Robinia pseudoacacia L.+Platycladus orientalis (L.). Franco mixed forest, Robinia pseudoacacia L.+Pinus tabulaeformis mixed forest, Robinia pseudoacacia L., Platycladus orientalis (L.) Franco and Pinus tabulaeformis. The biodiversity of shrub layer and Uniformity shows significant difference in different forest type. That is the secondary forest is higher than plantation. And that is contrary in herbaceous. From the β biodiversity result the mixed forest is better than plantation, compared to the secondary forest.(3)The litter thickness of CaiJiaChuan valley ranging from10-35mm; The litter layer枯biomass has huge difference among different forest type. Quercus liaotungensis. Is the most by6.79t/hm, Robinia pseudoacacia L.+Platycladus orientalis (L.) Franco mixed forest is the leas by0.56t/hm2. The moisture holding capacity of the litter is different from each other. Quercus liaotungensis is the most by23.57t/hm2. And the Platycladus orientalis (L.) Franco is the least by1.93t/hm2.(4)Considering the soil water-holding capacity, soil bulk density and porosity, Quercus liaotungensis has the best ecological function. And at this respect purebred forest is better than mixed forest.(5)Evaluating the ecological function of7different forest type, the ecological function of7types forests from large to small in turn is Quercus liaotungensis> Populus davidiana> Robinia pseudoacacia L.> Robinia pseudoacacia L.+Pinus tabulaeformis mixed for est> Pinus tabulaeformis> Robinia pseudoacacia L.+Platycladus orientalis (L.) Franco mixed forest> Platycladus orientalis (L.) Franco..To make sure the forest have a good biodiversity and ecological function, tree species mixed pioneer species should be used in afforestation, planting with herb species and shrub species is also necessary. After that, thinning is effective to make forest gap to promote the succession and species regeneration.