Study On The Characteristics And Ecological Functions Of The Main Forest Communities In The Beijing-Tianjin-Hebei Ecological Conservation Area In China

To reveal the basic characteristics of the main forest communities and the relationships between their ecological functions and community characteristics in the Beijing-Tianjin-Hebei Ecological Conservation Area is an important basis for carrying out sustainable forest management,and is of great significance for improving the ecological functions of the forest in the Beijing-Tianjin-Hebei Ecological Conservation Area.Focusing on the main types of forest communities in the Beijing-Tianjin-Hebei ecological conservation area,and based on the data of Chinese Forest Ecosystem Research Network and sample plot inventory,we quantitatively analyzed the ecological characteristics of species composition,biodiversity,niche etc.and the distribution patterns of plant biomass in different forest communities of this conservation area by the theories and methods of quantitative ecology.Upon which,the ecosystem services of different forest communities,such as water conservation,soil conservation,carbon fixation and oxygen release,SO2 absorption,nitrogen oxide absorption,dust retention capacity,etc.were studied.The main conclusions are as follows:1.The characteristics of plant diversity of main forest communities(1)The consistent performance of the main forest communities is that the species richness and species evenness of the shrub layers were lower than those of herb layers.(2)There are significant differences of heterogeneity among the main forest communities,and the performances of heterogeneity are differ between shrub layer and herb layer.The dissimilarity coefficients of the four couplings of Larix principis-rupprechtii and Pinus tabuliformis-Quercus mongolica fisch mixed forest(AF),Betula platyphylla and Pinus tabuliformis-Quercus mongolica fisch mixed forest(CF),Quercus mongolica fisch and Pinus tabuliformis-Quercus mongolica fisch mixed forest(DF),Pinus tabuliformis-Quercus mongolica fisch mixed forest and complex forest(FH)were the highest.The Quercus mongolica fisch forest and complex forest(DH)had the lowest dissimilarity coefficients;as to the herb layer,the coupling of Larix gmelinii-Betula platyphylla mixed forest and complex forest(EH)had the highest dissimilarity coefficient,the coupling of Larix principis-rupprechtii and the Larix gmelinii-Betula platyphylla mixed forest(AE)had the lowest dissimilarity coefficient.(3)There are obvious connectivities among the 14 species of main trees and the 15 species of main shrubs with obviously positive couplings and negative couplings.Among the following four couplings,the highest Chi-square is in the coupling of Picea wilsonii and Picea meyeri,the lowest Chi-squares are in the coupling of Pinus tabulaeformis and Picea meyeri,Pinus sylvestris and Picea meyeri,Pinus sylvestris and Picea wilsonii;among the shrub couplings,the highest Chi-square is in the coupling of Ziziphus jujube and Spiraea trilobata,the lowest Chi-square is in the coupling of Grewia biloba and Lespedeza bicolor.2.There are many obvious differences for the niche widths of the main tree and shrub species and significant differences for the niche overlap among the tree species in the main forest communities.The niche widths of coniferous tree species are larger than those of Broad-leaved except Quercus mongolica;the niche width of Spiraea trilobata is the largest and that of Corylus heterophylla is the smallest among the shrub species.The niche overlap of the coupling of Larix principis-rupprechtii and Betula platyphylla is the largest and that of Larix principis-rupprechtii and Malus baccata is the smallest among the tree species;the niche overlap of the coupling of Rhamnus davurica and Lespedeza bicolor is the largest and that of Rhamnus arguta and Grewia biloba is the smallest among the shrub species.3.The distribution of biomass in different forest communities is similar,but there are also differences among different forest types.The general rule is that the biomass proportions of organs is in the order of trunk > branch > root > leaf.However,the biomass proportions of organs of Platycladus orientalis and Pinus tabulaeformis forests range in order of trunk >root > branch > leaf.The change rules of the biomass distributions of forest communities are different among different species.The trunk biomass is always the maximum in the whole growth process,while the biomasses of branch,leaf and root show a law of periodically alternate increase and decrease.4.The water conservation functionof the main forest communities There are obvious differences in litter and soil hydrological characteristic among different forest communities,but the trends of variation of litter hydrological characteristics are highly consistent with those of soil.The litter thickness,reserves,water holding capacity and interception capacity of coniferous forest are higher than those of broad-leaved or mixed forests;litter water holding capacity of coniferous,broad-leaved and mixed forests show logarithmic relations with soaking time(Q = alnt + b),water absorbing rate shows exponential relation with soaking time(V = K tn);soil water holding capacity and interception capacity of coniferous forests are higher than that of broad-leaved forests,the infiltration rate of coniferous forest,broad-leaved forest and mixed forest show power relations with infiltration time(Y = A.XB).The order of soil infiltration capacities is broad-leaved mixed forest > coniferous and broad-leaved mixed forest > coniferous mixed forest.The abilities of coniferous forests are obviously higher than broad-leaved mixed forests in the aspects of water conservation,absorption of so2,absorption of fluoride and dust retention.Whereas,the abilities of broad-leaved mixed forests are obviously higher than coniferous forests in the aspects of soil conservation and carbon fixation and oxygen release.In general,the overall ecological functions of the coniferous forest communities are higher than those of broad-leaved.