Studies On Species Biodiversity And Biomass At Quercus Aliena Var.acutidentata Community About Different Age Classes In Baotianman Nature Reserve

In this paper, biodiversity, biomass, and soil microbial biomass carbon of Quercus aliena var.acutidentata community at different age groups (young growth, half-mature, mature and over-mature forest) in Baotianman National Natural Reserve were investigated using sample plot . The results were as follows:1) The community structures of plantations at different age groups were divided into tree layers, arbor, shrub and herb layers. The canopy density of communities at different age groups (young growth, half-mature(ⅠandⅡ) , mature and over-mature forest) were: 75%、83%、80%、90%、93% respectively. There were 21 types of plant species in the young growth forest (7 arbor species, 6 shrub species and 8 herb species), 34 types of plant species in the half-mature forestⅠ(9 arbor species,11 shrub species and 14 herb species), 30 types of plant species in the mature forestⅡ(9 arbor species, 9 shrub species and 12 herb species),17 types of plant species in the mature forest (5 arbor species, 6 shrub species and 6 herb species),17 types of plant species in the over mature forest (5 arbor species, 6 shrub species and 6 herb species). And then based on the sample-plot investgation data, the regression model between the height and diameter of Quercus aliena var.acutidentata were established.2) The species diversity index studies in Quercus aliena var.acutidentata community reflected the almost same trend. The species diversity index displayed the young growth forest index were the lowest, but gradually increased with the growth of tree age, the half-mature forest index was the highest, however, the species diversity index of the mature and over-mature forest were gradually decreased. Species evenness index revealed the young growth forest index were 0.8321, the mature forest indexⅠandⅡhad an gradual increase, and reached 0.8488 and 0.8877 respectively, the mature forest index were 0.9473, the over mature forest were 0.9158. The species diversity index at different age groups showed no obvious change relationship between different growth forms, The index of arbor layer was the highest in the mature forest and over-mature forest, the index of shrub layer was higher in the half-mature forest, The index of herb layer was higher in the young growth and half-mature forest.3 ) The biomass community relationship revealed that the biomass of half-mature forest was the highest at different age groups and was 280.68 t·hm-2, the biomass of mature forest was the second highest and was 199.450 t·hm-2, while the biomasses of young growth and overmature forest were 134.463 t·hm-2 and 132.816 t·hm-2 respectively. The biomass percentage of arbor layer was the largest ans was over 88%, the bush layer accounted for 2.24%~6.51% of total biomass, biomass percentage of litter fall and rootlet was 1.5%~4.78%, and the herb layer was the lowest and was less than 0.5%.4)Biomass distribution among individual plant components ranked in the order: tree trunk > tree root and tree branch > tree trunk skin and tree leaves. The ratio of underground biomass to aboveground biomass was 1:4. According to the measured data of individual plant components in arborous layer, the regression models of total biomass of individual plant species, tree trunk biomass, tree trunk skin biomass, tree branch biomass, tree leaf biomass, and tree root biomass, as well as diameter at breast height and tree height were established.5)The biomass of rootlets at different age classes was decreased with increasing depth of soil, the rootlet biomass at soil layer of 0～20 cm depth accounted for more than 80% of the total biomass, and its vertical distribution in the soil conforms to y=aebx exponential curve regression distribution.6)The soil microbial biomass carbon was decreased with the increasing of age class and soil depth. The microbial biomass carbon content of young forest was the highest and was 455.868 g·kg-1, and then was that of half-mature forest with an average of 376.211 g·kg-1, and the soil microbial biomass carbon of mature forest and overmature forest were 294.324 g·kg-1 and 281.590 g·kg-1 respectively.