Growth Model And Population Ecological Characteristics In Cyclobalanopsis Gracilis Forest

Cyclobalanopsis gracilis,a species for timber used in subtropical area,distributed in mountainous region of altitude 500-1600m.The growth characteristics,distribution princeple, regeneration princeple and ecological characters in Cyclobalanopsis gracilis forest were investigated and analyzed.The results will provide a basis for management and utilization of Cyclobalanopsis gracilis.The results were as follows:(1) The distribution law of moisture content of tree stem is a significant index,which reflect the biomass,and the measurement is an important foundational work in production practice.Measurement and analysis on the moisture content of stem of Cyclobalanopsis gracilis showed that the relationship between the moisture content of Cyclobalanopsis gracilis and its height of stem was significant,and the rate of moisture content increased as the location on its stem ascent.The height of stem was taken as the independent variable and the corresponding moisture content as a dependent variable when linear regression theory was used to establish mathematical model.The most superior mathematical model:y=1/(2.4253-0.0276x) was selected.(2) Using the stem analysis material of Cyclobalanopsis gracilis to make a fitting contrast among Richards equation,Logistic equation,Logarithmic curve equation,Korf equation as well as quadratic curve equation,an analysis of the relationship between the tree-measuring factors and the age of trees was carded out.The Richards equation was selected as the ptimal growth equation and the growth model of tree diameter at breast height(DBH),h(?)ht,volume was established respectively,thus an analysis and research of the growth law of Cyclobalanopsis gracilis was made.The result showed that the tree DBH and height of the current annual increment arrived at maximum when it was 25a and 22a respectively,while the timber volume current annual increment arrived at the maximum when it was 16a,and mean annual increment at the age of 26a,according to these to conform the age of quantitative maturity and provided a benefit reference for the production and management of Cyclobalanopsis gracilis forest.(3) To research the renewal of Cyclobalanopsis gracilis population in Mangdang Mountain Nature Reserve in Fujian province,the curves of age structures,survival curve, death curve,mortality rate curve and killing value were analyzed by drawing a static life table of Cyclobalanopsis gracilis population.The results showed that more than 90 percent of the individuals were seedlings,and the entire population was in the growing state.In the growth process from the seedling to young tree,with the higher mortality rate of the seedling, meaning the higher choosing intensity of the environmental screen.Few seedlings got across the environmental screen to young tree.The mortality rate was accorded with the killing value in the entire life process of Cyclobalanopsis gracilis population,with four fastigium.(4) Normal distribution,Logarithmic Normal distribution,Weibull distribution,Beta distribution and Gamma distribution were used for forecasting and fitting Cyclobalanopsis gracilis forest diameter structure on basis of analyzing and comparing the data from the 5 plots of Cyclobalanopsis gracilis forest stands.Five diameter structure was tested by X~2 test value.The correlations between the stand H & DBH,and the V & DBH were studied with the regression analysis method.The regression equations which are suitable for different stand were selected.The result showed that the most superior distribution used for forecasting and fitting Cyclobalanopsis gracilis forest diameter structure was Beta distribution.The best equations of the correlations between the stand H & DBH and the V & DBH were selected.(5) The spatial distribution pattern was studied by five aggregate indices(C,I,I_δ,C_A,M~*/(?)) and the equation of I wao,Taylor's model.The result showed that the type of spatial distribution of Cyclobalanopsis gracilis population in the Mangdang Mountain Nature Reserve was aggregate distribution.(6) The logarithmic series distribution model is used to calculate and inspect the species abundance distribution of Cyclobalanopsis gracilis natural forest community in Mangdang Mountain Natural Reserve,and the simulation effect was verified by the critical values of chi—square tests.The results showed that the value of community species diversity exponential and evenness were all high;the community has a complex structure and abundant species.Community species abundance distributed in accord with the logarithmic series distribution model.The species abundance distribution of arbor layer,shrub layer and all woody plants of the main communities in Cyclobanopsis gracilis natural forest all can be well described by logarithmic series distribution model,and which is suggested as a useful method for species abundance characteristics simulation in Cyclobanopsis gracilis natural forest.