In Analyzing Structure Of Cyclobalanopsis Elevaticostata Natural Forest Stands

The main object of this paper is to find out the current problem of the population development by systemic studies on Cyclobalanopsis elevaticostata natural forest which is rare and native broadleaf tree species. This paper use statistic method to thoroughly study the application of population structure, natural regeneration, spatial distribution pattern, Sampling Technique of Population, diameter structure law, age composition law, index of spatial pattern, competition relationship among species in forest and parameter of structure on cutting simulation, in order to fill the gaps on study of Cyclobalanopsis elevaticostata forest structure.According for guiding plantation construction and low production forest improvement, increasing variety of mixed species, and improving integrated status of stand structure in Fujian Province. The main conclusions are as follows:⑴Frequency test in Cyclobalanopsis elevaticostata population indicated all of the following distribution types accorded to more rate: Poisson distribution accorded to 70%, negative binomial distribution accorded to 90%, The method of moments negative binomial distribution accorded to 65%, Composite Poisson distribution accorded to 85%, Poisson-Binomial distribution accorded to 65%, Neyman(A) accorded to 70%, Neyman(N)accorded to 70%. The result of testing mathematic model indicated the population belonged to aggregated distribution in most sample plots, in which the individuals do not evenly distribute and frequently congregated into clusters, groups and blocks.⑵We found the most Cyclobalanopsis elevaticostata population took the aggregation distribution, and a few uniform distribution in sample plot by analyzing spatial distribution pattern, however, we found the 20 populations took random distribution by testing the diffusion coefficient C and diffusion index Iδ. Hereby, we thought the distribution pattern of Cyclobalanopsis elevaticostata population in the critical status between random and uniform distributions, but showed random distribution on the whole. Populations taking aggregation distribution had stronger adaptability to environment, steady population, and could keep a certain number individuals. At present, Cyclobalanopsis elevaticostata is a relative steady community.⑶At the condition of sampling error permit, we should extract more samples in low density plots, but fewer samples in high density plots, that is sampling amount should be decreased with increasing of average density. In the same density plots, sample numbers should decrease with increasing of sampling error permit. In field investigations, we can use Table (5-1) for reference to choose the most suitable academic sampling amount. In this study, the average population density of all the sample plots is 0.2~2stems/25m2, so we should extract 221 plots with 25 m2at least. Actually this study extract 500 plots which can satisfied the precision, so the conclusion of Cyclobalanopsis elevaticostata population belonged to aggregation distributions is credible.⑷Bying researching the diameter distribution structure of the natural Cyclobalanopsis elevaticostata stands, simulated and predicted the changes of the numbers and accumulation in various diameter-stages, played an important role in determination of tree growth ,volume calculations ,and so on, which will develop the forestry management level.⑸According to the static life stable and the survival analysis functions value of the Cyclobalanopsis elevaticostata population, it was the rare and endangered plants which had an basically similar trend in the rate of mortality and hazard , both of monotone increasing, but the rate of its survival was monotonic declining,the range of its increase and decrease in perior time was higher than latter time .But the range of decrease in latter time was flatted, expressed the higher rate of mortality in the young Cyclobalanopsis elevaticostata population ,We could further to see that the numbers of individual had an fluctuation in the forth age classes between the rate of mortality and hazard, the rate of mortality has an range form 50.4% to 82.4%, the rate of hazard has an range form 0.081% to 0.162%,while both appeared the the maximum.Expressed the death of the peak appear in the forth age classes , meanwhile it deduced a lot of plants dead in the forth age classes, which led to the rapid decrease in the numbers of indiviudl plants .The estimated value in four funtions expressed that the Cyclobalanopsis elevaticostata , rare and endangered plants,had the character with an increasing in the previous time and stabilitied in the latter time .⑹According to the analysis of aggregation index R, in the each standrad field: R<1,so the trees took on aggregated distribution ,the R amendments value of the standrads from NO. 2 to 9 were all less than 1,which indicated that the trees were aggregated distribution.The amendments value of R in the NO.1 standrad field was 0.97,close to 1, which expressed that the trend of forest was random distribution .The analysis of distribution frequency in distance of recently neighborhood showed that the majority standrad fields were high degree of aggregation.If the distance of trees was becoming smaller, the competition in individuals was stonger, and the result of competition was the natural thinning,which made the distance of individuals larger to alleviate the pressure of competition,and to sustain the stand in a relatively stable.⑺This lecture also used the three parameters of the spatial structure, incluing the mingling, diversity mingling ,differentiation and neighborhood comparison ,to describe the three fields of the spatial structure of the natural Cyclobalanopsis elevaticostata satnds, relatively interspecific, the distribution in the level direction and individual size included.The study on the spitial structure of the natural Cyclobalanopsis elevaticostata satnds considered each tree as the observed object, and analysised the structure state of the stand in the basic of optimum structure unit. Expressed the state of mingling and aggregation intraspecific and interspecific in the level direction,which supportted more distribution informations about the spatial structure parameters for the uneven-aged,minglings and double-layers nartrual forests .The research of spatial structure was an expands for the stands structure and the spatial pattern, and the organic intergation of parameters expresseded the spatial structure could be to completely express the spaital structure information of the stands,to support the theory and skill for the operators.