| The large-scale forest dynamics plot(FDP)has been an important platform for researches in community constructions.The method based on forest biodiversity monitoring in FDP provides accurate and reliable data for people to understand the mechanisms of species coexistence,and to understand the changes in biodiversity and its influence.Stand spatial structure parameters based on the relationship of neighborhood trees like uniform angle index(Wi),mingling(Mi)and dominance(Ui)are widely used both internationally and domestically in the studies of stand spatial structure analysis,competition among trees,calculation of dominance,species diversity measurement and structure recovery and reconstruction as well as optimization adjustment,this has yielded positive results.However,in the large-scale forest dynamics plot,application analysis of forest spatial structure did not get enough attention.Therefore,this research will use forest spatial structure method(spatial structure parameters)to analyse spatial structure characteristics dynamic changes of 1982-2010 years(seven complete censuses over 30 years)in the 50-ha forest dynamic plot of Barro Colorado Island(BCI),Panama.Furthermore,we discussed the application of spatial structure parameters in the FDP and the further improvement and validation of spatial structure parameter theory and the prospect of forest sptial structure accurate analysis and guidance of forest management in our country in near future.Through the analysis,the dissertation made the following main conclusions:(1)The univariate distribution characteristics and bivariate distribution characteristics of the spatial structure of alive trees(DBH?5cm)and corresponding above ground biomass(agb)of the 1-7 census of BCI plot were analyzed,the results show that,the 1-7 census of BCI plot spatial structure pattern were random distribution,most of the trees in intensity and high intensity mixed state,and the maximum number of trees in high intensity mixed dominant.About 40% individual trees were in random distribution and intensity mixed state.The above ground biomass of BCI plots showed that the minority(20%)of the individual trees contribution the majority(80%)above ground biomass of the plot.(2)The forest spatial structure of canopy trees and understory trees of 1-7 census in BCI plot and the corresponding above ground biomass distribution characteristics were analyzed,the results showed that,the spatial structure of the canopy was randomly distributed,more than 77% of canopy trees were in intensely mixed state,and most of trees belonging to the random distribution and absolute advangtage state.At the random distribution level(Uniform angle index=0.50),above ground biomass of canopy has the maximum frequency,accounted for more than half of the canopy agb.In intensity mingling and high intensity mingling grade(Mingling=0.75 to 1),almost the entire agb of the forest concentrated in this two grade.A few trees in the canopy(especially dominant trees)contributed to nearly 60% canopy agb.About 57% understory individuals belong to random distribution,a uniform distribution and non-uniform distribution only accounted for more than 3% individuals in understory.90% trees in the understory were in extremely intensity mingling and intensity mingling state,nearest neighbors belong to conspecific around the reference tree basically does not exist.The trees were mostly in absolute disadvantage random distribution in understory.90% agb concentrated in the trees at mixed intensity and high intensity grade.The agb decreased sharply with increasing dominance levels,20% of the trees in understory were combinationed 50% of agb distribution.The agb in understory is mainly concentrated in the extremely intensity mingling and intensity mingling state,which contributied 40% above ground biomass.Moreover,the absolute advantage trees in the random distribution contributed 40% of the above ground biomass.(3)Three quantitative indexes based on differentiation of diameter distribution-the tree differentiation of Simpson(DT),the tree differentiation of Shannon(HT)and the mean of tree differentiation(?T)were analyzed in 1-7 survey of alive trees in BCI plot,and the spatial structure of top 20 spatial dominance species were analyzed at the same time,the results show that,the 3 indexes in the canopy sptial structure can be more consistent for judging tree size diversity,but on the whole and the understory levels the many results not unified.The overall diversity index showed a unified trend of whole plot>canopy>understory.The each survey results of ?T were different,which can reflect the subtle differences in the survey,this slight difference has higher research value and significance impacts in the tropical forests of extremely high diversity.The spatial structure pattern of the top 20 spatial dominance species(Dsp)in the 1-7 BCI plot survey were examined,the results showed that,most of dominant species were in spatial aggregated distribution.This species in BCI mainly concentrated in Bombacaceae,Euphorbiaceae,Fabaceae,Moraceae,Meliaceae,Myristicaceae,Bignoniaceae,Rubiaceae,Apocynaceae,Annonaceae,Lauraceae,and Rutaceae.The Quararibea asterolepis is the highest space dominance species,followed by Hura crepitans. |
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