Studies On The Population Ecology Of Schima Superba

Population ecology of Schima superba community and its community ecological characteristics in different types communities in Wanmulin nature reserve in Fujian Province were analyzed and discussed by quantitative statistic method in this paper, including size structure, spatial distribution pattern, life process of the population, the growth of tree basal area of S. superba population, the crown structure of S. superba sapling, as well as studies on the niche characteristics of 11 main tree population in S. superba forests, the features of its community and the relationship between species number and area The results indicated as follows:(1) By applying the method of "spatial sequence instead of temporal change", size structures of S. superba population in five sites took on three kinds of forms (growing, stable and adult) with diameter as the indices of individual size, being not senescent form. Through comparing with the structure and dynamics of S. superba populations in Wuyi mounain, it showed that S. superba population had the characteristic of climax pioneer species, which was different from not only pioneer species such as Pinus massoniana ect. , and shade-intolerant tree species such as Liquidamber formosana ect. , but shade-tolerant tree species such as the Cinnamomum and the Castanopsis ect. S. superba tree is in the middle position of the forest succession stages.(2) The spatial distribution pattern and dynamics of S. superba population were presented using aggregate indices, Iwao's equation and Taylor's model in this paper, then the causes of evolved pattern was analyzed. The results indicated that the distribution patterns of seedling were all clumped in every community. With the succession going, the trend of aggregated patterns became more intensity. This patterns were consistant with the ecological and biological adaptive characteristics of S. superba population.(3 ) Time-specific life table of S. superba population was established based on diameter class, which revealed that seedlings were abundant relatively and structure of the population was the type ascending in the primary stage and stable in the late stage. The survival curve belonged to the typical type of Deevey-III with the high mortality in the earliness and the survival values fluctuating not large in the late stage. In the process of development of the population, there were three death peaks. The morality curve was the same as the killing power curve, that was to say, the killing power arrived to peak when the mortality was the most.Survivability of the population dropped down monotonously, and accumulative mortality rose up correspondently with increment of the age class, and varying extent was large in the earliness and small in the late stage, as reflected survival and dead states of the population on the given age classes. Death density function curve displayed the character of descent in the earliness and stabilization in the late stage with the concave point in the third age class. And the curve forms of danger scale function and mortality function were coincident.The results of spectral analysis showed that the characteristic of quantitative fluctuation of S. superba population was multi-harmonic superposition with minor cycle in the major cycle.Influences of these cycles varied and depressed with diminishment of cycle, effect of superior wave was the most prominent with obvious major cycle, and there existed more prominent wave of minor cycle at the same time. The wave of minor cycle was maybe correlative with the effect of the environmental sieve in the seedling period.(4) In this paper, Hong-Logistic model was proposed to approach the growth of tree basal area of S. superba population. The method of modified model simplex was applied to optimize the parameters of model, and the fitting results showed that Hong-Logistic model was suitable to the actual growth trend of S. superba population, and the highest growth rate of basal area was between the forth and the fifth age class, namely the phase when breast diameter was 32.5~42.5cm.(5) In this paper, the crown structure of S. superba sapling, e. g. the shape of crown, and the distribution of branch and leaf were studied. It was shown that the crown structure of the saplings was modified plastically in response to different light conditions. The samplings crown grew from broader to smaller with the increasing of light level. The samplings branches were the shortest under high light condition. Branches growed horizontally or upward under adequate shade condition. And under-canopy environment, the differentiation and length of branches was promoted intensely. The leaf densities of the samplings increased with the decrease of light level. With the decrease of light level, the first order branches decreased, whereas the differentiation of the first order branches of the saplings was promoted, and the second and the third branches tended to gather on higher stratum as well.(6) In the paper, the niche characteristics of 11 main tree population in S. superba forests, have been analyzed by quantitative mehod at the natural reserve of Wanmulin. The niche breadth, niche proportional similarity and niche overlap of main tree populations in S. superba forests were measured by taking community composition types as one-dimension resource states, and important value as the resource state descriptor of niche. The results indicated that S. superba had higher niche breadth value and would sustain stablity for a long time; all the dominant populations showed some adaptation to the community enviroment. In some degree, this results showed the succession tendency of the ecological system of the forests. The results would offer scientific theories for reserving, community structure and dynamic prediction of S. superba forests.(7) Schima superba forest is one of the main forest types in Wanmulin Nature Reserve. The study on the features of its community showed that the community is dominated by Theaceae and Fagaceae families and its dominant trees are Schima superba, Pinus massoniana, Castanopsis fabri. And with the succession of the community, the important value of S. superba became more largerer firstly, and then became smaller.(8) Both natural forest of S. superba and the plantation of S. superba were abundant with community species composition. In the paper the plantation of S. superba was compared with the natural S. superba forest in species composition, which showed that the species composition and community structure of the plantation became more complicated after some certain time's recovering, though it was affected by men. And the plantation and the natural forest of S.