| This paper focuses on Ulmus lamellosa, a rare and endangeredendemic plant of China. Based on the field investigation, Ulmuslamellosa population and community characteristics for TaiyueMountain were studied systematically and comprehensively byusing quantitative ecology methods. The community structurecharacteristics, distributional pattern, interspecific segregation,intraspecific and interspecific competition were studied, which arethe sientific basis for the efficient conservation of Ulmus lamellosa.The results show that:（1）There were abundant matured, but few young individuals,while the age structure of Ulmus lamellosa populations was stable;mortality rate and vanishing rate is almost the same change trend,all peak level appeared in age-class10, and the survival curve of thepopulations was Deevey type Ⅱ; Four survival functional curvesshowed that the Ulmus lamellosa populations grew stably at youngstage, decreased very quickly at mature stage and declined at old stage. Time sequence prediction models for different populationsafter2a,5a years indicated that the numbers of old individualswould increase in the beginning and finally decrease, giving rise todifficulties for maintenance of these populations if we don’t takeappropriate tending management measures to create conditions forseeding update.（2）By the method of point pattern analysis, this paper studiedthe spatial patterns of different age-class individuals in the Ulmuslamellosa forest in Taiyue mountain, and the spatial associationbetween the individuals. The results of showed that there existedgreater differences in the densities of different age-class Ulmuslamellosa individauls, e.g., age-class1had the density of6plantsper hectare, while age-class3had the density of493plants perhectare. The spatial patterns of different age-class individauls andthe spatial association between the individauls had a closerelationship with the spatial scale. The individuals of all age-classtended to disperse randomly within a small-scale. The pattern wasclumped with the increasing of scale. when the scale reaches acertain degree is also tend to be disperse randomly; The individualsof all age-class spatial correlation is essentially a positivecorrelation. This relation is conducive for Ulmus lamellosapopulations to make full use of resources, with the guarantee of the population survival and development.The technique of point patternanalysis is effective and easy to use method in species patternstudy. Its results are more consistent to the reality, especially forcommunity structure.（3）We analyzed interspecific segregation by using ArcView GISsoftware and the nearest neighbor method, interspecificsegregation was studied with an N×N nearest-neighbor contingencytable, a2×2nearest-neighbor contingency sub-table, and Pieloucoefficient of segregation(S). According to their adapt ability to theenvironment and relationships between plants and environment,assisting in principal components analysis, the14species dividedinto three ecological species groups (ESG). The result showed：most of the species pairs are randomly segregated (74.73%), somespecies pairs are positively segregated (23.07%), and only a fewspecies pairs are negatively segregated (2.2%). There are somedifferences among different species in the interspecificsegregation of all species. The Ulmus lamellosa in the communitiestended to be randomly segregated with other species. Positivesegregation appeared among dominant species, probably becauseof their stronger competitive vigor. For example, Carpinus cordata,Acer elegantulum and Populus davidiana are tended to be positivelysegregated each other. Negative segregation appeared among companion species in the communities, such as Carpinusturczaninowii, Acer grosser, Koelreuteria paniculata and Acerginnala. The interspecific segregation is related to theheterogeneity in the communities, in that aggregation often occursbetween two species which have different habitat requirements;while the segregation often appears between two species whichhave same or similar environmentally requirements. In Ulmuslamellosa communities, the14species divided into three ecologicalspecies groups. On the whole, the14species we studiedoverlapped in distribution and were characterized by overallnon-segregation. The interspecific relationship based on differentspecies are adapted and their biological requirements may be oneof the mechanisms which allow these species to stably coexist inthe Ulmus lamellosa community of the Taiyue Mountain in Shanxi.（4）We analyzed competition intensity by using the competitionindex (CI). The result showed that the intraspecific competitionintensity of Ulmus lamellosa decreased gradually with increasingtree diameter. In the community, there were many other species,but the number of these species was fewer than that of Ulmuslamellosa. As a result, the interspecific competition intensity ofU.lamellosa was relatively weaker than that of intraspecific. Theorder of competition intensity was Ulmus lamellosa-Ulmus lamellosa>Carpinus cordata-Ulmus lamellosa>Acer elegantulum-Ulmus lamellosa>other species-Ulmus lamellosa. The relationbetween competition intensity and individual growth of objectivetree followed closely the following equation CI=AD-B, and thechanging of competition intensity and individual was very smallwhen the diameter of the objective tree reached25cm. The modelcan simulate and predict the intraspecific and interspecificcompetition efficiently. |
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