Community Characterristic Of Pinus Tableaformis Forests In The Ziwuling Mountains

The forests in the Ziwuling Mountains is the most complete natural secondary forest in the loss platau region in northwest China. The special forest landscape was significant to ecological balance.Pinus tablaeformis forest was widely distributed as one of the dominant tree.We studied on Pinus tablaeformis community in Lianjiabian and Zhongwan in the Ziwuling Mountains. Based on the community survey data of 25 typical polts the structure characteristic of population and community ,quantity charecter,distributuion,interspecific relationship,niche and speciese diversity had been studied. The results were as follow:1. The Pinus tablaeformis forest was classified 6 associations groups and ordinated according to the difference of dominant species on shrub layer. They werePinus taleaformis-Cotoneaster multiflorus+ Quercus wutaishanica ; Pinus taleaformis -Cotoneaster acutifolius; Pinus taleaformis-Quercus wutaishanica+Malus baccata; Pinus taleaformis - Quercus wutaishanica ; Pinus taleaformis -Swida bretschneideri; Pinus taleaformis -Ulmus davidiana. Totally 6 associations groups were further classified into12 associations based on speicies composition of herb layer.2. Based on DBH, the population of Pinus taleaformis classified intoincreased population,steady population and declined population.The static life table and survival curve were drawed. The survival curve indicated the early-stage seedling of Pinus taleaformis were rich and belonged to increased population.3. The distribution of all 7 diameter classes were aggregative pattern in 25 plots. With the tree diameter increased, the trend of aggregative pattern decreased.It indicated the distribution of Pinus taleaformis population transited from aggreasive pattern to random pattern with time varying.4. 6 aggregasive indice were used to analyze the distribution of 13 more important tree species. It showed the distribution pattern of the most populations under Pinus tablaeformis forests was aggregative pattern but Quercus wutaishanica was even pattern.5. Association analysis indicated that most of population associations were not significant. However, the connection between Quercus wutaishanica and the other species showed the dramatic positive or negative relationship. It indicated the Quercus wutaishanica population was on the stage of competeion and spreading under canopy of Pinus tablaeformis forests.6. The niche analysis of shrub in Pinus tablaeformis forest showed that the Quercus wutaishanica, Cotoneaster acutifolius, Swida bretschneideri and Smilax stans had higher IV value and wider niche breadth.They were dominant tree species7. Niche breadth of most tree species range in median and niche overlap was less than 0.045. The similarity of Quercus wutaishanica was higher to niche-wide tree species than niche-narrow one. The range was from0.029 to 0.6281. The niche breadth of Pinus tablaeformis seedling was low, which indictated it's not dominant8. 55 tree species were found in shrub layer and 15 herbs in herb layer.The species diversity in herb layer was lower than in shurb layer, but higher than in tree layer in Pinus tablaeformis forests.