Study On Spatial Structure For Oak Forest Community In Mountain Xiaolongshan

The structure-based forest management being used in this study with regarding main trees of natural oak population in Mountain Xiaolongshan as object of study,we discuss effect of different cutting intensities on forest space structure,and change of spatial distribution and relationship for trees during different periods, in addition, and the competition relationship between dominant trees. During the process of dicussion, the spatial structured parameters as mingling, uniform angle index and neighborhood comparison was applied to talking about how to determine the most appropriate cutting intensity, and the O-ring function to analyse change of spatial distribution and relation, and both ecological niche and competition index were to evaluate competition power of different trees. Thus, the suitable cutting intensity and the best distribution of the whole forest was obtained, and their competition power was also known. Then, we propose some types of advices. Above all, the specific results are as follows:(1) Mingling value in forest of moderate cultivation was the largest, and the stand structure was also in most stable state; cultivation intensity had no obvious effect on neighborhood comparison and spatial distribution pattern of trees. The analyses of competitive relationship between cutting intensity and all stands or each tree species demonstrate that competition index of Quercus wutaishanica trees enlarged as the increase of cultivation, competition change curve of Pinus armandii trees shaped hollow and that of Tilia tuan presented reverse “J”, so spatial forest structure would be optimized and competition capacity be enhanced for using intensity of 20% or30%, furthermore, cutting intensity must be proper and not large.(2) Spatial pattern distribution of forest stand Quercus aliena var.acuteserrata was, as a whole, random over five years. Quercus aliena var.acuteserrata distributed randomly in the upper forest layer, more evenly in the middle and clumped obviously in the lower. The small number of Staphylea holocarpa and Acer davidii led to them with random distribution on most scales and then later, along with time variation, to them with lightly aggregated distribution on small part of scales. For changes of spatial population correlation, there was negative correlation between Staphylea holocarpa and Quercus aliena var.acuteserrata on most scales for competition at the stage of sapling, and independent distribution on small part of scales to the certain stage of growth. The relation between Quercus aliena var.acuteserrata and Acer davidii, and Staphylea holocarpa and Acer davidii kept independent on the whole, but gradually the correlation existed on a small scale. The research indicates that, in different survey time, change of spatial distribution pattern for dominant trees in Quercus aliena var.acuteserrata forest depended strongly on the scale, goodness of fit of the distribution pattern was high, and the forest stand on the whole was random distribution, namely spatial distribution pattern remained largely unchanged in five years; for principal species, the change of distribution pattern of Quercus aliena var.acuteserrata conformed to growth regulation of communities and that of Staphylea holocarpa and Acer davidii was more affected by number of trees; change of forest spatial correlation was connected with population structure and its stage of succession; but for successional process of community, successional change of forest community in five years won’t enough represent successional rule of all forest stand, and the study must be still carried out over a long period.(3) Distribution of diameter class in broad-leaved forest stayed concentrated and that of all trees appeared an inversed J form. The competition relations in a stand were complex and the relationship between diameter of main tree species and its competition index value was presented with power function. The intensity of competition changed gradually from strong to weak when diameter at breast height reached 30 cm, and then if trees of DBH less than 30 cm were cut, spatial forest structure can be optimized. Niche overlap values of each main tree species differed significantly, but its sequential order was unrelated to important value of trees, tree species of niche overlap values ranked from large to small were Lindera obtusiloba,Acer mono,Carpinus turczaninowii Hance,Meliosmacuneifoliavar.glabriuscula,Sorbus alnifolia,Cornus hemsleid Schneid Wanger,Carpinus Turczaninowii,Quercus aliena,Carpinus henryana,Fraxinus and platypoda Oliv. Niche overlap between dominant trees was high, but the niche overlap and their niche breadth had no absolutely positive correlation. Meanwhile, the correlation between treeniche overlap and tree competition intensity was nothing to some degree, because of different life form of tree species.