Study On The Spatial Structure Of The Natural Secondary Forest Of Low Mountains And Hills In Tongling

Three types of natural secondary forests of different years in Tongling Countywere selected as the research object in this paper. In the region the tree samples aresetted, and the sample size ranges from20×20m to30×30m. We use a total stationto measure three-dimensional coordinates(X,Y,Z) of tree species, where X,Y representthe plane rectangular coordinate, and Z represents the elevations. Meanwhile, wekeep detailed records of the species name, diameter, height of each tree,and so on. A5meter wide buffer strip is settled around the sample.The diameter measured is atleast from5cm. Based on the inquisitional data of sampling sites, The diversitynumerical characteristics of the arbors in nature forest stand of three types is analyzedby adopting Shannon-wiener index, evenness index and dominance index. Meanwhile,the mixing, competition, distribution pattern and spatial correlation of three kinds ofnatural forest tree species was analyzed by mingling, neighborhood comparison, andRipley k function. The results show that:(1)Quercus acutissima, which is the dominant tree species in Type I and Type II,its diameter structure is distributed close to normal distribution and inclines to the leftand in type I it swifts more left than the one in Type II, Feature of the stand diameterdistribution was typical evenaged forest character. The diameter structure ofCastanopsis sclerophylla in Type III presents a reverse "J" curve, its feature wasunevenaged forest character.(2) Tree species in three types of nature forests are compared from the followingindexes: Shannon-wiener index: typeⅡ（1.25）＞typeⅠ（1.02）＞type Ⅲ（1.0）;evenness index: typeⅡ（0.7）＞typeⅠ（0.57）＞type Ⅲ（0.35）; ecologicaldominance index: type Ⅰ（0.5）＞typeⅢ（0.48）＞typeⅡ（0.37）。(3)In the investigated spatial scale range，the distribution pattern of three types ofnatural forest dominate tree species switches from colony distribution to random anduniform distributed as the increase of spatial scale. It indicates that aggregation scaleof the dominate specie will gradually become smaller when age is increasing.(4) In type Ⅰ dominant tree species Quercus acutissima and its associated treespecies Cyclobalanopsis glauca and Pinus massoniana shows negative correlation insmall scale,dominant species and associated tree species has a certain competition atthis scale; In type Ⅱ dominant tree species Quercus acutissima has no relevancewith its associated tree species Platycarya strobilacea, there is less competition between two species; In type Ⅲ dominant tree species Castanopsis sclperophyllaand its associated tree species L．henryi and Sassafras tzumu are positive association,there are mutual promotions on the growth.（5）There was not significant association between age-class Ⅳ and the rest of thethree age in three types of natural forest. Age-class Ⅱ and age-class Ⅲ occurredwith a change in different years. in general the shorter for community growth anddevelopment, the age of two level, the more likely it tend to be a positive correlation.(6)Three types of natural forest stand average mixing of type Ⅱ (0.490)>typeⅢ (0.366)>type Ⅰ(0.347),the whole of the stand show weak degrees mixed; averageangle index of type (0.572)> type Ⅱ (0.523)> type Ⅲ(0.512),the whole of the typeⅢand Ⅱ present mission distribution, the whole of the type Ⅰpresent randomdistribution; average neighborhood comparison of type Ⅲ （0.502）>type Ⅱ（0.492）>typeⅠ（0.488）,the whole of the stand present moderate state.