| The spatial pattern reflected the bio-ecological characteristics of the population and the inter-species relationship at the macro level,and revealed the mechanism of how comlunity structure fomiate and regenerate,was a basic structural feature of forest communities,which was important in sustainable forest management.However,forest structure which based on the nearest neighbor,quantified the specific stand state at the micro level,and was more sensible in analysis the subtle structure of the forest,especially the binary distribution analysis of the spatial structure,which was meaningful for promote the optimization of forest spatial structure.And also,adequate update quantity was an important basis for the long-term sustainable development of forests.Seedlings characterized the establishment of regeneration and saplings were the result of competition among seedlings,which survived can grow into saplings.Seedlings and saplings were both important in forest studies,but the relationship between regenation quantity and factors were not yet common.Based on the collected data of 12 plots of broad-leaved mixed forest in the natural secondary forest of Maoershan,wihich included the previously neglected seedlings below 30cm,this study try to explore the structure of the second forest of Maoer Mountain from three aspects,namely spatial pattern,and structure based on nearest neighbor,and quantity of regeneration,by methods of O-ring statistic and counting model,repectively.The results were as follows:(1)With the increase of the height and diameter of the forest trees,the number of dominant tree species of different sizes increased,showed multi-dominant tree species of the stand structure.The most typical plot had regenerations with 2894 saplings and 3337 saplings per hectare,meaninged an unsuficient regeneration satus.(2)The stand and dominant tree species were clustered at the small scale(within 20m),then randomly distributed at the large scale.Seedlings showed aggregated while randomly distributed with growth and development.The seedlings were most affected by the big trees,the young trees are second,and the middle trees and the big trees always showed no significant association at most scales,The relationship between similar individuals were more harmony.The overall pattern of forest stands showed great similarity with the pattern of dominant tree species,the dominant tree species contributed lost to the pattern of the stand.(3)The binary spatial structure contained the content of the one-dimensional spatial structure distribution.When W took a fixed value,the tree proportion increased with Mci and op,and decreased with u·a·CI.When Mci took a fixed value,the tree proportion increased with op,decreased with u·a·CI.The op and u·?·CI showed a linear correlation trend.(4)The difference between the NB model and the ZINB model were not obvious,both had good effects,and the ZIP model was the inferior,and the Poisson model was the worst.The number of seedlings showed no obvious regularity,while the number of saplings was significantly negative associated with the averge DBH and crown of the upper stand.The generation number of hard wood showed negative associate with average DBH of upper stand and positive associate with average tree height of upper stand.The generate sapling number of stand and hard wood decreased with the DBH.The spatial structure index had no significant effect on the interpretation of the number of saplings. |
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