Spatial Pattern And Interspecific Associations Of Main Species In A Pinus Tabulaeformis Forest In Heilihe

The spatial pattern and spatial association and monthly changes of species diversity and interspecific associations of herbaceous layer were studied in a Pinus tabulaeformis forest located in Chifeng.The objective of the study was to obtain a better understanding of the structure of main trees and the successional dynamics of herbaceous species in that forest.The results of the study should provide a theory basis relating to maintain the natural structure and function and accelerated restoration of degenerated ecological system of Pinus tabulaeformis forests. According to O-ring statistics,the main trees of Pinus tabulaeformis forest were clumped at small scales,but randomly distributed at big scales. The saplings and the small trees of Pinus tabulaeformis showed an aggregated distribution at small scales, but the big trees showed a regular distribution at small scales,all the three trees showed random distribution at big scales.Spatial association among main trees were negative at small scales,positive at big scales. Spatial patterns of main species in shrub layer were different in scales from Om to 50m.As scales changed, the patterns were different.Their spatial patterns were aggregated distribution at small scales,but when the scales increased, they showed random distribution.Spatial association between main species in shrub layer were more negative and independent of each other,few were positive.Up to 41 herbaceous species, which can be categorized into 21 families and 38 genera, were investigated in our research. Interspecific association analysis of herb species showed that the ratios of positive to negative associations were 0.759,0.900,1.043 and 0.484 in our investigation period (from June to September). The number of species pairs with negative association was larger than that with positive associations in June, July and September, but smaller in August.The interspecific associations and the association strength of species pairs were differences in different periods.The overall association among herb plants was positive in our investigation period(from June to September).The overall association strengt herbaceous species was highest in August, lowest in June.The overall association strength among herbaceous species gradually increased from June to August, but decreased from August to September.