RESUMO
The spatial distribution and association of populations can reflect succession patterns and its adaptation strategies to the change of environmental factors, with important significance for vegetation restoration, reconstruction, and biodiversity conservation. We used the point-pattern analytical method to examine the spatial distribution and its association of the Loropetalum chinense population in karst hills of Guilin, China, based on field surveys. On the basis of Ripley K function, we used the pair-correlation function statistic derived to explore difference in the distribution patterns.We used Ripley L function to examine the spatial associations among the three diameter classes. The results showed that the diameter class structure of the population exhibited an irregular inverted "J" type, with the small diameter class occupying a large proportion, indicating an increased population structure with good regeneration capability. The individuals of the three diameter classes had a clumped distribution at the small scale. With the increases of spatial scales, the aggregation intensity gradually weakened and tended to be randomly distributed. There was an independent spatial association between individuals among the three diameter classes at small scale. As the scale increased, the spatial association between individuals with different diameter classes became positive or negative association. The greater the difference in diameter class of L. chinense population, the weaker their spatial correlation was, which might gradually turn into negative association. Our findings contributed to a clearer understanding of the ecological strategies and scale-dependent cha-racteristics of species coexistence and underlying mechanisms during the growth and development of L. chinense population in karst hills of Guilin, providing reference for the restoration, reconstruction, protection and management of forest in karst hills.
Assuntos
Ecossistema , Hamamelidaceae/fisiologia , Árvores , Biodiversidade , China , FlorestasRESUMO
Analyzing the interspecific association of major tree populations of Cyclobalanopsis glauca community and revealing the coexistence among the populations would provide theoretical basis for the restoration and reconstruction, management and biodiversity conservation of Karst hills in Gui-lin. Based on field survey, the χ2 test, association coefficient (AC), co-occurrence percentage (PC), Ochiai index (OI), Dice index (DI), and principal component analysis (PCA) were used to investigate the interspecific association and eco-taxonomic classification of the top 22 tree species in Cyclobalanopsis glauca community in Guilin Karst Rocky Mountains. The results showed that there was a significant positive correlation between the interspecific associations of the 22 main tree populations, indicating that this community was in a stable climax stage. The results of χ2 test showed that 108 pairs of 231 species pairs had positive associations, 115 species pairs had negative associations, 8 species pairs were unrelated, with the positive and negative linkage ratio being 93.9%. The vast majority of species pairs showed no significant association. The strong indepen-dence between species might be mainly caused by the higher habitat heterogeneity of the Karst hills in Guilin which led to the differentiation of niches between species. The results of AC, PC, OI and DI were basically consistent with that of χ2 test, indicating that the analysis of interspecific association should be based on the χ2 test and supplemented by AC, PC, OI and DI indices. According to the PCA and evaluation of interspecific relationships, the 22 main tree species were divided into three ecological groups. The species within each group had the same adaptability to habitat but different ecological requirements.