Multi-scale analysis on spatial patterns and tree species diversity in different forest types in Changbai Mountains, northeastern China

So far, the effects of spatial distribution of tree species on the community diversity patterns are not well known yet. In this study, the effects of tree species on local diversity patterns were validated at tree population level. Data from three 5.2 hm2 sample plots, a conifer and broadleaf mixed forest, a Tilia- Korean pine forest and a spruce-fir forest in Changbai Mountains were used for analysis. Ripley's K function was used to examine the spatial distribution of tree species. Our result revealed that: 1) most of studied species were aggregated at the small scales in three research plots. Acer barbinerve, Acer mono and Quercus mongolica were distributed randomly or uniformly at the large spatial scales ( 30 m) in the conifer-broadleaf mixed forest. The spatial scales had little effect on the distribution pattern of the Tilia- Korean pine forest and the spruce-fir forest, and the spatial patterns were almost the same at different spatial scales; 2) at species level, the same tree species had different effects on diversity patterns in different forests. However, at community level, the same pattern of diversity assemblage was observed in the conifer-broadleaf mixed forest, the Tilia-Korean pine forest and the spruce-fir forest. In general, the proportion of diversity accumulators decreased while that of diversity neutrals increased with increasing spatial scales. The diversity accumulators played leading role in community assemblage at the small and medium scales. However, diversity neutrals determined the pattern of community diversity at larger spatial scales; 3) there was no obvious correlation between spatial distribution and diversity maintenance for most of tree species. Meanwhile, for some coniferous species such as Abies nephrolepis, Pinus koraiensis and Picea asperata, the larger range of spatial scales they were aggregated, the larger range of spatial scales they acted as repellers and neutrals. We suggest that the forming and maintaining mechanism of community diversity should be studied from the point of species aggregation effects in the future.