Multi-scale analysis on tree diversity pattern in a secondary Populus davidiana-Betula platyhylla forest in Changbai Mountains, northeastern China

Understanding the effects of species on diversity assembly of local community from the perspective of plant population contributes to revealing the effect of interspecific interactions on the community assemblage, which would be likely covered when discussing at the community levels. The effects of specific species on local diversity patterns were studied at different spatial scales. And the relative contributions of diversity accumulators, neutrals and repellers to community diversity assembly were also examined. On the basis of a 5.2 hm2 research plot established in a secondaryPopulus davidiana-Betula platyphylla forest, individual species-area relationship model was used to calculate the ISAR and mISAR curves of 29 tree species. The complete spatial randomness method was used to test the significance of deviation of individual species-area relationship from the neutral patterns. Our results indicated that the effects of different tree species on local community diversity differ at varying spatial scales. Abies nephrolepis, Acer barbinerve, Acer mono, Populus davidiana, Sorbus alnifolia and Tilia amurensis are diversity accumulators in the research plot. Betula platyphylla and Ulmus davidiana var. japonica are diversity repellers. Fraxinus mandshurica, Quercus mongolica, Malus baccata, Syringa reticulata var. mandshurica are neutrals while other tree species are diversity accumulators at small spatial scales. A significant scale-dependent effect was derived from the influences of diversity accumulators, neutrals and repellers on the assembly of community diversity. The largest proportion of diversity accumulators was found in the medium and small scales of 0 -36 m, and they determined the diversity assembly in forest community. In contrast, neutral species shared the highest proportion and dominated the diversity assembly of forest community at larger scales. Therefore, diversity accumulators and neutrals together spatially structured community diversity assembly; however, the relative effects of them depended on the spatial scales of discussed issues.