Determinants of species abundance for eastern North American trees
Article first published online: 25 MAR 2014
© 2014 John Wiley & Sons Ltd
Global Ecology and Biogeography
Volume 23, Issue 8, pages 903–911, August 2014
How to Cite
Xing, D., Swenson, N. G., Weiser, M. D. and Hao, Z. (2014), Determinants of species abundance for eastern North American trees. Global Ecology and Biogeography, 23: 903–911. doi: 10.1111/geb.12167
- Issue published online: 4 JUL 2014
- Article first published online: 25 MAR 2014
- National Natural Science Foundation of China. Grant Numbers: 31011120470, 312111072
- NSF Macrosystem Biology. Grant Number: 1065844
- Dispersal limitation;
- environmental filtering;
- functional traits;
- maximum entropy;
- plant geography;
- species relative abundance
We aimed to quantify the relative contributions of trait-based selection and the flow of individuals across space created by differences in species abundance, i.e. mass effects, in determining local-scale species relative abundance (SRA) at 0.07 ha, 1° grid cell and subregion grains.
The eastern USA.
We coupled a maximum entropy model (MaxEnt) with nine species-specific plant traits and a continental-scale forest inventory dataset to perform our analyses. Mass effects were estimated using the next grain size up as the metacommunity (or the eastern USA at the subregion grain, and also at the 1° grid cell grain in a fourth analysis). Permutation tests were conducted to test the significance of trait constraints. The Kullback–Leibler divergence index was used to decompose the information content in each assemblage SRA.
Trait constraints were significant in predicting community structures at coarse scales, but were largely not significant at fine or medium scales. At the 0.07 ha grain little of the variation in local SRA can be explained by either trait constraints or a regional SRA. At the 1° grain c. 61% of the variation could be accounted for by a regional SRA represented by subregions. At the subregion grain c. 74% of the variation could be accounted for by trait constraints and the SRA of the entire study area.
Our results suggest that the relative importance of community assembly processes is scale dependent. Estimated mass effects predominated at small spatial scales where environmental gradients were weak. Trait-based selection was hard to detect at small scales and was strongest at large scales where environmental gradients are stronger. The fact that, at all scales, mass effects accounted for more variation in assemblage SRA than trait-based selection in our analyses suggests that regional processes are important in determining community structures more locally.