The application of carbon (C) substrates has been viewed as a promising tool for lowering soil nitrogen (N) availability in grassland restoration. However, experimental evidence shows that C additions can enhance, suppress, or have no effect on native species productivity, making it difficult to predict the effects of C-additions on plant communities. We used a community assembly approach to test the roles of environmental filtering and competition on community structure after C-additions. We applied 3 recalcitrant C-additions (wood chips, shavings, mixed chips + shavings), monitored temporal changes in soil N and P availability and species’ abundances, and used phylogenetic tools to examine changes in community structure. All 3 soil C-additions produced significant reductions in soil N and P fertility that, in turn, were correlated with increases in taxonomic species richness, diversity, and evenness, as well as shifts in community structure. In control and C-amended plots, however, communities were composed of taxa that were more closely related than expected by chance (phylogenetically clustered); this pattern occurred across all C-additions and years, and in both plot level and species pair-wise metrics. In nonamended plots, phylogenetic clustering was correlated with soil N availability, consistent with environmental filtering. In C-addition plots, biotic (clade specialization in different C additions) and abiotic factors (soil P variability) were important in structuring the community. These findings suggest that C-additions create a different set of environmental filters and that variations in ecological traits among phylogenetically close species may be important in understanding and predicting the effects of C-additions.
Environmental filtering mediates grassland community assembly following restoration with soil carbon additions
Year: 2016
