CANCELLED - Examining directional change in the abiotic environments and the understory plant communities across a chronosequence of oak woodland restorations

Background/Question/Methods

To improve biodiversity and ecosystem health, the Forest Preserves of Cook County in Cook County, IL have implemented widespread ecological restoration efforts across 12,200 acres. Among the ecosystem types under active restoration, include oak-dominated woodlands, characterized by a semi-open canopy of Quercus spp., with a high diversity of graminoids and herbaceous perennials in the understory. The outcomes of restoration efforts are typically assessed within a few years of implementation or not at all, leading to a significant gap in our understanding of the temporal changes that occur during ecological restoration. My research aims to understand the temporal trajectories of plant community change in restored oak woodlands. I am studying seven oak woodlands that have been restored using similar methods, but that vary in restoration age, ranging from 4-52 years of restoration. I am assessing the abiotic environment (soil pH, soil water holding capacity, leaf litter depth, and canopy light levels), taxonomic diversity, and functional trait diversity across 210 plots in this restoration chronosequence. Specifically, I am asking how taxonomic and functional trait diversity differ across restorations of different ages, and whether the observed changes in taxonomic or functional trait diversity are associated with changes in abiotic conditions.

Results/Conclusions

Restoration age is a significant predictor of soil pH (ANOVA, p=0.06), canopy light levels (ANOVA, p=0.04), and leaf litter depth (ANOVA, p=0.01). Both plant species richness (ANOVA, p= 0.002) and Shannon’s Index of Diversity (ANOVA, p= 0.003) increased with restoration age. However, visualization of community composition through non-metric multidimensional scaling (NMDS) revealed no clear difference in taxonomic community composition across sites of different restoration ages. Preliminary analysis suggests that functional trait diversity increases with restoration age (ANOVA, p=0.07). These results reveal notable directional changes in abiotic conditions, taxonomic and functional trait diversity. This suggests there may be different mechanisms of community assembly present at restorations of different ages. Future work will include structural equation modeling and variation partitioning to infer the relative impact that abiotic filtering, biotic interactions, and dispersal limitations have on the observed patterns of species and functional trait diversity. Through this research, I will contribute to our understanding of the trajectories of plant community change during ecological restoration. Ultimately, this work contributes to our basic understanding of the mechanism maintaining diversity in plant communities, while also contributing to the implementation of future ecological restoration efforts in oak woodlands.