PS 3-29 - Plant dispersal traits as predictors of grassland species composition along an old field chronosequence

Abstract: Grasslands are amongst some of the most converted and least protected ecosystems in the world with nearly 50% of all grasslands degraded to some extent. Land-use conversion can often reduce plant diversity and ecosystem functioning. However, we are also now facing a global increase in land recovering from agriculture, providing new and widespread opportunities to recover biodiversity. Currently, the mechanisms to the recovery of plant diversity post disturbance often remain elusive. Although recovery is well documented in some instances, it is often slow and fractional. Dispersal limitation of seeds likely plays a role in recovery, but can we use dispersal traits to predict the recovery of plant species along a recovering chronosequence of old fields after agricultural abandonment? Using plant survey data from Cedar Creek’s nearly 100 year old chronosequence, composed of 17 fields abandoned from agriculture at various points throughout history, we characterized species composition of the fields and compared them to nearby unplowed remnants. Furthermore, we use the 'Global Spectrum of Plant Form and Function Dataset' to quantify dispersal traits such as plant height and seed mass.



Using these data, we found that shorter plants took longer to colonize the recovering fields (p=0.03). We also observed that species which had completely failed to colonize any of the fields after agricultural abandonment were more likely to have heavier seed mass than the species that have recolonized thus far (p=0.01). Our results suggest that dispersal related traits may be able to serve as a predictor of species composition during recovery and that poor dispersal traits may be acting as one of the barriers to complete recovery of plant biodiversity. This work has great potential to elucidate which types of plant species would benefit from removing dispersal limitation through actions by land managers and stewards best practices in the recovery of difficult to establish species. Our findings may also further inform various theoretical frameworks such as the colonization-competition theory.