Leaf phenology and light availability influence plant invasion mechanisms within Eastern deciduous forests

Exotic invaders of Eastern deciduous forests in North America may benefit from extended leaf phenology (ELP, lengthier leaf lifespan) and/or high light availability. These factors may interact with other invasion mechanisms such as allelopathy (the release of toxic secondary compounds), plant-soil feedback, and herbivore-mediated apparent competition, resulting in invasion effects that would not be predicted based on studies of each of these factors in isolation.;Using experimental mesocosms, I found that access to light through ELP promotes the growth of invasive Euonymus fortunei and the survival of invasive Alliaria petiolata, but does not promote growth or survival in the invasive Lonicera maackii. Access to seasonal light or year-round high light availability facilitated Alliaria's negative impact on native species, but this was not fully explained by an increase in allelopathy in response to high light availability.;Light availability did influence the strength and direction of plant-soil feedback (PSF) in five native understory species and the invasive Euonymus fortunei. For the five natives, feedback weakened from strongly negative to weakly positive as light availability decreased, but feedback was neutral or positive across all light environments for invasive wintercreeper, consistent with the hypothesis that PSF contributes to invasion.;Using mathematical models, I found that ELP can provide invaders with an advantage in both direct competition and herbivore-mediated apparent competition. These results are relevant to invasive shrubs of Eastern deciduous forests that are consumed by white-tailed deer, potentially altering deer dynamics to the detriment of native plant species.;Overall, results indicate that ELP and light availability can influence invasion of Eastern deciduous forest communities by altering complex interactions amongst plants, soil biota, and herbivores.