The European VSD+PROPS model was applied to estimate changes in understory vegetation in response to changes in climate and atmospheric nitrogen deposition at three forested sites in the eastern United States. Model sites were located in a northern hardwood forest of the Hubbard Brook Experimental Forest in New Hampshire; a mixed oak forest in Shenandoah National Park, Virginia; and a sugar maple-mixed oak forest in Great Smoky Mountains NP, Tennessee. This is the first application of VSD+PROPS in the United States and was designed as a feasibility study to determine potential needs for model development and identify data gaps. Although simulation results suggested that future conditions may reduce the suitability of these forests to support the continued presence of their characteristic understory plant species, low data availability for building vegetation response models contributed to uncertainty in the results. In an ongoing follow-up project, we are addressing these uncertainties by including additional foundational data and alternate candidate predictor variables, among other potential improvements.
A peer-reviewed journal article which described the results of this research was published in 2018.