Date of Award

Spring 5-2018

Level of Access

Open-Access Dissertation

Language

English

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Advisor

Brian McGill

Second Committee Member

Jacquelyn Gill

Third Committee Member

Brian Olsen

Additional Committee Members

Brian Mitchell

Aaron Weiskittel

Abstract

The United States National Park Service mission is to preserve natural and cultural resources unimpaired for future generations. Given climate change, the paradigm of restoring natural resources to their pre-European settlement condition is no longer appropriate or achievable management. Instead, we must promote resilience and plan for adaptation. This approach poses many challenges, including knowledge gaps about the current condition of park ecosystems including wetlands, and lack of information about the matrix surrounding parks, which will strongly influence park ecosystem response to climate change. My dissertation research focused on filling these knowledge gaps to provide much needed information to managers in northeastern national parks (NP). We constructed multimetric indicators (MMIs) of wetland condition for vegetation, soil, water chemistry, and algae to assess wetland condition in Acadia NP, compared patterns of structure and tree diversity in park and matrix forests, and assessed migration potential of eastern tree species through dispersal simulations and spatial analyses of tree regeneration. Using the MMIs, we found Acadia NP wetlands to be in good condition overall, and identified degraded wetlands to prioritize for restoration. Our study of 50 eastern NPs found parks to have consistently older forest structure, such as higher density of large trees and greater coarse woody debris volume, than matrix forests. Our follow-up study in 39 eastern NPs documented consistently higher tree diversity in parks than matrix forests. These results suggest that park forests may respond differently and potentially be more resilient to climate change than matrix forests. However, our assessments of tree migration capacity documented significant dispersal barriers north of many southern oak (Quercus spp.), hickory (Carya spp.) and pine (Pinus spp.) species predicted to gain suitable habitat in the northeastern US. In roughly the same area, we documented widespread regeneration debt of these same southern tree species, with invasive plant species, deer overabundance, and anthropogenic land cover the likely drivers. Taken together, these results indicate that while parks may be somewhat resilient in the short-term, without intervention, longer-term adaptive capacity of northeastern forests to climate change will be severely impacted by migration barriers and regeneration debts in the mid-Atlantic region.

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