Herbivory, Climate Change, and the Future Landscape of Isle Royale National Park: Developing an Herbivory Monitoring Program to Adaptively Manage the Park's Terrestrial and Aquatic Ecosystems

Abstract

Climate change is expected to play a major role in the restructuring of forests and other vegetation communities across the globe in the coming century. Forests in particular currently occupy almost half of the Earth’s terrestrial surface, with other types of natural plant communities contributing a large proportion of land cover. Given the importance of these ecosystems with respect to their biological functions (i.e., water provisioning, climate regulation, nutrient cycling, carbon sequestration, habitat provisioning, etc.), understanding how these plant communities will respond to the growing threat of climate change will allow us to anticipate and quantify significant impacts to long-term human and environmental well-being. Climate change and subsequent rising temperatures, in concert with biotic drivers such as herbivory, is thought to have already altered the composition of plant communities in Isle Royale National Park (ISRO). Understanding what continuing changes these communities may still undergo is a major goal for National Park Service (NPS) resource managers, as this information will allow for more targeted conservation strategies. In this report we present a vegetation and herbivory monitoring protocol (Part I) intended to assess the combined effects of herbivory and climate change on the terrestrial plant communities of Isle Royale National Park (ISRO). This protocol will capture data on vegetation composition and structure, and on associated moose browsing of terrestrial (herbaceous, shrub, sapling, and overstory layers) vegetation to identify areas within the park most susceptible to forest change. We also present recommendations for the development of a protocol to monitor aquatic vegetation. The information collected through future applications of this protocol will inform park managers which plants are most vulnerable to heavy browsing, where vegetation in the park is expected to change in the future, and the effect that variable climate and wolf predation on moose will have on the vegetation of ISRO. In addition, to address NPS needs, our team has conducted a review of the available literature concerning direct and indirect climate change impacts on the vegetation communities of ISRO (Part II). Using the classification scheme of The Nature Conservancy (TNC) and the United States Geological Survey (USGS), we described 14 unique ecological communities on ISRO, including the dominant plant species found in each community. Based on our literature review of both community- and species-level climate change impacts in this system, we present a conceptual framework for how different ecological vegetation communities and the dominant species within them may respond to the multifaceted effects of climate change on ISRO in the coming century. Our review identifies potentially “winning” and “losing” vegetative community types under commonly predicted climate change scenarios in the upper Midwest region. This synthesis of literature provides resource managers a first pass at estimating climate change effects on the plant communities of ISRO and will help in prioritizing areas for climate change mitigation.