Development of strategies for monitoring and managing sandscape vegetation, with an assessment of declining vegetation in the Apostle Islands National Lakeshore

Abstract

Coastal dune habitats such as those of the Apostle Islands National Lakeshore (APIS) are regionally rare habitats of global and state-wide concern. Their dynamic, sandy landforms provide habitat for unique species specifically adapted to frequent disturbance, drought, and other stresses. Despite having disturbance-driven life histories, these species are at risk due to increased visitor use of sandscape habitats and environmental change. Resource managers at APIS have long understood the values of these sandscapes and threats presented by recreational trampling, but more recently they have recognized the precarious position that these coastal habitats are in due to their proximity to the lake and exposure to weather-related phenomena linked with long-term climate change. In recognition of emerging threats and the need to track impacts of these threats, park managers initiated a revision of their methods for monitoring sandscape vegetation. We applied these methods to 15 sandscape locations within the national lakeshore in 2014. Here, we outline what these revisions to the methods were, assess the current status of sandscape structure and composition, assess the utility of data collected with these methods, provide suggestions for further revisions of the sampling method, outline a two-tiered sampling approach for future monitoring, and we provide management recommendations. In a second section of the report, we provide a focused assessment of the size and health of Juniperus communis (common juniper), a target species of concern in these sandscape communities after it was observed by park managers to be dying or stressed on Michigan Island. Our assessments include the status of J. communis across all sandscapes monitored in 2014, and an analysis of change over time since 2012 in the health of J. communis on Michigan, Outer, and Stockton Islands. We provide evidence of impacts by rodents on foliar dieback, primarily on Michigan Island, and we discuss possible interactions with the non-native pale juniper web-worm (Aethes rutilana) and with climate change.