1. Assessment of Declining Vegetation on Rare Sandscapes and Development of Strategies for Management in the Apostle Islands National Lakeshore
In collaboration with the National Park Service, we will implement a revised protocol for surveying beach and dune vegetation on 14 sandscapes in the Apostle Islands National Lakeshore. The aim of this work is to ultimately be able to better assess declining vegetation in this rare coastal ecosystem and to develop strategies that will address causal agents. Loss of vegetation has potential future risks of soil erosion, exotic species invasion, and loss of wildlife habitat. Of specific concern is the apparent decline in the health and vigor of native species such as beach grass (Ammophila breviligulata) and common juniper (Juniperus communis) and the increasing invasion of the non-native winged pigweed (Cycloloma atriplicifolium) in nesting habitat used by the endangered piping plover. Our previous research on dieback on common juniper suggests that these coastal sandscapes may be experiencing changes due to declining water availability associated with heightened evaporative demand linked with rising annual temperatures, reduced precipitation, and declining Lake Superior water levels.
2. Dieback on Juniperus communis (Common Juniper) as a Possible Indicator of Climate Change Impacts to Sandscape Communities in the Apostle Islands National Lakeshore
This research explores the patterns and possible mechanisms for changes in the vegetation on sandscapes within the Apostle Islands National Lakeshore (APIS). Sandscape communities are rare within the Lakeshore and provide critical habitat for an assortment of specialized plant and animal species. The risks are high for species living in these harsh coastal communities subject to the stresses of wind, sand burial, waves, and ice scouring. These habitats have evolved with natural disturbances, which are critical for their development and maintenance. However, the frequency, duration, and severity of these natural disturbances are apparently shifting rapidly with global climate change. Biologists at APIS have noted die-offs of beach grass (Ammophila breviligulata) and of common juniper (Juniperus communis) on APIS sandscapes, both of which are important for stabilizing shifting sands in the dynamic sandscape system. We conducteda pilot study in August 2012 to begin evaluating possible causes for the declines in common juniper.
3. Influence of competition on the federally threatened seabeach amaranth (Amaranthus pumilus; Amaranthaceae) on the Atlantic Coast
Seabeach amaranth is a rare dune annual endemic to the highly dynamic foredune habitat of beaches along the U.S. Atlantic Coast. In collaboration with Claudia Jolls (ECU), Dr. Johnson’s research explored the role of interspecific and intraspecific competition on growth and survival of seabeach amaranth. Our results suggest that biotic interactions are likely an important factor limiting the upper limits of its distribution on beaches. The implications of this species’ poor competitive ability and, therefore suitable habitat, are important as it continues to be ‘squeezed’ out of its habitat due to increased beach development, building of artificial dunes planted with competitive perennials, off-road vehicle traffic in the foredunes, and increasing sea-levels.