Tuesday, January 26, 2016

On the value and function of barrrier island vegetation

By Julie Zinnert

Coastal barrier systems comprise 15% of coastlines globally and occur on all continents except Antarctica.  Along the Atlantic of North America, barrier islands are the frontline ecosystem to 78% of coastline, protecting 41.5 million people from nor’easters and hurricanes. These ecosystems protect mainland human infrastructure and areas of great economic value; thus, predicting the fate of barrier islands in uncertain climate conditions is essential. At the Virginia Coast Reserve Long-Term Ecological Research site, we have a unique view into the natural response of barrier islands without direct anthropogenic influence as the Virginia barrier islands are owned and protected by various entities (e.g. The Nature Conservancy, US Fish and Wildlife, Virginia Department of Conservation and Recreation). At the Coastal Plant Ecology Lab, our research focuses on the value and function of barrier island upland vegetation, an often overlooked landscape. 

With the advent of remote sensing, we have been able to obtain a broader perspective of barrier island change. In a paper soon to be published in Ecosystems, we have documented a 29% loss in Virginia barrier islands from 1984-2011. This is similar to the rate of ice melt in the Arctic (~11% per decade).  With such dramatic loss in upland communities, we have also documented dynamic changes in land cover and the expansion of woody vegetation across several islands. Considering that the upland portion of barrier islands is where anthropogenic development occurs, there is an urgent need to fully understand the ecological processes, function, and connection to other landscapes (e.g. marshes, lagoons).

Historically, ecological research on barrier island has focused on answering fundamental scientific questions at local scales. However, as our understanding of barrier island ecology has grown, so has the recognition that these systems are highly complex and dynamic across space and time. Over the next several weeks, I will highlight current research ongoing in our lab that examines the role of barrier island upland vegetation at both local and broad scales, and how this work is contributing to our understanding of such a unique, but globally distributed landscape. From overwash communities and dune vegetation to shrub expansion, vine infiltration and loss of maritime forests, we span islands, their communities, and underlying mechanistic processes. Given their unique position on the landscape and the harsh abiotic factors they constantly face, these sensitive ecosystems can inform us on both the effects of climate and resilience of our natural world to such dramatic change.

Hog Island: overwash fans from 2000 in the south (left) and shrub expansion in the north (right).

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