Plants in coastal ecosystems are being altered due to the effects of global climate change both atmospheric (e.g. temperature, precipitation) and oceanic (i.e. sea level rise). Historically, maritime forest was an important climax community on the Virginia barrier islands, increasing diversity and structure across the landscape. With rising sea-level and range expansion of native and invasive species, maritime forests are threatened communities and have been declining along the Atlantic Coast. On Parramore Island, Virginia, high rates of shoreline erosion, several disturbances (i.e. storms, fire), and shrub expansion of an ecosystem engineer (Morella cerifera) have the potential to dramatically alter maritime forest communities. Leveraging historic long-term data, we combined remote sensing analysis and recent surveys to quantify changes in maritime forest structure on Parramore Island, part of the Virginia Coast Reserve Long-Term Ecological Research (VCR – LTER) network. Given the multitude of physical and biotic disturbances, we hypothesized that maritime forest is declining, being replaced by expansion of M. ceriferaor lost to ocean through shoreline erosion.
Results/Conclusions
Landsat imagery was obtained in 1998 and 2016 and classified into five classes: grassland, woody vegetation, bare soil, marsh, and ocean. Plots were surveyed in 1997 and 2018 for species composition, basal area, and height. Importance values were calculated from both 1997 and 2018 datasets to determine dominant species. Based on Landsat imagery, 33% of the survey plots have converted to non-vegetative beach/ocean as a result of erosion and 32% of forest converted to grassland. Only 33% of maritime forest has been maintained in a woody dominated state. In 1997, maritime forest was dominated by three evergreen trees: Pinus taeda, Persea palustris, and Juniperus virginiana. In 2018, species composition of the remaining forest was mostly dominated by the expanding shrub, M. cerifera. The change towards homogeneous vegetative cover mimics that seen on other islands. This simplification in both species and structure may affect overall resilience of these islands. These results demonstrate the highly dynamic nature of this landscape and document significant changes in communities due to climate change effects of sea-level rise and warming temperatures.