MACURISA2018

***CANCELED***Disturbances are frequently the impetus for habitat change, but this is especially true at the land-sea interface. In coastal dunes that buffer upland areas, dynamic flux is the norm, and wind events, especially major storms, have the potential to drive change by denuding once vegetated microhabitats and creating hollow blowout depressions. These blowouts are considered ephemeral, ripe for recolonization, and inherent among coastal systems, both recently storm-affected and ‘healthy’, worldwide. However, we do not understand on what timescale recolonization operates or what factors control the rate and magnitude of localized changes associated with further erosion or vegetated stabilization. Since Superstorm Sandy, October 2012, we have conducted a yearly census of blowouts created by the storm along a 3km stretch of a model barrier island coastal dune system, Island Beach State Park, NJ. We use a Trimble GeoXT Explorer 2008 and vertex mapping to map the outermost vegetated blowout edges as a metric of extent change over time. Using various GIS tools, we split these polygon bowls up into quadrants and halves to explore extent shifts directionally within quadrants defined by compass direction as it relates to wind direction; substrate stability and blowout extent shifts are likely coupled with wind forcing dictating where vegetation is able to root and survive. We are also using structure from motion with drones to create RTK-GPS referenced digital elevation models (DEMs). With these models, we can explore how the boundaries of the bowls, as defined by ground truthing the plant extents, differs from the boundaries of the bowls, as defined the change in angle or drop off from foredune into the depression. Thus far, we have mapped the bowls with ArcMap and Trimble four times, since Sandy in Fall 2013, 2014, 2016, and 2017. After Sandy, there were 55 blowouts of various sizes and shapes within the foredunes. As of 2017, 29 of these 55 have become colonized and 26 remain unvegetated though their extents have changed. Distinctly new bowls have been created each year and fragmentation of existing bowls from colonization has also occurred. The edges of bowls have been changing location over time primarily due to vegetation encroachment via clonal growth, with negligible germination from the seedbank. Results show that the smaller the blowout, the more ephemeral it will be. We have thus far flown three drone flights, March 2017, December 2017, and March 2018. We can visualize the bowls with these flights and subtract the DEMS to look at changes in the bowl geometry. Similarly, we compare the March 2017 DEM extents to the Fall 2017 ground truthing to relate the two definitions that one might define as the boundary of a blowout. Understanding the controls on dune recolonization in a natural setting has implications for management with dictating planting locations as well so for understanding how habitats will likely change and evolve as a function of increasing disturbances related to climate change.
***CANCELED*** This talk has been canceled ***CANCELED***