The importance of species and functional groups to barrier islands

We are continuing to understand the importance of woody vegetation to barrier islands, especially in stabilizing sediments and reducing overwash/limiting rollover. In a forthcoming paper in Ecosphere "Woody expansion facilitates liana expansion and affects physical structure in temperate coastal communities", we show the prevalence of lianas on barrier islands and the strong dependency with woody vegetation. The harsh abiotic conditions (e.g. high light, salinity, varying water availability) of these communities are most influential in structuring woody vegetation while liana species are primarily generalists associated with any woody plants. Interacting and possibly synergistic effects of woody expansion and liana proliferation appear to alter the traditional successional processes in coastal environments. Using a space-for-time geographic substitution (i.e. chronosequence) on two stable, unmanaged barrier islands, we show the lack of maritime forest regeneration due to the high leaf area index of woody shrubs and associated liana tangles. Historical photos from the Virginia barrier islands shows significant pine-oak forests that have been washed away from several islands due to erosion. New maritime forest does not appear to be establishing on the islands but replaced by new functional groups. We are continuing to investigate the ecological and ecosystem service consequences of this shift in succession and community structure.

Historical photo from Hog Island shows extensive maritime forest

 

Ghost trees due to erosion of maritime forest from Parramore Island

 

Present day woody vegetation - shrub thicket and lianas on Hog Island