Impact of invasive Carex kobomugi on the native dune community in a US mid-Atlantic coastal system

Abstract

Dunes provide numerous ecosystem services including habitat for flora and fauna, coastal protection through mitigation of wind and wave energy, and as a barrier to storm flooding. Dune vegetation that inhabits these systems plays a vital role in building dunes and resisting erosion. In the United States, the Virginia coast is a transitional temperature zone for several dominant dune grasses, where the northern species, Ammophila breviligulata (C3) and the southern species, Uniola paniculata and Panicum amarum (both C4) overlap. At Back Bay National Wildlife Refuge (NWR), Virginia, warming temperatures are resulting in native species range shifts altering biotic interactions. Additionally, the invasive sedge, Carex kobomugi (C3) has become more prevalent in the region with unknown effects on the landscape. To understand the impact of Carex on the native plant community, we quantified species distribution and morphological traits of three dominant native species, A. breviligulata, Panicum, and Uniola as well as invasive Carex. We found that Carex was most dominant and exhibited similar individual traits when compared to native species. The suite of plant traits was unique in Carex, with less variation than in native species allowing for rapid nutrient acquisition and growth. These traits, combined with species distribution data suggest that Carex may limit Ammophila abundance. Similarly, presence of Carex had a negative effect on Panicum growth, but no discernible effect on Uniola. Success of Carex at Back Bay NWR may be indicative of the future spread of the species due to above and belowground morphological traits, which may give the invasive an advantage with climate warming.