Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A decade of expansion of the invasive plant Carex kobomugi in a coastal foredune system.

Abstract

Many plants show capacity for selective spatial and temporal expansion or foraging despite being sessile. In biogeomorphic coastal foredunes, the plant species that inhabit or colonize an area post-storm will affect habitat stability and thus future storm response. Along the mid-Atlantic US, invasive Asiatic sand sedge (Carex kobomugi) has come to dominate foredunes since its introduction in 1929 at Island Beach State Park, New Jersey. To understand controls on foredune invasive expansion, we mapped stand expanses along 3-km of foredune here since 2008, relative to shifting habitat features such as the location of the foredune crest and denuded areas ripe for colonization. Invasive stands have been laterally expanding from pre-existing stands with temporal variation in stand size and density. Stand area loss only occurred due to Hurricane Sandy, but burial level from Sandy did not impact this. Hurricane Sandy fragmented and destroyed stands, but these stands recovered by coalescing over time, and then expanded further whereby stands that lost more in the storm grew larger over 10 years than those that were eroded less. The invasive sedge shows some directionality in growth, typically expanding, but not consistenly across time, further from the crest which experiences less salt spray. Carex kobomugi also spread more extensively into adjacent vegetation than into bare areas, suggesting that replacement of natives is more likely than colonization of open habitat space. Plants are the foundation of coastal foredune systems. Understanding where invasive species are expanding and the underlying controls on invasion is key to predicting current and future impacts related to climate change and resultant changes in future storm frequency and intensity.