The persistence and conversion of coastal foredune and swale vegetation community distributions 63 years later

Abstract

Vegetation shifts can directly alter habitat dynamics and indirectly impact habitat stability relative to disturbance response. Barrier island dune habitats exhibit spatiotemporally dynamic topography that is affected by vegetation. However, vegetation distribution data can be rare and vegetation persistence is largely unknown such that species turnover over in communities can occur unnoticed. This is true despite concerns and documented cases of woody encroachment related to climate change in these ecogeomorphic habitats where physical stability to resist storm erosion varies with vegetation distribution and density. In 1956 and 1957, the vegetation of Island Beach State Park, NJ, was mapped as a permanent record for subsequent ecological study. In June 2020, we remapped the vegetation of 5.4 of 17 km north to south, seaward of the thicket community boundary. We maintained the same classification system as the historic record, physically mapping vegetation patches via GPS. We quantified changes in thicket, heather, and grass community distribution between the two time periods. Habitat persistence and conversion varied in the 63 years. Heath communities saw 80%–97% habitat loss in conversion to woody thicket. Conversely, thicket community distribution drastically increased, replacing heath where it was previously prevalent. This represents the first known documented instances of woody encroachment for Morella pensylvanica. When they did not expand, thicket communities receded landward or underwent turnover to an invasive species. Woody species of interest for dune stabilization occupied areas of similar habitat characteristics. Dune vegetation distribution persistence from 1957 to 2020 was relatively consistent and stable with the exception of heath habitat conversion. Barrier island stability is directly related to vegetation stability such that understanding where community shifts might occur over time can aid in managing and modeling efforts surrounding these dynamic ecogeomorphic habitats.

Dunes under attack: untangling the effects of landscape changes on Iceplant invasion (Carpobrotus spp., Aizoaceae) in Mediterranean coasts

“…However, monitoring IAPs on dynamic dune mosaics by traditional approaches performed through field campaigns is both resource-intensive and costly. The field campaigns often cover limited areas due to accessibility constraints, and historical distribution maps required for monitoring invasion dynamics at landscape scale, are frequently unavailable (Müllerova et al 2017;Cascone et al 2021, Charbonneau et al 2023. Consequently, the temporal changes of invasion process were barely explored and focused on limited number of IAP as Acacia saligna (Kutiel et al 2004), Carex arenaria (Nielsen et al 2011), Oenothera drummondii (Gallego-Fernández et al 2019, Carex kobomugi (Charbonneau et al 2020).…”