A novel hybrid beachgrass is invading U.S. Pacific Northwest dunes with potential ecosystem consequences
Cite this dataset
Askerooth, Risa et al. (2024). A novel hybrid beachgrass is invading U.S. Pacific Northwest dunes with potential ecosystem consequences [Dataset]. Dryad. https://doi.org/10.5061/dryad.x0k6djhr4
Abstract
Invasive plants formed via hybridization, especially those that modify the structure and function of their ecosystems, are of particular concern given the potential for hybrid vigor. In the U.S. Pacific Northwest, two invasive, dune-building beachgrasses, Ammophila arenaria (European beachgrass) and A. breviligulata (American beachgrass) have hybridized and formed a new beachgrass taxa (Ammophila arenaria × A. breviligulata) but little is known about its distribution, spread, and ecological consequences. Here we report on surveys of the hybrid beachgrass conducted across a 250-km range from Moclips, Washington to Pacific City, Oregon in 2021 and 2022. We detected nearly 300 hybrid individuals, or an average of 8–14 hybrid individuals per km of surveyed foredune. The hybrid was more common at sites within southern Washington and northern Oregon where A. breviligulata is abundant (75–90% cover) and A. arenaria is sparse and patchy. The hybrid displayed morphological traits such as shoot density and height that typically exceeded its parent species suggesting hybrid vigor. We measured an average growth rate of 30% over one year, with individuals growing faster at the leading edge of the foredune, nearest the beach. We also found a positive relationship between hybrid abundance and that of A. arenaria, suggesting that A. arenaria density may be a controlling factor for hybridization rate. The hybrid showed similar sand deposition and associated plant species richness patterns compared to its parent species, although longer-term studies are needed. Finally, we found hybrid individuals within and near conservation habitat of two Endangered Species Act-listed, threatened bird species, the western snowy plover (Charadrius alexandrinus nivosus) and the streaked horned lark (Eremophila alpestris strigata), a concern for conservation management. Documenting this emerging hybrid beachgrass provides insights into how hybridization affects the spread of novel species and the consequences for communities in which they invade.
README: A novel hybrid beachgrass is invading U.S. Pacific Northwest dunes with potential ecosystem consequences
https://doi.org/10.5061/dryad.x0k6djhr4
This folder contains datasets related to hybrid beachgrass distribution, spread, and ecological consequences. All .xlsx files have a Raw_Data tab that contains the dataset and a second Variable_Names tab that contains notes about the file and further explains each variable name. Any code will be provided upon request.
Description of the data and file structure
Included datasets are described below, organized into sections.
Beachgrass Searches
- HYBR_AMAR_Searches_Divided.xlsx:
- The search transect dataset, as described below, split into roughly <= 0.2 km segments using ArcGIS Pro for the purposes of analysis.
- HYBR_AMAR_Searches_Undivided.xlsx:
- Dataset of 53 search transects conducted in 2019 (by R. Mostow), 2021, and 2022 (by R. Askerooth, R. Mostow, S. Hacker, and field assistants). Search transects vary in length and each contain information about the number of Ammphoila arenaria and Ammophila hybrid individuals or “patches” found along the transect.
- HYBR_Patch_Locations.xlsx:
- Dataset of the distribution, location, and other identifying information of the hybrid patches found as of May 2023.
Vegetation and Beachgrass Measurements
- Beachgrass_Morphometrics.xlsx:
- Measurements of beachgrass morphology and growth form, from samples collected in a field setting and measured in the lab. Species measured include Leymus mollis and all Ammophila taxa.
- All_Quadrat_Data_v2.xlsx:
- All data collected from haphazard quadrat (0.5 m by 0.5 m) sampling in 2021 and 2022, including dune grass density, tiller height, and quadrat species richness and percent cover.
- All_Perimeters_v2.xlsx:
- Areas of all hybrid patches collected in 2021 and 2022, in a long format, including patches that were not resampled for growth.
- Hybrid_Perimeters_Growth.xlsx
- Areas of hybrid patches collected in 2021 and 2022 in a wide format, showing change over time for only patches that were sampled in 2021 and again in 2022.
- Point_Intercept_221216.xlsx:
- Point-intercept surveys, perpendicular to the shoreline, that document the presence or absence of vegetation. Number headings denote the position along a line, while a value of 1 indicates the presence of a taxon, and value of 0 indicates absence.
GPS Transects
- Transect_Metrics.xlsx
- Contains the three calculated metrics (Elevation, Volume, and Rugosity) derived from the Raw_transect_data folder. Processing of the transect data was performed in Matlab, while statistical analysis with the Transect_Metrics dataset was performed in R. Raw data of transects will be provided upon request.
Funding
NOAA Oceanic and Atmospheric Research, Award: NA19NOS4780180, Effects of Sea Level Rise
U.S. Geological Survey Northwest Climate Adaptation Science Center, Award: G17AC000218
National Science Foundation, Award: 2103713, Coastlines and People Hub
NOAA Sea Grant, Award: NA18OAR4170072
National Science Foundation, Graduate Research Fellowship