A novel hybrid beachgrass is invading U.S. Pacific Northwest dunes with potential ecosystem consequences

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 d..., , , # **A novel hybrid beachgrass is invading U.S. Pacific Northwest dunes with potential ecosystem consequences**

[https://doi.org/10.5061/dryad.x0k6djhr4](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***

1. **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.
2. **HYBR_AMAR_Searches_Undivided.xlsx**:
* Dataset of 53 search transects conducted in 2019 (by R. Mostow), 2021, and 2022 (by R. Askerooth, R. Mostow,...