The National Marsh Synthesis Team (NAMASTE) leveraged the Reserve System’s geographic diversity, nationally coordinated monitoring program, communication networks, technical expertise, and strong record of collaborative research to integrate data nationally across the NERRS and examine how tidal marsh plant communities are responding to climate change.

The Project

Tidal marshes are highly valued ecosystems that provide essential benefits including wildlife habitat, protection from coastal flooding and storm surges, filtration of nutrient pollution, carbon storage, and recreational activities. Today, tidal marshes face threats from climate change, including accelerating rates of sea level rise which inundate the marshes more frequently and for longer periods of time. Research within National Estuarine Research Reserve (NERR) sites has revealed that rising seas are causing striking changes in plant communities including shifts toward more flood tolerant species, lower overall plant diversity, and in some cases increasing swaths of bare ground. While prior studies have investigated the response of tidal plant communities to sea level rise, limitations of existing methods and protocols have hindered comparison of field-collected marsh vegetation data across regions and the ability to synthesize these data to support decision-making.

This project was the first in-depth study to leverage a nationally-coordinated dataset generated by 20 National Estuarine Research Reserves across 85 marshes in 17 coastal states to better understand how sea level rise is affecting tidal plant communities. After in-depth conversations with all participating reserves, the project team brought together datasets from individual reserves and integrated them into a standardized national dataframe. This dataframe was analyzed to quantify vegetation change across marsh characteristics at local, regional, and national scales. The project revealed five national trends in tidal marsh vegetation change:

• NERR marshes are changing at all scales;
• sea level rise (SLR) is a main factor associated with marsh change;
• marsh changes respond differently across salinity categories;
• marsh change differs across vegetation zone; and,
• marsh change differs across geographic regions.

The project’s output include a suite of publicly available products that address the technical, communication, and methodological challenges of coordinating a nationally cohesive dataset. Products include site to national level trends, a data tool package aiding in analyzing tidal marsh data (e.g, data templates, coding script, coding user guides and training videos, data visualization apps, a GIS dashboard) and communication tools (e.g., illustrations, logo, website). As the NERR system continues to collect tidal marsh data, these tools can be used by reserve staff or collaborators to integrate newly collected data with historical data. The tools can also be customized for use with marsh vegetation data outside the NERR system. In addition, broader audiences like educators, managers, and naturalists may use these tools to learn about the status of tidal marshes across the nation and at their local reserve.

The Impact

• Demonstrated key trends in tidal marsh vegetation change on local, regional, and national scales.
• Provided an innovative ecological indicator of marsh response to sea level change through the development of the Ecotone Migration Index (EMI).
• Integrated local datasets into a standardized national dataframe and created opportunities for broader syntheses of marsh change over time across regions and the nation with a new analytical toolbox.
• Provided recommendations to improve the NERR tidal marsh SOP around field and data management best practices.
• Prepared the NERRS to engage in more large-scale NERR collaborations.