SWISLR Webinar 5 - Ecosystem Reactions to SWISLR

The most recent SWISLR webinar discussed ecological system shifts throughout the NACP. Justin Wright and Aeran Coughlin introduced us to their work on plant and microbial community change in the Alligator River National Wildlife Refuge. The RCN hopes to synthesize the ecological impact of SWISLR. Existing studies are typically site-specific and species-based, limiting the possibilities for generalizations. However, a syntheses of existing studies will help determine what to expect and help develop best-practices for future coordinated research. Therefore the second half of the webinar was a discussion about what people are studying and how traits are being linked to SWISLR induced changes. 

Justin Wright starts off by talking through how SWISLR is inducing changes not only along the coast but affects inland plant communities due to human alterations. Specifically in the Albemarle-Pamlico peninsula, the drainage networks allow for salt to move inland. The wright lab has looked at how plant communities have changed because of this salt incursion into the peninsula. They found that species composition has shifted to varying degrees, but were not quite sure what the causes of these changes were. There was some hint that salt and elevation was correlated to the composition shifts, however the relationships were stronger for plant-traits such as basal area (Anderson et al. 2022). These findings indicate that SWISLR is responsible for the drastic ecosystem shifts into the transient state of ghost forests that are seen throughout the NACP. However, the mechanisms of these changes is not entirely known since correlations do not prove that salt is responsible for composition changes. So, Aeran is diving deeper into these interactions to identify why plants are reacting to salt coming into the soil in the Alligator River National Wildlife Refuge. They are focusing on plant-soil interactions and have already found that the microbial soils are important for tree and shrub growth, with forest soils in the Alligator River being primed for shrub growth. Being at the start of their dissertation, Aeran has many more questions to answer and has primmed the RCN to think about how to study plant interactions moving forward.
 
The RCN contains more than just plant ecologists, and people are thinking about many aspects of SWISLR from human land use to coastal hydrology. Most plant ecologists who were in the room said they mostly study community composition and measurements of function aren’t as prevalent.  Many use indicator species (like Justin and Aeran) to identify ecosystem changes due to SWISLR but it is hard to connect species to salinity specific stress since a lot of plant trait changes are the same regardless of whether a tree is stressed by inundation or salinization. A paper by Keryn Gedan and Eduardo Fernandez-Pascual was highlighted as an example of linking plant traits to salinization. Another example of linking plant traits to salinization is Serina Wittyngham’s work at VIMS. They are curious about what constrains the lower limit of Phragmites in the salt marsh since the upper limit is better understood. They are measuring plant traits and rhizome starch content of Phragmites to see how treatments such as salt and herbicide influence the energy stores and ability for spread.
 
You can watch the Wright lab talk and the summary of the discussion rooms on youtube.

The discussions so far have been 15-30 minutes long, often cutting some connections and thoughts short. We hope you all will continue these discussion at the upcoming all-hands meeting!