SOIL SALINITY AND THE OCCURRENCE OF INVASIVE PHRAGMITES AUSTRALIS IN

Anthony J. DeVecchis and Dr. Joseph K. Staples Abstract

 Background  Importance of tidal marshes like Scarborough Marsh  Phragmites australis as an invasive species  Previous research  Methods and Results  Analysis of soil salinity, temperature, and moisture  Plant community characteristics  Connection between soil salinity and P. australis  Significance  Insight and management – locally and beyond Background

 Functions of tidal marsh ecosystems  Productivity  Coastal Buffer  Key Habitat  Significance of Scarborough Marsh  Natural Areas Program Invasive Phragmites australis

 Spread in New England (Fussell et al., 2015)

 Tolerance (Vasquez et al., 2005)

 Changes to salinities in salt marshes (Fussell et al., 2015; Warren et al, 2001) Methods and Materials

 Analysis of Soil Moisture, Salinity, and Temperature  Paired Transects to upland edge (Morgan and Adams, 2018; Warren et al, 2001)  Upper tidal reaches  Conductivity as proxy for salinity (Yang et al. 2019)  Relationship of conductivity to plant species Analysis and Results

 Conversion of conductivity to specific conductance  Simple t-tests comparing Spartina and Phragmites data  Significant differences in soil specific conductance were observed along each transect Specific conductance

1400 1400 t-test P < 0.001 t-test P < 0.05 a t-test P < 0.02 1200 1200 a 1000 1000 ) µs/cm b b ) µs/cm 800 800

600 600

400 400 Specific Conductance ( Conductance Specific ( Conductance Specific 200 200

0 0 Spartina Spartina Spartina Spartina Phragmites Phragmites Phragmites Phragmites 1 Libby River 2 1 Nonesuch River 2 Significance

 Results yielding similar results to previous research (Fussell et al., 2015; Warren et al., 2001)

 Indication of freshwater input

 Fairly rapid, easily repeatable method

 Information for conservation efforts Complications

 Slow progress sampling in winter  Impact of ice on conductivity  Native vs. Invasive  Influences of road salting  Inability to access the  Details Conclusions

 Reliability of data  Future Research Acknowledgements

 Environmental Science and Policy Faculty at USM  Dr. Joseph Staples and Dr. Karen Wilson  Friends of Scarborough Marsh  Steve Pinette  Maine Department of Inland Fisheries and Wildlife  Brad Zitske  Field Data Collection Help  Sam Whitted References

Fussell, S. B., Dionne, M. L., & Theodose, T. A. (2015). Expansion rates of Phragmites australis patches in a partially restored Maine salt marsh. Wetlands, 35(3), 557-565. https://doi.org/10.1007/s13157-015-0645-3 Maine Natural Areas Program. (2013). Focus Areas of Ecological Significance: Scarborough Marsh. https://www.maine.gov/dacf/mnap/focusarea/scarborough_marsh_focus_area.pdf Morgan, P. A., & Adams, M. D. O. (2018). Tidal marshes in the estuary, Maine: A study of plant diversity and possible effects of shoreline development. Rhodora, 119(980), 304- 331. https://doi.org/10.3119/16-19 Vasquez, E. A., Glenn, E. P., Brown, J. J., Guntenspergen, G. R., & Nelson, S. G. (2005). Salt tolerance underlies the cryptic invasion of North American salt marshes by an introduced haplotype of the common reed Phragmites australis (poaceae). Marine Ecology. Progress Series (Halstenbek), 298, 1-8. https://doi.org/10.3354/meps298001 Warren, R. S., Fell, P. E., Grimsby, J. L., Buck, E. L., Rilling, G. C., & Fertik, R. A. (2001). Rates, patterns, and impacts of Phragmites australis expansion and effects of experimental Phragmites control on vegetation, macroinvertebrates, and fish within tidelands of the lower Connecticut River. Estuaries, 24(1), 90-107. https://doi.org/10.2307/1352816 Yang, S., Liu, F., Song, X., Lu, Y., Li, D., Zhao, Y., & Zhang, G. (2019). Mapping topsoil electrical conductivity by a mixed geographically weighted regression kriging: A case study in the heihe river basin, northwest china. Ecological Indicators, 102, 252-264. https://doi.org/10.1016/j.ecolind.2019.02.038