While the AgroEcoLab were out in the field this summer, slashing through endless stands of Phragmites to plant lysimeters, a seven-year project funded by the NCCOS summarized their findings by stating the obvious: the invader was spreading. Specifically, the authors concluded that Phragmites australis prefers altered shorelines with elevated nutrients, a fact we had become more than familiar with. Our team’s research dealt with the previously soil-bound nutrients that sea level rise may unleash as farmlands inundate, and how this might impact our state’s fragile marshes. But as we slogged our way through farms and marshes collecting samples, we saw firsthand how pervasive Phragmites outcompeted what precious few native plants remained. The researchers behind this project advocated management efforts that prioritized wetlands and restored native communities. Beyond that, they were scant on specifics.
There are few Eastern Shore wildlife managers that haven’t heard of Phragmites. The weed chokes out natives and creates a monoculture with virtually no wildlife habitat value; it also finds convenient inroads in the many coastal agricultural plots along the Chesapeake. One study found that combined management efforts spent upwards of $4.6 million on Phragmites control between 2005-2009, with 94 percent focusing on herbicidal efforts treating 80,000 hectares. Even more disturbing, the authors concluded there was no correlation between resources invested and management success. (Martin and Blossey, 2013) Clearly, we’re in need of a new approach, and preferably one that doesn’t involve treating our most vulnerable ecosystems with toxins. In my search for a better alternative, I found something astoundingly simple: livestock. A study out of Duke University found that controlled grazing by goats and other livestock could effectively reduce Phragmites cover by about half in just a three week period, meaning this low-cost treatment has the potential to outperform just about any herbicide. (Silliman et al., 2014) Giving farmers a low-cost, chemical-free alternative to control the spread of this invasive could turn the tides of the fight, and guarantee that we’ll always have a thriving, biodiverse marsh to protect.
While it might be met with some initial skepticism, I think farmers will jump at the chance to tackle Phragmites without contracting chemical companies. Conservation managers can divert already scarce funds elsewhere, and farmers can employ one another instead. Plus, we met a few goats in particular at Anderson Farm that seemed in need of a day job.
References: Kettenring, K.M., Whigham, D.F., Hazelton, E.L.G., Gallagher, S.K., and Weiner, H.M. (2015) Biotic resistance, disturbance, and mode of colonization impact the invasion of awidespread, introduced wetland grass. Ecological Applications 25(2): 466–480.
Martin, L.J. & Blossey, B. (2013) The runaway weed: costs and failures of Phragmites australis management in the USA. Estuaries and Coasts 36: 626. doi:10.1007/s12237-013-9593-4
Silliman BR, Mozdzer T, Angelini C, Brundage JE, Esselink P, Bakker JP, Gedan KB, van de Koppel J, Baldwin AH. (2014) Livestock as a potential biological control agent for an invasive wetland plant. PeerJ 2:e567 https://doi.org/10.7717/peerj.567