Phragmites
Samie Hermann & Mallory Munden
Introduction
Our wetlands are under attack.
To the untrained eye, many wetland systems across the nation look lush, green, and healthy. However, if you look closely you will discover a war is being fought right before your eyes. The war between the resisting natives and the taunting invasives.
Phragmites, also known as the common reed, is a perennial species of marsh grass. While a native subspecies exists (subspecies americanus), this page focuses on the more prominent and dominate invasive subspecies (subspecies australis).
This tall grass can reach upwards of 15 feet and is often topped with a fluffy plume. It grows in dense groups, crowding out native plants and wildlife alike (Bohling, 2018). This page will discuss how this invasive species came to be a common part of the wetland ecosystem and why they are so successful in the war they wage on the natives.
Taxonomy
Scientific name:
Phragmites australis
Common names:
Phragmites, common reed
(PHRAGMITES, 2007)
Full Taxonomic Classification
(Lansdown, 2017)
Phragmites is a member of the family Poaceae, the true grasses. It is fast growing and blooms with white flowers in the summer. It is listed as a species of least concern by the IUCN (Phragmites australis, n.d.)
Niche and Habitat
The native and invasive phragmites habitats overlap. Phragmites can be found in tidal and non-tidal wetlands, fresh and salt water marshes, and around lakes and rivers. Invasive phragmites also takes advantage of exposed soil and high nutrient areas such as roadsides, or construction areas ( Swearingen, & Saltonstall, 2010).
Phragmites is a widespread plant that can be found throughout the continental US as well as in Providences in Canada. The green map is a visual representation of the distribution of native phragmites, while the red map depicts the distribution of the invasive phragmites. Both maps where acquired from Phragmites Field Guide (Swearingen, 2010).
This species is found throughout North Carolina marsh systems. The photograph to the left is an image of a phragmites field in Carolina Beach State Park. Even the protected and highly monitored ecosystems, such as those within state parks, can be heavily impacted by this species.
Evolutionary History
European forms of phragmites was introduced along the Atlantic coast of the United States in the early 1800's (Saltonston, 2011). The invasive phragmites quickly became a successful primary producer in the US mainly because of its reproductive abilities and physical attributions.
Reproduction: Phragmites can spread both by wind pollination and vegetative propagules (Saltonstall, 2011). Propagules is where a part of the vegetation can become detached and give rise to a new plant. Phragmites utilizes three propagules methods: seeds, rooted shoots, and rhizome fragments (Ailstock, Norman, & Bushmann, 2001). Once established, phragmites is extremely difficult to eradicate.
Physical attribution: Phragmites is able to dominate most any ecosystem it is introduced to because of is physicality. Phragmites can rapidly grow up to 15 feet tall blocking the sun for the lower vegetation. Phragmites also grows in dense thickets inhibiting other vegetation to take root.
Environmental Impacts
Since Phragmites is invasive, it outcompetes native plants in the marsh such as cordgrasses. By taking over space typically occupied by various native plants, Phragmites can reduce plant diversity and productivity (Invasive species, 2017). Additionally, the thick growth can prevent movement of animals and prevent the formation of tidal channels that serve as valuable habitat and feeding grounds for birds, fish, and invertebrates (PHRAGMITES, 2007).
Not all ecological impacts of Phragmites are negative. It was previously hypothesized that increasing the abundance of Phragmites would impede the ability of marshes to stabalize shorelines, store carbon, and maintain plant diversity. However, recent research suggests that increasing the abundance of Phragmites in a natural marsh does not impact these important ecosystem services (Lee and Theuerkauf, 2017).
Conservation
Invasive Phragmites arrived from Europe in the 19th century and rapidly spread through human development and transportation advancements in the 20th century (PHRAGMITES, 2007). Phragmites thrives in disturbed habitats; 93% of the invasion is driven by shoreline development disturbances (Invasive species, 2017). Once the plants root, they can cause visual obstructions, block trails, and reduce recreational opportunities by reducing fish and bird populations. Additionally, the large amount of leaf litter created by die-offs each fall creates fuel for fires (PHRAGMITES, 2007).
Efforts to control and remove Phragmites are complicated and costly. Mowing and burning are largely unsuccessful and digging up the plant requires heavy machinery and expertise. Specialized herbicide application is successful in controlling Phragmites by preventing growth, but preventing the spread of the plant is a top priority. This is best accomplished by keeping wetlands in their natural state or reverting those spaces as close to their natural state as possible (PHRAGMITES, 2007).
Friends or Foes?
Phragmites has an ability to quickly and easily spread throughout a region; it has out-competed many native marsh plants. Phragmites not only distributes itself on a wide geographical region, but it typically has a higher biomass, growth rate, and reproductive output than most native marsh plants, earning the title "most aggressive introduced species across the region" (Saltonstall, K. 2011).
The dominate phragmites is able to out-compete the native vegetation, causing a decrease in habitat biodiversity and creating a less than ideal habitat for the native fauna such as birds. Control programs will have to be established to reduce phragmites and increase the plant diversity in these systems (Ailstock, 2001).
Videos
Web Resources for Audience to Explore
The bottom of this page from the NC Coastal Federation contains a hyperlink to download the presentations about Phragmites from the 2017 Phragmites working group meeting. These presentations discuss management strategies.
This information sheet from the US Forest Service explains the general biology and featues of Phragmites, how it was introduced, and how it is controlled.
This encyclopedia entry provides a comprehensive overview of Phragmites australis including additional data and media.
This journal article from the official journal of the Annals of Botany Company reviews 40 years of methods to manage invasive Phragmites.
This page describes a project funded through NOAA to use forensic techniques to understand genetic variation in spreading Phragmites.
Resources
Bohling, M. (2018, September 25). Invasive Phragmites australis: What is it and why is it a problem? Retrieved from https://www.canr.msu.edu/news/invasive_phragmites_australis_what_is_it_and_why_is_it_a_problem
Invasive species experts discuss ways to address Phragmites in North Carolina. (2017, August 9). Retrieved from https://www.nccoast.org/2017/08/phragmites-workshop/
Lansdown, R.V. 2017. Phragmites australis (amended version of 2015 assessment). The IUCN Red List of Threatened Species 2017: e.T164494A121712286. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T164494A121712286.en.
Lee, E., & Theuerkauf, S. (2017, May 9). Coastwatch Currents. Retrieved from https://ncseagrant.ncsu.edu/currents/2017/05/uncovering-an-invaders-multiple-rolesphragmites-in-the-n-c-coastal-reserves/
Phragmites australis (Cav.) Trin. ex Steud. (n.d.). Retrieved from https://eol.org/pages/1114576/data
PHRAGMITES: Questions and Answers. (2007, November). Retrieved from https://www.fws.gov/gomcp/pdfs/phragmitesqa_factsheet.pdf
Saltonstall, K. (2011). Remnant native phragmites australis maintains genetic diversity despite multiple threats. Conservation Genetics, 12(4), 1027-1033. doi:10.1007/s10592-011-0205-1
Swearingen, J., & Saltonstall, K. (2010). Phragmites field guide: distinguishing native and exotic forms of common reed (Phragmites australis) in the United States. Plant Conservation Alliance, Weeds Gone Wild. Weeds Gone Wild.
Ailstock, M. S., Norman, C. M., & Bushmann, P. J. (2001). Common reed phragmites australis: Control and effects upon biodiversity in freshwater nontidal wetlands. Restoration Ecology, 9(1), 49-59. doi:10.1046/j.1526-100x.2001.009001049.x