Invasive Species in the Chesapeake Watershed
What is Phragmites australis?
Phragmites australis, or Common Reed, is a perennial, coarse wetland plant that can be described as having
Its feathery and drooping inflorescences (clusters of tiny flowers) are purplish when flowering and turn whitish, grayish or brownish in fruit. Flowering occurs from July to October. The stalks are characteristically tough.
Recent work (Saltonstall 2002) has begun to distinguish the presence in North America of both native North American haplotypes and European haplotypes of P. australis Blossey (2002a) suggests the possibility that these native and introduced P. australis may have distinctive morphologic characteristics; these issues are discussed in more detail below.
P. australis is a cosmopolitan plant, occurring throughout temperate North America. Duke (1978; 1979) describes suitable P. australis habitat as
The common reed occurs in and near fresh to brackish wetlands, tolerates and even thrives in alkaline and acidic wetlands, with some populations tolerating salinities as high as 40 ppt (Marks et al. 1994). P. australis is a highly successful colonizer in that it propagates in several ways, by seed dispersion and rhizomes and stolon fragments. Marks et al. (1994) suggest that established stands of P. australis propagate primarily through vegetative reproduction.
Temperature, salinity and water levels affect seed germination. Marks et al. (1994) report that water depths of more than 5 cm and salinities above 20 ppt prevent germination and germination improves as salinity decreases. Germination is unaffected by salinities below 10 ppt. Germination success increases with increasing temperature from 16 to 25_C, while the time required for germination decreases from 25 to 10 days over the same temperature range.
P. australis colonization is commonly associated with disturbed marsh areas, which usually means areas where plant communities, hydrology and topography have been altered through natural events (e.g., storms, lightning strike fires) or anthropogenic events (e.g., logging, mining, waste disposal, intentional flooding, dredge spoils disposal). The plant can tolerate standing water, low oxygen levels and acidic sediments, which allow it to thrive in disturbed habitats often unsuitable for other plants (Marks et al. 1994; Bart and Hartman 2000). Numerous studies report on changes in disturbed marsh hydrology with the development of P. australis stands (see Marks et al. 1994; Chambers et al. 2002). Other researchers (Ailstock 2001; Bart and Hartman 2000; Burdick and Konisky 2002) suggest that P. australis has been successful in establishing itself, in part, because of an ability to modify disturbed habitats into conditions highly conducive to its further propagation and establishment.
Paleoecology studies of peat samples show that P. australis has grown in New England tidal wetlands for at least the last 3,000 years (Orson 1987). Many researchers (Blossey 2002a; Norris et al. 2002; Rice et al. 2000) note that during the 1900s in parts of North America, P. australis rapidly expanded its range and successfully invaded fresh and brackish wetlands, substantially altering the landscape of the coupled marsh-estuary system (Lathrop et al. 2002). Although there is ongoing debate and research to understand the apparently recent invasiveness of this species, many concur with the view of Marks et al. (1994) and Roman et al. (1984) that this population expansion may be partially driven by human activities that have led to habitat destruction, sedimentation, eutrophication, and decreased oxygen levels in water and sediments in marsh areas. Recently, concern has also been growing that the use of constructed wetlands to replace natural wetlands (lost to development) may compromise the function and value of the wetland ecosystem because constructed wetlands are susceptible to invasion by P. australis (Havens 2000; Havens 2002).
Concurrent with the observed expansion of P. australis , there has been discussion that the invasiveness of P. australis in North America over the last century may be attributable to the introduction of more aggressive European genotypes (Blossey 2002b; NJMSC 2002). Questions over this issue prompted genomic research to determine whether there were differences in genotype among stands of North American P. australis. Saltonstall (2002) recently reported the present-day existence of native North American haplotypes (lineages) and of introduced European haplotypes in North American stands of P. australis. These findings are summarized by Blossey (2002a) and reported here.
Current research (Blossey per. comm. 2002) is investigating whether the native and non-native genotypes are morphologically distinctive. These findings may further our understanding of the occurrence, colonization and expansion of P. australis in North America and the broader issue of what role genomic differences within species may play in species invasiveness.
Where is P. australis Found in the Chesapeake Bay Watershed?
P. australis is now the dominant macrophyte in a wide variety of intertidal environments in the Chesapeake Bay (Stevenson and Rooth 2002) and in freshwater nontidal wetlands (Ailstock et al. 2001). The species is not on the Maryland noxious weed list (Bean per. comm. 2002). U. S. Fish and Wildlife Service (USFWS) aerial surveys over tidal marshes in Maryland and Virginia from 1995 to 1997 detected 8,500 acres of P. australis in 4,138 sightings in Maryland's wetlands along the Chesapeake Bay. The largest patches of P. australis occur in dredge spoil areas. The greatest extent of P. australis in natural marshes was in the lower Eastern Shore from the Nanticoke River south to the Pocomoke River, the northern Eastern Bay and Chester River area, Baltimore Harbor, C&D Canal, and Aberdeen Proving Grounds (Forsell and Gerlich 2000).
The distribution map indicates areas where P. australis is reported in Pennsylvania. Highest concentrations occur in the southeast corner of the state along the Delaware estuary system.
Occurrence of P. australis is widespread in eastern Virginia and in some areas of western Virginia. A 1995 to 1997 aerial survey found over 1,700 acres of P. australis in more than 1,500 sightings in Virginia's wetlands along the Chesapeake Bay (Forsell and Gerlich 2000). These data show the largest patches of P. australis are located in or near dredge spoil areas and highly disturbed marshes. Areas with the greatest extent of P. australis in natural marshes were the upper Eastern Shore south of the Pocomoke River, on the lower James River, marshes near Tappahannock and the lower Pamunkey River (Forsell and Gerlich 2000). In 1995, the Nature Conservancy and the (USFWS) conducted an aerial survey to map P. australis in the interior of the barrier islands and along the mainland upland/salt marsh ecozone from Assawoman Creek south to the mouth of the Chesapeake Bay (Truitt 1996).
Overview of Management Efforts
Many jurisdictions in the United States are concerned about the rapid invasion of P. australis and the threat it may pose to biodiversity and ecosystem function. The reed can be considered a noxious weed and management of it is often aggressive. Several studies (Warren et al. 2001; Meyerson et al. 2000; Chambers et al 1999) report that stands of P. australis are not conducive to the establishment of other plant species and that colonization of disturbed wetland areas by P. australis usually ensures the development of a P. australis monoculture stand. Beyond this common lack of plant species diversity in P. australis -dominated wetlands, other aspects of ecological change are less clear, which suggest considerable differences may exist between P. australis colonies
Some researchers (Chambers et al. 1999; Osgood et al. 2002) report that P. australis invasion of tidal freshwater wetlands results in a reduction in insect, avian and other animal assemblages; however, other researchers found little or no difference in macroinvertebrate populations and mummichog foraging between P. australis marsh and nearby marsh not invaded by this reed (Fell et al. 1998). In addition, Parsons (2002) found that P. australis provided critical habitat for nesting wading birds in Delaware Bay. Able and Turner (2002) suggest any future faunal work should consider the status (variables such as spatial variation, tidal range, elevation, history of disturbance, etc.) and chronology of the P. australis invasion and control for these variables in studies and when making management decisions. Because of differences in scientific findings, some researchers (e.g., Campana and Perry 2000; Rooth and Stevenson 2002) argue that P. australis can be critical for armoring shoreline against erosion and may increase freshwater marsh accretion; their argument suggests the potential importance of these needs for management of marsh landscapes.
Given these scientific uncertainties, valuable research efforts could focus on the ecological benefits and losses associated with P. australis and the appropriate criteria to use when developing management strategies for P. australis wetlands. Two recent symposia focused on science and management strategies for P. australis (VDCR 2000; NJMSC 2002). Presentations and discussions at these meetings suggest the importance of considering adaptive management strategies for P. australis . At NJMSC (2002), the recent identification of native and non-native genotypes and the potential for differences in their invasiveness (Blossey 2002a, 2002b; Saltonstall 2002) was discussed with regard to P. australis management. It was noted at the meeting that management options might vary depending on the lineage of a particular stand of P. australis as well as its setting and invasion history. Morphologic differences (if confirmed) and invasive behavior differences between genotypes could be further important factors to consider when developing P. australis management decision strategies.
Control and Eradication of P. australis
The technical report "A summary of methods for controlling Phragmites australis" by Norris et al (2002) provides a review of current control methods for P. australis. Additional control methods are discussed at the web site www.invasiveplants.net.
Management Efforts within the Chesapeake Bay Watershed
Maryland initiated aPhragmites chemical (Rodeo) control program in 1995 with state landowners. As part of a legislatively mandated program, landowners who have substantial stands of P. australis that are deemed to significantly threaten the preservation of valuable wildlife habitat are allowed to control P. australis on their own property (Maryland General Assembly, SB65 1996). Maryland offers landowners a 50% cost share and coordinates the program through the Department of Natural Resources in cooperation with the Maryland Department of the Environment. In 1999, over 200 landowners participated in the program. Landowners cannot receive more than $12,000/year and DNR cannot spend more than $60/acre on control (Maryland General Assembly, SB65, HB 535). The mandating legislation, SB65, has no appropriation, so in 2001 funds were provided by MDE ($10,000) and the Governor's Office ($25,000 allocated to be spent over two years). These funds provided support for control of about 400 acres of P. australis on private lands in Dorchester, Wooster, Somerset and Wicomico Counties (Hindman pers. comm.; MDDNR 2002). A Landowner's Guide is distributed by the Maryland DNR to encourage participation in the program (www.dnr.state.md.us/wildlife/phrag.asp).
Maryland DNR also applied herbicide (Rodeo) by helicopter to 400 acres of P. australis on state-owned Wildlife Management Areas on the Eastern Shore during 2001(Maryland DNR 2002). P. australis management on public lands is supported by the Maryland Waterfowl Stamp Fund, about $30,000 was spent on treatment in 2001.
Other work in Maryland on management of P. australis included a five-year study of the effects of chemical controls on P. australis and the abilities of the reed to propagate in disturbed and vegetated soils (Ailstock et al. 2001). The sites were located in Cecil County (upper Chesapeake Bay) and Dorchester County (lower eastern shore). The former site received chemical and chemical and burn treatments in 1987 and 1988. At the Dorchester County location – three sites – vegetated, burned and bare soil (with seeds added) were studied. As with the studies discussed above, the effectiveness of the control program was ambiguous, leading the researchers to conclude, in part, that "control programs must be evaluated on an individual basis to achieve the goals of enhancing biodiversity" (Ailstock et al. 2002).
Maryland also has a demonstration area near Grasonville, Maryland, where P. australis is controlled and a wetland is being restored. The Department of Agriculture also does some P. australis control through a ditch spraying program (L. Hindman pers. comm.).
Efforts to control P. australis in Pennsylvania include work by the Pennsylvania State Parks to treat limited acreage with herbicide. On Presque Isle State Park in the Lake Erie area the State Parks department has an ongoing applied research program on control management strategies (John Melei pers. comm.). P. australis is not on the Pennsylvania noxious weed list and thus not managed by the state's Department of Agriculture (Leo Dunn pers. comm.).
In Virginia, P. australis is considered an invasive species and is on the Virginia Department of Conservation and Recreation's advisory list, which is a non-regulatory list. P. australis received the highest "invasiveness" ranking on the list (VDCR 2001). Cooperative efforts through partnerships between the state agencies, federal agencies, academia, private landowners and non-governmental organizations have resulted in a number of P. australis control and management efforts in the coastal bay areas, including Parramore and Hog Island (Curtis Hutto pers. comm.). A control and restoration demonstration project on 600 acres of the Hog Island Wildlife Management Area by the Virgina Department of Game and Inland Fisheries reported P. australis reduction after two years of treatment; however, cessation of treatment resulted in P. australis recolonization within a year (Askins 2000).
Efforts primarily driven by the Rappahannock Phragmites Action Committee, a public-private coalition to raise awareness about P. australis , started a small, coordinated herbicide control spraying effort for private landowners in the Rappahannock area (Wellford 2000). This ongoing program is currently supported by the U.S. Fish and Wildlife Service (Curtis Hutto pers. comm.). Other efforts include a monitoring and control research program covering about 11 acres at the Dameron Marsh Natural Area Preserve in Northumberland County, Virginia. This program started in 2000, is planned to run until 2004 and is funded through the Wetland Trust Fund (Curtis Hutto pers. comm.).
Able, K.W. and R.E. Turner. 2002. Fish, food, space andPhragmites: A review of the faunal responses to an invasive species, (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop, p.17. New Jersey Marine Sciences Consortium Workshop Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.*
Ailstock, M.S., C. M. Norman, P.J. Bushmann. 2001. Common Reed, Phragmites australis: Control and effects upon Biodiversity in freshwater nontidal wetlands. Soc. for Ecol. Restoration.
Askins, G. 2000.Phragmites management at Hog Island Wildlife Management Area by the Virginia Department of Game and Inland Fisheries, abstract. InPhragmites in Virginia: A Management Symposium. December 14, 2000. Virginia Department of Conservation and Recreation.
Bart, D. and J.M. Hartman. 2000. Environmental determinants of Phragmites australis expansion in a New Jersey salt marsh: an experimental approach. Oikos 89(1):59-69
Blossey, B. 2002a. Biological control of non-indigenous plants. Cornell University: http://www.invasiveplants.net/phragmites.
Blossey, B. 2002b. Replacement of native North American Phragmites australis by introduced invasive genotypes. BEN, no 284: www.ou.ed/cas/botany-micro/ben/ben284.html.
Burdick, D.M. and R. Konisky. 2002. Understanding success of Phragmites australis as it exploits human impacts to coastal marshes (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop, p.5. New Jersey Marine Sciences Consortium Workshop Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Campana, M. and J.E. Perry. 2000. Functional roles of Phragmites australis in tidal freshwater marsh communities, (speaker abstract). InPhragmites in Virginia: A Management Symposium. December 14, 2000. Virginia Department of Conservation and Recreation.
Chambers, R.M., D.T. Osgood, D. J. Bart and F. Montoalto. 2002.Phragmites invasion and expansion in tidal wetlands: Interactions among salinity, sulfide and hydrology, (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop, p.7. New Jersey Marine Sciences Consortium Workshop Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Chambers, R.M., L.A. Meyerson, and K. Saltonstall. 1999. Expansion of Phragmites australis into tidal wetlands of North America. Aquatic Botany 64:261-273.
Duke, J.A. 1983. Handbook of Energy Crops, unpublished.
Duke, J.A. 1979. Ecosystematic data on economic plants, Quart. J. Crude Drug Res. 12(3-4):91-110.
Duke, J.A. 1978. The quest for tolerant germplasm. Crop tolerance to suboptimal land conditions. ASA Special Symposium 32, p.1-61. Am. Soc. Argon. Madison, Wisconsin.
Fell, P.E., S.P. Weissbach, D.A. Jones, et al. 1998. Does invasion of oligohaline tidal marshes by reed grass, Phragmites australis (Cav.) Trin. ex Steud., affect the availability of prey resources for the mummichog, Fundulus heteroclitus L.? Jour. Exper. Mar. Bio. Ecol. 222: 59-77.
Forsell, D. and L. Gerlich. 2000. Distribution and abundance ofPhragmites in estuarine wetlands in Virginia's portion of the Chesapeake Bay (speaker abstract). InPhragmites in Virginia: A Management Symposium. December 14, 2000. Virginia Department of Conservation and Recreation.
Havens, K. 2000. Phragmites australis invasion of constructed wetlands and mechanisms to prevent recolonization (speaker abstract). InPhragmites in Virginia: A Management Symposium. December 14, 2000. Virginia Department of Conservation and Recreation.
Havens, K., W.I. Priest, III and H. Berquist. 2002.Phragmites expansion into constructed wetlands: Are we mortgaging our wetland future (abstract)? InPhragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop. p.11. New Jersey Marine Sciences Consortium Workshop, Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Lathrop, R. G. and L. Windham. 2002. DoesPhragmites expansion alter the structure and function of marsh landscapes? Patterns and processes revisited (abstract). InPhragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop, p.12. New Jersey Marine Sciences Consortium Workshop Jan 6-9, 2002. Cumberland County College, Vineland ,New Jersey.
Meyerson, L.A., K. Saltonstall, L. Windham, E. Kiviat and S. Findlay. 2000. A comparison of Phragmites australis in freshwater and brackish marsh environments in North America. Wetlands Ecology and Management 8:89-103.
Osgood, D.T., D.J. Yozzo, R.M. Chambers, S. Pianka, J. Lewis, and D. Jacobson. 2002. Factors controlling nekton habitat utilization patterns withinPhragmites and non-Phragmites marshes (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop, p.14. New Jersey Marine Sciences Consortium Workshop Jan 6-9, 2002, Cumberland County College, Vineland New Jersey. p.14.
Parsons, K.C. 2002. Reproductive success of wading birds utilizing Phragmites marsh and upland nesting habitats (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop. p.14. New Jersey Marine Sciences Consortium Workshop, Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Marks, M., B. Lapin, and J. Randall. 1994. Phragmites australis (P. communis): threats, management and monitoring. Natural Areas Journal 14:285 - 294
MDDNR. 2002. Phragmites Control Legislative report - 2001. Maryland Department of Natural Resources, prepared by Donald Webster and Edith Thompson. 8p.
NJMSC. 2002. Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop (abstract). p.39. New Jersey Marine Sciences Consortium Workshop, Jan 6-9, 2002. Cumberland County College, Vineland, New Jersey. 39p.
Norris, L., J.E. Perry, K.J. Havens. 2002. A summary of methods for controlling Phragmites australis. VIMS Wetlands Program Tech. Rep.
Orson, R.A. 1999. A paleoecological assessment of Phragmites australis in New England tidal marshes: changes in plant community structure during the last few millennia. Biological Invasions 1: 149-158.
Purdue. 1998. Phragmites australis (Cav.) Trin. Ex Steud. Description
Rice, R., J. Rooth, and J.C. Stevenson. 2000. Colonization and expansion of Phragmites australis in upper Chesapeake Bay tidal marshes. Wetlands 20(2):280-299.
Roman, C.T., Niering, W.A., and Warren, R.S. 1984. Salt marsh vegetation change in response to tidal restriction. Environmental Management 8:141-150.
Rooth, J.E. and J.C. Stevenson. 2002. The influence of 5- and 20-year old Phragmites on rates of accretion (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop, p.16. New Jersey Marine Sciences Consortium Workshop, Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Saltonstall, K. 2002. Kryptic invasion by non-native genotypes of the common reed, Phragmites australis, into North America. Proc. Nat. Acad. Sci. 99: 2445-2449.
Saltonstall, K. 2001. A set of primers for amplification of noncoding regions of chloroplast DNA in the grasses. Molecular Ecology Notes 1:76-78.
Stevenson, J. C. 2002. The influence of 5- and 20-year old Phragmites populations on rates of accretion, (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop. p16. New Jersey Marine Sciences Consortium Workshop, Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Stevenson, J. C. and J. Rooth. 2002. Historical and ecological perspectives of Phragmites australis in the Mid-Atlantic landscape (abstract). In Phragmites australis: A Sheep in Wolf's Clothing? A Special Technical Forum and Workshop. p16. New Jersey Marine Sciences Consortium Workshop, Jan 6-9, 2002. Cumberland County College, Vineland New Jersey.
Truitt, B. 1996. Low altitude remote sensing and mapping ofPhragmites utilizing videography, Abstract, Virginia Coast Reserve Long Term Ecological Research All Scientists Meeting, January 1996.
VDCR. 2000.Phragmites in Virginia: A management symposium, (peaker Abstracts). Library of Virginia, December 14, 2000, Virginia Department of Conservation and Recreation.
VDCR. 2001. Invasive Alien Plant Species of Virginia, Virginia Department of Conservation and Recreation and Virginia Native Plant Society, www.dcr.state.va.us/dnhl/.
Warren, R.S., P.E. Fell, J.L. Grimsby, E.L. Buck, G.C. Rilling, R.A. Fertik. 2001. Rate, 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.
Wellford, A.S. 2000. Protecting wildlife habitat in a private marsh (speaker abstract). Phragmites in Virginia: A Management Symposium. Library of Virginia, December 14, 2000. Virginia Department of Conservation and Recreation.
The Nature Conservancy Elemental Stewardship Abstract for Phragmites australis Common Reed.
Phragmites australis (Cav.) Trin. ex Steud
Phragmites: Common Reed
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Last modified October 10, 2012