Giant Grass may come under control
by Fred Schueler and Aleta Karstad
|"Autumn Phragmites" oil painting by Aleta Karstad|
Highway 416 east of Kemptville Ontario is totally lined with tall, plume-headed reed grass, and if you don't remember having seen it before the highway was twinned, you're not mistaken! This is Phragmites australis subspecies australis, the Common Reed of Europe, and it wasn't documented by museum specimens in eastern Ontario before 1976.
At the University of Toronto, Fred's Ph.D. outside minor was systematic botany, and his project was hybridization between the native Broad-leaved Cattail, Typha latifolia, and the now-thought-to-be-invasive Narrow-leaved Cattail, Typha angustifolia.
Through the 1970s and 1980s we tracked roadside stands of these species and their hybrid, Typha x glauca, all across Canada from eastern Ontario to Haida Gwaii. As the years went by, we seemed to notice more and more Phragmites among the Cattails, and in the early 1990s we decided these were increasing and began to record their positions.
Our first local database record was on 25 Aug 1992, a “roadside stand” in Grenville County, County Road 18, 2 km SE McRoberts Corner, topo mapped at 44.82601N 75.63968W. This is now an 87 m stand along a marsh and swamp, GPS centred at 44.82687N 75.63937W. It is flanked by 80 and 30 metre stands along the road in woods to the south, and 37 and 34 metre stands along a tilled field to the north.
|Heads of native (coarser/sparse) and invasive (fluffy/fine) Phragmites from along the Thousand Islands Parkway, 3 km ESE of Mallorytown, 23 January 2016.|
A major theme of the presentations was the amazingly well adapted rhizome system. We learned how the hollow, wire-tough, deep-probing, barrier-straddling rhizome system of Phragmites, allows the above-ground parts of the plant to attain as much as ten times the biomass of the marsh flora it displaces. The rhizomes probe as deeply as 70 cm into the soil, carrying oxygen that sustains them and their roots in reducing muds, and leaking oxygen which mineralizes both deep soil nitrogen and poisonous sulphides. The rhizomes help this giant invasive grass to survive many attempts to control the species. They're a dispersal mechanism when the shore is torn up by hurricanes, and they may push through the water of wide ditches that have been dug to contain them, as well as probing 10 m or more over the surface of the soil in a single season. They may also reach down into fresh water tables beneath the salty surface water, and translocate nutrients to new plants many metres into sulphide-rich dredging spoils where the pH is as low as 2.8, as well as other inhospitable environments where unsubsidized plants could not exist.
At this coastal conference, Phragmites was regarded as requiring fresh water conditions, but when freshwater marshes were discussed they were still likely to be tidal. So there was none of the Ontario talk of Phragmites' spread being due to road salting. There was also little mention of non-marsh invasions along roadside ditches, or the upland populations that infiltrate the woods around Montreal and Syracuse. We heard how “Phrag” had, in the past, been planted by Army Corps of Engineers to stabilize spoil banks and shores in places where it's now invasive.
The bombshell of the conference for us was to hear that the features we had noticed in northwestern Ontario and Renfrew County Phragmites clones match those that occur in demonstrably native strains. We'd described our northwestern Ontario stands as being broader-leaved than the usual invasive clones, with the leaves held in a pinnate array, sparser-headed, forming relatively open stands, and turning bright orange-yellow in the fall. Our Renfrew County stands had broad leaves, large, lax heads. and all the leaves dead in October when most roadside clones were still largely green. So it seems that native forms of Phragmites had persisted in Canada, while most of the Phragmites in the eastern states belonged to the European haplotype 'm'. Fred was very shy at this meeting, where we didn't know a single soul, and his only spoken comment was that Phragmites isn't invasive solely in mid-Atlantic tidal wetlands - the meeting had ignored the extensive northern and supra-tidal portions of the continent, where Phragmites was widespread and often invasive, as well as the northern tidal marshes where it's not yet invasive.
This eye-opening conference inspired our quiet campaign of warning Maritimers of the possibility that Phragmites may take over their tidal wetlands as it has in the eastern US and in parts of Quebec - and British Columbians of its threat to the Okanagan.
Fossils show that Phragmites has been in North America for thousands of years, even featuring conspicuously in some samples of Ground Sloth dung, but they only became invasive in the later 20th Century. As Phragmites was spreading across wetlands throughout the United States in the 1990s, at Yale University Kristin Saltonstall was analyzing the chloroplast DNA of living plants and herbarium specimens, finding that the invading stands were genetically the same as European Reeds.
Once the DNA had shown the way, visible characteristics of the two kinds in southern Ontario and New York were described by Bernd Blossy and Paul Catling: stands of natives are less dense, with other plants growing among them. Natives have narrower rhizomes (<15mm diameter) and a red or purplish colour on the upper portions of the sections (internodes) of their lower stems, which are smooth or even polished, in contrast to the rough texture and yellowish colour of the lower stems of the invaders. The seedhead parts, especially the “lower glume” of the natives are larger (>4.2 mm) than those of the invaders. The natives have been described as Phragmites australis subspecies americanus, and since only a few hybrids have been identified, they may, in fact, be separate species that rarely interbreed.
Kristin Saltonstall wasn't able to find any surviving native Phragmites in Connecticut, where the coasts are blanketed with the invaders. In southern Ontario natives still survive, though they've mostly lost the roadsides to the invaders. In Grenville County, Fred has found natives in each of the headwater wetlands between the Rideau and the St Lawrence. Along northern Ontario highways there are more stands of natives than of invasives, and no one knows how far the invaders will spread. You can see the natives fringing the St Lawrence marshes along the Thousand Islands Parkway, along the Fly Creek Road west of North Augusta, and beside O'Neill Road just west of Rock Road, north of Oxford Station.
It's now been worked out that the invasives arrived on the United States mid-Atlantic coast by 1910. In 1954 Fred took a shortcut through a tall Phragmites stand in coastal Connecticut, to get to his first grade school. By 1960 it had spread inland to New York, and our Uncle John has pointed out to us where the first stand was along US Interstate 81 in Syracuse. It proceeded to dominate the highway landscape in New York State, line the southern shores of Lake Ontario, and spread along Lake Erie's shoreline to Pennsylvania and Ohio - then into southern Michigan and southwestern Ontario.
Since the invasive Phragmites arrived in eastern Ontario it has become abundant along 400-series Ontario highways and along such roads as the Dwyer Hill Road, Old Hwy 16 (Co Rd 44) north of Kemptville, and Co Rd 20 west of Hwy 416. These latter stands seem to have originated during the paving roads around 1987, probably from the stand on the North Branch of the South Nation River that Aleta painted on 10 October 2011. Since 1999 we've been measuring each year's tallest stem in this stand (Co Road 20/North Branch South Nation River, 1.2 km ENE East Oxford, 44.91985N 75.63640W. Early measurements were the length of the stem from the highest roots to the tip of the seedhead, later ones to the base and tip of seedhead: 1999 [dry year] 410 cm, 2000 [wet year] 390 cm, 2001 [very dry year] 366 cm, 2002 [dry fall] 380 cm, 2003 [wet year] 385 cm, 2004 [very wet year] 344-374 cm, 2005 [wet year] 363 cm, 2006 [wet year & dry August] 403 cm, 2007 391 cm, 2008 [very wet year] 336 cm, 2009 340-369 cm, 2010 [neither wet nor dry] 354-394 cm, 2011 [wet early and dry later] 367-397 cm, 2012 [drought year] 368-399 cm, 2013 383-412 cm, 2015 [wet year] 370-404. The least growth in height seems to occur in the wettest years with this anecdotal classification of the years. We (and our neighbour Bob Woolham as well) remember this stand since at least the early 1980s, so it may be one of the earlier stands in eastern Ontario.
Like many other invasive plants, the frightening thing about invasive Phragmites is the way it spreads from places disturbed by people into a wide range of habitats: wet and dry roadsides, disturbance-opened forests, and oldfields, as well as its traditional wetlands habitat. These tall stands profoundly modify their environment. Nothing else grows in the dense stands, the fallen leaves blanket the soil, the matted growth fills small streams and channels, and the roots extract more nitrogen from the soil than anyone has been able to explain. The wind blowing across broken stems pumps air into the huge twisted rhizomes, to oxygenate and change pH and nutrient availability deep into the ground.
It's thought that Phragmites spreads by germination of the tiny seeds in mineral soil disturbed by earth-moving or along streams or beaches, or more usually, from sprouting fragments of stems, rhizomes or stolons, carried by currents or equipment. Once it's established it spreads steadily by underground rhizomes, or may leap across the ground with surface stolons. The stand on Cooper Road and Typhair Lane in Limerick Forest (44.85490N 75.64777W) went from 10 metres in 1993, to 50 m in 2005, and to 68 m in 2010, crossed Typhair Lane around 2013, and is now 53 m along the road and 70 m deep, the full width of the wetland.
While Phragmites is mostly a roadside problem in eastern Ontario, it has invaded and taken over vast areas of wetlands and beaches in the southwestern portions of the province, and there's a Phragmites Working Group of citizens and organizations working to control it. On 26 April, this group and the Ontario Invasive Plant Council held a workshop on “Best Management Practices for Roadside Control of Invasive Phragmites,” in Belleville, where Fred & Judy Courteau were the only participants from east of Kingston. Almost all the other attendees were roads and drainage staff and Conservation Authority or MNRF biologists, with a couple of park & municipal biologists.
One of the major frustrations of Phragmites control in southwestern Ontario is that the pesticides that are used pretty successfully to control the invader in flooded wetlands in the adjacent US are not registered for use in Canada. Janice Gilbert, the biologist for the Ontario Phragmites Working Group, who has the most experience with controlling the species, emphasized the to need to have a plan for dealing with each particular situation, and explained the danger of re-sprouting from nodes of apparently dead stems, or from rhizomes that may penetrate as much as 10 m into the ground, and cautioned that "Emergency registration" of pesticides is a very slow process.
Colin Cassin of OPIC led discussion of the Council's Clean Equipment Protocol which tries to limit the movement of seeds, rhizomes, and stems from one site to another on vehicles and other equipment. Problems were raised regarding taking high pressure/temperature cleaning equipment out to worksites, and contamination of the central workplace if the cleaning is done there.
The main control method used on invasive Phragmites is application of herbicide: we heard a presentation on a new formulation which leaves the stand looking intact but just prevents regrowth in the following spring, and how aerial application would be used over big stands in wetlands.
Murray Purcell of the Ministry of Transportation spoke about action taken in surveying and controlling along all provincial highways west of Guelph; Lu-Ann Marentette, Drainage Superintendent for Leamington, described the struggle to get general buy-in and co-operation for a control effort when a diversity of agencies and individuals control different stretches of a drainage system, and Nancy Vidler, of “Lambton Shores Phragmites Community Group” described how tall stands obscuring the real-estate-valued views of a lake can rouse popular action. She also pointed out the need to be alert to new sorts of Phragmites-promoting disturbance, such as wind turbine farms, and to write the control of invasives into their contracts.
At the Belleville workshop, focused as it was on "best management practices", Fred became alarmed by the apparent lack of concern for preserving native Phragmites while the invasives are being controlled. It is imperative for municipal and agency staff, as well as landowners, to learn to identify and appreciate the glassy-stemmed, wispy-plumed natives in their efforts to control the rough stemmed fluffy-plumed invasive.
The herbicide treatment currently used in southwestern Ontario involves spraying, crushing the stands, vigilant suppression of subsequent sprouts, and careful introduction of native replacement species. After safety, much of the concern for application is to make it look like the herbicide is not being applied. The main method of application has been within rotary mower heads as the stands are being mowed. Aerial application would be used over big stands in wetlands.
The thing that justifies the use of herbicides on invasive Phragmites is the vegetative nature of its spread - successful reproduction by seeds seems to occur only on exposed soil in the dense "seed-rain" near an establish stand. Once you take out an isolated stand, you've very largely protected many kilometres of roadside against recolonization. Due to the persistence of bits of rhizome around the periphery and deep in the soil, mechanical removal just doesn't work.
The only place in the United Counties of Leeds and Grenville where herbicide treatment of Phragmites is currently planned is a small stand of the invasive form at the edge of the botanically diverse Long Swamp Orchid Fen, north of Manhard. It was introduced in 2008 with replacement of a culvert, and in 2012 a backhoe removal failed to scoop out all of the colony.
Our own action items after the Belleville meeting were to (1) get back out to the stands in the Hydro Line through the Limerick Wetland E of Forsythe Rd that we waypointed in 2001 and 2004, to see how they have fared and check their native/invasive status; (2) measure how close the nearest other stand is to the invaders in the Long Swamp Fen; (3) urge South Nation Conservation to consider controlling the invasives in the Letrim wetland; (4) urge Parks Canada to consider taking out the scattered invasive stands along the Thousand Islands Parkway; (4) do some local publicity about the status of the species (this blog and its ancestral article).
There's little enough one can do to conserve the natives in landscapes dominated by invasive Phragmites: the lovely shining red stems of decorative natives in a roadside ditch are unlikely to soon replace Bluebird houses as the public sign of a conservationist household. But we've only known for a decade about the difference between the kinds, the natives are decorative, their open stands do benefit wildlife, they'd be just as useful as the invaders in waste treatment lagoons, and dispersal is the limiting step in their spread. With the new herbicide treatments the big stands of the invaders may perhaps be reduced, disturbed soil and roadsides can be patrolled for invasive shoots, and newly constructed ponds and wetlands can be inoculated with native Phragmites to pre-empt invaders - so maybe a modest investment in recognition and favouritism will sustain our native reeds into the future, while keeping the invaders under control.
For more on identification, see the identification page from Cornell University. Paul Catling of Agriculture and AgriFood Canada, reports on identification and the Canadian situation in Botanical Electronic News, (or google "site:http://www.ou.edu/cas/botany-micro/ben/ catling phragmites") Much of this text is derived from Fred's comments at Aleta's painting blog.
The most thorough treatment of the Canadian invasives is Paul M. Catling and Gisèle Mitrow. 2011. Major Invasive Alien Plants of Natural Habitats in Canada: Phragmites australis (Cav.) Trin. ex Steud. subsp. australis, European Common Reed (often just called Phragmites) (scoll down to the bottom)
The Ontario Invasive Plant Council Best Practices Library (scroll down to Phragmites)
SUGGESTED TEXT FOR CITATION:
Schueler, Fred, and Aleta Karstad 2016. Giant Grass may come under control.
Doing Natural History http://doingnaturalhistory.blogspot.com/2016/05/giant-grass-may-come-under-control.html
- posted 16 May 2016 by Aleta Karstad.