| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 417 November 12, 2009 | aceska@telus.net | Victoria, B.C. |
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Figures 1 & 2: http://bomi.ou.edu/ben/417/ben417_figures.pdf
The California Sword Fern, Polystichum californicum (D.C. Eat.) Diels, was first reported from British Columbia and Canada by Wagner (1979) based on the specimen that W.B. Anderson collected on Texada Island in August 1897. Until Wagner's 1979 revision of the genus Polystichum, W.B. Anderson's specimen (a small single frond) had been consistently misidentified as Polystichum scopulinum (D.C. Eat.) Maxon.* In August 2007, Terry Ludwar found a single plant of P. californicum on a rock wall in Maple Bay, north of Favada Point (Ceska et al. 2009). This plant had contorted leaves, probably as a result of the exposure to salt spray: http://bomi.ou.edu/ben/402/polystichum_californicum_photos.pdf and http://www.ou.edu/cas/botany-micro/ben/ben402.html#2
During the summer of 2008, James Mack and John Wood discovered a new site of Polystichum californicum at the wall of rock cliffs at the southwestern base of Surprise Mountain on Texada Island. In October 2009, the authors visited this site and found altogether 18 plants of this species. This population consisted of healthy plants with several young plants scattered along the rock wall for approximately 90 m. This site is about 3 km ESE of the single plant in Maple Bay that was reported earlier in BEN.
Polystichum californicum (D.C. Eaton) Diels - Dryopteridaceae Canada, British Columbia: Texada Island, Van Anda municipality, limestone rock walls at SW slopes of Surprise Mtn. 49° 43.22´ N. 124° 35.89´ W. UTM 10U 384810 E 5508761 N (NAD 83) elev.100 m. In fissures of limestone rock (Quatsino Formation) at the contact with basalts of the Karmutsen Formation. With Rubus ursinus Cham. & Schlecht. and Poa marcida A.S. Hitchc. Collection date: October 11, 2009 Collectors: Adolf & Oldriska Ceska, Helen Atthowe, James Mack, & John Wood Coll. No.: A&OC # 35000 (UBC) [2 fronds] Identified: Adolf & Oldriska Ceska - October 2009 [Photo confirmed by D.H. Wagner]
*[Note: this species was originally published on 11/12/09 as Polystichum setigerum (K. Presl) K. Presl.; corrected on 12/6/09 by -AC]
The Phragmites database at the Global Biodiversity Information Facility Website has recently been accessed at a rate of more than 50 times a week.
It is possible to go directly to the 297 records of Phragmites australis (Cav.) Trin. ex Steud.subsp. australis by following: http://data.gbif.org/species/16140669, or for 920 records of Phragmites australis subsp. americanus Saltonstall by following http://data.gbif.org/species/15940058, or to see all Canadian Phragmites (1634 records of both subspecies including 417 plants not identified to subspecies) follow http://data.gbif.org/datasets/resource/526/
The data are based on material that we have examined, verified and annotated in 20 herbarium collections and museums across Canada including ACAD, ALTA, CAN, DAO, MMMN, MT, MTMG, NSPM, QFA, QUE, SASK, TRT, TRTE, UBC, UNB, UPEI, UWO, V, WAT, and WIN (acronyms from Holmgren et al. 1990 and Holmgren 2005).
Research, some of which is published (Robichaud and Catling 2003, Saltonstall et al. 2004, Catling 2006, Catling et al. 2007) has established that Phragmites australis subsp. americanus differs from subsp. australis in having shorter first glumes and that glume length is strongly correlated with colour of lower stem internodes. Older collections and those from native habitats consistently have red lower internodes suggesting that this is characteristic of the native subspecies (e.g. Catling et al. 2007). In preparing the database all specimens with clearly red or reddish-purple lower stem internodes were referred to subsp. americanus, whereas all specimens with yellow internodes were referred to subsp. australis. Specimens without bases, of which there are many because plant collectors frequently collect only the reproductive portion of these tall plants, were identified using the following method which is based on a bimodal distribution of maximum lower glume length correlated with stem colour.
Using specimens with bases showing stem internodes and identifying them according to internode colour, we found that using the lower glume limit of 4.3 mm, the misclassification rate is approximately 6.7%. However, other limits can be selected by assigning individuals in the overlap zone to the category of "unknowns" and this was done for identification of specimens in the database. All plants with lower glumes under 3.8 mm long were assigned to Phragmites australis subsp. australis, with the result that 0.3 % of subsp. americanus (identified on basis of stem colour) would be misidentified. Thus P. australis subsp. australis in the database is fairly reliably identified. All specimens with lower glumes over 4.2 mm long were assigned to subsp. americanus which would result in 6.6 % of plants possibly referable to subsp. australis being misclassified. However, these misclassification rates may be based on rare mutants lacking red pigment or to hybrids. This method resulted in 15.8 % of specimens with only inflorescences being unidentified (as a result of occupying the overlap zone).
About half of the plants in the database (approx. 850) are without basal
stems so being able to identify the majority of these reliably using glume
length is useful in providing much additional data. Being able to identify
plants on the basis of glume lengths is also valuable in winter and spring
when stem internodes are not available. Of course plants collected in autumn
with lower stems and mature inflorescences are the best for identification.
Internode colour appears to be the most important character but is not
infallible (Catling et al. 2007) so that using other characters that
nevertheless overlap somewhat is helpful in determining the reliability of
an identification. The following key (Catling et al. 2007) appears to be the
most reliable for identification of Canadian plants. For information on how
these are distinguished from other species elsewhere in the world, see
Catling (2007).
We appreciate the extensive help of Ms. Lynn Black with databasing. Derek
Munroe and Guy Baillargeon assisted with making the database available
through GBIF.
Using the NatureServe ranking system (Morse et al. 2004) Phragmites
australis subsp. australis has been ranked as the top priority invasive
alien plant in Canada (Catling 2005). Although there have been relatively
few detailed studies of its impact on native biodiversity, the
circumstantial evidence for a huge impact is very strong since the plant now
occurs in many thousands of places previously occupied by a rich assemblage
of native species. A few examples of observations and studies in eastern
Canada indicate a very broad spectrum of impacts:
(1) St. Lawrence River wetlands: Of the invasive alien plants of wetlands of
the St. Lawrence River in Quebec, Phragmites austratlis was found to be
highly competitive and to have a greater impact on native plant biodiversity
than any of the other invasives present including purple loosestrife
(Lythrum salicaria L.. ). Studies of the impact of common reed on
biodiversity in the St. Lawrence region of southern Quebec are ongoing.
http://www.phragmites.crad.ulaval.ca/EN/projetsEn.asp
(2) Long Point Biosphere Reserve on Lake Erie: This area contains some of
the most important habitats for staging waterfowl in the Great Lakes.
Naturally the loss of native wetland vegetation here is a great concern. In
2003 P. australis subsp. australis was expanding in this area at a rate
of 50% per year (Meyer 2003). Based on a study of aerial photographs taken
from 1945 to 1999, Wilcox et al. (2003) found that four kinds of vegetation
had been extensively reduced by Phragmites australis subsp. australis
(Typha marsh, marsh meadow, sedge/grass hummock, and mixed emergents). In
a detailed study of impact on animals, Meyer (2003) found that the
development of dense stands of P. australis subsp. australis reduced
numbers of Swamp Sparrows, rails, waterfowl, Northern Leopard Frogs, and
Fowler's Toads but benefitted Least Bitterns, Red-winged Blackbirds,
warblers, meadow voles and shrews.
(3) Lake St. Clair marsh and wet prairie: Here P. australis subsp.
australis is threatening the habitat of the endangered Eastern Prairie
Fringed Orchid, Platanthera leucophaea (Nutt.) Lindl., and other rare
native prairie plants. It appeared here in early 1990's. Following decline
of the orchid, an invaded area was sprayed with glyphosate and later burnt
resulting in effective control and dramatic growth of the rare native
orchid. Without this decisive action, this population of an already
threatened species would have probably been eliminated. There has been
substantial loss of native marsh vegetation and particularly cattails to
Phragmites australis subsp. australis over the last few decades and
some useful methods of demonstrating decline have been developed on the
basis of studies in the Lake St. Clair region (Arzandeh & Wang 2003, see
also Pengra et al 2007).
(4) Fens: A number of fens in New York State have been taken over by
Phragmites australis subsp. australis with the loss of all native
vegetation (pers. obs.). It has taken over 27% of the open area of Bergen
Swamp, one of the most biodiversity-rich wetlands in the state. Not
surprisingly it is regarded as a threat to a large, attractive silk moth
(Hemileuca sp.) that is very rare and confined to a few fens in New York
State and Ontario: http://www.dec.ny.gov/animals/38944.html &
http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Hemileuca%20sp.%201
Fens are unusual on the landscape and contain many rare and
restricted species. The loss of Ontario fens (Minesing, White Lake, Hayes
Bay, Stoco, etc) to P. australis subsp. australis seems inevitable
without intervention based on the situation in New York, and it would likely
lead to the extirpation or serious endangerment of many species of plants
and animals.
(5) Farmland in eastern Ontario and southwestern Quebec: Phragmites
australis subsp. australis is invading cereal crops in parts of eastern
Ontario and southern Quebec, in some cases reducing yield by up to 50% on
parts of the cultivated land. Near St. Grégoire it has competed successfully
with corn along field edges eliminating 3 rows of corn (specimens in DAO,
P.M. Catling pers. obs.).
(6) St. Lawrence River estuary: Between 2003 and 2005 (Phragmites
australis subsp. australis was observed expanding in the tidal marshes at
Rivière du Loup and La Pocatière. It expanded through the upper marsh to
the edge of the Spartina alterniflora Loisel. zone. Species displaced by
the advancing stand comprised of P. australis subsp. australis alone
included Agropyron spp., Carex spp, Chenopodium spp., Convolvulus
sepium L. , Eleocharis spp., Festuca rubra L., Hierchloe odorata (L.)
P. Beauv., Juncus balticus Willd., Potentilla anserina L., Scirpus
spp., Solidago sempervirens L, Spartina patens (Aiton) Muhl. , and S.
pectinata Link (specimens at DAO 804213, 791517, P.M. Catling, personal
observation).
(7) Lake Huron shoreline: In a recent survey of Phragmites australis
subsp. australis in this area, Bickerton (2007) found the plant to be in
the early stages of invasion along a full 60 km of coastline. It was not
present in this area during a survey of coastal vegetation in 1975 (pers.
obs.) and is believed to have established beginning in 2002 based on
discussions with residents. Alarmingly, in this area it is growing on sandy
beaches and dunes, even with Dune Grass (Ammophila breviligulata Fern.).
Replacement of many kinds of native vegetation was reported (Artemisia
campestris L., Elymus canadensis L., Eupatorium spp., Scirpus spp.
Typha spp.). Wasaga Beach Provincial Park has recently developed an action
plan to deal with alien Phragmites which is considered a threat to the
endangered Piping Plover, since the bird requires open sand, which is being
replaced by dense stands of Phragmites australis subsp. australis.
Although there is no comprehensive list of the number of native North
American species negatively impacted by Phragmites australis subsp.
australis, it would probably be a substantial compilation (thousands).
Despite this, there are some success stories and innovative controls. One of
the more interesting is the use of grazing to control Phragmites in the
habitat of the endangered Bog Turtle in North Carolina
(http://www.edf.org/documents/3778May2004.pdf). Others are the success of
manual control by underwater cutting (Smith 2005) and a volunteer group
saving an important fen in Massachussetts (Martin 2001). Although P.
australis subsp. australis may have an extremely detrimental effect on
biodiversity overall, it is to be expected that in some situations, it will
benefit certain native species (see for example under Long Point above, and
Rodriguez 2006).
la. Lower stem internodes yellowish or yellowish-brown; lower glumes 2.6-4.2 (4.8) mm long; ligule of middle
leaf excluding fringe 0.1-0.4 mm high . . . . . . . . . . . . . . . . . subsp. australis (introduced)
lb. Lower stem internodes reddish-purple; lower glumes 3.8-7.0 mm long; ligule of middle leaf excluding fringe
(0.2) 0.4-0.9 mm high . . . . . . . . . . . . . . . . . . . . . . . . . . subsp. americanus (native)
Acknowledgements
Literature Cited
NOTES ON THE ACTUAL AND POTENTIAL IMPACT OF INVASIVE EUROPEAN COMMON REED (PHRAGMITES AUSTRALIS SUBSP. AUSTRALIS) IN EASTERN CANADA
From: Gisèle Mitrow & Paul M. Catling, Agriculture and Agri-Food Canada, Environmental Health, Biodiversity, Saunders Bldg., Central Experimental Farm, Ottawa, Ontario K1A 0C6 Canada [catlingp@agr.gc.ca]
Literature Cited
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