Eastern prairie fringed-orchid COSEWIC assessment and status report: chapter 7

Habitat

Eastern Prairie Fringed-orchid occurs in six types of habitat in Ontario some of which may be considered more important than others because they last longer and are more difficult to create and manage. The habitat types (particularly graminoid and shrub fen) may intergrade, but still provide a useful distinction when looking at the total range of habitat occupied by the species.

  1. Fens dominated by the sedge Carex lasiocarpa (e.g., sites 31, 24, 30, 10, 33).The latter 4 sites have been known for at least 35 years and are considered viable.These fens are often rather shrubby, with shrubs most commonly occurring on hummocks.The orchid is then usually found in the sedge-dominated hollows.
  2. Fens dominated by common reed grass (Phragmites australis) and sedges (e.g., sites 31 and 12).
  3. Boggy mats around lakes with sphagnum moss, heaths and cranberry, but not strongly acid and somewhat marly below the raised acid hummocks. Only one site (22) and possibly not long-lasting due to limited area.
  4. Cobble limestone shore.Only one site known (1) on Bruce Peninsula which has a long history. The lake has a broad, shallow shoreline which, depending upon beaver activity, is exposed annually.
  5. Wet mesic prairie with bluestems and other grasses and a high diversity of plants. The mesic and wet mesic prairie communities are largely confined to Lambton County and the St. Clair delta area and to the more limited area at Windsor (site 8). A description of these habitats is available in Faber-Langendoen and Maycock (1994).Brown (1985) lists plants associated with P. leucophaea at a site in Lambton County. These are long-lasting gradient habitats.
  6. Old fields with Poa compressa, Carex lanuginosa, Juncus spp., and early development of Cornus shrubs (e.g., sites 2, 3, 22). These habitats last for approximately 10 years before loss to succession.

An asterisk beside the site number indicates that the population is considered extant.Abbreviations under county are those employed by NHIC and are the first 4 letters. Sources include collections, literature references, and observations communicated via telephone (pers. com.) or via email (referenced). Observations from the year 2000 have been included under the 1990s column.

Table 1.Summary of Sites and Population Trend Data for Platanthera leucophaea in Canada
Site # County Location <1970
(number)
1970s
(number)
1980s
(number)
1990s
(number)
Sources
1* BRUC   1966 (sev doz.),
1967(0)
71(0),
78(900-1000)
80 (>300)
86(1)
91(3)
99(21)
00(114)
Collections made in 1934, 1950,1953 e.g. TRT 1396; Johnson (1990, pers. com. 1997); Cuddy et al. (1976); Kaiser (1994); Ford (1995); K. Young pers.com. 2000.
2* ESSE
A.
B.
- -
84(30-50)
84 (~150)
88(~10)
97 (30),
99(0)
97(0);
95(6)
97(1)
98(1)
M.Oldham pers.com. 1984; Ford (1995); V. Brownell obs. 1997,1999; B. Lebidich pers.com. 1997; Pratt pers. com. 1997, 2000.
3* ESSE   - - - 97 (3) V. Brownell obs. (1997)
4* ESSE   - - 86(~12) - G. Waldron obs. (NHIC database)
5 ESSE   - - 84(1) - M. Oldham obs. Probably lost to marina development.
6 ESSE   - - 80(8),
81(1),
84(0),
85(40)
97(0) M. Oldham pers. com. (1997); V. Brownell obs. (1997). Succession to thickets.
7* ESSE   - - - 95-96(2), 97(1) Pratt pers. com. 2000
8* ESSE A.
B.
- 76 (1) 83(5-6) 96(30)
99(1)
TRT 1936, Catling; Pratt (1979); A. Woodliffe pers. com. (1997); P. Pratt pers. com. (2000)
9 ESSE   1891(-) - - - DAO 171, Dearness
10* GREY   - 75(21+) 81(17)
87(14)
88(0)
89(3)
- TRT 1832 Reznicek; V.Brownell & M. Oldham obs. 1981; Johnson (1990, 1991).
11* KENT   - - - 91(36),
94(30-45)
97(7)
Discovered by John Haggeman, SCNWA, pers. com. 1997.
12* KENT   - - - 96
(245 fl., perhaps 1000 incl. veg.)
Discovered in late summer 1995 by A. Woodliffe, OMNR, Chatham. One of the largest populations in Ontario in last decade.
13 HURO   1892,
1900(-)
- - - J.A. Morton
14 LAMB (Site 1) 1898(-) - 84(2) - N. Tripp. Site partly destroyed & drainage altered by house construction in 1986.
15* LAMB (Site 2)
A.
B.
-
-

-
-
84-88
(~65)


97(1)
97(1)

Brownell obs. (1997)
16* LAMB (Site 3) - - 85(10-15)
86(65)
- Woodliffe & Allan (1996) note 12 plants. R. Brown recalls seeing ~65 plants in 1986. Usually about 10 plants seen.
17 LAMB (Site 4) - 77 82(0),
84(20-30)
- R. Brown obs. (1980s). Site lost in 1985 when converted to agriculture (Woodliffe & Allen 1996).
18* LAMB (Site 5) - 77(22)
78(19)
80(20)
83(35)
84(20)
- Brown (1985)
19 LAMB (Site 6) 1967
(5-8)
- - - Brown (1985). Searched for but not seen since.
20* LAMB (Site 7) - - 84(8-10)
87(7),
84-86(30-35)
97(1) Brown (1985), Woodliffe & Allen (1996), V. Brownell obs. (1997)
21* LAMB (Site 8) - - 84-86(5) 91(~6),
97(0)
Woodliffe & Allen (1996); R. Brown obs. (1991), V. Brownell obs. (1997)
22 LANA   1910-20 (-) - - - Morris and Eames (1929) (two Mud Lakes near Smiths Falls have been checked unsuccessfully in recent years)
23 LEED   1965(67) - 83(?) - CAN 301, Baldwin; DAO D65 Greenwood; Greenwood (1968), J. Robinson 1983 obs. (NHIC database)
24* LEED   1956 (-) 76(40),
78(9)
83 (~40) 97(42) 00(24+) DAO 171, Cody; Brownell obs. (1983, 1997, 2000). Obs. in 2000 incomplete due to post-anthesis.
25* LENN   - - - 94(2),
95(2),
97(0) 99(0)
T. Norris, OMNR, Kingston pers. com. (1997); DAO photo
26 MIDD   1887 (-) - - - W. Saunders HBC, UWO
27 MIDD A., B. (probably same as above) 1879
1896 (-)
- - - T. Burgess CAN 163
J. Dearness
28 NORT Murray Marsh ~1910(1-17) - - - Morris and Eames (1929)
29 NORT tamarac swamp near Port Hope 1910-20(-) - - - Morris and Eames (1929)
30* OTTA
A., B. (sub-populations are separated by approximately 1.5 km of largely unsuitable habitat (cedar swamp))

-

76(40)

84(40) 84(~100)

96(99+) 96(68), 00(202)
Reddoch (1977,1979);White (1985); Reddoch & Reddoch 1997); Cuddy pers. com. (2000). One of largest populations in Ontario in past decade. Cuddy estimated that in 1996 sub-population Aconsisted of between 400 and 1000 plants, but see textre. population estimates.
31* SIMC A.
B.
C.
1967-69 (1000-1500) ~75(500+) av.100-250 84 (100s) 88(0)
-
97(119) 99(97)
00(3)
99(19)
97(0)
CAN 371 Soper; Bobbette (1974); B. Ford, G. Allen, J. Gould obs. 1988; Ford (1995); V. Brownell, P. Catling & G. Allen obs. 1997. G.Allen & B. Bowles obs. 1999, 2000. One of the largest populations in Ontario, but numbers low in past decade. This may be partially due to undercounting as the site is difficult to access and find (Allen, pers. com.)
32 SIMC   - - 81(1) 97(0) TRT S. Varga; V. Brownell obs. (1997).
33* STOR   - - - 00(3), 00(2) Cuddy (2000), P. Catling obs.(2000)
34* YORK   - - 82(3fl.&~50nfl) 97(20). 00(8+) Varga obs. 1982; Brownell obs. (1997, 2000). Obs. in 2000 incomplete due to post-anthesis.

The Eastern Prairie Fringed-orchid is adapted to water level fluctuations. It may remain dormant or vegetative in areas that are either too wet or too dry along a gradient with fluctuating water levels. The problem now is that during periods of low water levels (particularly in the Great Lakes), agricultural cultivation extends further into the lower ground thus eliminating populations in the upper part of the gradient. Wet years result in flooding of cropland, rather than flooding of a natural habitat (see also Case 1987 p. 20).

Case (1987, p. 24) described an old field site in Michigan that was abandoned in 1964 after which a large population of P. leucophaea developed, which, however, had declined by 1976 as the area had become dominated by thickets of woody plants and by 1984, the population had gone. The duration of this site was thus approximately 10-15 years. A similar situation is described by Denny (1988) as follows: “Population decline is usually attributed to competition from invading woody plants. It has been observed that brush cutting, mowing, grazing, and fire all serve to set back competition from woody plants and stimulate flowering. ” In March 1979 and 1981, the Killbuck Wildlife Area in Ohio, which had been planted in corn until the mid-1970s, was burned to maintain field habitat for upland game species. In 1982, 387 flowering plants were discovered at the site. By 1986, however, less than 30 were present.

Denny (1988) notes as follows: This species “shows a marked preference to late-successional communities throughout much of its range. However, under certain conditions, these orchids apparently invade early-successional communities. They set seed freely and produce massive quantities of wind dispersed seeds”…”which appear capable of colonizing disturbed sites such as road embankments, lawns, and abandoned croplands where they tend to develop new populations relatively quickly. ” “Apparently adult plants can withstand and may even thrive on ecological disturbances. They tend to thrive in such situations until increased competition from other plants, or for some other unknown reason, population size is reduced. Clearly, there is much we have yet to learn about this elusive endangered species. ”

In fens where water levels fluctuate the succession is interrupted and restarted when shrubs are flooded out or die due to drying out or are burned. Rhizomes of these perennial orchids may survive these events below ground so that the populations do not actually disappear but only vary in their above ground appearance. The same is true of some prairie sites where either drought or high water prevent succession to shrub cover or domination by a few species, thus perpetuating an intermediate successional stage where the orchids can survive. Some of the sites in fens (e.g., site 31) or lake margins (site 1) fluctuate from hundreds or even thousands to none from year to year.

Additional information (to the 1984 status report) on habitat, including edaphic characteristics and associated species, is available in Bowles (1991) and Bender (1988).

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