Furbish's Lousewort Habitat Model
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Draft Date:
March 2001

Furbish's lousewort, Furbish's wood betony; Pedicularis furbishiae

Use of Study Area Resources:
Furbish's lousewort (aka Furbish's wood betony) is a federally endangered herb of the snapdragon (Scrophulariaceae) family. It is endemic to the St. John River Valley, and its entire range is limited to 225 km of the St. John River, extending from the town of Andover, New Brunswick (Canada) upstream to a point 2.4 km past the confluence with the Big Black River in Aroostook County, Maine (USFWS 1991). Occurrence information was provided by the Maine Natural Areas Program.

Habitat Requirements:
Furbish's lousewort grows in the zone subject to spring flooding and scouring by river ice and flood debris (Gawler 1983). It requires early- to mid-successional sites, relying on disturbance to open up new areas for colonization and to limit competing vegetation (USFWS 1991). It does not grow in undisturbed habitats that offer otherwise appropriate conditions, and has not been found on any tributaries of the St. John River (Gawler 1983). The majority of sites where it is found are limited to riverbanks facing northeast, north, northwest or west and above the average summer low water level (Gawler 1983, USFWS 1991). In a few cases successful populations occur on sites having east and southeast aspects (Gawler pers. comm.).

Suitable microhabitats include chunks of riverbank that have been undercut, and "slumped down from the higher parts of the bank" (Gawler 1983), damp, shaded areas below the treeline at the crest of the riverbank (Richards 1976), the slope at the foot of the steepest part of the riverbank, the gentle slope of the river-beach" (Gawler 1983), or wet, well-drained areas by seeps or rivulets (Richards 1976, Stirrett 1980 in Gawler 1983, Gawler 1983).

The majority of plants occur where canopy cover provides shade for most of the day (Richards 1976, Gawler 1983, Menges et al. 1985), competing vegetation is sparse (USFWS 1991), frequently on a mossy substrate (Menges et al. 1985). Studies found wide variability in suitable moisture levels and associated vegetation at sites where the plant is successful (Menges et al. 1983). High population growth rates with an associated high risk of local extinction are characteristic of plants growing on saturated, unconsolidated, gravelly substrate, versus lower growth rates and lower risk of local catastrophic extinction for populations on more stable, fine-textured silt deposits (USFWS 1991). These distinctions in sediments reflect the amount of energy in the river current at the time of deposition, and accordingly are also a measure of site stability.

Adjacent land covers are most often forests of the Eastern-Spruce-Fir association, and in a few cases forests of Aspen-Birch association, or a mixture of the two (Fish & Wildlife Information Exchange website, 1999).

This herbaceous perennial is known to be pollinated by only one species of bumble bee, Bombus vagans, and reproduces only by seed (Gawler 1983). A large number of seeds are produced, which drop beneath the parent plant and may form colonies or be distributed by wind and water (Environment Canada website 1999, Waller et al. 1987).

Furbish's lousewort is hemiparasitic - an obligate root parasite, at least at the seedling stage, but is not host specific (Macior 1978 in Gawler 1983, Gawler 1983, USFWS 1991). Experiments have shown that first-year plants did not survive overwintering unless their host was also perennial (Macior 1978 in Gawler 1983).

Appropriate soils consist of "well drained, calcareous sandy loams", with high calcium, low nitrogen and a pH ranging from 5.2 to 7.8, and more typically 6.6 or above (Macior 1978 in Gawler 1983, Brown 1982 in Gawler 1983, Hinds 1983). Soils of the St. John River Valley consist of thick glacial drift over Devonian age graywacke and Seboomook slate (Kite 1993 in USFWS 1991).

Habitat Mapping:
Habitat polygons were provided by the Maine Natural Areas Program, based on plant surveys and habitat delineations by Sue Gawler. Sites indicated to more consistently have higher numbers of plants were given a score of 1.0; sites hosting fewer plants and at more infrequent intervals, were assigned a score of 0.5. Downstream from these primary areas are a few scattered sites which had offered suitable habitat in the past. Because the downstream sites offer less favorable conditions overall, these sites were assigned a value of 0.3.

Environment Canada, Canadian Wildlife Service webpage dated 11/18/99 www.speciesatrisk.gc.ca/Species/English/SearchDetail.cfm?SpeciesID=179

Fish and Wildlife Information Exchange webpage http://fwie.fw.vt.edu/WWW/esis/lists/e705003.htm dated 12/10/99.

Gleason, H.A. and Cronquist, A. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, 2nd ed. New York Botanical Garden, Bronx, NY. p 486-487.

Gawler, S.C. 1983. Furbish's Lousewort (Pedicularis furbishiae S. Wats.) in Maine and its relevance to the Critical Areas Program. Planning report number 13. 69 pp.

Gawler, S.C. 1989. A demographic model for Pedicularis furbishiae, with implications for conservation strategies. (abstract only) Rhodora 91(865):153.

Hinds, H.R. 1983. Rare vascular plants of New Brunswick. 36 pp.

Kite, J.S. 1983. Late quaternary glacial, lacustrine, and alluvial geology of the upper St. John River basin, northern Maine and adjacent Canada. PhD. dissertation, University of Wisconsin, Madison, WI. 339 pp.

Macior, L.W. 1978. The pollination ecology and endemic adaptation of Pedicularis furbishiae S. Wats. Bulletin of Torrey Botanical Club 105:268-277.

Menges, E.S., S.C. Gawler and D.M. Waller. 1985 .Population biology of the endemic plant, Furbish's lousewort (Pedicularis furbishiae) 1985 research. unpublished report to the USFWS by Holcomb Research Institute, Butler University, 4600 Sunset Avenue, Indianapolis, IN 46208. 126 pp.

Richards, C.D. 1976. Furbish's Lousewort, Pedicularis furbishiae S. Wats., in Maine and its relevance to the critical areas program. Planning Report 13, State Planning Office, Augusta, ME. 9 pp.

Stirrett, G. 1980. The status of Furbish's lousewort, Pedicularis furbishiae S. Wats. in Canada and the United States. The Committee on the Status of Endangered Wildlife in Canada, Canadian Wildlife Service, Ottawa. 78 pp. Unpublished.

U.S. Fish and Wildlife Service. 1991. Revised Furbish Lousewort Recovery Plan. USFWS, Newton Corner, MA. 62 pp.

Waller, D.M., D.M. O'Malley and S.C. Gawler. 1987. Genetic variation in the extreme endemic Pedicularis furbishiae (Scrophulariaceae). Conserv. Biol. 1(4):335-340.