Bolander’s quillwort (Isoetes bolanderi) COSEWIC assessment and status report: chapter 7
Habitat
Isoetes bolanderi grows in unshaded, upper subalpine to alpine ponds and small lakes. Both Canadian sites occur within the Upper Subalpine Ecoregion (Achuff et al. 2002), with the Summit Lake site at 1950 m and the historic, Carthew Lakes site at 2200 m. Isoetes bolanderi sites appear to be associated with clear, oligotrophic water supporting little or no associated vegetation within Isoetes stands. The water at Summit Lake is somewhat calcareous (pH 7.3), but was the least basic of 21 lakes with pH values examined during 2002 and 2003, which ranged from pH 7.4 to 9.1 (Appendix 1). The substrate around Isoetes roots, a 3-14 cm layer of silt and silty-sand over a coarser sand, is likely more acidic than pH 7.3. Isoetes bolanderi plants appear to occupy most of the bottom of Summit Lake and occur in shallow water to a depth of at least 1.5 m (Smith and Bradley 2003).
The subalpine habitat of Isoetes bolanderi in Canada apparently has been stable for many decades. However, in recent decades, the forests on the slopes surrounding Summit Lake have changed due to the death of many whitebark pine (Pinus albicaulis) from white pine blister rust (Cronartium ribicola), an introduced disease. No effect on the I. bolanderi population has been noted.
The Summit Lake population occupies a relatively stable, shallow-water situation and is not directly affected by an inlet stream, intensive wave action or other dynamic site elements. Physical impact by large ungulates has been noted but these appear to be localized events. No water level controls are present.
It is not known if habitat change was involved in the extirpation of the Carthew Lakes population. The status and trend of Isoetes bolanderi habitat in the USA is unknown.
The existing and historically known locations of Isoetes bolanderi in Canada are entirely within Waterton Lakes National Park and the species is protected by the Canada National Parks Act and Regulations, which provide for the protection of flora, including prohibiting removal, damage or destruction of plants. Isoetes bolanderi has been identified as a special feature within Waterton Lakes National Park (Achuff 1997) and has been recognized for special consideration in planning and environmental assessment, including the most recent Park Management Plan (Parks Canada 2000).
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