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Bryological and Lichenological Section/ABLS

Cleavitt, Nat [1].

Taking the high road: controls on altitudinal limits for two species of Mnium in the Front Ranges of the Canadian Rocky Mountains.

Factors determining the altitudinal limits of plants have been relatively well explored for many land plant groups, but not for bryophytes. Bryophytes typically represent a significant portion of alpine floras with many species specific to highland systems. Yet there has been no documentation of differences between highland and lowland bryophytes that could explain altitudinal limits in this group of land plants. In this study, a subalpine and a lowland moss were reciprocally both planted as apical fragments and transplanted as adults between sites at 1400m and 2000m in the Front Ranges of the Rocky Mountains, Alberta over three field seasons. The lowland species, Mnium spinulosum, was less tolerant of conditions at 2000m than the subalpine species, M. arizonicum, was to conditions at 1400m. In particular, M. spinulosum had lower regeneration from both apical fragments and spores at higher elevation sites. Both species had significantly lower establishment during the abnormally cold growing season of 1999, but M. arizonicum was able to respond by adjusting investment in regeneration. In addition to physiological aspects of altitudinal limits, the possibility of competition from dominant feather mosses at lower elevations was tested for M. arizonicum. Establishment of M. arizonicum was lower in Hylocomium mats than on bare humus regardless of site elevation; however, stem survival in adult transplants was higher in Hylocomium mats than in Mnium dominated microsites at the higher elevation. Differences in the regeneration abilities of a highland and a lowland species in the genus Mnium were able to explain the respective altitudinal restrictions of these species. In the adult stage, the possible existence of facilitation between species represents a promising line of inquiry into the ecology of bryophytes growing at higher elevations.

1 - Cornell University, Natural Resources, 8F Fernow Hall, Ithaca, New York, 14853-3001, US

reciprocal transplant.

Presentation Type: Paper
Session: 47-1
Location: Magpie (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 8:30 AM
Abstract ID:81

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