Mosses Associated with Waterfalls in Central Labrador, Canada

Abstract

One hundred and thirty moss species (including 20 new to Labrador) were collected within reach of spray from four subarctic waterfalls in central Labrador. The floristics, ecology, and phytogeography of these species are discussed, along with possible reasons for the enriched bryoflora of spray zones. Some northern and some southern mosses appear to be restricted to spray zones in central Labrador, but the majority of spray zone species belong to a wide-ranging north temperate-subarctic element. The spray zone environment tends to favour snow-bed mosses, the more calciphilic mosses, and hydrophilic mosses, and allows bryophytes to successfully outcompete lichens as the dominant cryptogams in these restricted sites. Polytrichastrum alpinum (Hedw.) G. L. Smith var. brevifolium (R. Br.) Brassard is a new combination. In 1970 and 1971 I spent several months investigating the bryophyte flora of central Labrador, centred around Churchill Falls (Fig. 1). The most intensive work was done in the vicinity of Churchill Falls (within the zone reached by spray from the falls) and in spray zones of three other waterfalls in the same general area (Fig. 2). This paper presents a list and assessment of the mosses associated with these subarctic waterfalls, and the importance of such microclimatic enclaves to the bryoflora of central Labrador as a whole. A separate paper now in preparation will treat the liverworts in similar fashion. Few parts of central Labrador have been investigated for bryophytes. Crum and Kallio (1966) reported the only substantial list of mosses and liverworts from this area. As was to be expected, my studies have added several species to the known bryoflora of Labrador and numerous species to the bryoflora of the Churchill Falls region. The present paper, however, deals only with mosses directly associated with spray zones of waterfalls; in general these have a bryoflora much more diverse than that of the surrounding spruce-Cladonia woodland and subarctic taiga. It is these small humid oceanic oases within the continental subarctic taiga which have provided most of the additions to the bryoflora of the region. 1 Studies in Biology from Memorial University No. 347. I thank the International Biological Programme, the National Research Council of Canada (Grant A-6683), and Memorial University for financial support. The Churchill Falls (Labrador) Corporation provided logistic support which greatly facilitated the field studies. I also thank Dr. Howard Crum, Dr. Timo Koponen, Dr. Dale Vitt, and Mr. Harry Williams for identifying difficult specimens. Dr. Victor Snieckus and Mr. Ed Delaney provided assistance with some aspects of the field work. 2 Department of Biology, Memorial University, St. John's, Newfoundland, Canada. This content downloaded from 157.55.39.157 on Fri, 08 Jul 2016 04:31:57 UTC All use subject to http://about.jstor.org/terms 1972] BRASSARD: MOSSES OF LABRADOR WATERFALLS 517