Bryophyte Vegetation and Habitat Gradients in the Tikhaia Bay Region, Hooker Island, Franz Josef Land, Arctic Russia

Abstract

A quantitative analysis of contemporary moss assemblages is presented for forty-seven bryophytes occurring in 31 sites in the Tikhaia Bay region of northwestern Hooker (Gukera) Island, Franz Josef Land Archipelago. Fifteen (31%) of these species were found in only one site and 7 (15%) species were found in only two sites. Two-way indicator species analysis, TWINSPAN, resulted in three major species groups. Canonical correspondence analysis, CCA, results showed species distribution patterns correlated with major environmental variables of moisture, slope, fertilized sites, and exposure. The three species groups are projected on the CCA ordination. Group 1 dominates steep, rocky, fertilized slopes with northern exposures while group 3 is at the other extreme of these variables. Group 2 is intermediate along these variables and spans the moist-dry habitat gradient. Bryophytes are an important component of the vegetated surfaces in the northernmost arctic islands. The large dome ice caps on the Franz Josef Land islands result in limited exposed terrestrial habitats. Most surfaces are covered by snow, ice, and glaciers. Only south-facing sites below active bird rookeries are dominated by vascular plant communities. The remaining vegetated surfaces in the exposed, ice-free sites are dominated by rich non-vascular plant communities. In contrast to only 57 vascular plants reported for the islands, a total of 102 mosses, 55 liverworts, and 115 lichens have been reported by Aleksandrova (1983). Her list of bryophytes for the archipelago was compiled using Fischer (1896), Hanssen and Lid (1932), Palibin (1903), Safronova (1983), Tikhomirov (1948), Tolmachev (1931), and Tolmachev and Shukhtina (1974). The first reports of bryophyte collections in the Archipelago were published as a result of the Jackson-Harmsworth Expedition in 1894-1897. Five bryophytes were identified (Fischer 1896). It was not until 30 years later that the Russian Sedow expedition of 1929 and 1930 explored the Archipelago. This more extensive study was published in Russian and summarized in French. It described 83 mosses and 7 liverworts (Savicz 1936). Simultaneously in 1930, the Norwegian sealer, Bratvaag, of Alesund explored Aleksandra and Prins Georga Islands. This expedition found a total of 25 taxa of bryophytes (Stormer 1940). This paper reports on results from the 1991 Norwegian-Russian-Polish expedition to the Tikhaia Bay region in Franz Josef Land. This was the first opportunity for a western botanist to enter the archipelago since 1930. The purpose of this study was, for the first time, to describe some of the environmental factors that influence bryophyte distributions in the extreme arctic habitats of Tikhaia Bay region in the Franz Josef Land Archipelago. To accomplish this goal all species of all the exposed major habitats were collected and seven environmental parameters were recorded. Further, the second purpose was to summarize the findings in the form of a multivariate analysis. The resulting species-environment relationships are inferred from community composition data and associated environmental scalar values.