262 F. L. Bunnell et al. 



The Basidiomycetes and Ascomycetes, including the Discomycetes, 

 which dominate the mycoflora, are distributed among 17 families includ- 

 ing 30 genera and about 1 10 species (Kobayasi et al. 1967, 1969, Miller et 

 al. 1973, Laursen 1975, Laursen et al. 1976). In the Deciduous and Con- 

 iferous Forest Biomes one would expect at least 50 families and not less 

 than 250 genera. The number of species would be variable but the total 

 would range from 400 to 1200 species or more, depending on the com- 

 plexity of the plant community (Miller and Farr 1975). 



Most species that are mycorrhizal associates of the coniferous or 

 woody dicotyledonous plants are rarely encountered or are absent in tun- 

 dra. Their absence is due in large part to the reduced higher plant flora. 

 Similarly, the vast numbers of wood-rotting fungi (Aphyllophorales: 

 Basidiomycetes) encountered in other Biomes are reduced to three spe- 

 cies in the Barrow research area. One, Thelephora terrestris, is mycorrhi- 

 zal and the other two, Polyporus elegans and Thelephora anthocephala, 

 are decay organisms on the few woody substrates present, such as stems 

 of Salix and Cassiope. Basidiomycete decomposers on leaf and litter 

 substrates such as Galerina subannulata and Naematoloma (Hypho- 

 loma) udum are apparently dominant and found fruiting in large num- 

 bers. It is noteworthy that basidiolichens are represented by four species: 

 Omphalina ericetorum, O. hudsoniana, O. luteovitellinia and Multi- 

 clavula mucida. For many years the only lichenized Basidiomycetes were 

 thought to be the small groups in the tropics (Poelt 1973). While there are 

 still only about 20 species known (Letrouit-Galinou 1973), they are clear- 

 ly more cosmopolitan than initially thought. 



The taxonomic information for fungi as well as bacteria documents 

 a diversity much reduced from that of the microflorae of temperate 

 regions. A portion of the reduction, in particular among the Phycomy- 

 cetes, appears associated with lower temperatures while reduction in sub- 

 strate diversity further limits mycorrhizal and wood-rotting fungi. 

 Aquatic fungi, which exploit the common moist areas, show less reduc- 

 tion in diversity; 15 genera and 26 species are present. 



The relative dominance of the Basidiomycetes in numbers of species 

 and the relatively high contribution they make to the total fungal bio- 

 mass at Barrow is in contrast to subarctic tundra sites (Pildt and Nann- 

 feldt 1954, Rail 1965) and to temperate regions (Miller et al. 1975, Laur- 

 sen 1975). The reason, in part, is their role as mycorrhizal symbionts of 

 arctic plants (Miller and Laursen 1978). It is also possible that the more 

 versatile, dikaryotic hyphal system of the Basidiomycetes has enabled 

 many of these species to adapt physiologically to the rigorous environ- 

 mental conditions of the Arctic. In contrast the monokaryotic hyphal 

 system of many yeasts and imperfect fungi as well as ascomycetes may be 

 less versatile and therefore less responsive to environmental stress. 



