The Microflora: Composition , Biomass, and Environmental Relations

Tundra micro flora show the same low species diversity evident among the plants and herbivores. Two groups with broadly different dynamics dominate the micro flora: rapidly changing bacterial populations that typically degrade smaller molecular compounds and more slowly changing fungal populations that are more capable of degrading larger molecules. The accumulation of orga,nic matter in tundra systems reflects historical imbalances between production and decomposition. This chapter presents an overview of the composition , abundance and diversity of decomposer populations in the coastal tundra at Barrow as related to soil characteristics previously described (Chapter 7). Activities of the microflora are treated in Chapter 9. The overview presented is unavoidably influenced by the isolation methods employed (Table 81). The usual cautions appropriate to interpretations of micro floral isolations apply. Isolation techniques select only a portion of the total viable flora. Microorganisms that grow readily on artificial media and appear to be dominant may not be dominant in their natural habitat. Similarly, fungi that fruit prolifically in the field may not contribute the greatest biomass of active vegetative cells. Therefore , the orientation of this discussion is broadly functional rather than strictly taxonomic, particularly when bacterial groups are being discussed. The bacteria are examined as they contribute to transformations of carbon , nitrogen and sulfur , whereas fungi are treated in more taxonomic detail.