ISBN 82-7420-010-1. ISSN 0802-8478.
The study presents the results from an integrated approach to hydromorphology, species distribution, and ecological conditions in SE Fennoscandian bogs and poor fens. Patterns of distribution are observed on spatial scales ranging from 0.25 m2 to whole mires (1 km2), and the scope of the study extended to include the regional perspective. Detailed ecological studies studies are performed within a restricted part (0.3 km2) of one mire complex, N. Kisselbergmosen, Rødenes, SE Norway, while the distribution of plant species and hydromorphological mire types is studied within parts (1000 km2) of Akershus and Østfold counties, SE Norway. Patterns are interpreted by use of multivariate techniques, in particular ordination by detrended correspondence analysis (DCA). On the scale of one mire, four complex-gradients are shown to account for most of the vegetational variation. The relative merits of different sampling procedures and classification systems are discussed. On a broader scale, gradient relationships of vegetation, hydromorphology and species distributions can mostly be ascribed to variation in thermal and hygric factors, often operating in conjunction. Their effects on the vegetation are often mediated by differential water supply. Structuring factors in boreal mires are discussed, and interspecfic interaction as well as abiotic factors are important. The importance of interactions is higher in the bottom layer in the field layer. On a fine scale, boreal mires are considered to conform to the patch dynamics theory of non-equilibrium coexistence of species. On a broad scale, boreal mires appear to be in a dynamic equilibrium with present climatic conditions east of the limit for the onset of erosion. The common conceptual basis for descriptive biogeography and vegetation ecology is emphasized. Arguments in favour of scaling ecological gradients in units of compositional turnover are forwarded, and the properties of one such scaling method, the nonlinear rescaling procedure in DCA ordination, is outlined. The advantage of an integrated approach to ecological problems is emphasized.
Keywords: Bog, DCA, Fennoscandia, Gradient scaling, Hydromorphology, Mire, Phytogeography, Vegetation.
Rune Halvorsen Økland, Botanical Garden and Museum, University of Oslo, Trondheimsveien 23B, N-0562 Oslo 5, Norway.