ISBN 82-7420-044-6. ISSN 0800-6865.
The macrofungal species composition and its relationships to ecological factors and vegetation were investigated in a boreal coniferous forest area. Macrofungi were recorded in 99 16-m2 macroplots, each divided into 16 subplots of 1 m2. Presence/absence of each species was recorded in every subplot and frequency in 16 subplots was used as abundance measure. Two 1-m2 plots within each macro plot had previously been analysed with respect to vascular plants, bryophytes and macrolichens. All plots were provided with measurements of 36 environmental variables. Parallel DCA and two-dimensional LNMDS ordinations of macroplots identified the same two coenocline axes. One more coenocline axis identified by DCA was also possible to interpret ecologically. The first fungal coenocline corresponded to the main coenocline for vegetation, comprising the variation from pine to spruce dominated forests; from ridge via slope to valley bottom. This coenocline is interpreted as the response to two independent complex-gradients: (1) a topography-soil depth complex-gradient in the pine forest, and (2) a complex-gradient in soil nutrient status in the spruce forest. While macro-scale topographic variables were relatively more strongly correlated with the vegetational coenocline, soil pH and nitrogen content were more strongly correlated with the fungal coenocline. It is argued that the soil moisture deficiency hypothesis, i.e. that species differ in drought tolerance, proposed as an explanation for variation along the main vegetational coenocline in pine forests, also applies to pine-forest macrofungi. The responses of macrofungi and plants to edaphic conditions in spruce forest were found to differ in one important respect: while plants common on poor soils are normally present also in richer sites, many macrofungal species were absent or rare there. Reasons for this are discussed. The second coenocline (only identified by DCA), only relevant for the spruce forest, reflected the variation from bryophilous fungal species that avoided sites with dense deciduous litter to saprotrophic species living on incompletely decayed Populus and Betula litter and ectomycorrhizal fungi associated with deciduous trees. The third coenocline strongly correlated with median soil moisture and also related to fine-scale canopy closure was interpreted as due to a fine-scale paludification gradient. The correspondence between ordination results obtained for fungi and plants demonstrates (1) that distributional patterns of macrofungi and plants within forests to a large extent (but not completely) are caused by the same major environmental complex-gradients and (2) that the same field and analytical methods are applicable to both groups of organisms.
Keywords: Boreal coniferous forests, DCA, Environmental factors, Fungi, Gradient, LNMDS, Macromycetes, Mycorrhiza, Norway, Ordination.
Egil Bendiksen and Vegar Bakkestuen, Norwegian Institute for Nature Research, P.O. Box 736 Sentrum, N-0105 Oslo, Norway
Rune H. Økland, Botanical Museum, Univ. of Oslo, P.O. Box 1172 Blindern, N-0318 Oslo, Norway, and Norwegian Institute of Land Inventory, P.O. Box 115, N-1430 Ås, Norway
Klaus Høiland, Department of Biology, Division of Botany and Plant Physiology, University of Oslo, P.O. Box 1045 Blindern, N-0316 Oslo, Norway
Odd Eilertsen, Norwegian Institute for Nature Research (present address: Norwegian Institute of Land Inventory)