sommerfeltia 30 Bendiksen, E., Økland, R.H., Høiland, K., Eilertsen, O. & Bakkestuen, V. Relationships between macrofungi, plants and environ­ mental factors in boreal coniferous forests in the Solhomfjell area, Gjerstad, S Norway 2004 is owned by the Natural History Museum and Botanical Garden, University of Oslo, and edited by its botanical departments. SOMMERFELTIA is named in honour of the eminent Norwegian botanist and clergyman Søren Christian Sommerfelt (1794-1838). The generic name Sommerfeltia has been used in (1) the lichens by Flörke 1827, now Solorina, (2) Fabaceae by Schumacher 1827, now Drepanocarpus, and (3) Asteraceae by Lessing 1832, nom. cons. SOMMERFELTIA is a series of monographs in plant taxonomy, phytogeography, phytosociology, plant ecology, plant morphology, and evolutionary botany. Authors of Norwegian institutions other than the Natural History Museum, University of Oslo pay the cost of technical editing plus NOK 30, other authors pay the cost of technical editing plus NOK 100 per printed page. SOMMERFELTIA appears at irregular intervals, normally one article per volume. Editor: Rune Halvorsen Økland. Editor of this volume: Per Sunding. Technical editing by Jan Wesenberg. Editorial Board: Scientific staff of the botanical departments at the Natural History Museum and Botanical Garden, University of Oslo. Address: SOMMERFELTIA, Natural History Museum and Botanical Garden, University of Oslo, P.O. Box 1172 Blindern, NO-0318 Oslo, Norway. Order: On a standing order (payment on receipt of each volume) SOMMERFELTIA is supplied at 30 % discount. Separate volumes are supplied at the prices indicated on pages inserted before the back cover. Copyright: The author(s) & Natural History Museum and Botanical Garden, University of Oslo. sommerfeltia 30 Bendiksen, E., Økland, R.H., Høiland, K., Eilertsen, O. & Bakkestuen, V. Relationships between macrofungi, plants and environ- mental factors in boreal coniferous forests in the Solhomfjell area, Gjerstad, S Norway 2004 ISBN 82-7420-044-6 ISSN 0800-6865 Bendiksen, E., Økland, R.H., Høiland, K., Eilertsen, O. & Bakkestuen, V. 2004. Relationships between macrofungi, plants and environmental factors in boreal coniferous forests in the Solhomfjell area, Gjerstad, S Norway. – Sommerfeltia 30: 1-125. Oslo. 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; and Odd Eilertsen, Norwegian Institute for Nature Research (present address: Norwegian Institute of Land Inventory). 4 SOMMERFELTIA 30 (2004) CONTENTS INTRODUCTION ................................................................................................. 6 THE INVESTIGATION AREA ........................................................................... 7 GEOLOGY AND GEOMORPHOLOGY 7 CLIMATE 8 FOREST HISTORY AND HUMAN INFLUENCE 9 PHYTO- AND FUNGAL GEOGRAPHY 9 MATERIAL AND METHODS ........................................................................... 10 THE SAMPLING DESIGN 10 RECORDING OF MACROFUNGI 10 RECORDING OF EXPLANATORY VARIABLES 11 Vegetational gradients 11 Recording of vegetation 11 Vegetational explanatory variables 11 Environmental variables 12 Tree measurements 12 Macro-scale variables 14 Meso-scale variables 14 Meso-scale humus-layer variables 15 Transformation of environmental variables 16 Spatial variables 16 CLASSIFICATION OF VEGETATION AND DIVISION INTO DATA SUBSETS 16 Classification 16 Division into data subsets 18 GRADIENT ANALYSIS OF FUNGI 18 Ordination 18 The nature of gradients in fungal species composition 18 Ordination methods 19 Comparison of ordinations 20 Interpretation of ordination results 20 Variation in species abundance and other properties of the funga along DCA axes 20 Constrained ordination 21 Variation explained by single explanatory variables 21 Variation partitioning 21 NOMENCLATURE AND TAXONOMIC NOTES 22 RESULTS ............................................................................................................. 23 CLASSIFICATION 23 FUNGAL SPECIES DENSITY 23 SOMMERFELTIA 30 (2004) 5 ORDINATION 23 Characteristics of, and comparison between, ordinations of fungi 23 Ordinations of the MAF 97 data set 23 Ordinations of the MAF 95 data set 25 Comparison between the ordinations of the MAF 97 and MAF 95 data sets 27 DCA ordinations of data subsets 28 Relationship between fungal ordinations and vegetational variables 31 Ordinations of the MAF 95 data set 31 DCA ordinations of data subsets 34 Interpretation of ordinations by means of environmental variables 35 Ordinations of the MAF 95 data set 35 DCA ordination of the spruce-forest subset MAF 58A 38 DCA ordination of the pine-forest subset MAF 37B 38 Variation in species abundances in the DCA ordination of the MAF 95 data set 38 Ectomycorrhizal fungi 40 Saprotrophs 46 CONSTRAINED ORDINATION 76 Variation explained by single explanatory variables 76 Variation partitioning 77 DISCUSSION ....................................................................................................... 78 ENVIRONMENTAL INTERPRETATION OF GRADIENTS IN FUNGAL SPECIES COMPOSITION 78 The main gradient and its relation to broad-scale topography and soil nutrient content 78 Relationships with environmental variables in the spruce and pine forests 78 Spruce forest: the complex-gradient in nutrient status 78 Pine forest: relative importance of factors related to topography and nutrients 81 Spruce forest: a gradient in cover by deciduous litter and bryophytes? 85 Pine and spruce forests: the fine-scale paludification gradient 86 FACTORS DETERMINING VARIATION IN FUNGAL ABUNDANCE 88 COMMENTS ON FIELD METHODOLOGY AND INTEGRATED APPROACHES TO MACROFUNGI AND PLANTS 89 GENERAL CONCLUSIONS 89 ACKNOWLEDGEMENTS ................................................................................ 91 REFERENCES .................................................................................................... 92 APPENDICES.................................................................................................... 103 Appendix 1 103 Appendix 2 109 Appendix 3 110 Appendix 4 118 6 SOMMERFELTIA 30 (2004) INTRODUCTION Variation in the macrofunga of coniferous forests is partly known from floristical observations and descriptions in floras, partly from studies relating fungi to predefined vegetation types.