Polypore communities in broadleaved boreal forests

317 www.metla.fi/silvafennica · ISSN 0037-5330 The Finnish Society of Forest Science · The Finnish Forest Research Institute SILVA FENNICA Silva Fennica 46(3) research articles Polypore Communities in Broadleaved Boreal Forests Anni Markkanen and Panu Halme Markkanen, A. & Halme, P. 2012. Polypore communities in broadleaved boreal forests. Silva Fennica 46(3): 317–331. The cover and extent of boreal broadleaved forests have been decreasing due to modern forest management practices and fire suppression. As decomposers of woody material, polypores are ecologically important ecosystem engineers. The ecology and conservation biology of polypores have been studied intensively in boreal coniferous forests. However, only a few studies have focused on the species living on broadleaved trees. To increase knowledge on this species group we conducted polypore surveys in 27 broadleaved forests and 303 forest compartments (539 ha) on the southern boreal zone in Finland and measured dead wood and forest characteristics. We detected altogether 98 polypore species, of which 13 are red-listed in Finland. 60% of the recorded species are primarily associated with broadleaved trees. The number of species in a local community present in a broadleaved forest covered approximately 50 species, of which 30–40 were primarily associated with broadleaved trees. The size of the inventoried area explained 67% of the variation in the species richness, but unlike in previous studies conducted in coniferous forests, dead wood variables as well as forest structure had very limited power in explaining polypore species richness on forest stand level. The compartments occupied by red listed Protomerulius caryae had an especially high volume of living birch, but otherwise the occurrences of red-listed species could not be predicted based on the forest structure. Keywords birch, deciduous, slash and burn, species-area relationship, wood-inhabiting fungi Addresses Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail [email protected] Received 6 March 2012 Revised 25 June 2012 Accepted 2 July 2012 Available at http://www.metla.fi/silvafennica/full/sf46/sf463317.pdf 318 Silva Fennica 46(3), 2012 research articles 1 Introduction Fennoscandian boreal forests are mostly dominated by two coniferous tree species, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). However, there are several broadleaved tree species that may either grow mixed with the coniferous species or, in some conditions form mixed broadleaved forests. These species include Silver birch (Betula pendula), Downy birch (Betula pubescens), European aspen (Populus tremula), Grey alder (Alnus incana), Black alder (Alnus glutinosa) and Goat willow (Salix caprea). The current distribution and extent of mature broadleaved forests, as well as the structure of broadleaved forest stands, are mostly a result of historical land use practices, such as slash and burn cultivation, cattle grazing and farming. The broadleaved forest cover has been varying historically due to the changes in land use (Axelsson et al. 2002, Wallenius et al. 2007, Eriksson et al. 2010). The relative cover of broadleaved forests or mixed forests rich in broadleaved species before anthropogenic influence has been debated, but obviously there has been some broadleaved forests growing after severe stand replacing fires, as well as some growing along swamps and water courses (Kuuluvainen 2002). Nowadays broadleaved forests are rare biotopes and all of them are red-listed as threatened biotopes in Finland (Tonteri et al. 2008). As decomposers of woody material, polypores have ecologically important role in forest ecosystems throughout the world (Harmon et al. 1986). With other wood-inhabiting fungi they contribute to the carbon and nutrient cycles of the forests (Boddy et al. 2008) and provide substrates and resources for other organisms, especially insects and other arthropods (Komonen 2003, Boddy and Jones 2008, Schigel 2011), but also bacteria (de Boer and van der Val 2008), slime moulds and vertebrates. Polypores have also an important role in the regeneration of forests as they facilitate natural disturbance dynamics by killing old trees (Edman et al. 2007) and modify resources suitable for young seedlings (Lonsdale et al. 2008). Polypores have been a popular subject of biodiversity studies in boreal forests because many of them are sensitive to environmental change (Berglund and Jonsson 2005), their habitat requirements are often specialized (Renvall 1995, Penttilä et al. 2004) and they are regarded as good indicators of habitat worthy of conservation (Nitare 2000, Niemelä 2005, Halme et al. 2009a, Halme et al. 2009b). In their recent review, Junninen and Komonen (2011) listed 76 papers from Fennoscandia treating the conservation ecology of polypores. However, most of the studies have focused on spruce-dominated forests and polypores growing on coniferous trees (Junninen and Komonen 2011). In many studies broadleaved trees have also been considered besides conifers (e.g. Hottola and Siitonen 2008, Komonen et al. 2008, Lõhmus 2011a), but the studies have been conducted in young stands or in forests dominated by coniferous trees. The few studies focusing on the polypores occupying broadleaved trees have been targeted only at aspen-dependent species (Lõhmus 2011b) or alder-dominated forests (Strid 1975). In addition, there are some studies conducted on clear-cuts and focusing on retention trees (Lindhe et al. 2004, Junninen et al. 2007). The higher polypore species richness in oldgrowth spruce-dominated forests compared with overmature managed forests is at least partly due to species dependent on broadleaved trees and particularly on large-diameter aspen logs (Penttilä et al. 2004). Similarly spruce-dominated lakeside riparian forests (Komonen et al. 2008) and woodland key habitats (Hottola and Siitonen 2008) have been found to host more polypore species than control forests because of the higher proportion of broadleaved trees and broadleaved dead wood. Aspen, especially hosts unique species assemblages and is considered to be a keystone tree species also for polypores (Miettinen 2001, Junninen et al. 2007, Lõhmus 2011b). In addition, one biogeographical study has discussed the ecology of wood-inhabiting fungi living in alderdominated boreal forests (Strid 1975). However, there are no studies focusing on the polypore communities occupying other broadleaved trees that are common in boreal forests, such as birch or goat willow, and there are no studies focusing on polypore communities in mature boreal broadleaved forests (Junninen and Komonen 2011). This is relatively surprising since broadleaved trees are an important substrate for polypores. In Finland there are 230 polypore species, the majority of which are wood-dependent and about 319 Markkanen and Halme Polypore Communities in Broadleaved Boreal Forests 60% of these can at least occasionally grow on broadleaved trees (Niemelä 2005). Because broadleaved forests are different to coniferous forests considering at least their disturbance dynamics and the distribution of tree species, age and size (Axelsson et al. 2002, Kuuluvainen 2002, Eriksson et al. 2010), it may well be that the ecology of polypores inhabiting them is also different to that of the one inhabiting coniferous forests. Thus the current situation that most of the knowledge about the conservation ecology of polypores is derived from spruce-dominated forests (Junninen and Komonen 2011), is risky in terms of extrapolating knowledge to different conditions. Our aim in this study is to give a reference to the studies conducted in coniferous forests. Therefore we report the basic community parameters of polypore communities and the factors affecting them in mature and overmature broadleaved boreal forests. We tackle this task based on an extensive data set collected from the south boreal zone of Finland. The geographical extent of the data is large and the data cover most of the relevant mature and overmature broadleaved forests in the area. More specifically, we address the following questions: 1) What are the characteristic polypore species in boreal broadleaved forests, 2) How is the polypore species richness in boreal broadleaved forests affected by area, dead wood variables and forest age and 3) Are the forest compartments occupied by redlisted species structurally different from the other studied compartments? 2 Material and Methods 2.1 Study Sites and Wood Measurements The surveys of the study sites were launched by the Natural Heritage Services of Metsähallitus (the Finnish Forest and Park Service). Their motivation was to achieve reliable information about the species occurrences in these broadleaved forests to guide habitat management actions and future conservation decisions. The study area (covering 27 forests or groups of adjacent forests, later “sites”) was located in southern and south-eastern part of Finland in the biological provinces of Tavastia australis (12 sites), Savonia australis (12 sites) and Karelia ladogensis (3 sites) (Heikinheimo and Raatikainen 1971) in the southern boreal vegetation zone (Ahti et al. 1968) (Table 1). The surveys were conducted on the scale of forest compartments. In Finland the forests are divided into compartments based on the forest site type and age class. So ideally a forest compartment is a patch of forest of one site type and age class. Thus one forest may (and usually does) include several compartments. The surveyed area per study site varied between 2.5 and 73 hectares (Mean 19.9, SD 16.8) and the number of studied forest compartments in the study sites varied between 1 and 55 (Mean 8.0; SD 10.8), Table 1). Altogether we surveyed 539 hectares on 303 forest compartments. However, if the compartments were really small (< 0.5 ha) and/or difficult to distinguish in the field, they were pooled together in the field and compartment groups were used so that there were 216 compartments or group of compartments (later compartments). All study sites are nature conservation areas. The data set includes most of the large conserved broadleaved forests of the study area, south-eastern Finland. All the forest compartment-specific measurements of living and dead tree volumes were conducted by Metsähallitus according to their standard procedures. The dominant tree species in the study sites are Betula spp. (mainly Betula pendula, but also Betula pubescens). Other common broadleaved tree species are Populus tremula, Alnus glutinosa and Alnus incana. Besides broadleaved species, coniferous species (Norway spruce [Picea abies] and Scots pine [Pinus sylvestris]) are also common in the study sites. The average volumes of each tree species in the study sites are given in Table 2. Total volume of living trees per surveyed compartments was an average 274.8 m3/ha (SD99.0) and the volume of broadleaved trees was an average 185.9 m3/ha (SD 92.1). Most of the study sites have been under a heavy anthropogenic influence in the past, historically mostly slash and burn cultivation, and cattle grazing. More recently, active habitat management (mostly spruce removal) has been conducted in many of the sites to maintain the forests as broadleaved, as all broadleaved forest types are endangered habitats in Finland (Tonteri et al. 2008) and because many of the 320 Silva Fennica 46(3), 2012 research articles sites are occupied by endangered White-backed Woodpecker (Dendrocopos leucotos) which favors broadleaved forests (Virkkala et al. 1993). The age of the oldest broadleaved tree cohort of the studied forest compartments was an average 86 years (SD 20.8), the total volume of dead wood was an average 13.1 m3/ha (SD 13.5) and the volume of broadleaved dead wood was an average 9.2 m3ha (SD 10.9). For dead wood measurements the dead wood pieces with a diameter ≥ 7 cm were measured from a minimum of two sample plots with a size of 300m2 on each forest compartment. However, if the total volume of dead wood per compartment was by eye estimated to be less than 5 m3/ha it was not measured (Silvennoinen 2003). Information of living and dead trees was not available for all of our study compartments. In all the analyses all the compartments with available information were used. Table 1. Study sites, their location (municipality and biological province), inventoried area (hectares (ha) and number of forest compartments) and recorded polypore species (in total and species associated with broadleaved trees). Study site Municipality Biological province a) Total area (ha) No. of compartments Total no. of species No. of broadleaved associated species Linnansaari Rantasalmi / Savonlinna Sa 73.0 55 67 38 Puulavesi Hirvensalmi Sa 56.9 24 46 27 Kivijärvi Hollola Ta 28.3 16 36 22 Leivonmäki Joutsa Sa 27.2 14 47 34 Tenhola Hattula Ta 15.8 13 30 21 Kyyvesi Kangasniemi / Mikkeli Sa 38.1 10 48 31 Molikko Luhanka Ta 26.9 9 43 30 Tieransaari Joutsa Sa 23.9 9 48 31 Läpiä Heinola Ta 5.4 7 22 14 Tolvasmäki Joutsa Sa 14.6 7 38 25 Hipeli Luhanka Ta 25.3 6 42 28 Kuruvuori Luhanka / Korpilahti Ta 18.2 6 37 26 Vainoniemi Valkeakoski Ta 10.8 6 31 22 Lempää Luhanka Ta 15.1 5 39 22 Vähäpää Asikkala Ta 6.0 5 25 16 Pyhäniemi Mäntyharju Sa 22.7 4 29 16 Siikalahti Parikkala Kl 17.3 4 30 25 Lautjärvi-Laukkala Pertunmaa Sa 8.0 3 22 16 Niukkala Parikkala Kl 31.9 3 30 20 Maisanmäki Parikkala Kl 3.1 2 18 17 Paistjärvi Heinola Ta 35.3 2 25 10 Alatalo Pertunmaa Sa 6.3 1 13 8 Haukkavuori Ruokolahti Sa 6.8 1 23 15 Kinalampi Mäntyharju Sa 9.4 1 16 12 Lahnaniemi Mäntyharju Sa 2.5 1 20 12 Metsänkylä-Ellilä Hattula Ta 4.8 1 19 16 Saksala Padasjoki Ta 5.0 1 11 11 a) Sa = Savonia australis, Ta = Tavastia australis, Kl = Karelia ladogensis We also calculated the dead wood diversity index of the dead wood variables. As a basis we used the index developed by (Siitonen et al. 2000), where every dead wood type (position and size classes), wood species and decay class adds the value of the index. As our dead wood data were relatively robust, we simplified the index to reflect the variation in dead wood species, decay stage (on scale one to three) and position (standing/downed). Thus the index got higher along with each of these categories that were present in the dead wood data (i.e. standing dead aspen in decay stage two yields one score). As this index is commonly used, we propose calling it the “Siitonen index” and our treatment the “Simplified Siitonen Index”. 321 Markkanen and Halme Polypore Communities in Broadleaved Boreal Forests 2.2 Polypore Inventories The polypore inventories were carried out in 2007 and 2008 during August–October, which is the peak fruiting season of polypores in the study area (Halme and Kotiaho 2012). We used the Nordic concept of polypores, meaning all the poroid Aphylloporales, a delimitation that is widely used in northern Europe (Niemelä 2005, Junninen and Komonen 2011). Our aim was to list all the polypore species fruiting on each forest compartment. We used the opportunistic search method (Stokland and Sippola 2004), which emphasizes the sampling of many habitats and substrate qualities to collect a high number of species and to get a representative picture of the species composition of the study area. In most forest compartments we sampled the majority of coarse woody debris, and in addition the old living trees which may also host some polypore species. It can be presumed that the great majority of the species which were fruiting were detected by the method we used, but the abundances may be skewed towards the species with large and visible fruit bodies and the species that fruit on charismatic substrates (Lõhmus 2009). Therefore we used only presence/absence data at the forest compartment scale in this study. We identified the fruit bodies of polypores in the field if possible, but in doubtful cases collected specimens for microscopic identification. The voucher specimens are preserved in the Jyväskylä University Museum’s Section of Natural Sciences (JYV) or in the personal collections of authors. Nomenclature follows Kotiranta et al. (2009) and red-list categories are according to Kotiranta et al. (2010). In addition we listed the regionally threatened species (RT) which are threatened in some regions of Finland (in this data “Lake district in southern boreal zone”) (www. ymparisto.fi). Polypore species were divided to coniferous and broadleaved associated species according to the substrate, which Niemelä (2005) reported to be the most important one for each species. In reality many species are generalists, but they still usually have a more or less clear preference for either coniferous or broadleaved trees. To maintain maximum robustness in our classification we did not use a more detailed classification. For the same reason, and to give some classification for each species, we did not use the data based specialist-generalist division by Hottola (2009), which classifies species to generalists if they have a notable proportion of occurrences on their less desirable substrate. 2.3 Statistical Analyses To test the structural differences between the compartments occupied by each red-listed species and the ones without them, we conducted nonparametric Kruskal-Wallis test on the measured tree and dead wood variables. We used nonparametric test because the data on most red-listed species was very scarce. We conducted this analysis only Table 2. Total volume of living trees (n = 282) and dead wood (n = 265) in studied forest compartments.  Living trees Dead wood  Mean m3/ha SD Mean m3/ha SD Pinus 47.39 78.88 1.60 7.19 Picea 41.05 69.15 2.10 12.02 Betula 128.18 87.13 5.76 7.85 Populus 31.41 53.91 1.70 12.33 Alnus 18.81 91.00 1.48 4.73 Salix 0.63 2.19 0.07 0.49 Other broadleaved a) 6.83 20.77 0.16 1.10 Other conifers b) 0.45 5.93 0 0 Unknown 0 0 0.22 2.52 a) Other broadleaved = Sorbus aucubaria, Prunus padus, Acer platanoides, Tilia cordata, Ulmus laevis and unknown broadleaved b) Other conifers = Abies sibirica and Larix sibirica 322 Silva Fennica 46(3), 2012 research articles on the red-listed species with the minimum of three records in the data. To explore the relationship between polypore species richness and environmental variables at forest compartment scale we conducted a multiple linear regression analysis on both the total number of polypore species and number of broadleaved associated polypore species. In these analyses the number of species (either total or broadleaved associated) was the dependent variable and the area of forest compartment (log transformed), volume of living trees (total or broadleaved), volume of dead wood (total or broadleaved), age of the oldest broadleaved tree cohort on the compartment and simplified Siitonen index were added as covariates. To find out the relationship between the size of the studied area and number of polypore species we conducted regression analysis on these two variables. We expected the relationship to be either logarithmic or power function and conducted both analyses. We also report both of them as they are commonly used to describe the relationship between increasing area and number of species. We wanted to study this subject on larger areas and therefore pooled the data for this analysis from forest compartment to study site level. As our 27 study sites vary a lot in their size, the data enable strong analysis on this topic. 3 Results Altogether 98 polypore species were recorded at the 27 study sites. 59 of the species are primarily associated with broadleaved trees and 39 with conifers (Table 3). The proportion of broadleaved associated species per study site varied between 40 and 100% (Mean 68.0; SD 12.1) (Table 1). With the exception of one study site, in all sites majority of the recorded species were broadleaved associated. Most of the species (66) were recorded on less than 10% of the forest compartments and 23 species were recorded only once or twice (Table 3). Only 7 species (Fomes fomentarius, Fomitopsis pinicola, Phellinus igniarius coll., Piptoporus betulinus, Inonotus obliquus, Phellinus tremulae and Trichaptum abietinum) were recorded on more than 50% of the compartments and 21 species were recorded on more than 20% of the compartments. 67 records of 13 red-listed species were recorded: three vulnerable (VU) (Antrodia pulvinascens, Funalia trogii and Polyporus badius), nine near-threatened (NT) (Protomerulis caryae, Antrodia mellita, Skeletocutis odora, Ceriporiopsis aneirina, Perenniporia subacida, Antrodiella americana, Ceriporia excelsa, Haploporus odorus and Onnia tomentosa) and one data deficient species (DD) (Rigidoporus obducens). Three of the red-listed species are also regionally threatened in the study area (RT) (Protomerulius caryae, Skeletocutis odora and Haploporus odorus). All red-listed species were recorded on broadleaved wood, except Onnia tomentosa which is a parasite of coniferous trees and grows on ground (Niemelä 2005). Four red-listed species (P. caryae, A. mellita, A. pulvinascens and S. odora) had a sufficient number of records for studying their habitat preferences. The only forest characteristics which significantly explained the occurrences of any red-listed species, were the volume of living birch (Independent samples Kruskal-Wallis test, H = 21.4, d.f. = 4, p < 0.001) and the age of the oldest broadleaved tree species (Independent samples Kruskal-Wallis test, H = 12.7, d.f. = 4, p = 0.013). In addition the volume of living alder tended to have some predicting power (Independent samples Kruskal-Wallis test, H = 8.5, d.f. = 4, p = 0.076) (Fig. 1). The size of the studied area was a powerful predictor of the polypore species richness on the study site level, both power and logarithmic regression explained more than 65% of the variation in species richness (Fig. 2, Logarithmic: r2 = 0.668; F1.25 = 50.194; p < 0.001 Power: r2 = 0.656; F1.25 = 47.606; p < 0.001). The local species richness in the studied forests seemed to level out at about 50 species with the exception of one site, Linnansaari national park where we detected 67 species. The same functional relationship prevailed for species associated with broadleaved trees, though somewhat weaker (Fig. 3, Logarithmic: r2 = 0.500; F = 24.998; p < 001 Power: r2 = 0.442; F = 19.777; p < 0.001). Considering broadleaved associated species, the local species richness leveled out at about 30–40 species, even though the pattern was not as clear as with all polypore species. 323 Markkanen and Halme Polypore Communities in Broadleaved Boreal Forests Table 3. Records of species. Broadleaved associated species are divided according to Niemelä (2005) and marked with bold face. Most important substrate is also according to Niemelä (2005). Substrates in the data are given for red-listed species (number of records in parentheses). The total number of studied compartments was 216. Species Status No. (and %) of compartments Most important substrate Substrates in the data Fomes fomentarius 203 (94) Betula Fomitopsis pinicola 185 (86) Picea Phellinus igniarius coll. 153 (71) broadleaved trees Piptoporus betulinus 147 (68) Betula Inonotus obliquus 140 (65) Betula Phellinus tremulae 122 (56) Populus Trichaptum abietinum 108 (50) Picea Trametes ochracea 102 (47) Betula Antrodiella pallescens 74 (34) Betula Bjerkandera adusta 64 (30) broadleaved trees Gloeoporus dichrous 59 (27) Betula Phellinus laevigatus 59 (27) Betula Trechispora hymenocystis 52 (24) conifers Cerrena unicolor 51 (24) Betula Phellinus punctatus 50 (23) Salix Inonotus radiatus 49 (23) Alnus Postia tephroleuca 49 (23) Picea Datronia mollis 48 (22) Populus Phellinus conchatus 48 (22) Salix Postia alni 48 (22) Populus Gloeoporus pannocinctus 45 (21) Betula Skeletocutis biguttulata 42 (19) Pinus Antrodia sinuosa 40 (19) Pinus Hapalopilus rutilans 38 (18) Prunus Protomerulius caryae NT, RT 37 (17) Betula Betula (40), Alnus (2), Populus (1) Rigidoporus corticola 30 (14) Populus Postia caesia 29 (13) Picea Lenzites betulinus 25 (12) Betula Polyporus leptocephalus 24 (11) Populus Trichaptum fuscoviolaceum 24 (11) Pinus Ganoderma applanatum 23 (11) Populus Antrodia xantha 22 (10) Picea Trametes hirsuta 20 (9) Sorbus Antrodia serialis 19 (9) Picea Skeletocutis amorpha 16 (7) Pinus Postia stiptica 15 (7) Picea Sistotrema muscicola 14 (6) Picea Steccherinum nitidum 14 (6) Salix Phellinus lundellii 12 (6) Betula Rigidoporus populinus 12 (6) Acer Gloeophyllum sepiarium 11 (5) Picea Polyporus brumalis 11 (5) Betula Tyromyces chioneus 11 (5) Betula Spongiporus undosus 10 (5) Picea Trametes velutina 10 (5) Betula Ceriporiopsis pseudogilvescens 8 (4) Populus Oligoporus sericeomollis 8 (4) Pinus Postia leucomallella 8 (4) Pinus Sistotrema alboluteum 8 (4) Picea Skeletocutis carneogrisea 8 (4) Picea Hyphodontia radula 7 (3) Alnus Phellinus pini 7 (3) Pinus 324 Silva Fennica 46(3), 2012 research articles Table 3 continued. Species Status No. (and %) of compartments Most important substrate Substrates in the data Postia fragilis 7 (3) Pinus Porpomyces mucidus 6 (3) Betula Steccherinum luteoalbum 6 (3) Pinus Trametes pubescens 6 (3) broadleaved trees Antrodia mellita NT 5 (2) Populus Populus (4), Salix (1) Ceriporia reticulata 5 (2) broadleaved trees Cinereomyces lindbladii 5 (2) Picea Irpex lacteus 5 (2) Sorbus Pycnoporellus fulgens 5 (2) Picea Albatrellus ovinus 4 (2) Picea forests Antrodiella faginea 4 (2) Salix Antrodiella romellii 4 (2) Corylus Leptoporus mollis 4 (2) Picea Meruliopsis taxicola 4 (2) Picea Phellinus populicola 4 (2) Populus Antrodia macra 3 (1) Salix Antrodia pulvinascens VU 3 (1) Populus Populus Bjerkandera fumosa 3 (1) broadleaved trees Heterobasidion parviporum 3 (1) Picea Inonotus rheades 3 (1) Populus Ischnoderma benzoinum 3 (1) Picea Pycnoporus cinnabarinus 3 (1) Sorbus Skeletocutis odora NT, RT 3 (1) Picea Populus Ceriporiopsis aneirina NT 2 (1) Populus Populus Gloeophyllum odoratum 2 (1) Picea Hyphodontia paradoxa 2 (1) Betula Perenniporia subacida NT 2 (1) Picea Alnus (1), unidentified broadleaved tree (1) Phellinus ferrugineofuscus 2 (1) Picea Phellinus nigrolimitatus 2 (1) Picea Polyporus ciliatus 2 (1) Betula Antrodiella americana NT 1 (0.5) Salix Alnus Ceriporia excelsa NT 1 (0.5) Populus Betula (1), Populus (1) Funalia trogii VU 1 (0.5) Populus Populus Haploporus odorus NT, RT 1 (0.5) Salix Salix Heterobasidion annosum 1 (0.5) Pinus Onnia tomentosa NT 1 (0.5) Picea Phaeolus schweinitzii 1 (0.5) Pinus Physisporinus vitreus 1 (0.5) Alnus Polyporus badius VU 1 (0.5) Acer Populus Polyporus melanopus 1 (0.5) Betula Postia hibernica 1 (0.5) Pinus Postia ptychogaster 1 (0.5) Pinus Rigidoporus obducens DD 1 (0.5) Quercus Ulmus Skeletocutis kuehneri 1 (0.5) Picea Steccherinum lacerum 1 (0.5) broadleaved trees Trechispora mollusca  1 (0.5) conifers  325 Markkanen and Halme Polypore Communities in Broadleaved Boreal Forests Fig. 2. Species-area relationship for total number of polypore species. Fig. 1. The volume of living birch and alder (m3/ha) and the age of the oldest broadleaved tree cohort in the forest compartments without detected occurrences of any red-listed species and compartments occupied by the red-listed species with the minimum of three occurrences in the data.