Forest Ecology and Management 310 (2013) 508–516

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Forest Ecology and Management

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Effects of forest restoration by fire on polypores depend strongly on timesince disturbance – A case study from Finland based on a 23-yearmonitoring period

0378-1127/$ - see front matter � 2013 Elsevier B.V. All rights reserved.http://dx.doi.org/10.1016/j.foreco.2013.08.061

⇑ Corresponding author at: Finnish Forest Research Institute, PO Box 18, FI-01301Vantaa, Finland. Tel.: +358 40 801 5268; fax: +358 29 532 2103.

E-mail address: reijo.penttila@metla.fi (R. Penttilä).

Reijo Penttilä a,c,⇑, Kaisa Junninen b, Pekka Punttila c, Juha Siitonen a

a Finnish Forest Research Institute, PO Box 18, FI-01301 Vantaa, Finlandb Metsähallitus, Natural Heritage Services, c/o UEF, PO Box 111, FI-80101 Joensuu, Finlandc Finnish Environment Institute, PO Box 140, FI-00251 Helsinki, Finland

a r t i c l e i n f o

Article history:Received 3 June 2013Received in revised form 27 August 2013Accepted 28 August 2013Available online 24 September 2013

Keywords:Restoration burningForest fireBoreal forestRed-listed speciesDead woodWood-decaying fungi

a b s t r a c t

Fire is increasingly used in management and restoration of forest ecosystems, in order to rehabilitatehabitat structure and to create habitats for species dependent on forest fires and dead wood. However,information on the impacts of fire on saproxylic species is scanty, and long-term studies on the effectsare almost totally lacking. Here we present results from a long-term field study conducted in eastern Fin-land in 1988–2011. Two pine-dominated boreal forest stands, a seminatural and a managed one, wereintentionally burnt in 1989. We inventoried polypores 1 year before the fire, in the year of burning,and 1, 2, 6, 13 and 22 years after the fire. The short-term effects of fire were destructive for polypore com-munities. However, species numbers recovered to the pre-fire level 6 years after the fire. After 13 years,the number of species was clearly higher than before the fire, due to the large input of fire-killed deadtrees. The number of red-listed species was strikingly high (18 species) in the seminatural stand 13 yearsafter the fire including several species which have earlier been considered as old-growth forest indicators,and remained at high level (17 species) still 22 years after the fire. The number of red-listed species wasmuch lower in the formerly managed stand (6 and 8 species, respectively). We conclude that burning ofstands can be a very effective method to create habitats for red-listed polypore species, at least if thestand is located close to high-quality source areas and contains a sufficient amount of large-diametertrunks of different tree species.

� 2013 Elsevier B.V. All rights reserved.

1. Introduction

Fire is one of the most important disturbance factors in borealforests under natural conditions. Wildfires create landscape mosa-ics consisting of stands at different successional stages, affect standstructure and dynamics, and produce large amounts of dead woodby causing tree mortality (Johnson et al., 1998; Jonsson and Siito-nen, 2012; Niklasson and Granström, 2000; Shorohova et al.,2009). A large group of organisms in boreal forests, mainly consist-ing of invertebrates and fungi, are dependent on or favored by fire(Dahlberg, 2002; Saint-Germain et al., 2004; Wikars, 1992). Theseso-called pyrophilous species occur mainly in recently burnt sitesand at site types where natural fire frequency is the highest suchas dry pine forests. Studies on the effects of fire on post-fire fungalsuccession have concentrated on ground-dwelling fungi (Horikoshiet al., 1986; Moser, 1949; Petersen, 1970; Vásquez Gassibe et al.,

2011; Zak and Wicklow, 1980). According to these studies, thereare several strictly fire-dependent species, especially in Ascomyce-tes, which usually emerge very soon after fire. Most fire-dependentmacrofungi seem to be soil and litter saprophytes. For example, inSweden a total of 40 macrofungal species have been reported asfire-dependent, and of these 32 are soil and litter saprophytes(Dahlberg, 2002).

During the last century, modern forestry and other land-useforms coupled with efficient fire suppression have replaced fireas the main disturbance factor in large regions in the boreal andtemperate zones. This change from natural to human-caused dis-turbance dynamics has greatly affected forest composition andstructure and, consequently, also biodiversity. In some regions,numerous organisms dependent on fire have declined and becomethreatened because of lack of fires (Kouki et al., 2012; Wikars,2001). For instance, reduction of burnt forest areas (including otheryoung stages of natural succession) has been identified as the maincause of threat to eight regionally extinct and 68 threatenedspecies in Finland (Rassi et al., 2010). In other regions, such as inseveral types of coniferous and mixed forests in North America,

R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516 509

the fire regime has shifted to the other direction, so that fires areless frequent but larger and more intensive than in the past (Allenet al., 2002; Fulé et al., 2012). The altered fire regime may have se-vere negative effects on biodiversity (Driscoll et al., 2010). A gen-eral, widely applicable objective of fire management is to avoidpopulation extinctions within a defined management area due tothe effect of an adverse fire regime. Prescribed burning can be usedto reduce fire loads and risk of uncontrolled wildfires, but also torestore habitats for fire-dependent and dead-wood inhabitingspecies.

Polypores are principle decomposers of dead wood in borealand temperate forests (Boddy, 2001). Besides providing the basicecosystem services, wood decomposition and nutrient cycling,they provide habitats for many other saproxylic forest species(Siitonen, 2012; Stokland and Siitonen, 2012). Many polypore spe-cies have declined owing to intensive forest management whichhas caused loss of old-growth forests and reduced the amountsof decaying wood (Lonsdale et al., 2008; Junninen and Komonen,2011a).

Several recent studies have explored the effects of wildfire orprescribed burning on wood-inhabiting species, including saproxy-lic beetles (Hyvärinen et al., 2009; Saint-Germain et al., 2004; Toi-vanen and Kotiaho, 2007a) and wood-decaying fungi (Junninenet al., 2008; Olsson and Jonsson, 2010; Penttilä and Kotiranta,1996). However, all these studies have only followed the short-term effects (1–5 years) of fire on species assemblages. Accordingto these studies, the short-term effects on saproxylic beetles aregenerally positive, i.e. burnt sites have higher species richnessand higher numbers of rare and red-listed species, whereas theshort-term effects on wood-decomposing fungi appear to be nega-tive. The only studies in which the more long-term (29 and16 years, respectively) changes in saproxylic beetle assemblageswere investigated are not experimental follow-up studies but ret-rospective chronosequence studies (Boulanger and Sirois, 2007;Toivanen and Kotiaho, 2007b). Knowledge on the long-term effectsof fire on wood-decaying fungi seems to be almost totally lacking.A recent study by Kurth et al. (2013) explored long-term changesin communities of wood-inhabiting fungi in a 32-year chronose-quence study based on wood samples and molecular identificationof fungi. However, there were very few polypores and other speciesbelonging to Basidiomycota in the species assemblages they found.

The aim of this study was to describe both the short-term ef-fects of fire on wood-decaying fungi, and the long-term (>20 years)changes in species composition, and particularly in the occurrenceof red-listed species. In addition, the aim was to explore how theamount and quality of dead wood affect the post-fire fungalsuccession.

2. Materials and methods

2.1. Study area and study sites

The study area is situated in Patvinsuo National Park in easternFinland close to the Russian border. The area lies in the middle bor-eal zone, just next to the border between southern and middle bor-eal zones. Climate in the area is slightly continental. The extent ofthe national park is about 100 km2 and it is characterized by largepeatlands and pine-dominated forests. Before the park was estab-lished in 1982, part of the area had been managed for forestry pur-poses. Consequently, at the moment 48% of the forests in the parkare young or middle-aged, previously managed stands, but thereare also large tracts of old-growth forests within the park.

Two separate forest stands were used in the study. The firststand was close to natural state, the other one had been previouslymanaged. Hereafter we refer to these stands as ‘‘seminatural’’ and

‘‘managed’’. Both were small (about 1 ha), pine-dominated (Pinussylvestris) forest islands surrounded by open peatlands and locatedabout 200 m from the closest edge of a larger old-growth forestand 4 km from each other. Both stands were burnt in 1989. Toour knowledge, this was the first time when standing forest wasburnt for restoration purposes in Europe.

In the seminatural stand, only some medium-sized pines hadbeen selectively cut several decades before the fire. Most of thedominating pines were about 100 years old, but there were alsodozens of large, 200- to 300-year-old pine individuals. Norwayspruce (Picea abies) and birches (Betula pubescens, B. pendula) oc-curred as admixed tree species. Before the fire, the total volumeof living trees was about 200 m3/ha and the volume of dead treesabout 40 m3/ha. Most dead trees were large fallen pines andspruces, with some fallen birches and some large, dead standingpines.

The managed stand had been logged before the national parkwas established, and the dominant pines were 40 years old. Someold, living pines had been left as seed trees in the logging. A fewlarge birches and groups of small-diameter grey alders (Alnus inca-na) occurred as admixed tree species. Before the fire, the total vol-ume of living trees was about 75 m3/ha and the volume of deadtrees 10 m3/ha. The volume of dead wood was mainly composedof a few large fallen pines.

Burning of the stands took place on the 26–27th June in 1989. Inboth stands, the ground layer burnt almost completely, except for afew patches that remained unburnt in the seminatural stand.

Almost all living spruces and birches and most of the livingpines were killed by the fire. The survival probability of pines in-creased with tree diameter and was > 50% in trees that were over20 cm in diameter, and > 80% in trees that were over 30 cm indiameter (Kolström and Kellomäki, 1993). Of the pre-fire deadwood, most of the barkless pine snags burnt from the base and fell.Most lying trees burnt strongly (seminatural stand) or verystrongly (managed stand). Fallen pines and spruces burnt morestrongly than birches.

2.2. Inventory of polypores

Polypores were surveyed in both stands one year before the fire(in 1988), in the year of burning, and 1, 2, 6, 13 and 22 years (in2011) after the fire. The inventories were carried out during Sep-tember–October when the detection probability of annual speciesis at its largest. In every inventory, all dead and living trees witha minimum diameter of 5 cm within the whole stands werechecked for polypore fruiting bodies. One or several fruiting bodiesof a species per one substrate unit (or several units originatingfrom the same tree) were counted as one record. Abundance ofeach species in each inventory was the sum of its records. Deadperennial fruiting bodies were excluded from the data and furtheranalyses. The nomenclature of polypores follows Kotiranta et al.(2009) and the classification of red-listed species Kotiranta et al.(2010).

In every inventory, all trees with polypore fruiting bodies weremeasured. The host-tree variables included tree species, diameter,length of pieces of trees, decay stage (five classes after Renvall1995) and degree of burn (six classes according to Penttilä andKotiranta 1996). In 2002 and 2011 (13 and 22 years after the fire)also ‘empty’ trees without any polypore fruiting bodies were re-corded and measured, to enable calculation of total dead-woodvolume. In the pooled data of 2002 and 2011, the total numbersof inventoried substrate units were 2283 in the seminatural standand 2129 in the managed stand. The diameter distribution of entiredead trees differed between the two stands, so that the proportionof large-diameter trees was higher in the seminatural than in themanaged stand (Fig. 1).

Fig. 1. The diameter distribution of dead trees in the seminatural and managedstand (pooled data from 2002 and 2011 inventories).

510 R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516

2.3. Data analysis

The effects of fire on the species richness of polypores wereexamined by counting the total numbers of species and the num-ber of red-listed species per stand recorded in each inventory.

The effect of tree diameter on the occurrence probability of red-listed species and other species (i.e. non-red-listed species) was ex-plored graphically by comparing the proportions of occupied treesin different 10-cm diameter classes. We tested the effect of treediameter on the occurrence probability (presence-absence) ofred-listed species and other species separately by logistic regres-sion using R statistical environment (version 3.0.1, R Core Team,2013). These analyses were based on the 2002 and 2011 invento-ries when all trees (also those without polypores) were measured.

To study the fire preferences of species we calculated the aver-age degree of burn of host trees (measured on the spot where thefruiting bodies were growing) for each species based on the 1991,1995 and 2002 inventories.

To explore changes in the species composition of polyporeassemblages, we applied non-metric multidimensional scaling(NMDS) using the package vegan (version 2.0–8, Oksanen et al.,2013) in R statistical environment (version 3.0.1, R Core Team,2013). In the NMDS, we utilized the vegan function metaMDSwhich, in addition to performing NMDS, aims to find a stable solu-tion from several random starts and scales the axes to half-changeunits. Bray-Curtis dissimilarity measure, square root transforma-tion and Wisconsin double standardization were applied (Oksanenet al., 2013). We fitted the environmental variables, i.e. study stand(factor) and time since disturbance (vector), into the ordinationspace using the vegan function envfit and tested their fit with a per-mutation test (n = 99999 permutations). We also analyzed the rela-tionship between species composition and the environment (here:the stand and the study year) without ordination (in full space)using the vegan function adonis (permutational multivariate anal-ysis of variance using distance matrices). In this analysis dissimilar-ities were partitioned among the stand (managed vs. seminatural),time since disturbance, and their interaction. Finally, we used thevegan function betadisper to study whether the within-stand heter-ogeneity (i.e. the magnitude of year-to-year variation) differed be-tween the two stands. We used Bray-Curtis dissimilarity as thedistance measure and a permutation test to investigate the statisti-cal significance of the results of these analyses.

3. Results

3.1. Dead wood

In 2002, thirteen years after the burning, the volume of deadwood in the seminatural stand was 125 m3/ha, of which

71 m3/ha was pine, 39 m3/ha spruce and 15 m3/ha birch. In 2011,twenty-two years after the burning, the volume had declined to95 m3/ha, of which 64 m3/ha was pine, 25 m3/ha spruce and5 m3/ha birch. In 2002, the volume of dead wood in the managedstand was 32 m3/ha, of which 25 m3/ha was pine, 5.5 m3/ha birchand 1.5 m3/ha grey alder. In 2011, the volume had declined to28 m3/ha, of which 23 m3/ha was pine, 4.1 m3/ha birch and0.5 m3/ha grey alder.

3.2. Effects of fire on species richness and abundance

During the whole study period, a total of 107 species of polyp-ores with 5018 records (one species per one substrate unit perinventory) were observed in the two forest stands. Of these, 96species were found in the seminatural stand and 75 in the man-aged stand (Appendix).

Before the fire (BF), the total number of all polypore species was45 in the seminatural and 29 in the managed stand. After the fire(AF), species richness developed very similarly in both stands untilthe last year of investigation (Fig. 2A). The total number of speciescollapsed in the fire. Starting from the first post-fire year, the num-ber of species increased steadily and reached the pre-fire level6 years AF. Thirteen years AF, the number of species was 64 (45%more than BF) in the semi-natural stand and 48 (66% more thanBF) in the managed stand; the total species richness seemed tohave reached its peak in both stands. After that, the number of spe-cies remained at the same level in the seminatural stand butstarted to decrease in the managed stand. The total abundance ofpolypores, on the other hand, started to decrease in both stands(Fig. 2B). The decrease in abundance was mainly driven by the de-crease in the total amount of dead wood, but also by decay succes-sion: 22 years after the fire, the fire-killed trees had mostly reachedan advanced decay stage in which the dominant, abundant pioneerpolypores (Trichaptum spp., Piptoporus betulinus, Fomes fomentari-us, Fomitopsis pinicola etc.) had either disappeared or persisted onlyin low abundances.

Unlike the total number and abundance of all species, the num-ber (Fig. 2C) and abundance (Fig. 2D) of red-listed species devel-oped differently in the two stands. BF, the number of red-listedpolypore species was seven in the seminatural and six in the man-aged stand. In the seminatural stand, the fire decreased the num-ber of species slightly, and 6 years AF it had not yet recovered tothe pre-fire level. However, 13 years AF, the number of red-listedspecies had almost tripled (to 18 species), and it remained at highlevel (17 species) still 22 years AF. In the managed stand, the firedecreased the number of red-listed species more than in the semi-natural stand. Thirteen years AF, the number had reached the pre-fire level, and 22 years AF, it had increased just above the pre-firelevel (to eight species). The abundance of red-listed species(Fig. 2D) increased steeply in the semi-natural stand AF, but stayedat low level in the managed stand.

The diameter of trees affected the occurrence of red-listed spe-cies. The proportion of trees inhabited by at least one red-listed spe-cies increased steadily from the smallest diameter class 5–9 cm(<1% inhabited) to larger trees and was the highest (about 17%inhabited) in trees P 40 cm in diameter (Fig. 3A). In contrast, theoccurrence of other species did not depend on tree diameter exceptfor the smallest diameter class. About 60% of trees P 10 cm wereinhabited by at least one polypore species irrespective of the treediameter (Fig. 3A). Results of logistic regression gave support tothese qualitative observations. The occurrence probability of bothred-listed species and other species depended significantly on treediameter when all the studied trees (n = 3875) were included(p < 0.001 for both red-listed and other species). However, whenonly trees P 10 cm in diameter were included into the analyses,tree diameter affected significantly the occurrence probability of

Fig. 2. The development of species richness and abundance of all polypore species (A and B) and red-listed species (C and D) in the seminatural and managed stand after thefire.

R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516 511

red-listed species (p < 0.001) but not other species (p = 0.396)(Fig. 3B). Since most of the trees were included into the analysestwice (they were inventoried both in 2002 and 2011), we also ranthe analyses separately for each year but the results remainedessentially the same.

3.3. Changes in the composition of polypore assemblages

A two-dimensional NMDS-ordination (stress �0.09, Fig. 4)showed that the composition of the polypore assemblages of thetwo stands was clearly different through the study years (goodnessof fit of the factor stand r2 = 0.35, p < 0.01, fit of the vector timesince fire r2 = 0.82, p < 0.001). Similarly, a permutational ANOVAof the Bray-Curtis dissimilarity matrix showed that both the standand time since fire affected significantly the polypore species com-position whereas the interaction of these variables (stand ⁄ timesince fire) did not (Table 1). Finally, the within-stand heterogeneityamong the study years was larger in the managed (average dis-tance to medoid = 0.51) than in the seminatural stand (average dis-tance to medoid = 0.37) (No. of permutations = 999, p (> F) < 0.01).

Thus, the direction of changes in the community structure afterthe fire was rather similar in both stands, but the magnitude ofchanges was greater in the managed than in the seminatural stand.Two to 13 years AF, the species assemblages of the seminatural andmanaged stands resembled each other more than the pre-fireassemblages. This was due to the remarkable increase in abun-dance of a similar set of common pioneer species (such as Trichap-tum abietinum and T. fuscoviolaceum; see Appendix) and speciesfavoring open habitats and burnt trees (e.g. Antrodia sinuosa andGloeophyllum sepiarium) in both stands. By 22 years AF, however,the species assemblages in the two stands differentiated again.

There were only four species that were found only BF, and onlysingle individuals were recorded (Appendix). Of these species, Pos-tia parva is a rare pine specialist, whereas the other species are allspecialists on deciduous trees (Inocutis rheades on aspen, Phellinus

alni on alders and P. conchatus on willows). All other species foundBF reappeared AF.

Almost all species growing on deciduous trees peaked6–13 years AF, and even the most abundant species (such asP. betulinus, F. fomentarius, Phellinus cinereus, P. laevigatus andTrichaptum pargamenum) had practically disappeared by 22 yearsAF. This was due to the fact that most dead deciduous trees hadalready disappeared or reached an advanced decay stage by then.The only species on deciduous trees that peaked late, 13–22 yearsAF, was Trechispora mollusca that mainly grows on dead fruitingbodies of F. fomentarius. In contrast, except for the early succes-sional Trichaptum species mentioned above, most of the speciesassociated with conifers peaked later, starting from 13 years AF.Some relatively abundant species did not reach their highest abun-dance until 22 years AF, e.g. Steccherinum luteoalbum, Cinereomyceslindbladii and Skeletocutis biguttulata (Appendix).

The average degree of burn of all trees inhabited by at least onepolypore species in the post-fire data (inventory years 1991, 1995and 2002) was 1.7. Thus, species with a clearly higher average de-gree of burn can be considered as species favoring burned wood inthese data (see Appendix). However, if there are only few recordsof a species, the fire preference may be unreliable. Abundant spe-cies that clearly favored charred wood included A. sinuosa (theaverage degree of burn 3.1), Antrodia xantha (3.1) and Rhodonia pla-centa (2.9). Species that seemed to avoid charred trees (the averagedegree of burn < 1.4) include most of the Skeletocutis species, allTrichaptum species, F. fomentarius and P. betulinus (Appendix).

A total of 28 red-listed species were recorded during the wholestudy period; of these, 18 species were not observed until 13 or22 years AF.

4. Discussion

According to our results, the short-term effects (<5 years) of fireon polypore communities were negative. This result is similar to

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Fig. 3. The proportion of dead trees inhabited by at least one red-listed species(shaded columns) or other polypore species (empty columns) in different diameterclasses (pooled data from 2002 and 2011 inventories) (A). Fitted logistic regressionmodels showing the predicted proportions of trees P10 cm inhabited by at leastone red-listed species (solid line) or other polypore species (dashed line) (B).

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Managed

Fig. 4. NMDS ordination depicting the changes in species composition of polyporeassemblages in the managed and seminatural stands following the fire. The firstsymbol in each trajectory represents the year before the fire (1988), and the arrowsshow the direction of changes during the consecutive inventories until the lastsymbol, 22 years after the fire (2011).

Table 1Permutational ANOVA table testing the effects of stand and inventory year (i.e. timesince fire) and their interaction on the composition of polypore assemblages.

Variable Df SumsOfSqs Mean Sqs F. Model R2 Pr(>F)

Stand 1 0.7440 0.74399 4.2339 0.20548 0.00126Year 1 0.7759 0.77594 4.4157 0.21431 0.00177Stand:year 1 0.3435 0.34354 1.9550 0.09488 0.07608Residuals 10 1.7572 0.17572 0.48533Total 13 3.6207 1.00000

512 R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516

previous studies in which short-term effects of fire on wood-decomposing fungi have been investigated (Junninen et al., 2008;Kurth et al., 2013; Olsson and Jonsson, 2010; Penttilä and Koti-ranta, 1996). Intensive fire destroys the mycelia and decreasesthe inoculum potential of many fungi by consuming dead woodand by creating extreme environmental conditions (Pugh and Bod-dy, 1988). Consequently, species diversity usually decreases afterthe fire. The positive effects started to become visible later, morethan 5 years after the fire when the fire-killed trees had decayedfurther. The number of species increased to a higher level than be-fore the fire, even in the seminatural forest. The number of poly-pore species observed per hectare both 13 and 22 years after thefire (64 species) in the seminatural stand is an exceptionally highnumber of species for such a small area (see Junninen and Komo-nen, 2011a, 2011b).

The few existing studies on the effects of fire on wood-decayingfungi in boreal forests suggest that there are very few if any strictlyfire-dependent wood-decaying fungi, but many species seem to befavored by fire (Eriksson, 1958; Junninen et al., 2008; Olsson andJonsson, 2010; Penttilä and Kotiranta, 1996; Renvall, 1995; Ylisir-niö et al., 2012). Of the species recorded in our study, the red-listed

species Antrodia primaeva, Dichomitus squalens, Gelatoporia subver-mispora and Physisporinus rivulosus are species that are known tobe associated with forest fire areas and charred wood (see theabove references). An unexpected and new observation in thecourse of our study was that several polypore species that havebeen regarded as old-growth indicator species requiring undis-turbed forests with long continuity (Bader et al., 1995; Bredesenet al., 1997; Karström, 1992; Niemelä, 2005), such as Amylocystislapponica, Fomitopsis rosea and Steccherinum collabens, actually ap-peared or increased in abundance ten to twenty years after fire. Infact, the majority of red-listed species were not observed until 13or 22 years after the fire. Our results are consistent with other re-cent studies, which suggest that many red-listed species seem tobe more adapted to disturbances than has been thought earlier,and which emphasize the importance of the open stage of succes-sion with abundant dead wood for the diversity of wood-inhabit-ing fungi (Berglund et al., 2011a, 2011b; Junninen et al., 2006Junninen et al., 2007; Ylisirniö et al., 2012). Almost all species ob-served before the fire were also recorded after the fire. This indi-cates that species producing fruiting bodies in the mature closedforests either survived the fire or were able to re-colonize the standwithin 10–20 years after the fire.

Species richness increased after the fire in both stands, but thenumber and abundance of red-listed species increased strikinglymore in the seminatural than in the managed stand. The obviousexplanation for this difference is the larger amount and variety of

R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516 513

dead wood in the seminatural stand, and particularly the highernumber of large-diameter dead trees of which a higher proportionwas inhabited by red-listed species than of smaller trees. In gen-eral, large-diameter trees are more important to red-listed speciesthan small-diameter trees (e.g. Bader et al., 1995; Renvall, 1995;Heilmann-Clausen and Christensen, 2004). Species compositionchanged less in the seminatural forest than in the managed forest.The reason for this may be the more abundant and more variabledead-wood pool in the seminatural forest, which may have func-tioned as a buffer against the disturbance.

Our results show that prescribed burning of stands can be avery effective method to create habitats for red-listed polyporespecies, at least if the stand is located close to high-quality sourceareas and contains a sufficient amount of large-diameter trunks ofdifferent tree species. Existing evidence indicates that the efficientdispersal distance of polypores (and other wood-decay fungi) maybe only a few hundred meters (Edman et al., 2004; Norros et al.,2012). The results are relevant also to the discussion about the ef-

Appendix A

Polypore species and their abundances (numbers of records) in eac(1988) and after (1989–2011) the burning. Threatened (EN = endangerspecies indicated with bold; their status according to Kotiranta et al. (2and Nordén et al. 2013): 1pine, 2spruce, 3coniferous tree, 4deciduous tcolumn DB (Degree of Burn) shows the average degree of burning of hosing) for each species based on the 1991, 1995 and 2002 inventories.

SPECIES M88

M89

M90

M91

M95

Amylocystis lapponica2 NT – – – – –Anomoporia bombycina3 NT – – – – –Anomoporia kamtschatica1 – – – 1 1Antrodia albobrunnea1 NT 1 – – – –Antrodia infirma1 VU – – – – –Antrodia primaeva1 VU – – – – –Antrodia serialis2 1 – – – –Antrodia sinuosa3 9 – 1 12 47Antrodia sitchensis3 EN – – – – –Antrodia xantha3 18 2 2 3 20Antrodiella citrinella2 NT – – – – –Antrodiella pallasii3 – – – – –Antrodiella pallescens4 – – – – 1Antrodiella romellii4 – – – – –Antrodiella sp. – – – – –Bjerkandera adusta4 – – – 2 –Byssoporia mollicula5 1 1 1 1 1Ceriporia purpurea4 NT – – – – –Ceriporia viridans4 – – – – 1Ceriporiopsis pseudogilvescens4 – – – – –Cerrena unicolor4 1 – – 1 1Cinereomyces lenis1 NT – – – – –Cinereomyces lindbladii5 2 – – – 1Datronia mollis4 – – – – –Dichomitus squalens1 VU 1 1 1 1 –Diplomitoporus crustulinus2 VU – – – – –Fibroporia norrlandica3 – – – – –Fomes fomentarius4 1 1 1 – 11Fomitopsis pinicola5 1 – – – 3Fomitopsis rosea2 NT – – – – 1Gelatoporia subvermispora5 NT – – – – –Gloeophyllum abietinum3 NT – – – – –

fects of post-fire salvage logging on biodiversity (Lindenmayeret al., 2008). Young successional stages of forest with plenty of leg-acy structures such as logs and snags can be very important forbiodiversity. However, the long-term positive effects of distur-bances on ecosystem functions and species communities may notbecome visible until after a decade or more.

Acknowledgements

We thank the organizations that funded our study: Metsähall-itus, Ministry of the Environment, Finnish Environment Institute(project: Restoration of forests for species recovery), Maj and TorNessling Foundation and Finnish Cultural Foundation. We thankKaija Eisto, Raimo Heikkilä, Heikki Kotiranta, Tuomo Niemelä, Jor-ma Pennanen, Seppo Piirainen and Raimo Virkkala for their valu-able help and co-operation during this project and JuhaHeikkinen for advice and help in the statistical treatment of thedata.

h inventory in the managed (M) and semi-natural (S) stand beforeed, VU = vulnerable), near threatened (NT) and data deficient (DD)010). Host tree preferences of species (according to Niemelä 2005

ree, 5generalist. Nomenclature follows Kotiranta et al. (2009). Lastt trees (measured on the spot where the fruiting bodies were grow-

M02

M11

S88

S89

S90

S91

S95

S02

S11

DB11

– – – – – – – 1 7 3.0– – – – – – – – 1 –– 13 – – – – – – 6 1.01 1 3 2 2 2 3 6 3 1.8– – – – – – – 1 1 2.01 – – – – – – 1 – 4.0– – 9 2 2 5 12 46 84 1.861 37 14 4 5 45 117 124 80 3.1– – – – – – – – 1 –31 41 22 5 8 34 67 68 103 3.1– – – – – – 1 1 1.03 – – – – – – – – 2.71 – 1 – – – 2 5 – 1.34 – – – – – – 2 – 1.0– – – – – – – – 1 –– – 4 1 – 1 1 – – 1.71 2 – – – – – – – 1.0– – – – – – – – 1 –– – – – – – – – – 2.01 – – – – – – – – 1.0– – 10 3 4 4 4 2 1 1.2– – 1 – – – – – 1 –14 23 1 – – 1 – 17 31 1.8– – – – – – – 1 – 1.0– – – 1 1 1 1 2 2 2.0– – – – – – – – 1 –1 – – – – – – 1 3 1.019 3 42 18 20 22 119 68 5 1.25 – 35 15 23 31 74 85 18 1.5– – 2 2 2 2 7 16 12 2.34 – – – – – – 6 – 2.4– – – – – – – – 1 –

(continued on next page)

Appendix A (continued)

SPECIES M88

M89

M90

M91

M95

M02

M11

S88

S89

S90

S91

S95

S02

S11

DB11

Gloeophyllum odoratum2 – – – – – – – – – – – – – 1 –Gloeophyllum sepiarium5 2 – – 14 10 1 – 8 3 5 12 25 50 34 2.2Gloeoporus dichrous4 – – 1 3 – – – 3 1 7 13 5 2 – 2.3Gloeoporus pannocinctus4 – – 1 1 – – 1 – 1 3 12 9 1 – 2.4Hapalopilus aurantiacus3 NT – – – – – – – – – – – – 2 – 2.0Hapalopilus ochraceolateritius3

NT– – – – – – 1 – – – – – – – –

Hapalopilus rutilans4 – – – – 2 – – 1 – – – 4 – – 1.1Hyphodontia paradoxa4 – – – – 1 – – – – – – – – – 1.0Inonotus obliquus4 3 1 1 1 1 1 – 11 6 7 7 3 1 – 1.5Inonotus radiatus4 – – – – 1 – – – – – – – – – 2.0Inonotus rheades4 – – – – – – – 1 – – – – – – –Ischnoderma benzoinum3 – – – – – – – – – – – 1 1 – 1.5Leptoporus mollis3 – – – 1 – – 1 – – – – 3 5 5 2.0Meruliopsis taxicola3 – – – – 1 6 – – – – – 2 – 1 1.8Oligoporus rennyi3 1 – – 1 – – – – – 1 1 – – 1 2.0Oligoporus sericeomollis3 8 1 1 1 2 4 4 5 – 3 3 4 14 35 2.4Perenniporia subacida5 NT – – – – – – – – – – – – 7 5 1.0Phaeolus schweinitzii3 – – – – – – – 1 – 1 1 – – – 2.0Phellinus alni4 2 – – – – – – – – – – – – – –Phellinus cinereus4 – – – – 2 5 1 13 5 6 11 13 11 2 1.3Phellinus conchatus4 – – – – – – – 1 – – – – – – –Phellinus ferrugineofuscus2 – – – – – – – 3 1 1 1 1 10 7 1.3Phellinus laevigatus4 1 1 1 1 5 8 4 1 – – – 19 24 3 1.1Phellinus lundellii4 – – – – – – – 1 – 1 1 3 2 – 1.2Phellinus pini1 – – – – 1 – – 4 2 3 4 4 5 3 1.3Phellinus viticola3 2 – 1 1 1 1 4 5 2 3 1 1 6 15 1.5Physisporinus rivulosus4 VU – – – – – – – – – – – – 1 – 5.0Physisporinus vitreus4 – – – – – 2 – – – 1 2 2 6 – 1.5Piptoporus betulinus4 1 – 1 5 47 16 – 15 4 5 43 144 52 1 1.1Polyporus brumalis4 1 – 1 – 3 – – – – – 1 6 3 1 1.5Polyporus ciliatus4 – – – – – 1 – – – – – 1 3 1 2.0Postia alni4 – – – – – – – – – – – 1 – – 3.0Postia caesia3 – – – – – 3 – 1 – – 2 8 9 38 1.7Postia fragilis3 – – – – – 5 14 1 – – – – 1 6 1.3Postia guttulata3 NT – – – – – – – – – – – – – 2 –Postia hibernica3 – – – – – 3 10 – – – – – 2 2 1.2Postia lactea5 – – – – – 1 – – – – – – – – 1.0Postia lateritia1 NT 1 – – – – – 1 1 – – – 1 1 1 1.0Postia leucomallella3 1 – – – – 2 – 2 – – – – – 2 1.0Postia luteocaesia1 – – – – – – – – – – – – – 1 –Postia parva1 NT 1 – – – – – 1 – – – – – – –Postia ptychogaster5 – – – – – – 1 – – – – – – 1 –Postia stiptica5 – – – – – – – – – – – – 2 – 1.0Postia tephroleuca5 1 – – – – 1 1 – – – – 3 22 10 1.0Protomerulius caryae4 NT – – – – – – 1 – – – – – 1 – 1.0Pycnoporellus fulgens2 – – – – – – – – – – – 1 – – 3.0Pycnoporus cinnabarinus4 – – – 1 1 1 2 1 1 – 1 – 1 2.0Rhodonia placenta3 1 – – – 1 4 4 – – – – 11 12 1 2.9Rigidoporus corticola4 – – – – – 2 1 – – – – – – – 1.5Sarcoporia polyspora3 – – – – – – – 1 – – – – 1 3 1.0Sistotrema alboluteum5 – – – – – – – – – – – – – 1 –Sistotrema dennisii5 DD – – – – – 1 1 – – – – – – – 1.0Sistotrema muscicola5 – – – – – 1 – – – – – – 1 – 1.0Skeletocutis amorpha3 – – – – – 5 1 18 3 3 7 3 – – 1.3Skeletocutis biguttulata3 2 – – 1 2 36 41 2 – – 2 2 3 11 1.6Skeletocutis brevispora2 NT – – – – – – 1 – – – – – 1 – 1.0Skeletocutis carneogrisea3 – – – – – 4 – 7 2 1 6 – 19 1 1.2Skeletocutis kuehneri3 – – – – – 3 2 – – – – – 9 2 1.1Skeletocutis lilacina2 VU – – – – – – – 1 1 1 1 – – – 1.0

514 R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516

Appendix A (continued)

SPECIES M88

M89

M90

M91

M95

M02

M11

S88

S89

S90

S91

S95

S02

S11

DB11

Skeletocutis odora5 NT – – – – – – – – – – – 2 2 – 2.3Skeletocutis papyracea3 – – – – – 1 2 – – – – – 2 7 1.0Skeletocutis stellae3 VU 1 1 1 1 1 – – – – – – – 1 2 1.0Spongiporus undosus5 – – – – – 1 1 – – – – – – 3 1.0Steccherinum collabens3 NT – – – – – 2 1 – – – – – 3 11 1.0Steccherinum luteoalbum3 1 1 – – 1 21 51 8 1 – 6 9 16 51 1.6Trametes hirsuta4 – – – – 4 – – – – – 1 – – – 2.6Trametes ochracea4 – – – 6 1 – – 7 3 – 4 5 – 1 2.0Trametes pubescens4 – – – 2 – – – 2 1 2 – – 1 – 1.0Trametes velutina4 – – – – – – – – – – – 1 – – 1.0Trechispora hymenocystis5 – – – – – – – – – – – – – 1 –Trechispora mollusca4 – – – – – 1 2 – – – – – 16 11 1.0Trichaptum abietinum3 2 – – – 57 128 – 70 34 33 44 170 285 42 1.2Trichaptum fuscoviolaceum3 – – – 8 65 101 1 19 4 5 12 31 35 11 1.3Trichaptum pargamenum5 NT 1 – – – 5 1 1 1 1 1 2 25 10 – 1.2Tyromyces chioneus5 – – – – 1 3 1 – 1 – – 1 4 1 1.3Total number of species 29 9 14 23 35 48 35 44 30 31 37 47 64 64Total abundance of species 69 10 15 69 304 523 275 361 130 161 348 932 1118 703Number of threatened species 2 2 2 2 1 1 – 1 2 2 2 1 5 5Number of NT and DD species 4 – – – 2 5 8 6 3 3 3 5 13 12Abundance of threatened species 2 2 2 2 1 1 – 1 2 2 2 1 6 7Abundance of NT and DD species 4 – – – 6 9 8 9 5 5 6 38 57 46

R. Penttilä et al. / Forest Ecology and Management 310 (2013) 508–516 515

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