Functional diversity of ectomycorrhizal fungal communities along a peatland–forest gradient

Pedobiologia - Journal of Soil Ecology 74 (2019) 15–23

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Functional diversity of ectomycorrhizal fungal communities along a peatland–forest gradient

T

Algis Aučinaa, Maria Rudawskab, Robin Wilganb, Daniel Janowskib, Audrius Skridailaa, ⁎ Stasė Dapkūnienėa, Tomasz Leskib, a b

Botanical Garden of Vilnius University, 43 Kairenu Str., LT-10239, Vilnius, Lithuania Institute of Dendrology Polish Academy of Sciences, 5 Parkowa Str., 62-035, Kórnik, Poland

A R T I C LE I N FO

A B S T R A C T

Keywords: Čepkeliai bog Symbiosis Exploration types Functional ecology Pinus sylvestris

Peatlands are valuable wetland ecosystems that are widespread in boreal forest regions. In addition to harboring numerous uniquely adapted species, they play a major role in global climate regulation due to their ability to sequester large amounts of carbon in soil. Despite their significance, however, many aspects of peatland ecology remain largely unknown. Our study aimed to deepen the understanding of one such aspect, namely peatland ectomycorrhizal (ECM) fungal communities. The structure of belowground ECM fungal communities of Scots pine along a peatland – forest ecotone in the Lithuanian Čepkeliai peatland was examined by molecular identification of ectomycorrhizae collected at the study sites. Additionally, the ectomycorrhizae functionality, as expressed by exploration types, was assessed. The results revealed significant differences in the taxonomic composition of ECM fungal communities along the gradient. Moving from peatland to forest, a gradual increase in ECM fungal taxonomic richness was observed. As the soil water content increases, the medium and long distance exploration types of ectomycorrhizae became more prevalent and dominated on the peatland site. To our knowledge, this study is the first to document ECM fungal communities of Scots pine in peatland conditions and in European peatlands more broadly.

1. Introduction Peatlands cover approximately 3.5% of the Earth’s land surface and are a widespread wetland subtype in the landscape of boreal forest regions (Martini et al., 2006). Storing up to an estimated one-third of the world’s soil carbon content, peatland ecosystems play an important role in the global carbon cycle (Joosten and Clarke, 2002). Peatlands are classified based on their trophic status and water source, being divided into ombrotrophic peatlands (bogs) and minerotrophic peatlands (fens) (Charman, 2002). Specifically, bogs are only fed from precipitation and are characterized by acidic, saturated peat, in a nutrientpoor environment with sphagnum moss coverage, woody vegetation, and ericaceous shrubs (Bridgham et al., 1996; Kaunisto, 1997; Gignac et al., 2000). In Lithuania, fens and bogs cover about 8% and 1% of the land surface, respectively (Taminskas et al., 2012). One of the largest peatlands in the Baltic region, and the largest in Lithuania, is the Čepkeliai bog (5858 ha), which covers more than half of the Čepkeliai State Strict Nature Reserve. This nature reserve was established in 1975 to maintain one of the oldest and most unusual peatlands in Lithuania – the ⁎

forested continental dunes, the relict lakes and isles and the natural hydrological regime (Švažas et al., 2000). This territory is distinguished by its exceptionally high diversity of flora and fauna species. As such, it has been included on the Ramsar list (sites protected under the Ramsar Convention on Wetlands of International Importance especially as Waterfowl Habitat) since 1993 as one of the wetlands of international importance (Ramsar Site No. 625, https://rsis.ramsar.org/ris/625). Most tree species growing in peatlands and their surroundings are, like many woody species of the temperate and boreal zones, dependent on symbiotic associations with ectomycorrhizal (ECM) fungi, which are necessary for plant development under natural conditions (Smith and Read, 2008). This symbiotic relation brings trees an enhanced nutrient and water uptake, while increasing tolerance to environmental extremes and resistance to root pathogens (Molina et al., 1992; Amaranthus, 1997); however, stressful conditions, such as flooding, can be unfavorable for mycorrhizal formation by some ECM fungi (Stenström, 1991). In Lithuania, Scots pine is a native tree species with a wide distribution and broad range of habitats (Danusevičius, 2000). Recent field studies have reported an increase in Scots pine coverage in Lithuanian

Corresponding author. E-mail address: [email protected] (T. Leski).

https://doi.org/10.1016/j.pedobi.2019.03.001 Received 22 November 2018; Received in revised form 19 February 2019; Accepted 7 March 2019 0031-4056/ © 2019 Elsevier GmbH. All rights reserved.

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uva-ursi (L.) Spreng in the understory. The lichens and mosses included Cladonia rangiferina (L.) Web., Cladonia arbuscula (Wallr.) Flot., Dicranum polysetum Michx., Pleurozium schreberi (Brid.) Mitt., Ptilium crista-castrensis (Hedw.) De Not., and Hylocomium splendens (Hedw.) Schimp. The soil was an Albic Arenosol (FAO, 2006) with a thin organic horizon (2.9 ± 0.6 cm), a mixed humus–podzol horizon (4.2 ± 1.2 cm), a podzol horizon (13.4 ± 1.8 cm) and an eluvial horizon (22.7 ± 3.2 cm). The PF zone was irregular in width, ranging from 10 to 15 m along the length of the sampling plot. F site was a pine stand located in the forest (54°01ʹ28.94ʺN, 24°37ʹ25.59ʺE, 129 m elevation) and classified as a Cladonioso-Pinetum forest type. The ground vegetation included V. vitis-idea, C. vulgaris, Festuca ovina L., and Calamagrostis arundinacea (L.) Roth. The mosses and lichens observed at this site included Polytrichum piliferum Hedw., Polytrichum juniperinum Hedw., D. polysetum, P. schreberi, C. arbuscula, and C. rangiferina. The site was an Albic Arenosols (FAO, 2006) with a thin organic horizon (2.0 ± 0.3 cm), a podzol horizon (9.1 ± 1.5 cm) and an eluvial horizon (27.4 ± 6.4 cm). All studied sites were covered by naturally self-seeded Scots pine trees of similar age (40–45 years old), but different in size. The Scots pine trees growing at the dry forest site were considerably taller than the ones growing in the permanently flooded Čepkeliai bog (13 m vs. 3 m, respectively). Pine tree coverage was relatively dense and homogeneous at all sites. Individual birch trees grew only at F. The three studied sites were spaced about 200 m apart.

peatlands (Edvardsson et al., 2015). Taking this continuing change into consideration, insights into different aspects of the ecology of peatland Scots pine stands, particularly their ECM fungal community structure, become even more relevant. Environmental gradients are important factors shaping ECM fungal community composition (Swaty et al., 1998; Toljander et al., 2006; Peay et al., 2010). They may influence the ECM fungal community directly, by environmental selection of the most adapted and competitive fungi, or indirectly, by selecting specific host plants suitable to a given habitat (Moeller et al., 2014). Even though soil water content is a crucial factor shaping the belowground (regarding the ECM root tips) ECM fungal communities (Kennedy et al., 2015), little is known of those communities’ response to shifts in soil moisture. The peatland–forest transect, associated with a natural moisture gradient, is an adequate model for studying this relationship. Previous research on North American boreal wetland ECM fungal communities in Alaska and British Columbia demonstrated differences in ECM fungal species richness and community composition between wetlands and forest stands (Wurzburger et al., 2004; Robertson et al., 2006). However, climate and flora, two important factors shaping fungal communities, are very different between North America and Europe. The present study is the first to focus on the belowground ECM fungal communities along the peatland–forest environmental gradient in Europe. It adds to the previous research on wetland fungal communities in Eurasia, which was limited only to sporocarp surveying (Stasińska 2011, Filippova and Thormann, 2014). Comparing the quantitative and qualitative aspects of ECM fungal communities located across a peatland–forest transect, differentiated in terms of soil water content, was the aim of this work. We hypothesized that: (i) the taxonomic richness of ECM fungi increases from peatland to forest, including the peatland–forest ecotone; (ii) the ECM fungal community composition and abundance of discrete ECM fungal taxa vary depending on the site and soil moisture; and (iii) there are functional aspects to the differences in ECM fungal communities between distinctive stand types. In addition, we sought to examine whether the patterns of ECM fungal diversity found in North American wetlands correspond to those of the European sites (Čepkeliai Reserve).

2.2. Experimental design and field sampling Soil sampling was performed using the following scheme. At each site, three 110-m-long lines were oriented parallel to a peatland–forest boundary and spaced 4 m apart from each other (Fig. 2). Along each line, 12 consecutive sampling points were designated and spaced at least 10 m apart so as to provide a statistically independent distance between the individual samples (Lilleskov et al., 2004). Thus, 36 points per site were sampled. Samples from each separate line of 12 sampling points were collected annually. Over three consecutive years (2013–2015), 108 samples were taken from the peatland, peatland–forest ecotone and forest sites all together. Soil samples (20 × 20 × 30 cm, length × width × depth) with pine roots were carefully excavated using a spade. The excavated roots with adhering soil were placed into labeled plastic bags and analyzed at the Laboratory of Symbiotic Associations (Institute of Dendrology, Polish Academy of Sciences).

2. Materials and methods 2.1. Study sites The study area was located in the fluvio-glacial lowland in southeastern Lithuania, on the eastern border of the Čepkeliai Reserve (Fig. 1). In the studied area, three sites were selected to represent the environmental gradient – peatland (P), the peatland–forest ecotone zone (PF) and forest (F). According to the Köppen-Geiger classification system, the regional climate is temperate continental/humid continental (Dfb) (Kottek et al., 2006). The mean annual temperature is 6.2 °C and the average annual rainfall is 673 mm. The mean number of rainy days is 169 per year. P site, located in the peatland (54°01ʹ25.58ʺN, 24°37ʹ15.01ʺE, 134 m elevation), was classified as a Ledo-sphagnoso-Pinetum forest type, with Ledum palustre L., Eriophorum vaginatum L., Andromeda polifolia L., Oxycoccus palustris Pers., Vaccinium uliginosum L., Drosera rotundifolia L., Chamaedaphne calyculata (L.) Moench and Empetrum nigrum L. in the understory. The surface area was dominated by sphagnum mosses, especially Sphagnum magellanicum Brid. The soils were Terric Histosols (FAO, 2006) with an organic horizon from the surface to a depth of 38.4 ± 2.6 cm characterized by highly decomposed organic materials with strongly reduced amounts of visible plant fibers and a very dark grey to black color (Huang et al., 2009). PF site was situated in the peatland–forest ecotone zone (54°01ʹ27.72ʺN, 24°37ʹ19.70ʺE, 131 m elevation) and was classified as a Cladonioso-Pinetum forest type, with Vaccinium vitis-idea L., Calluna vulgaris (L.) Hull, Deschampsia flexuosa (L.) Trin., and Arctostaphylos

2.3. Chemical analysis of the soil Twelve soil samples for chemical analysis were taken from P, PF, and F sites. The soil samples were collected from locations adjacent to the root sampling points for ECM fungal analysis. The sampled soil was packed into labeled plastic bags and transported to the Chemical Research Laboratory of the Lithuanian Research Centre for Agriculture and Forestry. In the laboratory, the soil samples were air-dried, sieved through a screen with a 2-mm mesh and stored in a plastic bag at 4 °C to await analysis. The determination of organic soil matter (%) was based on weight difference, estimated by combustion at 550 °C for 2 h. Soil pH and water content were analyzed by standard methods, as described in Aučina et al. (2011). 2.4. Mycorrhizal evaluation The root samples with adhering soil were stored at −20 °C prior to processing. These frozen samples were prepared in sets of three to minimize the influence of thawing. The Scots pine roots with mycorrhizas were separated manually from adhering soil, mosses, grasses and ericaceous plant roots, and washed under running tap-water using a 0.5 mm mesh size sieve. The roots with a diameter of ≤2 mm (fine 16

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Fig. 1. Map showing study area.

evident mantle), a cross-section of the potential mycorrhizas was prepared in order to determine the presence or absence of a Hartig net and a mantle using a compound microscope Axio Imager.A1 (Carl Zeiss, Germany) at 400–1000 fold magnification. All morphotypes were also classified into different exploration types, as defined by Agerer (2001) – contact (C), short-distance (SD), medium-distance smooth (MDS), medium-distance fringe (MDF), and long-distance (LD) – based on the emanating hyphae extent along with the presence and structure of the rhizomorphs. The ectomycorrhizae were also classified on the basis of their exploration type as hydrophilic or hydrophobic according to previous studies (Rambold and Agerer, 1997; Agerer, 2001, 2006, Rosinger et al., 2018). For each morphotype, the number of vital mycorrhizas and the relative abundance (number of root tips of each morphotype/total number of mycorrhizas) was calculated separately for each sample. Three to four representative root tips from each morphotype were placed in 1.5 ml Eppendorf tubes and stored at −20 °C to await further identification by molecular methods. Separate morphotypes from each study site were treated individually during the molecular identification and were pooled for abundance calculations only after the molecular analysis confirmed that the morphotypes belonged to the same taxon. Fungal symbionts were identified by the sequencing of amplified internal transcribed spacers (ITSs) of rDNA, using ITS-1F and ITS-4 primers. Sequencing of the ITS region was done on a CEQ 20000XL automatic sequencer, using the same set of primers, at Adam Mickiewicz University in Poznań (Poland). In total, 414 sequences were obtained.

Fig. 2. The field sampling scheme. Black circles represent twelve subsequent sampling points per year.

roots) were cut into approximately 2-cm-long sections and observed under a stereomicroscope (Zeiss Stemi 2000-C, Carl Zeiss, Germany) at 10–60 fold magnification. From each soil sample 230–275 fine root tips were randomly selected for further analysis. The root tips were classified as dead (scurfy surface and easily detachable cortex, with or without remnants of ECM mantle) or vital (swollen, without root hair, covered by fungal mantles) ectomycorrhizae (Agerer, 1991; Scattolin et al., 2008; Aučina et al., 2015). The vital mycorrhizae were assigned to separate morphotypes based on morphological features according to Agerer (2012). In cases of uncertain morphotypes (e.g., thin or non-

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Table 1 Relative abundance, observed total and average taxa richness, estimated taxa richness (Chao1, bootstrap), Shannon diversity and evenness indices of ECM fungi identified on the roots of Scots pine trees at the peatland (P), peatland-forest ecotone (PF) and forest (F) sites. Values are mean ± SE of 36 samples. Mycorrhizal fungal taxa

Ascomycota Acephala macrosclerotium Cenococcum geophilum Meliniomyces bicolor Basidiomycota Amanita excelsa Boletus edulis Clavulinaceae Cortinarius acutus Cortinarius armeniacus Cortinarius sp. 1 Cortinarius fuscescens Cortinarius sp. 2 Cortinarius quarciticus Cortinarius semisanguineus Cortinarius sp. Hebeloma incarnatulum Inocybe sp. Lactarius helvus Lactarius rufus Lactarius sp. Leccinum scabrum Paxillus involutus Piloderma olivaceum Piloderma sphaerosporum Pseudotomentella vepallidospora Russula adusta Russula atrorubens Russula betularum Russula clavipes Russula decolorans Russula emetica Russula paludosa Suillus flavidus Suillus sp. Suillus variegates Thelephora terrestris Tylospora sp. Tomentella sp. Tomentella sublilacina Tomentellopsis echinospora Tretomyces sp. Tricholoma equestre Unidentified UN fungus 1 (Cortinarius type) UN fungus 2 UN fungus 3 UN fungus 4 (Suillus type) UN fungus 5 (Russula type 1) UN fungus 6 (Tomentella type) UN fungus 7 (Russula type 2) Statistics Observed taxa richness at site Average taxa richness per sample Average number of vital mycorrhizal root tips Average number of dead root tips Chao 1 Bootstrap Shannon diversity index (Hʹ) Evenness

Site

Explorationtype

Hydrophobicity/hydrophilicity

P

PF

F

7.3 ± 3.82 13.1 ± 3.02 b* e

0.3 ± 0.16 23.0 ± 2.94 a e

e 19.6 ± 2.79 a 7.1 ± 2.22

SD SD SD

hi hi hi

e e 2.5 ± 2.54 1.9 ± 0.82 e e e 5.6 ± 1.58 a 8.5 ± 4.05 0.01 ± 0.01 0.8 ± 0.55 1.5 ± 0.65 e 0.3 ± 0.22 b 0.2 ± 0.18 e e e e 31.0 ± 4.56 a 2.4 ± 1.70 e e e e e 0.3 ± 0.21 b 2.6 ± 0.92 b 2.5 ± 0.91 5.3 ± 2.04 4.2 ± 1.63 a e 1.0 ± 1.00 3.2 ± 2.48 e 0.4 ± 0.24 e e

e e 0.1 ± 0.08 e e e e 6.5 ± 1.41 a e 0.03 ± 0.03 0.4 ± 0.38 0.1 ± 0.05 0.2 ± 0.23 14.1 ± 3.94 a 0.4 ± 0.38 e e 0.3 ± 0.31 e 18.2 ± 3.01 a 0.01 ± 0.01 e e e 0.2 ± 0.23 11.7 ± 4.85 1.5 ± 0.89 ab 13.3 ± 4.22 ab 0.1 ± 0.04 2.8 ± 1.52 2.1 ± 1.10 ab e 0.5 ± 0.31 e 0.4 ± 0.39 e e e

0.1 ± 0.14 0.1 ± 0.11 e 4.3 ± 1.58 0.7 ± 0.66 0.7 ± 0.42 0.7 ± 0.31 0.8 ± 0.70 b 0.1 ± 0.15 e e 0.01 ± 0.01 0.1 ± 0.08 0.1 ± 0.13 b 2.4 ± 1.46 11.2 ± 3.12 0.04 ± 0.04 0.4 ± 0.26 6.3 ± 3.54 2.1 ± 0.99 b e 4.4 ± 1.67 0.1 ± 0.07 0.9 ± 0.67 e e 4.0 ± 1.15 a 10.6 ± 2.92 a e 2.2 ± 1.05 0.1 ± 0.08 b 0.2 ± 0.15 e e e e 13.8 ± 3.09 5.2 ± 1.78

MDS LD SD MDF MDF MDF MDF MDF MDF MDF MDF MDF SD C C C LD LD MDF MDF SD MDS MDS MDS MDS MDS MDS MDS LD LD LD MDS SD SD C MDS MDF MDF

hi ho hi ho ho ho ho ho ho ho ho ho hi hi hi hi ho ho ho ho hi hi hi hi hi hi hi hi ho ho ho hi hi hi hi hi ho ho

5.1 ± 2.63 e e 0.1 ± 0.05 e e e

2.7 0.1 e e 0.4 0.1 0.5

0.4 ± 0.29 e 1.2 ± 0.85 e e e e

MDF SD MDF LD MDS SD MDS

ho hi ho ho hi hi hi

23 5.2 ± 0.45 166.2 ± 14.07 137.4 ± 18.89 a 23.5 25.0 1.07 ± 0.09 0.67 ± 0.03

27 5.0 ± 0.31 146.9 ± 18.23 84.3 ± 14.87 b 28.0 32.4 1.17 ± 0.07 0.71 ± 0.03

± 1.52 ± 0.12

± 0.39 ± 0.14 ± 0.49

31 5.3 ± 0.32 132.8 ± 14.32 49.4 ± 8.38 b 31.5 34.6 1.21 ± 0.06 0.71 ± 0.02

* Different letters indicate statistically significant differences between sites (P < 0.05; Mann–Whitney U and Kruskal–Wallis tests for relative abundance; Tukey’s (HSD) test for average taxa richness per sample, average number of vital mycorrhizal root tips, average number of dead root tips, Shannon diversity and evenness indices between sites).

ectomycorrhizal or non-ectomycorrhizal lineages (Tedersoo et al., 2010). Selected representatives of each unique ITS sequence were deposited in the National Center for Biotechnology Information GenBank with the accession numbers MG590023–MG590068.

These sequences were compared to the sequences from the UNITE and GenBank databases using the BLAST tool. Sequences were assigned to a given fungal species if their similarity to the reference sequence surpassed a 97% threshold. Mycorrhizal or non-mycorrhizal status of identified taxa was verified based on their phylogenetic assignment to 18

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2.5. Statistical analysis

3. Results

The physical and chemical parameters of the soil, average number of vital mycorrhizal root tips, average number of dead root tips and average fungal species richness per sample were evaluated by two-way analysis of variance (ANOVA); the site was the fixed factor with the year, treated as a block, as the random factor. The Shapiro–Wilk and Levene’s tests were used to determine the normal distribution of the data and homogeneity of variance, respectively. Post hoc comparisons of means among study sites were done using Tukey’s HSD test at a significance level of P < 0.05. All data from the tested parameters were square root transformed before analysis. For each study site, the variance homogeneity for relative abundance over the three consecutive years was determined; the data were analyzed as a repeated measure through time. The relative abundance differences of mycorrhizal morphotypes among the study sites were determined using the Kruskal–Wallis and Mann–Whitney U tests and the data were arcsine square root transformed prior to statistical analysis. The statistical analysis was performed using the Statistica 5.5 software (StatSoft Inc., 2000). The estimated species richness (bootstrap and Chao 1) was determined by the EstimateS program v.8.2.0 (Colwell and Elsensohn, 2014). ECM fungal taxon accumulation curves from all three sites were constructed in order to examine ECM fungal community richness, depending on the number of sampled ECM root tips. The Shannon diversity and evenness indices for the assessment of belowground ECM fungal diversity were computed using PAST 1.89 software (Hammer et al., 2001) based on square root transformed data. A nonmetric multidimensional scaling (NMDS) ordination technique, based on the Bray–Curtis matrix, was used to visualize differences in ECM fungal community structure. Difference assessment in the ECM fungal taxa relative abundance among study sites was carried out using oneway analysis of similarity (ANOSIM). A similarity of percentages (SIMPER) was performed to identify the main explanatory taxa contributing to these differences. Canonical correspondence analysis (CCA) was performed using CANOCO software (v.4.5) to visualize relationships between mycorrhizal exploration types and environmental variables, which were superimposed over fungal community composition data as vectors for the tested sites. The significance of the vectors was defined by the gradient length (in this study, the gradient length = 2.824), which showed that the selected unimodal method (CCA) was appropriate (ter Braak and Šmilauer, 2002). An estimate of gradient length was obtained using detrended correspondence analysis, in which the detrending by segments method was chosen, and no transformation of the data was performed (Hill and Gauch, 1980). For the CCA, the data were log transformed (log 10 + 1). CCA in Hillʼs scaling, with a focus on interspecies distances, was performed. The significance of the species–environment relationship was assessed using the Monte Carlo permutation test with 499 permutations under a reduced model.

Statistical analysis of the physical and chemical parameters of the soil indicated significant differences overall between the tested sites (P = 0.025), with the year having no significant effect (P = 0.806). The concentration of total soil organic matter and soil water content were significantly greater (P = 0.007) at P than at PF or F. The pH of the soil ranged between 2.7 and 3.65, and was significantly greater (P = 0.0001) at F than at P or PF. A total of 25,136 root tips (15,779 vital mycorrhizal and 9357 dead) from Scots pine trees across the peatland–forest gradient were collected. Typically, 133–166 vital mycorrhizas and 49–137 dead root tips were present in each soil sample. The average number of dead root tips was significantly greater (P = 0.002) at P than at PF or F (Table 1). No significant differences among the sites were found in the average number of vital mycorrhizal root tips. Based on molecular identification, a total of 48 ECM fungal taxa were identified from the morphotypes determined at all tested sites. In addition, five non-ECM fungal taxa were found (Supplement 1). Based on the ITS sequences, 31 fungal taxa were identified at the species level, nine at the genus level and one taxon at the family level. The seven morphotypes not identified by molecular analysis were classified as unidentified fungal taxa (UN fungus 1–7, Supplement 1). The total number of fungal taxa at P, PF, and F was 23, 27, and 31, respectively (Table 1). No significant differences in average taxa richness per sample among the study sites were noted. Eleven fungal taxa were common to all three sites, whereas 26 were found only from single sites (16 found exclusively at F, 7 at PF, and 3 at P). The ECM fungal accumulation curves for the tested communities clearly showed that F had the highest slope and ECM fungal taxa richness (Supplement 2). The Chao1 and bootstrap richness estimators predicted values of 23.5 and 25.0 taxa for P, 28.0 and 32.4 taxa for PF, and 31.5 and 34.6 taxa for F, respectively (Table 1). Based on the relative abundance of each ECM taxon, Piloderma sphaerosporum was found to be the most abundant at P, while Cenococcum geophilum was the most abundant at PF and F (Table 1). Cenococcum geophilum was the second to most abundant ECM fungal species at P, while P. sphaerosporum was the second to most abundant at PF and Tretomyces sp. was the second to most abundant at F. The Shannonʼs diversity indices for the Scots pine ECM fungal communities ranged from 1.07 to 1.21, but did not identify significant differences among the study sites. No significant differences in the ECM fungal community evenness were found among the sites. The ANOSIM and NMDS ordinations were used to evaluate the influence of the site on local ECM fungal communities. The NMDS ordination of the ECM fungal communities indicated partial separation (P/ F) and apparent overlap (P/PF/F) (Fig. 3). The ANOSIM revealed a significant difference among the sites (global R = 0.29, P = 0.0001) and in a pairwise comparison (P/PF, R = 0.14; PF/F, R = 0.25; P/F,

Fig. 3. Nonmetric multidimensional scaling ordination, based on Bray–Curtis similarity index, of ectomycorrhizal fungal communities found on the roots of Scots pine trees across peatland-forest gradient. Abbreviations P, PF, and F as in Fig. 1. 19

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Table 2 Relative abundance of mycorrhizal exploration types, hydrophilic and hydrophobic mycorrhizas identified on the roots of Scots pine trees at the peatland (P), peatland-forest (PF) and forest (F) sites. Values are mean ± SE of 36 samples. Site

P PF F P>F

Mycorrhizal exploration types C

SD

MDS

MDF

LD

0.5 ± 0.28 b* 14.8 ± 3.95 a 13.7 ± 3.33 a 0.005

29.6 ± 5.19 24.3 ± 3.08 26.8 ± 2.79 0.722

3.3 ± 1.00 b 27.6 ± 5.94 a 20.3 ± 4.05 a 0.001

54.5 ± 5.55 a 28.0 ± 3.91 b 36.3 ± 4.08 b 0.0001

12.1 ± 3.46 5.3 ± 2.54 2.8 ± 1.24 0.398

Hydrophilic

Hydrophobic

33.4 ± 5.32 b 66.7 ± 4.16 a 60.9 ± 4.09 a 0.0001

66.6 ± 5.32 a 33.3 ± 4.16 b 39.1 ± 4.09 b 0.0001

* Within a column, values with different letters are significantly different after Tukey’s (HSD) test (P < 0.05).

exploration types correlated with certain soil variables. The MDF and LD exploration types correlated positively with soil organic matter and water content, while C and MDS correlated negatively with those parameters. Manual forward selection of the environmental variables indicated that the soil organic matter (F = 14.6, P = 0.002) and water content (F = 10.8, P = 0.002) were significantly associated with the distribution of exploration types, explaining 91.4% and 69.1% of their variation, respectively.

R = 0.46; P = 0.0001 for all pairwise comparisons). SIMPER analysis showed that P. sphaerosporum, C. geophilum, R. paludosa, Tretomyces sp., and L. helvus were the principal species associated with the dissimilarity of ECM fungal communities among the sites (with a 14.6%, 12.0%, 8.5%, 6.0%, and 5.3% contribution to dissimilarity, respectively). Assessment of the ECM fungal community functional diversity indicated significant differences among the three sites in the relative abundances of the C (P = 0.005), MDS (P = 0.001) and MDF (P = 0.0001) exploration types along with the hydrophilic and hydrophobic fungi (P = 0.0001) (Table 2). The ECM fungal community at P was dominated by fungi of the MDF exploration type (55%) followed by fungi of the SD and LD exploration types (30% and 12%, respectively). At PF, the relative abundances of the MDS and MDF exploration types was similar (28%), while fungi of the C and SD exploration types comprised 15% and 24% of the ECM fungal community, respectively. At F, the relative abundances of the C, SD, MDS and MDF exploration types constituted 14%, 27%, 20%, and 36% of the fungal community, respectively. At P, fungi with hydrophobic mycelia were about twice as abundant as fungi with hydrophilic mycelia, whereas at PF and F, hydrophilic mycorrhizae were more abundant (Table 2). The CCA-based ordination diagram revealed relationships among the environmental variables (organic matter, soil water content and pH) and the mycorrhizal exploration types at the sites (Fig. 4). A CCA summary showed that the first two axes, with eigenvalues of 0.090 and 0.003, explained 13.4% of the variance in exploration type, and 99.7% of the relationship between exploration type and environmental variables (most of this, 96.1%, is contributed by the first axis). A Monte Carlo permutation test indicated that the first canonical axis (F = 15.2, P = 0.002) contributed significantly to the variance in mycorrhizal exploration type. The ordination diagram demonstrated that certain

4. Discussion To the best of our knowledge, this is the first paper to describe the diversity and community structure of ECM fungi associated with Scots pine growing in natural European peatland. Moreover, an analysis of the current state of knowledge on ECM symbiosis indicates that our work is one of the first studies focused on the belowground ECM fungal communities in a peatland–forest environmental gradient in general. A total of 48 ECM fungal taxa harbored by Scots pine across the studied peatland–forest gradient were identified; a considerably large number of ECM fungal symbionts compared to what is usually reported for wetland fungal communities (Wurzburger et al., 2004; Robertson et al., 2006). As hypothesized, a gradual increase in taxa richness was observed from the peatland site (P: 23 taxa) to the forest site (F: 31 taxa). This is consistent with the findings from wetlands in Alaska, where the bog sites were shown to host a lower ECM fungal richness than the surrounding forests (Wurzburger et al., 2004). However, a similar study in British Columbia, comparing local wetlands with their surrounding forests, showed the observed taxa richness to be similar across all stand types (Robertson et al., 2006). Nevertheless, the studies in Alaska and British Columbia featured only a small number of mycorrhizae identified at the species, or even the genus, level. This is similar to many early molecular studies, as the resolution of this methodology gradually increased over the years. It is important to note, that the Robertson et al. (2006) study uses restriction fragment length polymorphisms (RFLP) as the base of taxa identification, rather than DNA sequencing. This is a less reliable approach resulting in low taxonomic resolution and was largely replaced by DNA sequencing in recent studies. For this reason, while informative, the taxonomic diversity reported by Wurzburger et al. (2004) and Robertson et al. (2006) has to be viewed with caution. Moreover, although both studies focused on wetlands, there are important differences between those two study sites and this study. According to the Köppen-Geiger climate classification, all three were located in different climate areas (Alaska: temperate oceanic [Cfb]; British Columbia: cool continental/subarctic [Dfc]; Lithuania: temperate continental/humid continental [Dfb]) (Kottek et al., 2006). The main tree species also differed among the sites. Pinus sylvestris, Pinus contorta and Picea mariana were the dominant tree species in the studied wetlands of Čepkeliai peatlands, Alaska and British Columbia, respectively (Wurzburger et al., 2004; Robertson et al., 2006). Another issue to keep in mind when comparing those results is the different sampling area included in the studies. The present study was performed at a relatively small scale, due to its location in a National

Fig. 4. Canonical correspondence analysis diagram of environmental factors and mycorrhizal exploration types. Exploration types are represented by grey circles and soil variables by black arrows. Abbreviations: C – contact, SD – short-distance, MDS – medium-distance smooth, MDF – medium-distance fringe, LD – long-distance exploration types, OM – organic matter, SWC – soil water content. 20

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results from the presence of more favorable environmental and soil conditions in the forest than in the peatland sites. Moreover, the reduced soil aeration inherent in flooded soils (Lodge, 1989) may explain the relation between ectomycorrhizae formation and soil water content. An increase in soil moisture moving from forest to peatland means that, in the latter, low oxygen availability may become a limiting factor to the ECM fungi. A review of the exploration types and hydrophobicity of the identified fungal species revealed that there is also a functional aspect to the differences in the ECM fungal communities of the study sites. At the peatland site (P), around two-thirds of the ectomycorrhizae belong to MDF and LD exploration types, which are often grouped together due to their similar properties (Hagenbo et al., 2018; Rudawska et al., 2018), and are considered to be hydrophobic (Agerer, 2006; Lilleskov et al., 2011). This group consists most notably of the genera Cortinarius and Suillus. The more similar sites (PF and F) harbored ECM fungal communities with reversed proportions, both dominated at around twothirds by hydrophilic mycorrhizae of the C, SD, and MDS types, represented by genera such as Russula and Lactarius. Low oxygen availability is known to limit ectomycorrhizae development (Rydin and Jeglum, 2006). On sites such as peatlands, where the soil water content is high, water may adhere to hydrophilic surfaces, covering them with a layer hindering air access, thus discriminating against hydrophilic ectomycorrhizae. In such environments, having a hydrophobic surface preventing water adhesion (Unestam, 1991; Unestam and Sun, 1995) is an advantage, ensuring access to oxygen. The CCA analysis also supports this hypothesis, as the ECM exploration types are distributed almost in parallel to the soil water content vector. The single most common exploration type in all of the study sites was MDF. While hydrophobic properties may be used to explain its high abundance in the bog site (P), as with Cortinarius spp. or P. sphaerosphorum, they do not seem to play a major role in the more dry sites (PF and F), where a high share of taxa such as Piloderma spp., Tricholoma equestre or Tretomyces sp. were observed. Some of those taxa, like the Piloderma species, may be favored due to their preference for low soil nutrient levels (Lilleskov et al., 2011). Another factor that may promote MDF ectomycorrhizae is the root density varying between the study sites. Peay at al. (2011) suggested that the longer exploration types, such as MDF, are, due to their dispersal abilities, more apt to colonize less compact root systems. Both the bog–forest ecotone site (PF) and the forest site (F) were characterized by a lower average number of root tips (both vital and dead) than the bog site (P). Moreover, as F had, on average, fewer root tips per soil sample than PF, accordingly it also had a higher share of MDF ectomycorrhizae. In conclusion, our study highlights the relationship between a peatland–forest environmental gradient and the ECM fungal community structure. A gradual increase in ECM fungal taxa richness moving from peatland (23 taxa) to ecotone (27 taxa) to forest (31 taxa) was demonstrated. All the sites along the environmental gradient differed in terms of harbored fungal taxa, with over half of the identified fungal species being uniquely present at a single site, and only a few species being present at all three study sites. Based on the exploration type and hydrophobicity of the ectomycorrhizae, a functional differentiation among the studied fungal communities was identified. The conditions inherent in peatlands, mainly soil water content, are limiting to hydrophilic ECM fungal taxa. Other environmental factors, such as nutrient availability and root density, also played a role in shaping the ECM fungal community along the peatland–forest environmental gradient. As the present study was performed on a limited area of a National Park, is important for future research to further evaluate our observations and conclusions. A comprehensive understanding of how environmental gradients, such as the one studied here, shape fungal communities is going to become an increasingly important issue in mycology. As various natural habitats – peatlands included – are affected by progressive climate change, they will undergo a gradual transition into the neighboring

Park, which limited the ability for replications. Future research done on a larger sample area is required to confidently identify the reasons for differences observed between our work and previous studies. Over 56% of the total number of ECM fungal taxa detected in this study belonged to the families Russulaceae, Cortinariaceae and Thelephoraceae. Those families contain widespread ECM fungal taxa, regularly reported in forest ecosystems. Studies have confirmed Russulaceae to be one of the most abundant ECM fungal families in Scots pine forests, especially in mature stands (Goldmann et al., 2015; Rudawska et al., 2018). At the stand level, we observed the highest diversity of Russulaceae in the forest stand (F), where almost all of the taxa identified from this family were present. Both their species richness and abundances decreased along the studied environmental gradient. This observation coincides with reports from wetlands in British Columbia and West Siberia (Robertson et al., 2006; Filippova and Thormann, 2014) where Russulaceae were underrepresented in the ECM fungal communities. Conversely, although no clear pattern was observed across the study sites in their species richness, Cortinariaceae noticeably increased in abundance moving from forest to peatland. A dominant share of this family was also reported in the West Siberia wetlands (Filippova and Thormann, 2014). While it is clear that there are some patterns in the distribution of these ECM fungal families across the peatland–forest environmental gradient, these are not universal. In a study on the fungal communities of diverse wetland types in Pomerania, Stasińska (2013) reported on wetland fungal communities that followed the structure observed in our study, dominated by Cortinariaceae, but also on fungal communities that diverged from our observations, where Russulaceae were the most abundant taxa. Thus, further studies, focusing on the relations between the ECM fungal community structure and the environmental variables in other European wetlands, will be necessary to achieve a more general understanding of wetland fungal ecology. Our results demonstrated that the observed differences in ECM fungal community structure between P, PF and F were statistically significant (Fig. 2), with a greater difference between P and F than between any neighboring fungal communities (P/PF or PF/F). The ECM fungal community of each habitat consisted of a single or a few abundant taxa and a large number of infrequent taxa. This distribution is similar to the ones reported in previous studies (Horton and Bruns, 2001; Taylor, 2002; Godbold, 2005; Aučina et al., 2011; Rudawska et al., 2016). The ECM fungal species that we found to be predominant – P. sphaerosporum and C. geophilum – were present at all study sites, although their relative abundances differed greatly depending on the stand type. For example, while dominating at P (31%) and being one of the major taxa at PF (18%), P. sphaerosporum was uncommon at F (2%). At the fungal community level, a high number of ECM fungal species with low abundances can be recognized as a functional redundancy of taxa performing similar functions and occupying similar ecological niches (Allen et al., 1995). While the tolerance range for environmental conditions overlaps for taxa occupying similar ecological niches, their environmental optima might often be different (Allen et al., 1995). This would account for the change in ECM fungal community structure across the peatland–forest gradient being gradual (as we observed) and the fungal communities being less vulnerable to disturbances. We recognized that the number of redundant ECM fungal taxa increased successively from peatland to forest (Table 1). A similar trend applies to the taxa specific to a given stand – the least are present in the peatland and the most in the forest. It cannot be excluded, that the differences among the ECM fungal communities harbored by Scots pines on the studied sites are to some extent affected by other factors, like the size of the trees or their root systems; however, those were not analyzed in present study. As ECM fungi must be locally adapted to the soil environmental conditions (Allen et al., 1995), it could be assumed that the increase in ECM taxa richness across the peatland–forest environmental gradient 21

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habitat type (Edvardsson et al., 2015). Their fungal communities will shift accordingly. Knowing the distribution of discrete fungal taxa along the environmental gradient would help in predicting the fungal community dynamics, and identifying species that may become endangered in the future.

community shifts underpin declining mycelial production and turnover across a Pinus sylvestris chronosequence. J. Ecol. 106, 490–501. https://doi.org/10.1111/13652745.12917. Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. Past: paleontological statistics software package for education and data analysis. Palaeontol. Electronica 4. Hill, M.O., Gauch, H.G., 1980. Detrended correspondence analysis: an improved ordination technique. Vegetation 42, 47–58. https://doi.org/10.1007/BF00048870. Horton, T.R., Bruns, T.D., 2001. The molecular revolution in ectomycorrhizal ecology: peeking into the black-box. Mol. Ecol. 10, 1855–1871. https://doi.org/10.1046/j. 0962-1083.2001.01333.x. Huang, P.-T., Patel, M., Santagata, M., 2009. Classification of Organic Soils. https://doi. org/10.5703/1288284314328. Joosten, H., Clarke, D., 2002. Wise Use of Mires and Peatlands. International Mire Conservation Group and International Peat Society, Saarijärvi. Kaunisto, S., 1997. Peatland forestry in Finland: problems and possibilities from the nutritional point of view. In: Trettin, C.C., Jurgensen, M.F., Grigal, D.F., Gale, M.R., Jeglum, J.K. (Eds.), Northern Forested Wetlands: Ecology and Management. CRC Press, Boca Raton, pp. 387–401. Kennedy, N.M., Robertson, S.J., Green, D.S., Scholefield, S.R., Arocena, J.M., Tackaberry, L.E., Massicotte, H.B., Egger, K.N., 2015. Site properties have a stronger influence than fire severity on ectomycorrhizal fungi and associated N-cycling bacteria in regenerating post-beetle-killed lodgepole pine forests. Folia Microbiol. (Praha) 60, 399–410. https://doi.org/10.1007/s12223-014-0374-7. Kottek, M., Grieser, J., Beck, C., Rudolf, B., Rubel, F., 2006. World Map of the KöppenGeiger climate classification updated. Meteorol. Zeitschrift 15, 259–263. https://doi. org/10.1127/0941-2948/2006/0130. Lilleskov, E.A., Bruns, T.D., Horton, T.R., Taylor, D., Grogan, P., 2004. Detection of forest stand-level spatial structure in ectomycorrhizal fungal communities. FEMS Microbiol. Ecol. 49, 319–332. https://doi.org/10.1016/j.femsec.2004.04.004. Lilleskov, E.A., Hobbie, E.A., Horton, T.R., 2011. Conservation of ectomycorrhizal fungi: exploring the linkages between functional and taxonomic responses to anthropogenic N deposition. Fungal Ecol. 4, 174–183. https://doi.org/10.1016/j.funeco.2010.09. 008. Lodge, D.J., 1989. The influence of soil moisture and flooding on formation of VA-endoand ectomycorrhizae in Populus and Salix. Plant Soil 117, 243–253. https://doi.org/ 10.1007/BF02220718. Martini, I.P., Martinez Cortizas, A., Chesworth, W., 2006. Peatlands: Evolution and Records of Environmental and Climate Changes. Elsevier Science. Moeller, H.V., Peay, K.G., Fukami, T., 2014. Ectomycorrhizal fungal traits reflect environmental conditions along a coastal California edaphic gradient. FEMS Microbiol. Ecol. 87, 797–806. https://doi.org/10.1111/1574-6941.12265. Molina, R., Massicotte, H., Trappe, J.M., 1992. Specificity phenomena in mycorrhizal symbioses: community-ecological consequences and practical implications. In: Allen, M. (Ed.), Mycorrhizal Functioning: An Integrative Plant-Fungal Process. Springer Science, pp. 357–423. Peay, K.G., Kennedy, P.G., Davies, S.J., Tan, S., Bruns, T.D., 2010. Potential link between plant and fungal distributions in a dipterocarp rainforest: community and phylogenetic structure of tropical ectomycorrhizal fungi across a plant and soil ecotone. New Phytol. 185, 529–542. https://doi.org/10.1111/j.1469-8137.2009.03075.x. Peay, K.G., Kennedy, P.G., Bruns, T.D., 2011. Rethinking ectomycorrhizal succession: are root density and hyphal exploration types drivers of spatial and temporal zonation? Fungal Ecol. 4, 233–240. https://doi.org/10.1016/j.funeco.2010.09.010. Rambold, G., Agerer, R., 1997. DEEMY – the concept of a characterization and determination system for ectomycorrhizae. Mycorrhiza 7, 113–116. https://doi.org/10. 1007/s005720050171. Robertson, S.J., Tackaberry, L.E., Egger, K.N., Massicotte, H.B., 2006. Ectomycorrhizal fungal communities of black spruce differ between wetland and upland forests. Can. J. For. Res. 36, 972–985. https://doi.org/10.1139/x06-001. Rosinger, C., Sandén, H., Matthews, B., Mayer, M., Godbold, D., 2018. Patterns in ectomycorrhizal diversity, community composition, and exploration types in European beech, pine, and spruce forests. Forests 9, 445. https://doi.org/10.3390/f9080445. Rudawska, M., Pietras, M., Smutek, I., Strzeliński, P., Leski, T., 2016. Ectomycorrhizal fungal assemblages of Abies alba Mill. outside its native range in Poland. Mycorrhiza 26, 57–65. https://doi.org/10.1007/s00572-015-0646-3. Rudawska, M., Wilgan, R., Janowski, D., Iwański, M., Leski, T., 2018. Shifts in taxonomical and functional structure of ectomycorrhizal fungal community of Scots pine (Pinus sylvestris L.) underpinned by partner tree ageing. Pedobiologia. 71, 20–30. https://doi.org/10.1016/j.pedobi.2018.08.003. Rydin, H., Jeglum, J.K., 2006. The Biology of Peatlands. Oxford University Presshttps:// doi.org/10.1093/acprof:oso/9780198528722.001.0001. Scattolin, L., Montecchio, L., Agerer, R., 2008. The ectomycorrhizal community structure in high mountain Norway spruce stands. Trees 22, 13–22. https://doi.org/10.1007/ s00468-007-0164-9. Smith, S.E., Read, D., 2008. Mycorrhizal Symbiosis. Elsevierhttps://doi.org/10.1016/ B978-0-12-370526-6.X5001-6. Stasińska, M., 2013. Macrofungi of raised and transitional bogs of Pomerania. Monogr. Bot. 101, 1–142. https://doi.org/10.5586/mb.2011.001. StatSoft, 2000. STATISTICA for Windows (Computer Program Manual). StatSoft, Tulsa, OK. Stenström, E., 1991. The effects of flooding on the formation of ectomycorrhizae in Pinus sylvestris seedlings. Plant Soil 131, 247–250. https://doi.org/10.1007/BF00009455. Švažas, S., Drobelis, E., Balčiauskas, L., Raudonikis, L., 2000. Svarbios Lietuvos pelkės ir seklūs vandenys. OMPO Vilnius, Vilnius. Swaty, R.L., Gehring, C.A., Van Ert, M., Theimer, T.C., Keim, P., Whitham, T.G., 1998. Temporal variation in temperature and rainfall differentially affects ectomycorrhizal colonization at two contrasting sites. New Phytol. 139, 733–739. https://doi.org/10.

Acknowledgements We thank Dr Leszek Karliński and Dr. Marcin Pietras for their help with the fieldwork and valuable discussions. We are also grateful to Alicja Okrasińska, Maria Wójkiewicz and Halina Narożna for their technical support. We thank the staff of Čepkeliai State Strict Nature Reserve, individually Dr. Mindaugas Lapelė and Gintautas Kibirkštis, for providing accurate and authoritative information and comments. This research was partly performed within the framework of COST Action FP1305 (‘Linking belowground biodiversity and ecosystem function in European forests [BioLink]’). Vilnius University (Lithuania) and the Institute of Dendrology Polish Academy of Sciences (Poland) shared financial support. Appendix A. Supplementary data Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.pedobi.2019.03.001. References Agerer, R., 1991. Characterization of ectomycorrhizae. In: Norris, J.R., Read, D.J., Varma, A.K. (Eds.), Techniques for the Study of Mycorrhiza. Academic Press, London, pp. 25–73. Agerer, R., 2001. Exploration types of ectomycorrhizae. Mycorrhiza 11, 107–114. https:// doi.org/10.1007/s005720100108. Agerer, R., 2006. Fungal relationships and structural identity of their ectomycorrhizae. Mycol. Prog. 5, 67–107. https://doi.org/10.1007/s11557-006-0505-x. Agerer, R., 2012. Colour Atlas of Ectomycorrhizae, 15th ed. Einhorn-Verlag, Schwäbisch Gmünd. Allen, E.B., Allen, M.F., Helm, D.J., Trappe, J.M., Molina, R., Rincon, E., 1995. Patterns and regulation of mycorrhizal plant and fungal diversity. Plant Soil 170, 47–62. https://doi.org/10.1007/BF02183054. Amaranthus, M.P., 1997. The Importance and Conservation of Ectomycorrhizal Fungal Diversity in Forest Ecosystems: Lessons From Europe and the Pacific Northwestern United States. Portland, OR. . Aučina, A., Rudawska, M., Leski, T., Ryliškis, D., Pietras, M., Riepšas, E., 2011. Ectomycorrhizal fungal communities on seedlings and conspecific trees of Pinus mugo grown on the coastal dunes of the Curonian Spit in Lithuania. Mycorrhiza 21, 237–245. https://doi.org/10.1007/s00572-010-0341-3. Aučina, A., Rudawska, M., Leski, T., Skridaila, A., Pašakinskiene, I., Riepšas, E., 2015. Forest litter as the mulch improving growth and ectomycorrhizal diversity of bareroot Scots pine (Pinus sylvestris) seedlings. iForest – Biogeosci. For. 8, 394–400. https://doi.org/10.3832/ifor1083-008. Bridgham, S.D., Pastor, J., Janssens, J.A., Chapin, C., Malterer, T.J., 1996. Multiple limiting gradients in peatlands: a call for a new paradigm. Wetlands 16, 45–65. https://doi.org/10.1007/BF03160645. Charman, D., 2002. Peatlands and Environmental Change. John Wiley & Sons, London. Colwell, R.K., Elsensohn, J.E., 2014. EstimateS turns 20: statistical estimation of species richness and shared species from samples, with non-parametric extrapolation. Ecography (Cop.) 37, 609–613. https://doi.org/10.1111/ecog.00814. Danusevičius, J., 2000. Pušies selekcija Lietuvoje [Breeding of pines in Lithuania]. Lututė, Kaunas. Edvardsson, J., Šimanauskienė, R., Taminskas, J., Baužienė, I., Stoffel, M., 2015. Increased tree establishment in Lithuanian peat bogs — insights from field and remotely sensed approaches. Sci. Total Environ. 505, 113–120. https://doi.org/10. 1016/j.scitotenv.2014.09.078. FAO, 2006. World Reference Base for Soil Resources 2006. Food & Agriculture Org., Rome. Filippova, N.V., Thormann, M.N., 2014. Communities of larger fungi of ombrotrophic bogs in West Siberia. Mires Peat 14, 1–22. Gignac, L.D., Halsey, L.A., Vitt, D.H., 2000. A bioclimatic model for the distribution of Sphagnum-dominated peatlands in North America under present climatic conditions. J. Biogeogr. 27, 1139–1151. https://doi.org/10.1046/j.1365-2699.2000.00458.x. Godbold, D.L., 2005. Ectomycorrhizal Community structure: linking biodiversity to function. Progress in Botany. Springer-Verlag, Berlin/Heidelberg, pp. 374–391. https://doi.org/10.1007/3-540-27043-4_15. Goldmann, K., Schöning, I., Buscot, F., Wubet, T., 2015. Forest management type influences diversity and community composition of soil fungi across temperate forest ecosystems. Front. Microbiol. 6. https://doi.org/10.3389/fmicb.2015.01300. Hagenbo, A., Kyaschenko, J., Clemmensen, K.E., Lindahl, B.D., Fransson, P., 2018. Fungal

22

Pedobiologia - Journal of Soil Ecology 74 (2019) 15–23

A. Aučina, et al.

Toljander, J.F., Eberhardt, U., Toljander, Y.K., Paul, L.R., Taylor, A.F.S., 2006. Species composition of an ectomycorrhizal fungal community along a local nutrient gradient in a boreal forest. New Phytol. 170, 873–884. https://doi.org/10.1111/j.1469-8137. 2006.01718.x. Unestam, T., 1991. Water repellency, mat formation, and leaf-stimulated growth of some ectomycorrhizal fungi. Mycorrhiza 1, 13–20. https://doi.org/10.1007/BF00205897. Unestam, T., Sun, Y.-P., 1995. Extramatrical structures of hydrophobic and hydrophilic ectomycorrhizal fungi. Mycorrhiza 5, 301–311. https://doi.org/10.1007/ BF00207402. Wurzburger, N., Hartshorn, A.S., Hendrick, R.L., 2004. Ectomycorrhizal fungal community structure across a bog-forest ecotone in southeastern Alaska. Mycorrhiza 14, 383–389. https://doi.org/10.1007/s00572-004-0301-x.

1046/j.1469-8137.1998.00234.x. Taminskas, J., Pileckas, M., Šimanauskienė, R., Linkevičienė, R., 2012. Wetland classification and inventory in Lithuania. Baltica 25, 33–44. https://doi.org/10.5200/ baltica.2012.25.03. Taylor, A.F.S., 2002. Fungal diversity in ectomycorrhizal communities: sampling effort and species detection. Plant Soil 244, 19–28. https://doi.org/10.1023/ A:1020279815472. Tedersoo, L., May, T.W., Smith, M.E., 2010. Ectomycorrhizal lifestyle in fungi: global diversity, distribution, and evolution of phylogenetic lineages. Mycorrhiza 20, 217–263. https://doi.org/10.1007/s00572-009-0274-x. ter Braak, C.J.F., Smilauer, P., 2002. CANOCO Reference Manual and CanoDraw for Windows User’s Guide: Software for Canonical Community Ordination (Version 4.5). Microcomputer Power, Ithaca, NY.

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