Notes on the ecology of Ascocoryne turficola (Ascomycota: Helotiales) in West Siberia

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INTRODUCTION A. turficola is a discomycete with rare sightings in Europe, North and South America (Shetland islands), and probably Africa [Van Vooren, 2012]. Its habitat is strongly connected with peatland ecosystems, where it grows as a saprotroph on remains of sphagna and other plants in strongly hydrated conditions [Vasutova et al, 2013; Van Vooren, 2012; Bunyard et al., 2008]. The West Siberian plain is one of the highly bogged areas of the world, and the occurrence of this species here is expectable. Our first collections of A. turficola in West Siberia were made in four locations in northern and middle taiga zones [Filippova et al., 2013], where the species was sighted by opportunistic method in ombrotrophic graminoid-sphagnum hollows and treed ombrotrophic bog. The phytocoenological preference of the species and its abundance there were unsufficiently studied before. Fungi are key decomposers of bog ecosystems, occupying different niches and showing high species diversity [Thormann, 2006]. Discomycetes represent large part of total fungal diversity of bogs and their functional role is therefore important [Filippova, 2012]. The ecology of different species is necessary information for community modelling. The goal of present paper was to reveal phytocoenological preferences, occupied substrates and estimate abundance of A. turficola - a species with fidelity to bogs. STUDY AREA The investigated bog ("Mukhrino bog") is located in the middle taiga zone of West Siberia (N60.892° E68.674°). Eutrophic and mesotrophic types of peatlands are present here, but oligotrophic bogs prevail. The floristic classification of bogs described by Lapshina [2010] in the southeastern part of West Siberia applies well for the area. The climate of the study area is subarctic, with wet warm summer and quite severe snowy winters. The average temperature of the coldest month (January) about -20° C, of the warmest month (July) - 17° C. Mean sum of precipitation about 500 mm. METHODS Data on the ecology of A. turficola were collected along the study of community of larger fungi at Mukhrino bog. The investigated site (2 km2 in north-eastern part of the bog) lies close to the Mukhrino field station monitoring polygon [INTERACT, 2012]. Temporary count-plots were placed in four types of bog communities: 1) treed pine-dwarfshrubs-sphagnum bog, 2) treed pine-dwarfshrubs-sphagnum ridges in ridge-hollow complex, 3) graminoid-sphagnum lawns, 4) graminoid-sphagnum hollows in ridge-hollow complex. 20 plots were established (5 plots per each type), each included 40-60 micro-plots 5 m2 (the total counted area was 4600 m2). Fruitbodies were counted on circular micro-plots, the circles were bordered with a pole and a rope as described in Lodge et al. [2004]. Micro-plots were placed along transects at a distance of about 5 m inside plot borders. The vegetation was described in the plots within 10 m2 area according to standart geo-botanical procedure. Described plots were assigned to associations by comparison with developed floristic classification [Lapshina, 2010]. Physical parameters (pH, bog water level) were measured in 5 points inside plot borders (table 1). Meteorological parameters were measured at local micro-climate station of Mukhrino polygon. Standard minimum (TM-2) and maximum (TM-1) thermometers installed at a 2 m height inside a shelter (at the same bog where plots were monitored), data reading accomplished once a day. Apothecia of A. turficola are submerged in the upper sphagnum layer, their hymenial disc exposed at the surface. Given the small diameter and greenish color of the structures, they are not easy to find. Although counting in micro-plots raises the chance of collection (compared with route method), underestimation is also possible. Each apothecium was counted, though some of them were growing in clusters. If clusters are counted, the number drops about 15% (estimated on two plots). Collections of A. turficola (15 specimens) were processed using standard methods for storage in the Yugra University Fungarium. RESULTS The total number of the encountered A. turficola apothecia was 104, including 98 from the plot count and 6 from accidental collections. A. turficola appears in the study area in late summer-autumn. The first apothecia collected August, 29, were underdeveloped; overmature apothecia started to appear in mid-September. At this time, night temperatures at the bog were approaching zero (fig. 1); this period corresponds to the yellowing of leaves of aspen and birch on mineral soil, and reddening of evergreen leaves of Chamaedaphne calyculata at the bog. Period of A. turficola registration Figure 1. Daily minimum and maximum temperature course at Mukhrino bog in August-September 2013. Red line - maximum, blue - minimum day temperatures; line break - data absent From four investigated community types, A. turficola was found in two (lawns, and hollows in ridge-hollow complex). It inhabited all plots in lawns (18, 18, 7, 8, 33 apothecia per plot; 2.7-16.5 apothecia per 100 m2), and 3 from 5 plots in hollows (0, 0, 4, 5, 5 apothecia per plot; 0-1.7 apothecia per 100 m2) (fig. 2). The mean value of density of A. turficola was about 4.8 apothecia per 100 m2. Lawns and hollows made from a mosaic of several plant associations. A. turficola was collected in three of them with different frequency and morphological characteristics. Scheuchzerio palustris-Sphagnetum cuspidati Osvald 1923. About 1/3 of all registered collections come from this association. Ascocarps grew on buried in sphagnum litter of Carex limosa, Rhinchospora album, Scheuchzeria palustris, Eriophorum vaginatum, and on brown decaying sphagnum parts; often the place of attachment couldn't be described more accurately than mixed soft (decaying) sphagnum-graminoid litter. The stem base could be above or below water level, with the disc laying exposed at the surface among sphagnum capitulas. The stipe of apothecia was 1-5 cm long, and the disc 0.5-1 cm in diameter (fig. 3). Eriophoro vaginati-Sphagnetum baltici Bogd.-Guiheneuf 1928. Two collections were registered in this association. Apothecia grew inside a Eriophorum vaginatum hummock with stipes rooting in densely packed plant sheaths. Apothecia were prominently large (the largest in all collections), up to 6 cm long, disc 1.2 cm broad. The second collection was made accidentally at a side of the hummock among leaf litter with apothecia 3 cm high. Hepatico-Rhynchosporetum albae Bogd.-Guiheneuf 1928. This association produced most of the registered collections; apothecia were collected on sides of hollows, on liverworts covered peat surface with admixture of different plant remains. Apothecia there were usually small, turbinate or short-stipitate, up to 1 cm high and with the disc up to 5 mm wide. Figure 2. Location and abundance of A. turficola at the study site (satellite QuickBird image of NW part of Mukhrino bog). Gray marks the plots without collections; white - with number of apothecia per plot; dashed line marks the boardwalks of Mukhrino field station CONCLUSIONS From the data of the investigated site, A. turficola is a regular inhabitant of communities of lawns and hollows in the ombrotrophic bog. It was encountered 6 times more often in lawns compared to hollows in ridge-hollow complexes, with an average of 4.8 apothecia per 100 m2; and was absent in treed communities. On lawns and hollows, the species was registered in three floristic associations (class Scheuchzerio-Caricetea). Association Hepatico-Rhynchosporetum albae yielded most of collections, the fungus has small, turbinate apothecia, located at the surface of sphagnum covered by liverworts. Associations Scheuchzerio palustris-Sphagnetum cuspidati and Eriophoro vaginati-Sphagnetum baltici are relatively rarely occupied, but apothecia there are larger, with long stem. The occupied substrate is variable: dead parts of sphagna mixed with litter of bog plants: Carex limosa, Eriophorum russeolum, E. vaginatum, Rhinchospora alba, Scheuchzeria palustris. Fruitbodies appear in August-September. Literature analysis shows that the species occurs in other regions in transitional bogs and bogged forests where sphagnum is present, on acidic, water-saturated sites. This suggests that other types of peatlands in the area should be studied, as well as other associations of ombrotrophic bogs which have not been touched by this study. Also, a representative collection of plots in similar communities in other parts of the region would be of value. Table 1. Examples of plant composition of three inhabited associations (plants with their % cover) and phytocoenological differentiation of A. turficola Species Eriophoro vaginati-Sphagnetum baltici Scheuchzerio palustris-Sphagnetum cuspidati Hepatico-Rhynchosporetum albae Andromeda polifolia 20 1 1 Oxycoccus palustris 5 Eriophorum vaginatum 30 E. russeolum + + Scheuchzeria palustris + 10 1 Carex limosa + 3 Rhinchospora alba 5 Menyanthes trifoliata 1 Drosera rotundifolia + D. anglica + Sphagnum balticum 100 10 5 S. papillosum 20 S. junsenii 80 5 S. compactum 3 S. majus + 5 S. lindbergii 3 5 Cladopodiella fluitans 5 Gymnocolia inflata 45 Bog water level, cm 10-15 0-10 1-5 pH, mead value 3.2 3.6 3.8 A. turficola abundance 2 collections About 1/3 collections About 2/3 collections A. turficola substrate E. vaginatum leaf sheaths Litter of Carex limosa, Rhinchospora album, Scheuchzeria palustris, Eriophorum vaginatum mixed with Sphagnum litter On peaty surface among liverworts A. turficola morphological features Long-stipitate, with thick stipe, 6 cm height Long-stipitate, with slender stipe, 1-5 cm height Turbinate or short-stipitate, near 1 cm height

About the authors

N V Filippova

Yugra State Unversity, Khanty-Mansiysk

Email: filippova.courlee.nina@gmail.com

T M Bulyonkova

A.P. Ershov Institute of Informatics Systems Russian Academy of Sciences, Novosibirsk

Email: ressaure@gmail.com

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