Aphyllophoroid fungi in insular woodlands of eastern Ukraine

Abstract Background Fungi play crucial roles in ecosystems and are among the species-richest organism groups on Earth. However, knowledge on their occurrence lags behind the data for animals and plants. Recent analyses of fungal occurrence data from Western, Central and Northern Europe provided important insights into response of fungi to global warming. The consequences of the global changes for biodiversity on a larger geographical scale are not yet understood. Landscapes of Eastern Europe and particularly of eastern Ukraine, with their specific geological history, vegetation and climate, can add substantially new information about fungal diversity in Europe. New information We describe the dataset and provide a checklist of aphyllophoroid fungi (non-gilled macroscopic Basidiomycota) from eastern Ukraine sampled in 16 areas between 2007 and 2011. The dataset was managed on the PlutoF biodiversity workbench (http://dx.doi.org/10.15156/BIO/587471) and can also be accessed via Global Biodiversity Information Facility (GBIF, parts of datasets https://doi.org/10.15468/kuspj6 and https://doi.org/10.15468/h7qtfd). This dataset includes 3418 occurences, namely 2727 specimens and 691 observations of fructifications belonging to 349 species of fungi. With these data, the digitised CWU herbarium (V. N. Karazin Kharkiv National University, Ukraine) doubled in size A most detailed description of the substrate's properties and habitat for each record is provided. The specimen records are supplemented by 26 nuclear ribosomal DNA ITS sequences and six 28S sequences. Additionally, 287 photographs depicting diagnostic macro- and microscopic features of fungal fruitbodies as well as studied habitats are linked to the dataset. Most of the specimens have at least one mention in literature and relevant references are displayed as associated with specimen data. In total, 16 publication references are linked to the dataset. The dataset sheds new light on the fungal diversity of Eastern Europe. It is expected to complement other public sources of fungal occurrence information on continental and global levels in addressing macroecological and biogeographical questions.


Introduction
Fungi play crucial roles in ecosystems and are among the species-richest organism groups on Earth (Mora et al. 2011, Heilmann-Clausen et al. 2014, Peay et al. 2016). However, their occurrence has been poorly documented so far due to the difficulties of species detection, identification and delimitation. The situation is now rapidly changing due to substantial improvements in the methods used to identify and communicate the taxa of fungi , Hibbett et al. 2016). On the other hand, possibilities to digitise the taxon occurrences during the few last years have been additionally improved, providing great benefits for all biodiversity researchers including mycologists (Abarenkov et al. 2010, Senderov et al. 2016. Europe is the continent with the most advanced knowledge of fungal diversity due to a long-standing tradition of mycological research (Dahlberg et al. 2010). In the last decades, numerous national projects documenting fungal diversity have been initiated. Furthermore, national efforts have been consolidated into the international projects. Such cooperation enables researchers to investigate important ecological questions, for example, speciesand community-level responses of fungi to global warming (Andrew et al. 2016, Kauserud et al. 2012. Answering macroecological questions may be facilitated by broad spatial coverage of the dataset, as exemplified by "Climate Change Impacts on the Fungal Ecosystem Component" project,ClimFun (Andrew et al. 2017). There is a place to further expand geographic coverage of successful projects such as ClimFun, but this requires filling sampling gaps and digitisation efforts for national datasets, especially from Eastern Europe. In this region, sparse data availability and accessibility generally result from low numbers of both professional mycologists and citizen scientists (Dahlberg et al. 2010).
The environment of eastern Ukraine (Kharkiv, Donetsk and Luhansk regions) offers a special possibility to study fungal diversity associated with woody plants. Severe continental climate substantially limits the distribution of forests on the local scale, resulting in forest patches of limited size. These "forest oases" are separated from each other by the steppe vegetation or human-managed lands (Popovych 1990). Unlike the other parts of Ukraine and Europe, the European beech and Norway spruce are totally absent in the forests, while pedunculate oak and other numerous deciduous trees form a forest canopy. A specific geological history of the region resulted in the development of forest habitats on chalk outcrops or sandy sediments which are unique on a European scale (Fedorova 1980, Onyshchenko et al. 2007, Didukh and Pashkevich 2003. Fungal diversity of eastern Ukraine remains insufficiently known. The first scanty documentation of fungal occurrences dates back to the beginning of 19th century (Akulov et al. 2003). The first inventory, specifically focused on the region, was completed four decades ago (Wasser and Soldatova 1977). Less than a decade ago, we reported the results of aphyllophoroid fungi species inventories in several protected areas of eastern Ukraine (Ordynets and Akulov 2011, Ordynets and Akulov 2012, Ordynets et al. 2013. However, these were mostly species lists with sparse metadata, spread over several "floristic papers". This valuable information on fungal occurrences hardly meets the criteria of accessibility, reusability and sharing claimed for biodiversity data nowadays (Senderov andPenev 2016, Costello et al. 2013). Moreover, during the last four years, specimens collected by us were involved in a series of taxonomic studies and were re-identified. All the past and future identifications of the specimens represent valuable information which ideally should be easily updated and traced. Finally, the research area is affected by military activity for more than three years (Vasyliuk et al. 2015) and its preservation and accessibility for research in the forthcoming decades is questionable. Therefore, a proper preservation of the currently available data is required. In this data paper, we describe the effort of digitising and sharing the dataset of aphyllophoroid fungi in selected areas of eastern Ukraine according to the current standards of publishing biodiversity information.

General description
Additional information: The project focuses on the diversity of aphyllophoroid fungi. These fungi form neither an evolutionary nor an ecological group but are often targeted as a research object because of both strong taxonomic tradition and sampling convenience. During most of the 20th century, fungi with macroscopic fruitbodies were taxonomically classified according to their fruitbody morphologies. Several generations of mycologists were trained using the morphological classification of fungi. Though these morphological groups barely represent monophyletic taxa and are usually the result of convergent evolution (Hibbett 2007), the present-day identification keys for macrofungi for practical reasons are still compiled based on the principal fruitbody type (e.g. Bernicchia and Gorjón 2010, Krieglsteiner andKaiser 2000, Ryvarden andMelo 2014).
Aphyllophoroid fungi represent those basidial macrofungi which do not develop gills or closed reproductive structures but have smooth, toothed, irregularly folded to poroid hymenophore and one-celled basidia. They were previously treated as a single taxonomic order but are now found among ca. 20 orders mostly of the class Agaricomycetes (Kirk et al. 2008. Aphyllophoroid fungi are among the best-known groups of fungi globally and especially in Europe (Bernicchia and Gorjón 2010, Ryvarden and Melo 2014). They comprise a highly diverse group both in terms of species richness and functional differentiation. They are the most important agents of wood decay globally (Stokland et al. 2012), but also include mycorrhizal species, plant pathogens and litter saprotrophs . In general, aphyllophoroid fungi are strongly dependent on woody plants in terms of nutrition and habitat.

Project description
Study area description: Within the project, we inventoried aphyllophoroid fungi on 16 sampling areas located in eastern Ukraine and covering parts of three administrative regions, namely Kharkiv, Donetsk and Luhansk. All sampling areas are located in the middle basin of Siverskyi Donets River, Black Sea basin and their geomorphology developed due to the erosive activity of the river on the massive Upper Cretaceous sediments. We focused on the inventory of the well-preserved areas. We carried out the inventory in two Nature Reserves, i.e. the most strictly protected areas according to the Ukrainian conservational legislation (3 sampling areas), one National Nature Park (8 sampling areas) and one Regional Landscape Park (one sampling area). Four areas had no protected status but were located close to the protected ones. The list of areas with their definition, short characteristics including protection status, links to the areas as PlutoF objects and visiting/sampling statistics are provided in the The sampling areas lie in the East European Plain. The elevation varies between 35 and 220 m a.s.l. The Upper Cretaceous sediments (of a chalk and marl) form a series of hills along the right bank of the Siverskyi Donets River, often with outcroppings. Quaternary sediments were formed mostly on the left bank of the river as alluvial and massive sandy accumulations (Bondarchuk 1959). The soils vary according to the bedrock characteristics.
On the products of eolation, the ordinary chernozems with medium humus contents were formed. Slopes of the river valley and ravines are covered with the leached sod-calcareous soils. The river floodplain is dominated by meadow chernozems. Alluvial sand accumulations of the second river terrace bear sod-podzolic soils (Didukh and Pashkevich 2003).
According to the Köppen climate classification, the region falls into the area of a cold forest climate with severe winters and dry, long and hot summers (Jylhä et al. 2010). Compared to the rest of Ukraine, here the climate has the most pronounced continental characteristics. The mean annual temperature is 7.5°С, with recorded minimum of -40°С (January) and maximum of 39°С (July). The average annual precipitation is 400-540 mm, while the evaporation is 580-650 mm. Up to 60 days per year with very strong hot dry winds are possible (Popov et al. 1968).
According to the classification of terrestrial ecoregions of the world, the study area belongs to the biome of temperate grasslands, savannahs and shrublands (Olson et al. 2001). It is also known as a steppe region (EEA 2015). In these conditions, the natural woody vegetation mostly represents forest patches of limited size. The few striking exceptions exist due to their proximity to the large Siverskyi Donets River, as well as hilly landscape. Two broadleaf forests (called Teplynska dacha and Maiatska dacha) are the largest forest massifs on the watershed in the Ukrainian steppe zone (Onyshchenko et al. 2007).
The pedunculate oak Quercus robur L. is one of the most important tree species in the area. In the forests on the watershed, this oak species is accompanied by Fraxinus excelsior L., Tilia cordata Mill., Acer platanoides L., A. campestre L., A. tataricum L. and Corylus avellana L. In the Siverskyi Donets floodplain, the oak forest grows mosaically with the forests composed of Alnus glutinosa (L.) Gaertn., various poplars (Populus nigra L., P. alba L. and P. tremula L.), willows (Salix alba L., Salix fragilis L.) and Acer negundo L. (Popovych 1990).
The massive sandy terrace of the Siverskyi Donets River is basically a habitat for the psammophytic grasses and herbs. However, there are numerous depressions which provide a suitable microclimate for the development of the wetland local forests (groves). The usual trees in these habitats are: Betula pendula Roth, B. pubescens Ehrh., Populus tremula, P. nigra and P. alba, Alnus glutinosa and Crataegus spp. The willow shrubby communities of Salix acutifolia Willd. and Salix rosmarinifolia L. are common in some localities (Popovych 1990). As a result of land-use in the 19th and 20th centuries, large areas of the sandy terrace are currently covered not by primary vegetation of psammophytic grasses and herbs, but by plantations of Pinus sylvestris L. However, some of these stands are about 200 years old and resemble natural forests. The true natural pine forests in the region are currently confined to the chalky outcrops with the sod-calcareous soils. These populations were treated in the past decades as a relict species Pinus cretacea Kalen. (Didukh andPashkevich 2003, Fedorova 1980) currently regarded as a variety of Scots pine, P. sylvestris var. cretacea (Kalen.) Kom. (Gardner 2013

Sampling methods
Sampling description: In 16 areas, we sampled living fungal fruitbodiesaccording to the standards for macrofungi collecting (Lodge et al. 2004). We were interested in recording the majority of species from the local species pool. Therefore we sampled not within fixed areas, but covered larger areas by sampling along the forest paths. We were passing up to ten kilometres of forest paths per day. We spent more time at the points which visually harboured higher amounts and diversity of deadwood. Visiting and sampling statistics for each area are provided in Table 1.
If the species could be readily identified in the field, the occurrence was recorded without taking a specimen, i.e. as observation, except for the very first finding of the species during the field work. All fruiting bodies from a single woody substrate or growing in a single cluster on debris or litter were treated as a single individual. For the records on woody substrata (which prevail in the dataset), principal tree fraction, diameter class, decay stage, spatial location and presence/absence of the direct contact with soil were recorded. For all the records, plant species of the substrate as well as characteristics of forest habitat and mesorelief were described ( Quality control: One of the challenges in inventorying fungal diversity based on fruiting bodies is the temporal irregularity of fruiting. To reduce the bias associated with this phenomenon, within five years (2007-2011), we carried out 15 expeditions, usually making one expedition per season (spring, summer and autumn). The earliest and latest sampling dates were March 9 and November 22 respectively. Each expedition lasted as a minimum three and as a maximum seven days. Within a single expedition, we visited up to four sampling areas (see Table 1). Some areas could be visited only once. This may be Table 2.
Substrate and habitat characteristics of fungal occurrence data recorded in the project.
acceptable in the case of aphyllorphoid fungi which, as opposed to other fruiting fungi, in general create more lasting fruitbodies.
Along with the specimens which were more or less easily identified, there were also collections whose identifications were verified by another expert or collections which we could identify to the genus level only. Wolfgang Dämon, Ivan Zmitrovich, Anton Shyriaev, Heikki Kotiranta, Masoomeh Ghobad-Nejhad, Philomena Bodensteiner, Sergey Volobuev, Viacheslav Spirin and Erast Parmasto kindly helped us in such issues. The names of the experts who verified or improved our identifications are provided in the pane "Identifications", fields "Identifiers" and/or "Remarks" on the respective specimen page as viewed in PlutoF. Additionally, each PlutoF observation linked to our dataset was verified by the platform developer as seen in the pane "Discussion" on the single observation page.
Step description: Noticeable specimens were photographed directly in the field or after drying in the laboratory. The micromorphology study of the dried specimens was performed under 1000× magnification using light microscopes Zeiss Primo Star (Carl Zeiss Jena GmbH, Jena, Germany) and Nicon Eclipse 90i (Nikon Corp., Tokyo, Japan). The specimens were examined in 5% aqueous potassium hydroxide solution, Melzer's reagent and 1% Congo red solution in concentrated ammonia (Ryvarden and Melo 2014). The main identification keys used were Bernicchia and Gorjón (2010), Kõljalg (1996), Larsson (1992), Ryvarden and Melo (2014).

Geographic coverage
Description: The extent of all sampling areas covers about 180 km in the longitudinal and 60 km in latitudinal direction. The total area of study is 380 km .

Taxonomic coverage
Description: The dataset contains 3418 species occurrences. It has 2727 specimens and 691 observation records, containing 349 species of fungi from the phylum Basidiomycota.
Additional 16 items have no specific epithet but only genus-level (in one case order-level) identification (Table 3).   From 19 specimens representing 16 species, we generated 19 nuclear ribosomal DNA ITS sequences and four 28S sequences. Further seven ITS and two 28S sequences were produced in collaborative studies focusing on a particular taxonomic problem (see Table 4). The sequences can be found in the public repositories UNITE ) and GenBank (Benson et al. 2013) and linked to the respective CWU vouchers in PlutoF. The sequence UDB033929*1 from specimen CWU4336*1 is the first barcode sequence for the species Phellinus rhamni. Our photographs of Dichomitus squalens ( CWU6509) and Lenzites warnieri (CWU6505) linked to the dataset illustrate the respective species in the latest key to European polypores (Ryvarden and Melo 2014).

Traits coverage
The assignments to the 1) lifestyle and 2) fruiting-body principal configuration (morph) type were provided for each species. Lifestyle is a predefined field in PlutoF, from which we used the categories saprotroph, symbiotroph and parasite.
The principal fruitbody configuration of macrofungi is an increasingly addressed species trait in the ecological and evolutionary studies (Abrego et al. 2016, Hibbett 2007. We classified the species of our datasetinto the following groups: those where fruitbodies have smooth spore-producing surface (corticiod), species with cup-shaped fruitbodies (cyphelloid), species with toothed hymenophore (hydnoid), species developing pores (poroid), species having gelified fruiting bodies (heterobasidial) and species having coralloid, club-like or funnel-like fruiting bodies which grow negatively geotropic (clavarioid). As the trait module for fungi in PlutoF is still under development (July 2017), we specified the fruiting body morph in the field "Identifications.Remarks" for each specimen and observation. Specimen preservation method: Fresh specimens were dried with an electric fan dryer on the day of collection and placed in grip seal plastic bags. Shortly after drying, the specimens were placed into a deep freezer (-20°C) for a week, to prevent their destruction by insects. Specimens are preserved in cardboard herbarium boxes.