Plot-based observations of terrestrial macrofungi in different forest types of boreal zone in West Siberia (2015-2021)

Study Extent

The studied area is located in the middle taiga zone of Western Siberia. The climate is continental subarctic according to Köppen climate classification. The average annual temperature is –1.3 °C, the mean temperature of the coldest month (January) –19.8 °C, the warmest month is July with its average of 18 °C (Bulatov 2007). Vegetation of the middle taiga zone of Western Siberia is characterized by dark coniferous and pine forests and their secondary formations. The forests are made up of spruce (Picea obovata), Siberian stone pine (Pinus sibirica) and fir (Abies sibirica) tree canopy and the undergrowth of various small herbs, ericoid shrubs and feather mosses. The dark coniferous forests are replaced by their secondary communities with Pinus sylvestris, Betula spp., and Populus tremula. The middle taiga of Western Siberia is a highly bogged region, with peatlands covering up to 50% of its area. The transition between forests and bogs is represented by pine-birch and pine-dwarfshrub forests (Ilyina 1985). For the purpose of permanent monitoring, an area located in 20 km from the Khanty-Mansiysk town was chosen which is at the same time situated within the borders of the natural park «Samarovskiy Chugas» and is relatively intact. A number of clear-cuts were held here from 5 to 30 years ago which diversified old coniferous forests by their secondary communities. The detailed description of the studied plots is flows: Plots 1-4 represent old coniferous forests with dominance of P. sibirica (50%) with some P. obovata and a smaller proportion of A. sibirica (each 10-30%). P. sylvestris is present as admixture, and deciduous trees (B. pendula, P. tremula) represent a small proportion (2-5% each). The undergrowth is weakly developed and made up of coniferous regrowth and Sorbus sibirica. The herbaceous layer (including ericoid dwarfshrubs) is made by 5 species with the total projective cover of about 15%. The moss layer is well developed (average 70% of cover), represented by 5 species of feather mosses. The age of the three largest trees of P. sibirica measured by annual rings count was 80 to 100 years. Plots 5-7 are located in an old cutting site and represent secondary aspen forests. P. tremula dominates in the community (60%) with an admixture of B. pendula (5%) and regrowth of coniferous trees (average 2%). The total number of herbaceous plants reaches 28 for all these plots with the cover ranging within 14-26% between the plots. The age of the largest aspen was 25-30 years. Moss layer is underdeveloped and makes 3-5% of cover in plots 5-6 and 11% in plot 7. Plot 8 represents fresh cutting site where clear-cut was about 5 years ago. The tree layer is absent except for isolated survived trees (P. sibirica, A. sibirica, P. obovata). The regrowth made by P. tremula (30%), number of shrubs and herbs reaches 30 species (total projective cover up to 60%). Mosses are reduced to 4% and represented mainly by Polytrichum spp. Plot 9 located in a small in size bogged locality with waterlogged soil (peat) and residual falling trees. Presumably a fire could have some impact in the past. B. pubescens dominates in tree layer with admixture of conifers. Plants represented by 10 species with projective cover up to 35%. Moss layer is made by sphagnum and green mosses, where S. angustifolium dominates (80%). The site represents a relatively recent bogging stage with peat layer depth about 50 cm. Plot 10 is located in proximity to plot 9 on a relatively drier position occupied by wet birch forest. B. pubescens dominates in tree layer (80%) with admixture of conifers. The herb layer made by 15 species with total 10% of projective cover. Moss layer well developed (80%) and made by green mosses. Presumably a fire and a followed cutting could have some impact in the past. Photographs of vegetation of studied plots are available under the link: https://www.flickr.com/photos/fungariumysu/albums/72157672157314073

Sampling

Ten permanent plots were established in spring 2015 distributed over an area of about 10 square kilometers. The locations were chosen to assess major homogenous contours of different forest types, e.g. old-growth coniferous forests and their after-cut secondary forests 5, and 20-30 years after cutting, plus a wet birch forest site and a bogged site. Two plots were established in each forest type when the contour was extensive and uniform (plots 1-6). For smaller and relatively mosaic vegetation contours a single plot for each contour was only applicable (plots 7-10). Each plot consisted of 20 or 40 circular 5 m2 micro-plots 5 m apart aligned in a 200 m long line(s). The observation area of a plot thus equals 100 or 200 m2 and the total area of plot-observation during the survey was 1600 m2. Centers of each micro-plot were marked by plastic poles. A rope was used to draw the outlines of a plot during its examination. The total number of fruiting bodies of each species was counted on each micro-plot. Counted fruitbodies were removed in order to avoid repeated count in following visits. A few species where the counting would be impossible due to their high abundance were counted by estimated number. Some species with densely clustered growth were counted by number of clusters (e.g. Collybia cirrhata). The plots were visited from the end of May (soon after snow melt) until the middle of September (when fungal fruiting was suppressed by the first frosts). The time interval between subsequent visits of each plot ranged between 14-23 days, resulting in total of 5 visits per plot and 5 visits per random route during the season (one visit per month). The temperature regime of the plots was measured by temperature loggers located in 5 plots of different vegetation types at 5 cm above soil level (Thermochron loggers (DS1921G-F5).

Quality Control

The collection database is available at http://bioportal.ugrasu.ru. All determinations could be checked online or by the request of specimens from the YSU Fungarium and re-identified. Future thorough taxonomic work is also necessary for some taxonomically difficult groups like Cortinarius spp., Russula spp.

Method steps

1. A total of 320 circular 5 m^2 (for a total area of 1600 m^2) long-term monitoring plots were established in May 2015. The plots were visited regularly during entire vegetation seasons (from May until September) from 2015 to 2021 (except for August 2017 when observations were interrupted), and carpophores of different fungal taxa were counted.
2. The description of vegetation composition of the plots was done once and climatic parameters of corresponding habitats were measured by a located in each plot loggers at -10 cm and +10 cm above soil level, during the entire observation period.
3. The common and easily recognizable species were identified in the field. The detailed identification of doubtful species was done in the laboratory. For that, the collections were processed as described in Lodge et al. (Mueller et al., 2004, Biodiversity of fungi). Fresh fruiting bodies were wrapped in aluminium foil and carried to the laboratory to be processed on the day of collection. The processing of specimens included: 1) photographing on a photo-studio table, 2) description of vital characters, 3) preliminary microscopy and determination, 4) filling the data in the database, 5) labeling, and 6) drying at 50°C to store in the Fungarium of Yugra State University.
4. The detailed identification was done during the winter following the collection season. Dry specimens were rehydrated in tap water or KOH (10 %); dyes and other chemicals (Congo Red, Melzer reagent, ammonia) were applied when necessary. A Zeiss Axiostar microscope with Achromat 5/0.12, 10/0.25, 40/0.65 (dry) and 100/1.25 (oil immersion) objectives was used for microscopical examination.
5. Most of the finds were identified using Funga Nordica keys (Knudsen and Vesterholt, 2008. Funga Nordica) and some additional monographs on particular taxa were used when necessary.

Terrestrial macrofungi were studied during the survey. The group was defined as the macrofungi which confine to terrestrial habitat as opposed to wood-inhabiting species representing another prominent community in boreal forests. However, these groups partially overlap and we recorded species growing on mossy old trunks or buried wood within the plots. Our study included following groups in the analysis: Discomycetes, Agaricoid, Boletoid, Aphyllophoroid fungi (we omitted brackets, crusts and jellies but included clubs and coral fungi) and some other groups in minority.

1. Fungi
   rank: kingdom

The studied area is located in the middle taiga zone of Western Siberia. For the purpose of permanent monitoring, an area located in 20 km from the Khanty-Mansiysk town was chosen which is at the same time situated within the borders of the natural park «Samarovskiy Chugas» and is relatively intact. A number of clear-cuts were held here from 5 to 30 years ago which diversified old coniferous forests by their secondary communities.