Arachnids (Aranei, Opiliones) from grass stand and forest litter in the Urals, Russia

Study Extent

The study was conducted in the southern taiga zone of the Central and Southern Urals, Russia, in the lowest part of uplands (300–400 m altitude above sea level). A total of twelve sampling plots (=locationID) were established across three types of biotopes: primary spruce-fir (4 plots), secondary aspen-birch forests (2 plots), pine-birch forest (3 plots), and secondary upland meadows (3 plots). All the represented schemes are ongoing long-term monitoring projects. At the present time, the following periods are covered: May, 12, 2004 – September, 08, 2009; June, 14, 2013 – September, 02, 2013; May, 24, 2018 – August, 21, 2018.

Sampling

1. Sampling of meadow grass stand invertebrates with biocenometer was carried out no closer than 10 m from the forest edge. The points for installing the biocenometer were chosen randomly but at intervals of no less than 5 m. The sampling procedure was carried out in period from 9 to 21 of local time. The sampling plots were examined on the same day. Morning-, midday-, and evening-time-collected samples were available for each investigated plot. Sampling was timed to the second half of every summer month (10 samples per plot) from 2006 to 2008. 2. Sampling of forest litter invertebrates was conducted with two general schemes. Line-designed scheme includes 5 pitfall traps per trapping line, with a spacing of 3 m, and 3 lines per sampling plot (a total of 8 plots). Matrix-designed scheme includes 7×7 matrix of pitfall traps with 10 m spacing on a single sampling plot. Locations of every trap were permanent throughout the study. Traps were emptied once per 3 to 6 days. Sampling was conducted in two-time sets – May–June and August–September (which is timed to the peak abundance of spring-summer and summer-autumn species) in 2004, 2009 and 2013 (for line-designed trapping) and in 2005 and 2018 (for matrix-designed trapping).

Quality Control

All collected specimens of arachnids (more then 10 400) are wet-preserved in 70% alcohol and stored in depository of Laboratory for Population and Community Ecotoxicology of IPAE UB RAS. Most of the adult specimens were identified to species (except for severely damaged during the sampling). Identification of species throughout the entire period has been made by permanent team of researchers (IPAE UB RAS) and cross-checked by specialists of Department of Zoology, Perm State University. All determinations that appear controversial are welcome to be discussed upon request. Taxonomic nomenclature has been verified for spiders using (Platnick, 2020); for harvestmen using (Jong et al., 2014) and local catalog of Ural’s fauna (Farzalieva, Esyunin, 1999).

Method steps

1. 1. Sampling of grass stand invertebrates was carried out at 3 permanent free-form sampling plots (approximately 2500 m² in size) that were positioned at distance of 100–300 m from each other in the lower parts of the secondary upland meadows resulting from forest clear-cutting more than 60 years ago. Sampling was timed to the second half of every summer month from 2006 to 2008. Sampling was proceeded by modified biocenometer consisting of a bottom (metal frame 50×50 cm), hermetically connected to a cube-shaped covering of a dense cloth. One of the lateral sides of covering was sewn from nylon gauze (mesh diameter 0.25 mm) and used as a light screen for attraction of invertebrates with positive photokinesis. The opposite-to-screen side of covering contains an aperture with an inlet valve for the researcher. Invertebrates from a light screen and inner surfaces of biocenometer were collected with suction sampler until the new targets stopped appearing. All the plants that were got inside were also processed with suction sampler (to gather invertebrates), cut with scissors at ground level and taken away for a manual check for hidden invertebrates. Then the biocenometer was turned over and looked through the inner surface and seams, as well as the soil surface and bases of plant stems. All detected invertebrates were devitalized by ethyl acetate and preserved in 70% alcohol. The sampling procedure was carried out in period from 9 to 21 of local time. All three sampling plots were examined on the same day. Morning-, midday-, and evening-time-collected samples were available for each investigated plot. The points for installing the biocenometer were chosen randomly but at intervals of no less than 5 m. 10 samples per plot were taken in each summer month.
2. 2. Pitfall trapping was carried out in biotopes, most typical for the studied areas: primary spruce-fir forest, secondary aspen-birch forest, and pine-birch forest. Sampling plots were founded in sites with the lowest degree of degradation of woody vegetation. Barber’s traps were used (plastic glasses, diameter 8.5 cm, 3% acetic acid solution as a fixative) in line–designed and matrix–designed schemes. Line-designed scheme (5 traps per line with 3 m spacing between traps, 3 lines per sampling plot no closer than 100 m from each other, 8 plots (each approximately 2400 m² in size) in total was proceeded both in spruce-fir (3 plots) and aspen-birch (5 plots) forests; matrix-designed (7×7 matrix of traps with 10 m spacing) on a single square-form sampling plot (3 600 m²) in a spruce-fir forest. All plots and locations of every trap were permanent throughout the study. Sampling was conducted in two-time sets – May–June and August– September (which is timed to the peak abundance of spring-summer and summer-autumn species) in 2004, 2009 and 2013 (for line-designed trapping) and in 2005 and 2018 (for matrix-designed trapping). The traps were emptied once per 3 to 6 days; all collected invertebrates were preserved in 70% alcohol.
3. 3. Identification was carried out in laboratory using (Nentwig et al., 2019) for spiders, and identification keys of (Farzalieva, Esyunin, 1999) for harvestmen, and some additional monographs.

The dataset contains all information obtained during the sampling for the Arachnida class (including Aranei and Opiliones orders). General taxonomic coverage is 1 phylum, 2 orders, 23 families, 115 genera, 178 species.

1. Arachnida
   common name: arachnids rank: class
2. Aranei
   common name: spiders rank: order
3. Opiliones
   common name: harvestmen rank: order

The studied areas are located in the southern taiga zone of the Central and Southern Urals. The polygon at the Central Urals is disposed 60–70 km westbound from Yekaterinburg in primary spruce-fir and secondary aspen-birch forests with secondary upland meadows resulted from clear-cutting. At the Southern Urals two polygons are located in 10 and 60 km NE from Miass, in pine-birch forest.