Collembola of the relict forests of the Russian Far East

Study Extent

The diversity and population density of small soil arthropods – springtails were studied in relict broad-leaf – cedar pine forests of the Primorskii krai of Russia. The records were carried out on the territory of Ussuriiskii, Sikhote-Alinsky and Kedrovaya Pad’ natural reserves. A multiscale and intensive sampling was used to reveal species diversity. The data on the numbers for 175 species (about 24 thousand individuals in the 648 cores) from 8 forest sites are presented.

Sampling

Short descriptions of some sampling plots (“Turova”, “Grabovaya”, “Kedrovaya”, “Pikhtovaya”) were published (Kuznetsova et al., 2019). The descriptions of the others plots given for the first time. The sampling plot “Turova” is in the Ussuriiskii Nature Reserve; it is cedar pine–deciduous forest on a flat slope (Pinus koraiensis, Acer mandshuricum, Quercus mongolica, etc.); in the undergrowth Lonicera maackii, Eleutherococcus senticosus, etc.; in the abovesoil cover Oxalis acetosella, Carex spp., Adiantum pedatum, etc. The dead cover was ~10 cm. The sampling plot “Grabovaya” is in the Ussuriiskii Nature Reserve; it is on the Mount Grabovaya, fir–hornbeam forest (A. holophylla, Carpinus cordata, P. koraiensis, Betula costata, etc.); in the undergrowth are C. cordata, Acer tegmentosum, A. barbinerve, E. senticosus, etc.; in the above-soil cover are O. acetosella, Leptorumohra amurensis, etc. The dead cover is >80%, and the thickness of the litter is ~4 cm. The sampling plot “Kedrovaya” is in the Kedrovaya Pad’ Nature Reserve; it is cedar pine–fir broadleaved forest on a slope (P. koraiensis, A. holophylla, Tilia mandshurica, C. cordata, etc.); in the undergrowth are five maple species, including A. tegmentosum and A. barbinerve; in the above-soil cover are L. amurensis, Dryopteris crassirhizoma, Maianthemum dilatum, O. acetosella, etc. The dead cover ~50%, and the litter thickness is 4 cm. The sampling plot “Pikhtovaya” is in the Kedrovaya Pad’ Nature Reserve; it is a valley fir and deciduous forest (A. holophylla, Juglans mandshurica, P. koraiensis etc.); in the undergrowth are J. mandshurica, C. cordata, A. tegmentosum, A. mandshuricum, A. mono, etc.; in the above-soil cover are L. amurensis, D. crassirhizoma, etc. The dead cover is ~50%, and the thickness of the litter is 3–4 cm. The sampling plot «Phori» is in the Sikhote-Alin Nature Reserve, Kabani station, at 932 m alt.; it is coniferous wood (Abies nephrolepis, Betula platyphylla, P. koraiensis); in the undergrowth are Rhododendrom Fori, Acer ukurunduense, Picea jezoensis; in the above-soil cover are L. amurensis, Oxalis acetosella, Maianthemum bifolium, Clematium japanicum, etc. The dead cover is 50 -100%, and the thickness of the litter is 3–7 cm. The sampling plot «Kema» is nearby the Sikhote-Alin Nature Reserve, in the valley of Brusnichnaya River (tributory of Kema); it is mixed forest (P. koraiensis, Populus maximowiczii, P. jezoensis, Ulmus glabra, A. nephrolepis); in the undergrowth are Acer mono, Acer barbinerve, A. tegmentosum, Philadelphus tenuifolius, Eleutherococcus senticosus etc.; in the above-soil cover are L. amurensis, O. acetosella, M. bifolium, вороний глаз, Carex siderosticta, Cardamine leucantha, Cacalia hastata, etc. The dead cover is 5-65%, and the thickness of the litter is 7–10 cm. The sampling plot «Chuguev» is in the Chuguevski District near Verkneussuriyski Station of Federal Scientific Center of the East Asia Terrestrial Biodiversity); it is valley mixed forest (A. nephrolepis, P. maximowiczii, Fraxinus mandshurica, Betula costata P. koraiensis, etc.); in the above-soil cover are A. nephrolepis, Acer mono, A. tegmentosum, Lonicera maackii, Philadelphus tenuifolius, etc.; in the above-soil cover are O. acetosella, L. amurensis, Carex campylorhina, C. leucantha, Athyrium rubripes, etc.). The dead cover is 20-85%, and the thickness of the litter is 6–9 cm. The sampling plot «Anikin» is in the Ussuriyski Nature Reserve, Suvorovskoye Forest District, Anikinsky Station, valley of Anikin River; it is valley broadleaf forest (Juglans mandshurica, P. maximowiczii, Fraxinus mandshurica) with P. koraiensis; in the above-soil cover are Carex spp, L. amurensis, etc. The dead cover is 50-90%, and the thickness of the litter is 3–4 cm. A corer of 8 sq. cm was used in all sampling plots. Soil was investigated up to the full depth of the forest litter with the inclusion of the first centimeters of mineral layers of the soil. 81 cores were taken in each forest when sampling. Cores were placed in the corners of different-scale equilateral triangles inscribed in squares with sides 10 cm, 25 cm, 1 m and 10 m. The different-scale triangles were designed following the principles of fractal geometry. The scheme was described in detail earlier (Saraeva et al., 2015) Tullgren’s funnels we used for extraction of springtails into 70% alcohol. The material was mounted on slides in Phoera liquid according to a standard procedure (Ghilarov, 1975; Potapov, Kuznetsova, 2011). Some species were described as new for the science in the material: Anurida - 6 spp. n. (Babenko et al., 2019), Oligaphorura – 2 spp. n. (Xin et al., 2019); Pseudachorutes – 1 sp. n. and redescription of 3 species (Babenko et al., 2021). Data on species were digitized, standardized, the quality of data was checked and errors were corrected, and then published.

Quality Control

We used we used modern taxonomic papers and key by Martynova (1988) for the taxonomic determination of the material.

Method steps

1. The aim of the study was to find out the upper limit of the local species diversity of Collembola. Especially high species richness of various groups of organisms was noted in the forests of East Asia (Latham, Ricklefs, 1993). The highest diversity of insects in the temperate zone is described for forests in the south of the Russian Far East (Chernov et al., 2011). This area was not covered by Pleistocene glaciers and preserved an exceptionally high diversity of vegetation cover especially in areal of broad-leaf – cedar pine forests. It is included in the UNESCO World Heritage List (Central Sikhote-Alin (unesco.org). To estimate the local diversity of springtails of these forests, we chose an intensive sampling scheme with a high concentration of cores in small areas (Saraeva et al., 2015). This approach allows us to effectively reveal the species composition of Collembola and adequately compare their diversity on different territories. The fractal design of sampling helps to save sampling effort when analyzing the multiscale spatial structure of diversity (Marsh, Ewers, 2013). We used the smallest core size (8 cm2), which can still be taken without disturbing the soil structure. This made it possible to study the structure of the diversity of Collembola at the micro level: within a few square centimeters.

1. Arthropoda
   rank: phylum
2. Collembola
   rank: class

Primorskii krai of Russian Far East