Ulmus japonica (Ulmaceae) communities in Western Transbaikalia: Distribution, value for biodiversity conservation and perspectives of protection

Abstract

The East Asian tree Ulmus japonica (Rehder) Sarg. is a nemoral relict species for Western Transbaikalia (See Fig. 1). A few localities of this tree are known in the region, those in the lower reaches of the Selenga River (Yugovo site; Republic of Buryatia) and the Chikoy River (Zhindo site; Zabaikalskii Krai), remote from the main distribution area (See Fig. 2). The study aimed to verify the distribution of U. japonica and to estimate the value of U. japonica communities for biodiversity conservation in the region. Based on the data collected, we discussed some opportunities and suggested approaches for the protection of these unique ecosystems. During the fieldwork in 2018 and 2019, we studied all known localities of U. japonica in Western Transbaikalia and revealed a pleiad of new locations within the site Yugovo as well as a new location (the site Murochi) in the Chikoy River valley within the Republic of Buryatia (See Fig. 2 and 3). Information on the occurrence of U. japonica in the vicinity of Podlopatki village (in the Khilok River valley) was not confirmed. Also, our attempts to find this species at the site within the Barguzin River valley according to the label of the existing herbarium specimen failed. Based on 93 relevés, we examined species composition in woodlands where U. japonica is a codominant species and revealed the main features and peculiarities of the communities in the region. At all sites, monodominant coppices of U. japonica and coenoses where it is mixed with Padus avium Mill. occurred. Nevertheless, Ulmus japonica communities from the site Yugovo differ from those of Zhindo and Murochi in a greater phytocoenotic diversity and the composition of characteristic plant species. Additionally, at Yugovo rather xeromesophytic sparse communities where U. japonica is mixed with Pinus sylvestris L. and Betula platyphylla Sukaczev were found. Characteristic species of shrub and herbal layers at Yugovo site are Carex arnellii Christ ex Scheutz, Circaea lutetiana L., Elymus pendulinus (Nevski) Tzvelev, Festuca extremiorientalis Ohwi, Filipendula palmata (Pall.) Maxim., Hesperis sibirica L., Lamium album subsp. orientale Kamelin & A.L. Budantzev, whereas at Zhindo and Murochi they are Anemonidium dichotomum (L.) Holub, Carex sordida Van Heurck & Müll. Arg, Menispermum dauricum DC., Rhamnus davurica Pall., and Rubia cordifolia L. According to our studies supplemented with data from the literature sources, there are 16 species of vascular plants, lichens, beetles, and lepidopterans registered in Ulmus japonicaforests that are included in the Federal and/or in regional Red Data Books (See Table 1). We have revealed 31 additional rare and relict species of plants, fungi and insects (See Table 2). In total, 19 species were found in Western Transbaikalia or within this plant community type for the first time. The newly revealed rare and relict species could be recommended for listing in the regional Red Data Book or inclusion in the list of species of special surveillance. As a perspective of the protection of communities with U. japonica, we propose to maintain them as distinct clusters under the management of the existing protected areas. Namely, the site Yugovo can be protected as a separate cluster of the Baikal Natural Reserve, likewise, the protection of the site Zhindo can be managed by the Chikoy National Park. The newly discovered site Murochi might be included in the preliminarily proposed Russian-Mongolian trans-boundary Selenga protected area.