Salix herbacea L. (Salicaceae) in the Maramures massif of the Ukrainian Carpathians

Salix herbacea is a relict plant species related to the circumpolar arctic-alpine element of the Holarctic group. The aim of the study was to clarify the data on the distribution of S. herbacea within the Maramures massif of the Ukrainian Carpathians since this species is reported by different authors for the massif without specific geographical and habitats descriptions. Field studies were conducted in the Maramures massif on the slopes of Pip Ivan Marmarosky (1936 m a.s.l.) and Rapa (1872 m a.s.l.) mountains in 2017– 2019. The S. herbacea distribution chorology was analyzed based on the inventory of UU, KW, KWHA, LW, Herbarium of the Carpathian Biosphere Reserve, and Herbarium of the Biology and Ecology Department of the Vasyl Stefanyk Precarpathian National University collections. We have found S. herbacea confined to cliffs on a rocky tourist path between the peaks of Pip Ivan Marmarosky and Rapa mountains in the Rakhiv district of the Transcarpathian region (Zakarpattia oblast). Recently, these rocky formations were occupied by tall grasses such as Calamagrostis villosa, Poa pratensis and Festuca picturata. Meanwhile, the occurrence of Holarctic and Alpine-Carpathian species Vaccinium uliginosum, Potentilla aurea, Pulsatilla alba, Thamnolia vermicularis and Cetraria islandica substantially decreased. These changes were probably caused by a decrease in livestock grazing intensity during the past years in this area, as well as more favorable climate conditions for tall grass species. The exact location and phytocoenological conditions of the site, which is endangered and requires additional conservation measures, were outlined. The necessity of these measures to preserve the habitat of S. herbacea on the Maramures massif was stressed out.


Introduction
The genus Salix L. comprises about 450 species in the world flora (Argus et al., 2010), with 24 species represented in the flora of Ukraine (Gorelov, 2002;Fuchylo & Sbytna, 2009). There are 18 Salix species distributed in the Ukrainian Carpathians and Transcarpathia, including 15 species distributed on the territory of the Carpathian Biosphere Reserve. Six Salix species are listed in the Red Book of Ukraine: S. alpina Scop., S. lapponum L., S. myrtilloides L., S. starkeana Willd., S. herbacea L., and S. retusa L. (Didukh, 2009).
Salix herbacea is a relict species related to the circumpolar arctic-alpine element of the Holarctic group (Meusel et al., 1965;Malynovskyi, 1980;Didukh, 2009). It is common in the Arctic as well in North America, whereas in Central and Southern Europe, it becomes progressively less frequent (Tralau, 1963;Jalas & Suominen, 1976;Elven & Karlsson, 2000). It is a perennial shrub, chamaephyte, 10-30 cm tall, with well developed underground stolons. In the Ukrainian Carpathians S. herbacea, habitats are limited to rocky outcrops and sites in the alpine and subalpine vegetation belts. The only few known populations of S. herbacea occur in the summit areas of Chornohora, Svydovets, and Maramures, where they cover relatively small areas (Didukh, 2009;Prokopiv & Volgin, 2009;Kobiv, 2010). Populations of S. herbacea in the Ukrainian Carpathians are endangered due to the growing anthropogenic pressure and obviously could be under the impact of climate change in the future (Kobiv, 2009). At present, detailed information about localities, habitat preferences, and floristic composition of communities with S. herbacea in the Maramures Mts. is absent. Hence, this investigation aimed to clarify it.

Material and methods
Field studies were conducted in the Maramures massif on the slopes of the Pip Ivan Marmarosky (1936 m a.s.l.) and Rapa (1872 m a.s.l.) mountains in 2017-2019 ( Fig. 1). This territory is a part of the Carpathian Biosphere Reserve. The location of the habitat was determined using a GPS navigator Garmin eTrex 30x with an accuracy of up to 10 meters.
The names of the plant taxa are given according to The Plant List (2013), the names of the lichen taxa are given according to MycoBank (2020).
Vegetation description was performed using the Braun-Blanquet approach (Yaroshenko, 1961;Braun-Blanquet, 1964). Herbarium collections were transferred to the herbarium of the Carpathian Biosphere Reserve and the herbarium of the M.M. Gryshko National Botanical Garden, National Academy of Sciences of Ukraine (KWHA). The S. herbacea distribution was analyzed based on the inventory of vouchers preserved in the UU, KW, KWHA, LW (see Index Herbariorum (Thiers, 2020) for acronyms), Herbarium of the Carpathian Biosphere Reserve and Herbarium of the Biology and Ecology Department of the Vasyl Stefanyk Precarpathian National University.

Results
Different authors provided data on the present occurrence of S. herbacea in the Maramures massif (Dobrochaeva et al., 1987;Kricsfalusy, 1982Kricsfalusy, , 1999Didukh, 2009;Kobiv et al., 2017). Malynovskyi (1980) reported S. herbacea from the Polytrichetum sexangularis Br.-Bl. 1926 basing on Deyl (1940), who was the first to describe this association for the Maramures massif. However, neither Malynovskyi (1980) nor Deyl (1940) provided details about the presence of S. herbacea here. Moreover, the dwarf willow is mentioned for Maramures in the Flora of the USSR (Nazarov et al., 1952), but also there without providing precise locations and without the support of observed herbarium vouchers.
Specimens  the Maramures massif (Rakhiv district of Transcarpathian region, at the border of Ukraine and Romania), which also we have observed and investigated close to a rocky tourist path (Fig. 1) Rhododendron myrtifolium, Ligusticum mutellina (L.) Crantz, Carex sempervirens Vill., and Juncus trifidus L. The base of the rocky outcrops is colonized by tall-grasses such as Calamagrostis villosa (Chaix) J.F. Gmel., Poa pratensis L., Festuca picturata Pils. Moreover, the occurrence of the holarctic and Alpine-Carpathian species Vaccinium uliginosum L., Potentilla aurea L., Pulsatilla alba Reichenb., Thamnolia vermicularis, and Cetraria islandica was particularly relevant (Fig. 3). The occurrence of tall grasses and forbs resulted from the decrease of livestock grazing intensity in this area in the past years.

Conclusions
As a result of an inventory of certain herbarium collections, it was found that vouchers of S. herbacea hosted at the KW are the only known from the Maramures massif, and all of them referenced to the Pip Ivan Marmarosky. However, all these reports of S. herbacea most probably concerned the only population between the peaks of Pip Ivan Marmarosky and Rapa mountains of the Maramures massif.
The area of the identified habitat of S. herbacea on the rocky tourist path between the peaks of Pip Ivan Marmarosky and Rapa mountains in the Maramures massif is about 200 m². The cover of the species in the habitat ranges from 7 to 20 %.
Recently, the site was partially occupied by tall grasses such as Calamagrostis villosa, Calamagrostis arundinacea, Poa pratensis, Festuca picturata, and the occurrence of Holarctic and Alpine-Carpathian species substantially decreased. It is probably caused by a decrease in livestock grazing in the area and more favorable climate conditions for tall grass species.
Taking into account observed transformations, it is necessary to develop and implement urgent conservation measures to save the population of S. herbacea on the Maramures massif.
Salix herbacea in the Maramures massif of the Ukrainian Carpathians