Developing the GIS-based maps of the geomorphological and phytogeographical division of the Ukrainian Carpathians for routine use in biogeography

Author(s): Novikov, Andriy | Abstract: The paper introduces GIS-based maps of the geomorphological and phytogeographical division of the Ukrainian Carpathians (a part of Eastern Carpathian Mts.), which were developed for routine use in biogeography and based on the consolidation of the existing publications. The map of geomorphological division includes 57 OGUs (operational geographic units), and the map phytogeographical division – 18 OGUs of the lowest rank. Geomorphological units are supported with available synonyms, which should help in work with different topic-related Ukrainian publications. Both maps follow strict hierarchical classification and are briefly discussed.


INTRODUCTION
The Ukrainian Carpathians (UC) is part of the Eastern Carpathian mountain province (Kondracki 1989), artificially delimited by the western border of Ukraine and covering about 24,000 km 2 . In general, these are not high mountains -only seven peaks of the UC slightly exceed 2000 m of elevation, and all these peaks, including the highest point of Ukraine, Mt. Hoverla (2061 m a.s.l.), are concentrated in the same Chornohora mountain range (Hiletskyi 2006). Tsys (1962Tsys ( , 1968 published the first complete geomorphologic division of the UC. Besides five mountainous regions, this division also included adjacent foothills and lowlands (Ciscarpathia and Transcarpathia) and comprised 36 districts. Such regionalization of the UC was further developed by many Ukrainian scientists (Herenchuk 2 al. 2015, Cherepanyn 2017, Korzhyk 2018. It also served as a basis for the floristic regionalization of the UC, which delimits nine floristic regions, and is most widely applied for phytogeographical purposes in Ukraine (Chopyk 1977, Chopyk & Fedoronchuk 2015. Despite the long history of investigation, divisions of the UC lack consistency in terms of a hierarchical classification of the operational geographic units (OGUs) and common principles of their delimitation (Hiletskyi 2012, Feoli et al. 2019. In particular, OGUs of the same hierarchical level can differ by area by orders of magnitude (e.g., Skolivski Beskydy or Transcarpathia), have no clearly argued limits (e.g., Krayovi Gorgany and Zovnishni Gorgany), are delimited without reason (e.g., Chyvchyny Mts., which are consistent with Marmarosh Mts., are often delimited in Ukrainian papers), or are excessively split (e.g., certain regions of Yalovychory Mts. and Ciscarpathia), even in the same publication (e.g., Tasenkevich 2004, Kruhlov 2012, Chopyk & Fedoronchuk 2015. The delimitation principles of natural geomorphological OGUs of the UC are best described by Hiletskyi (2012). A well-argued congruence of the natural geomorphological OGUs has been reached by Korzhyk et al. (2015) and Korzhyk (2018). However, these divisions cover only the part of the Ukrainian Carpathian Region (UCR) that includes the mountainous part (the UC) and adjacent territories. Kondracki (1989) proposed the geomorphological division of the Carpathians with different regionalization of its Ukrainian part. Following this scheme, the UC covers five macroregions and 17 mesoregions (some of the macroregions have no subdivision). In contrast to the division of Tsys (1962), the division of Kondracki (1989) is much better known outside of Ukraine. It is often applied for contemporary biogeographical studies in the Carpathian region (Kukuła et al. 2003, Zemanek 2009, Mráz & Ronikier 2016, Kłapyta 2020 Kruhlov (Kruhlov 2008(Kruhlov , 2012, based on the ideas of Miller & Fedirko (1990) and Melnyk (1999), combined geomorphological and ecological data and proposed one of the most recent regionalizations of the UC. The first version of this division (Kruhlov 2008) included 33 'morphogenic meso-ecoregions', but later was completed (Kruhlov 2012), and covered 44 OGUs grouped in 15 main classes (including island OGUs attached to the main Carpathian mountain range). This division is one of the most comprehensive, combining different aspects of spatial, geological, geomorphological, and ecological analyses and clusterization of obtained OGUs. Like Korzhyk et al. (2015) and Korzhyk (2018), Kruhlov's division is also GIS-based, with the OGUs of comparable size and more or less strict hierarchy. However, due to the application of ecological factors (i.e., bioclimatic elevation belts that are delimited based on the vegetation belts, the sum of active annual temperatures, and insolation), the separation and delimitation of some meso-ecoregions (e.g., Hutsulska Verkhovyna, Inner and Outer Bukovyna Mts., Krayovi and Zovnishni Gorgany) are debatable.
In 2015, in the frames of the investigations of the distribution of endemic plants in the Carpathian Mts., the necessity of a GIS-based map of the geomorphological division of the UC arose (Novikoff & Hurdu, 2015). The map of Kruhlov (2008Kruhlov ( , 2012 was the only one completely covering the UC region and GIS-based simultaneously, but due to the above-mentioned issues, it was dismissed. Similarly, Kruhlov's map did not find wide application among other scientists. Hence, starting from all mentioned above publications, a consolidated scheme for the geomorphological division of the UC following ideas of hierarchy and nomenclature of biogeographic units (Cox 2001, Kreft & Jetz 2010, Morrone 2018, Cervellini et al. 2020 3 was developed and reported at the conference "Biogeography of the Carpathians" in Cluj, Romania in 2017 (Novikov & Hurdu 2017).
The preliminary version of the geomorphological division of the UC comprised three hierarchical levels and 53 OGUs of the lowest level (mesoregions). Later, based on newly received data and revisions (e.g., Chorney 2011, Korzhyk et al. 2015, Korzhyk 2018, this scheme was improved (i.e., limits of some mesoregions were corrected, synonyms were completed, and the division was revised). Here we would like to introduce the final version of this scheme and an adapted scheme of Tasenkevich's (2004Tasenkevich's ( , 2005 phytogeographical division of the UC to help other scientists in their biogeographical explorations.

MATERIALS AND METHODS
The map was developed in QGIS 3 (https://www.qgis.org/) environment with the application of the Diva-GIS shapefile of the administrative borders (https://www.divagis.org/Data), the 15 arc-second resolution layer of the river network (https://geodata.lib.ut exas.edu/catalog/stanford-pv700jx1402), and the sublayer of OpenStreetMap (OSM, https://www.openstreetmap.org/). First, the background sublayer of OSM was imported to the QGIS. After that, the shapefiles of administrative borders and water bodies were uploaded to the project and converted to the WGS 84 coordinate system (EPSG 4326). The initial maps of Tsys (1962), Kondracki (1989), Tasenkevich (2004Tasenkevich ( , 2005, and Chopyk & Fedoronchuk (2015) were scanned and, after that, georeferenced in QGIS 3 with the following transformation settings: linear transformation type and the "Nearest neighbor" resampling method. Finally, the map of Kruhlov's division also was uploaded to the initial project. As a result, we obtained several overlapping semitransparent layers, which were visually inspected and analysed on consistency to natural barriers (i.e., river valleys). In case if the limits of the OGUs did not correspond to the natural barriers (e.g., went along or crossed the mountain ridges, went along the river valley but was shifted to higher elevation), they were bookmarked as having problematic topology, and after that corrected using QGIS in-built facilities. Hence, the primary limits of geomorphological and phytogeographical OGUs were ascertained based on the mentioned maps and later clarified and corrected concerning other published materials. In particular, the consolidated map of geomorphological division of the UCR was developed based on the analysis of the following principal publications dealing with physical and geographical aspects of the UCR regionalization: Dolenko (1962), Tsys (1962), Kondracki (1989), Gofstein (1995), Voropay & Kunytsia (1996), Melnyk (1999), Kravchuk (1999Kravchuk ( , 2005Kravchuk ( , 2008, Slyvka (2001), Marynych et al. (2003), Rudenko (2004), Kruhlov (2008Kruhlov ( , 2012, Korzhyk et al. (2015), and Korzhyk (2018). The map of phytogeographical division of the UCR was developed based on the map published by Tasenkevich (2004Tasenkevich ( , 2005 and, after that, partly adapted to the natural limits of geomorphological units. The final maps, represented in this paper, were reprojected using pseudo-Mercator WGS 84 coordinate system (3857) and extracted as independent ESRI shapefiles excluding other sublayers.

RESULTS AND DISCUSSION
The map of the geomorphological division of the UCR includes three main levels of OGUs -subprovinces, macroregions, and mesoregions. The intermediate OGU level between macro-and mesoregions was additionally ascertained. In total, 57 OGUs of mesoregional level were delimited in frames of this map (Figure 1, Table 1, Supplementary File 1).   Challenges were found in the use of different toponyms for the same OGU in Ukrainian publications (e.g., Transcarpathian Lowland sometimes is also mentioned as Tysa Lowland, Prytysenska Dolina, or Tysenska Dolina). Therefore, special attention was paid to the search and verification of available synonyms, which, if recognized, were provided in the select columns near each OGU.
The hierarchy, subdivision, and IDs of the OGUs of the developed map of the phytogeographical division of the UCR strictly follow Tasenkevich's concept, which ascertained three main levels of phytochorions -sector, county, and district. Besides this, Tasenkevich also distinguished a fourth level of subdistricts for certain OGUs, but only a few of them lay in the UC. The only exception was the additional inclusion of the Transcarpathian Lowland as an independent unit to this map. As a result, this map has three hierarchical levels with 19 lowest OGUs ( Figure 2, Table 2, Supplementary File 2). The map of the phytogeographical division of the UC does not fully correspond to the outlines of the map of geomorphological division due to several reasons. First, as mentioned before, Tasenkevich (2004Tasenkevich ( , 2005 developed her map based on the Carpathian division of Kondracki (1989), which was schematic and, as a result, not always clearly followed the natural limits. Moreover, Kondracki omitted the Ciscarpathia and Transcarpathia in his division because they do not belong to the Carpathian Mountains in a strict sense (Kliment et al. 2016, Mráz & Ronikier 2016) but rather represent adjacent independent highland and/or lowland territories (Kondracki 1989, Kravchuk 1999, Tasenkevich 2004. Similarly, in his first version, Kruhlov (2008) did not consider these territories. However, he introduced them to the second extended version of the map (Kruhlov 2012) as independent geomorphological units belonging to the UCR in a broad sense. Interestingly, 8 Ciscarpathia and some of Transcarpathia OGUs were introduced by Kruhlov (2012) as isolated island units.
Nevertheless, the Carpathian Mountains have a strong influence on the flora of the adjacent territories, and therefore they are often considered a part of the UCR and included in analyses by Ukrainian florists (Fodor 1974, Chopyk 1977, Tkachyk 2000, Pryhara 2013, Chopyk & Fedoronchuk, 2015. On the other side, Transcarpathia is a floristically unique territory that belongs to the Pannonian biogeographic region (Fodor 1974, Tasenkevich 2006, Sundseth 2009, Fekete et al. 2016. This was the reason why Tasenkevich (2004) included to her map only a narrow strap of Ciscarpathia basing on the eastern distribution limit of the mixed fir-beech forests and did not include Transcarpathia.
It was not our intention to engage in the debates about the appropriateness of inclusion of Transcarpathia and Ciscarpathia in the UC, and our decision was based on simple technical reason: these regions can be helpful for the analysis of the distribution of some taxa that are spread out of the UC (e.g., subendemics) and as transitional/buffer biogeographical zones (Lenormand et al. 2019). The built maps can be modified for different purposes, and, if needed, Transcarpathia and Ciscarpathia OGUs can be easily excluded from the analyses. If we would not include these regions, their delimitation could be challenging for other researchers due to scattered and published mainly in Ukrainian data.