DATASET FOR VASCULAR PLANTS IN THE RED DATA BOOKS OF TRANSBAIKALIA: SPECIES DISTRIBUTION AND PATHWAYS TOWARDS THEIR CONSERVATION

The dataset of the Red Data Book vascular plants of Transbaikalia was created based on the latest editions of the Red Data Book of the Republic of Buryatia and the Red Data Book of the Zabaikalsky Krai (Russia). The dataset provides the most updated information regarding the distribution of 271 rare vascular plants (2920 distribution records). The distribution of the studied species was recorded during field surveys using GPS navigators, georeferenced from herbarium specimens, and digitised from printed distribution maps. Each entry in the dataset has various attributes, including belt zone, distribution, ecological, and life-form group features. Distribution patterns for various groups of rare and endangered species were analysed by means of QGIS 3.10 software. Our study has revealed a number of localities of vascular plants listed in the Red Data Book and clarified their distribution within the federal Protected Areas of Transbaikalia, among which Tunkinsky National Park has the highest diversity. Distribution of some rare and endangered species falls under federal protection, but some plants, including endemic species, require better protection. Analysis of various belt zones and distribution groups showed their distinct spread within the study region. Among the studied species, mesophytes and short rhizome perennial plants prevailed. It is also important to preserve vascular plants in the Red Data Book outside Protected Areas. Hence, information from our dataset can be useful for conservation monitoring programmes. Our study provides a basis for future conservation activities and can be applied in the establishment of new Protected Areas or Important Plant Areas in Transbaikalia.


Introduction
One of the general topics of biodiversity conservation refers to studies of rare and endangered plants species (Balding & Williams, 2016). Habitat loss, fragmentation, degradation, overexploitation, penetration of invasive species, pollution, and anthropogenic climate change are the main threats leading to a decreased plant diversity (Corlett, 2016). The complex approaches used in studies of rare and endangered plant species have been increasingly applied over the last decades (Heywood & Iriondo, 2003). Previous studies revealed three national biodiversity hotspots in Russia: North Caucasus, South Siberia, and Far East (Venevsky & Venevskaia, 2005). Also, a recent paper on the global distribution of endemic plants has recognised Crimea, North Caucasus, and the southern part of the Russian Far East as the centres of endemism within Mediterranean, Iran-Turanian, and East-Asian floras (Hobohm et al., 2019).
The first data on rare and endangered plant species of Transbaikalia were summarised by Boikov (1999) and later extended for the whole area of Central Siberia (Boikov, 2005). These studies were based on the data from previous editions of the Red Data Books of the Republic of Buryatia (hereinafter also -Buryatia) and Zabaikalsky Krai. Later, in 2012, the list of rare vascular plants for Protected Areas of Buryatia was completed (Krasnopevtseva & Krasnopevtseva, 2012). Recent studies have resulted in the identification of new localities of Transbaikalian rare plants, together with research into their conservation status and conditions. Based on these findings, the species list of Transbaikalian rare plants has been revised and published in the new editions of the Red Data Book of the Republic of Buryatia (2013) and the Red Data Book of the Zabaikalsky Krai (2017).
Consolidating species distribution records in a specific dataset can help with various statistical analyses to determine ecological factors limiting the distribution of certain species (Sandanov, 2019), which informs us how to prioritise rare plant monitoring (Laskey et al., 2020). Species occurrence data can be applied in the analysis of eco-geographic patterns of species richness . Moreover, available information (population quantity, seed dispersal and productivity, growth forms, ecological preferences) about rare and endangered plants can be applied in further conservation activities.
The aim of this study was to develop a GIS analysis approach to elucidate distribution patterns of rare and endangered vascular plants of Transbaikalia. For this purpose, we established three research tasks: (i) to compile distribution records for vascular plants listed in the Red Data Books for the Republic of Buryatia and Zabaikalsky Krai; (ii) to make specific layers for GIS and organise them into one single spatial dataset; (iii) to test distribution patterns of the focal plants on various levels. We hypothesised that the analysis of various Red Data Book vascular plant attributes can reveal particular biological and ecological features of species, which will be helpful in organising future conservation activities.

Study area
Transbaikalia represents a large region of Southern Siberia consisting of numerous mountain ranges within the upper basins of three large rivers: River Amur (Pacific Ocean basin), River Yenisei, and River Lena (Arctic Ocean basin). The study area is located within 49.22°-58.30° N and 98.60°-121.95° E. The major part of Transbaikalia area is covered by forests. However, the steppe vegetation is an inherent component in its southern parts. Steppes are widely represented within the steppe and forest-steppe mountain belts, as well as in the vast plains of the southeastern part of the studied area.

Data compilation
Some data of rare plants in Buryatia were recorded by using GPS navigators (i.e. Garmin eTtrex 10 and Garmin eTtrex 20 with WGS84 co-ordinate system) during field surveys. Other data were geo-referenced from herbarium vouchers. Distribution records were imported into QGIS v. 3.10 to create species distribution maps for the Red Data Book of the Republic of Buryatia (2013). A preliminary analysis of the distribution of rare plants in Buryatia was presented previously (Sandanov, 2016). Distribution maps for rare plants in the Zabaikalsky Krai have been made in raster format, and species localities were marked on the map using the graphic editor Adobe Photoshop. These maps have not been previously digitised. Both bordering regions are usually united as Transbaikalia and have similar eco-geographic features. These factors were the reason to develop one dataset for the whole area.
The dataset containing the occurence of species was registered in GBIF (Sandanov et al., 2021). Later this dataset has been enlarged by adding attributive information for each species. Species belt zone confinement and their distribution were identified according to Malyshev & Peshkova (1984). Ecological groups and life forms were compiled according to Boikov (2005). Ecological groups are represented by the following categories: euxerophyte, xerophyte, xeromesophyte, mesoxerophyte, mesophyte, eumesophyte, mesohygrophyte, hygromesophyte, hygrophyte, and hydrophyte. Original data on life forms were detailed following the Russian botanical tradition, including tree, shrub, woody liana, subshrub, dwarf shrub, dwarf subschrub, bunchgrass, compact-tussock grass, long rhizome, short rhizome, taproot, bulbous, bulbotuberiferous, roottuberous, short-lived, and annual. However, for a general view, we unified several biomorphs into groups. For example, subshrubs, dwarf shrubs, and dwarf subshrubs are included in a group of dwarf shrubs; bunchgrass and compact-tussock grass in bunchgrass; bulbous and bulbotuberiferous plants in bulbous plants; short-lived plants and annuals in annuals. Long rhizome plants are characterised by a leptocaul subterranean rhizome that sends out shoots from its nodes. Short rhizome plants have pachycaul subterranean rhizome, which permanently grows from the apical side and dies from the basal side. Missing data for other attributes were obtained from the literature survey and the results of our own field observations. All data were merged in the spatial dataset in QGIS 3.10. Altitude data presented by the GTOPO30 digital altitude model are available at http://eros.usgs.gov/#/Find_Data/Products_and_ Data_Available/gtopo30_info.
Digitisation of distribution maps of the species found in Zabaikalsky Krai was performed in QGIS 3.10 software by means of the georeferencing tool. Source raster maps were georeferenced by snapping control points to a destination vector shapefile, which in our case was the border of Zabaikalsky Krai. We used control points (usually 5-8) to link raster maps to the destination shapefile, which was resulted in the transformation of the maps according to the spatial projection of destination features (WGS84). Subsequently, species distribution locations were digitised from each map. The coordinates of each location were calculated in the attribute table. The accuracy of digitised records of Zabaikalsky Krai was tested arbitrarily for a randomised set of rare species, ranging from 1.5 km to 6 km. Relatively low accuracy (up to 6 km) is not suitable for analysing the local environment of species. However, it is sufficient to study rare species distribution patterns at the scale of Zabaikalsky Krai with a low digitisation accuracy.

Results
The dataset of rare vascular species contains 1216 distribution records of 157 plant taxa for the Republic of Buryatia (Sandanov, 2016) and 1704 distribution records of 164 plants for Zabaikalsky Krai, totally 2920 distribution records of 271 vascular plants. The distribution of Red Data Book vascular plants is mostly associated with river valleys and mountains (Fig. 1). The eastern area of Buryatia and central area of the Zabaikalsky Krai, from 52° N to 55° N, have a small number of rare species. Many species and their localities are observed in the steppe zone of the Zabaikalsky Krai.
In the study area, the taxonomic diversity of the Red Data Book vascular plants is 268 species and three subspecies from 164 genera and 73 families. The top ten families hold almost half of the species (50.6%) and distribution records (49.3%) ( Table 1).  One of the key questions in plant conservation is how many rare species are distributed within Protected Areas. Our data is taken from 14 federal Protected Areas in the study area, including state nature reserves, national parks, and sanctuaries (Table 2).
Tunkinsky National Park was found to have the highest number and diversity of the Red Data Book vascular plants. A high species diversity was also observed in the Baikalsky State Nature Reserve, Barguzinsky State Nature Reserve, Sokhondinsky State Nature Reserve, and Zabaikalsky National Park. Two records of two rare species (Sorbus sibirica (Hedl.) Prain and Berberis sibirica Pall.) were found in Alkhanai National Park. Only one rare species with eight records was observed for Kabansky Sanctuary (Nymphaea tetragona Georgi), while the adjacent Altacheisky Sanctuary was found to have no rare plant species. Dolina Dzerena Sanctuary was found to have the highest diversity of rare species out of all the sanctuaries surveyed.
The dataset gives additional information for rare plants such as their confinement to belt zones, distribution, ecological groups, and data on their life forms. A thorough analysis of this information may reveal interesting features and distribution patterns for rare vascular plants. Distribution patterns for various belt-zones groups (alpine, meadow, and typical steppe) show their distinct spread in Transbaikalia (Fig. 2). Analysis in QGIS helped us to estimate their differences in altitude ranges. Alpine species mostly occur at altitudes of 1600-2200 m a.s.l. Rare steppe species were spread across the southern part of the region and within Eravna, Barguzin, and Upper Chara depressions. The latter two depressions are the most northern boundaries of steppe communities in Transbaikalia. The typical steppe beltzone group usually occupies altitudes from 500 m a.s.l. to 1100 m a.s.l. Meadow species, such as Gastrolychnis popovii Peschkova, Iris sanguinea Hornem., and Turczaninowia fastigiata (Fisch.) DC. occur at the Vitim Plateau in the northeastern part of Buryatia. The latter two species are also found in the Zabaikalsky Krai. Turczaninowia fastigiata has only two records in the southeastern part, while Iris sanguinea is widely distributed throughout the region. The altitude preferences of meadow species vary from 500 m a.s.l. to 1500 m a.s.l. It is interesting that rare species from hypoarctomontane group (plants that occur in various mountain belts and hyparctic phytogeographical belt), such as Adoxa orientalis Nepomn., Astragalus frigidus (L.) A. Gray, and Dryopteris fragrans (L.) Schott, can be found only in the Zabaikalsky Krai. The first species is a rare relict endemic with small populations on the east of the region. The latter two species are widespread throughout Northern Eurasia; however, they are rare in Zabaikalsky Krai.
One of the main features of the dataset we developed was the analysis of the distribution patterns of rare vascular plants. This can be done under the analysis of various distribution groups (Fig. 3). Red Data Book vascular plant species with East-Asian distribution are the most prevalent in the study area. Endemic species have a high species diversity with a low number of distribution points. Rare endemic species are mostly represented by alpine plants (ten species with 50 distribution records, 23.8% of the total number). Some groups presented in various floristic provinces can be easily distinguished (Fig. 4).
Our analysis of rare endemic species distribution shows that Buryatia (34 species with 207 distribution records) has a diversity three times higher than Zabaikalsky Krai (11 species with 44 distribution records). A considerable number of endemic species in Zabaikalsky Krai (seven species with 29 distribution records) are concentrated in the northern part of Stanovoye highlands (mountain ridges of Kodar, Udokan, and Kalarskii). Other species are distributed within the steppe zone in the south of the region.
Analysis of ecological groups revealed the prevalence of mesophyte plants (Fig. 5A). Eumesophytes and mesophytes represented more than half of the rare vascular species recorded (54%). Mesophytes are well presented in forest beltzone areas, including the preboreal group (31 species with 340 distribution records), groups of light-coniferous for-groups of light-coniferous for-light-coniferous forests (24 species with 385 distribution records), and dark-coniferous forests (11 species with 134 distribution records). These plants are also abundant in highlands within alpine (23 species with 120 distribution records) and mountainous (11 species with 125 distribution records) beltzone groups. Mesoxerophytes and xerophytes have an average proportion among studied species (15% and 12%, respectively). They are formed mainly by groups from mountain steppe (30 species), typical steppe (23 species), and desert steppe (11 species). These steppe plants usually belong to taproot or short rhizome growth forms, which are dominant among the study species (Fig. 5B).    Short rhizome plants (29% of the total number of rare species) are often observed among species from Orchidaceae and Ranunculaceae families. A high percentage of long rhizome plants (14% of the total number of rare species) is mainly observed for forest plants. Plants of other life forms cover less than 10% for each group and in total represent 38% of the studied species.

Discussion
Overall this research revealed that rare and endangered vascular plants of Transbaikalia are well studied but there still remain territories that have a small number of known localities for these plants (Fig. 1). The low diversity is observed where the dominant type of plant communities is floristically pure such as larch forests, meadows, and swamps, which mostly contain common and widely distributed plant species. A high diversity of rare and endangered vascular species is observed in moun-tainous areas, which is a clear pattern on the local (Sandanov, 2016), regional (Venevsky & Ve-& Ve-Venevskaia, 2005), and global scales (Noroozi et al., 2018;Muellner-Riehl et al., 2019). It is also true that in Transbaikalia, many rare species are found in highlands and mountain ridges, and many of them are endemic. This also explains why this study found the highest number of localities and highest rare species diversity in Tunkinsky National Park, an area that contains the eastern part of the East Sayan mountains and the southeastern part of the Big Sayan Mountains.
The present analysis was focused on many federal Protected Areas in the study region, and we found that these Protected Areas do not contain the majority of rare species diversity (Table 2). The species distribution within Protected Areas is uneven, with most species having only one or two localities, and only a few can usually be found in Protected Areas. A similar situation was observed for the neighbouring Jewish Autonomous Region (Rubtsova & Gaidash, 2007). A recent review also highlighted conservation activities within Protected Areas but concluded that there is a need to invest significantly more efforts in plant conservation outside of them (Heywood, 2019).
The prevalence of rare species with East-Asian distribution was also previously observed for Baikal Siberia (Boikov, 2005). These species have the northwest edges of their distribution in Transbaikalia with a low population quantity (Peshkova, 1968;Boikov, 2005), vitality (Sandanov, 2009), low projective cover in plant communities, biomass, and seed productivity (Sandanov, 2010). For example, the distribution and population features of the East Asian rare species Scutellaria baicalensis Georgi in Transbaikalia fit with an «abundance-centre model», where the edge populations of the species have the lower population quantity and vitality . This pattern is also connected with regional and local environmental factors (Sandanov & Rosbakh, 2019) and proved by a sharp floristic gradient on the western part East-Asian phytogeographical region (Krestov, 2005;Galanin & Belikovich, 2006). In general, among the rare vascular plants, species of Asian origin were the most dominant type. It is similar with the flora of Baikal Siberia (Malyshev & Peshkova, 1984) and the steppe flora of South Siberia (Peshkova, 2001), which support the idea of indigenous origin of these floras.
Buryatia has a smaller number of species and localities of Red Data Book vascular plants compared to the Zabaikalsky Krai, which could refer to differences in floristic provinces. This is consistent with a recent study that revealed confinement of rare flora of Buryatia to South Siberia, while the Red Data Book species list for the Zabaikalsky Krai floristically was close to the Far-East regions of Russia (Khapugin et al., 2020). The area of Buryatia is situated within various floristic provinces where many plant species are located at the limits of their ranges (Namzalov, 2009;Kamelin, 2013). Here we can find many rare and endangered plant species on the western and eastern part of their distribution (Fig. 3, Fig. 4), as well as northern limits for some species widely distributed in Mongolia (Kamelin, 2013). The heterogeneity of the Buryatia landscape results in a high diversity of endemic species. Moreover, recent botanical studies in Buryatia have discovered many new localities of rare endemic species (Selyutina et al., 2016(Selyutina et al., , 2019Chimitov et al., 2017;Chimitov & Imetkhenova, 2019;Sandanov, 2020). Similar investigations reporting new findings of endemic species are also known in the Zabaikalsky Krai (Popova et al., 2020). These data are not included in our dataset, allowing us to have a similar timescale of data for the whole study area. A future revision of the rare species lists in the subsequent editions of the Red Data Books and compilation of the new distribution data will finally improve our dataset.
The high ratio of alpine plants among endemic species is similar to the flora of Baikal Siberia and can be explained by a high level of ecological isolation in the highlands in comparison with mountain ridges as a whole (Malyshev & Peshkova, 1984). The conservation of endem- Peshkova, 1984). The conservation of endemic species within habitats outside Protected Areas is one of the main priorities (Douma et al., 2012;Heywood, 2019), as was shown in a study revealing ten endemic species found outside Protected Areas in Buryatia (Sandanov, 2016). Moreover, the number of non-protected localities is twice as high as those under protection (Sandanov, 2020). The conservation of endemic species of vascular plants in the Magadan Region faces the same problem. Ten species out of 17 endemics are found outside Protected Areas (Khoreva & Mochalova, 2012). In the Zabaikalsky Krai, the situation is of higher concern, with only two localities of Aquilegia turczaninovii Kamelin & Gubanov and Rhodiola pinnatifida Boriss., found in the Sokhondinsky State Nature Reserve. A high diversity of endemic species in the Stanovoye highlands is observed in the Kodar National Park and the neighbouring Vitimsky State Nature Reserve (Irkutsk Region). To better preserve endemic species of Transbaikalia, it is necessary to extend the territories of Protected Areas or organise specific buffer zones with a high concentration of endemic species, revise the schemes of functional zoning for national parks or establish Important Plant Areas with detailed descriptions of species habitats. These studies need to be complemented by a detailed analysis of the population structure of rare plants to inform the planning of more effective conservation activities (McDonald-Madden et al., 2008;Selyutina & Sandanov, 2018).
Available data about ecological and biological features of Red Data Book vascular plants can provide more details for better conservation. For example, the high ratio of mesophytes among studied species can be explained by the mountainous landscape and prevalence of forests in Transbaikalia. There are many species from forests and highlands that are usually characterised by humid conditions. Rapid climate warming in Transbaikalia (Ippolitov et al., 2007) connected to the drought period (Obyazov, 2010) has led to high rates of aridisation over the last decades. These processes can be one of the main challenges in the conservation of rare mesophytic plants in the future.
Confinement of the plants to specific life forms and consolidating these data within the dataset is a good tool for studies of species richness and its determinants (Liu et al., 2019;Sandanov et al., 2020), for analysis of growth-form plasticity in rare and endemic species (Mills & Schwartz, 2005), and for detection of rare plants using remote sensing (Cerrejón et al., 2021). Our results revealed the prevalence of short rhizome plants among rare and endangered species. This can be explained by a high ratio of orchids, which are usually represented in regional Red Data Books as well (Khapugin et al., 2020). In forest communities, a high number of long rhizome plants is observed due to the thick organic soil layer formed by detritus and leaf litter (Bezdeleva, 2015). This data matches species ecology well because orchids and forest long rhizome plants usually grow in mesophytic habitats.

Conclusions
Our studies reveal the main distribution patterns of the Red Data Book vascular plants of Transbaikalia. The highest rare and endangered species diversity and number of localities is observed in Tunkinsky National Park. Our results show that the distribution of some rare and endangered species falls under federal protection, but some plants, including endemic species, need stricter protection. It is also essential to preserve vascular plants included in the Red Data Book from outside Protected Areas, and information from our dataset will be useful for conservation monitoring programs. The compilation of additional information for each species is helpful for the detailed analysis of their distribution and a better understanding of their ecological and biological features. Complex studies using the same techniques could add more meaningful information to the current dataset and could be helpful during the planning and implementation of future conservation activities.