Ferns at the digital herbarium of the Central Siberian Botanical Garden SB RAS

Abstract Background According to the data in Index Herbariorum as of 1 December 2020, there are 3426 active herbaria in the world, containing 396,204,891 specimens and 124 herbaria in Russia with more than 16,175,000 specimens. The Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences (CSBG SB RAS, Novosibirsk), founded in 1946, historically has two herbarium collections (NS and NSK). Currently these collections contain about 800,000 herbarium specimens comprising vascular plants, mosses, lichens and fungi gathered from all over the world. Digitisation of the NSK type specimens of vascular plants began in 2014 by using the special scanner Herbscan. In 2018, we started digitisation of the NS and NSK collections by using ObjectScan 1600. Pteridophytes (ferns, lycophytes and their extinct free-sporing relatives) are a diverse group of plants that today comprises approximately 12,900 species and plays a major role in terrestrial ecosystems. All herbarium specimens of ferns, collected over 170 years between 1851 and 2021 and stored in the NS and NSK collections, were digitised in 2021, placed at the CSBG SB RAS digital Herbarium (http://herb.csbg.nsc.ru:8081) and published through GBIF. Twenty families of Polypodiopsida, but not Equisetaceae, were included in this dataset. Family Ophioglossaceae was digitised and published in GBIF as a separate dataset. New information By August 2021, more than 62,600 specimens with good quality images and fully-captured label transcriptions had been placed at CSBG SB RAS Digital Herbarium. A total of 7,758 records of fern occurrences of 363 taxa in the world with 92% geolocations including 5100 records from Russia with 98.7% geolocations that are new for GBIF.org in 2021 were entered. In the dataset specimens from 43 countries of Europe, Asia, America, Africa and Australia (Oceania), 89% of them from Russia, are presented.


Introduction
Herbarium specimens act as a source of information, to determine: • what the plants look like; • where they are found; • what environmental niche they occupy; • which species are threatened by extinction; • what morphological and chemical variation occurs; • when they flower or produce seed.
Specimens can be used to provide samples of DNA to study relationships and evolutionary processes (Royal Botanic Gardens, Kew 2021). They also act as vouchers to validate scientific observation (Willis et al. 2017). The Herbarium is therefore of immense practical use and of fundamental importance to science.
CSBG SB RAS, the largest botanical institute in the Asian part of Russia, has two herbarium collections with registration in the Index Herbariorum (Thiers 2021): the collection named after I.M. Krasnoborov (NS) and the collection named after M.G. Popov (NSK). The consortium of two Herbaria NS and NSK was formed in 1978 when the NSK Herbarium collection and staff of laboratory were transferred from Irkutsk to Novosibirsk. Together, these collections have ca. 680,000 herbarium specimens of vascular plants . They are active collections in continuous growth.
With the digitisation of natural history collections over the recent decades, their traditional roles for taxonomic studies and public education have been greatly expanded into the fields of biodiversity assessments (Kovtonyuk 2015, Besnard et al. 2018, Nelson and Ellis 2018, Miller 2020, climate change impact studies, trait analyses, DNA-sequencing (Shen et al. 2020), automated herbarium specimen identification (Carranza-Rojas et al. 2017), 3D object analyses etc. Biodiversity monitoring and conservation status assessments are based on a consensus classification and accurate information on geographic ranges, often in the form of maps that present the complete range of species occurrence across countries. International collaborative approaches, such as the Global Biodiversity Information Facility (GBIF.org 2021) are increasingly facilitating access to specimen and observational data. They enable broad-scale biodiversity analyses and, as such, depend on the linkage of these data to an authoritative taxonomic and floristic source of information on all known plant taxa (Borsch 2020).
Digitisation activities across Russia were described by A. Seregin (Seregin 2020). The contribution of small herbaria to the digitisation process has been steadily growing over the last few years (Seregin and Stepanova 2020). We work for future generations by preserving specimens and scanning collections, databasing herbarium labels and high quality images; these data are and will be used for research and education.
The creation of the Digital Herbarium of CSBG SB RAS began in 2018 (Kovtonyuk et al. 2018. All specimens of ferns were digitised by using two herbarium scanners Object Scan 1600 (Microtek 2021) in accordance with the international standards developed at the Royal Botanic Gardens, Kew. Specimens from the family Ophioglossaceae kept at NS and NSK collections were digitised and published in GBIF as a separate dataset (Kovtonyuk et al. 2021), Botrychium specimens being tested by Dr. Jason Grant (Dauphin et al. 2020) of the University of Neuchâtel (Switherland).
The earliest herbarium specimens of ferns stored in CSBG SB RAS were collected in 1851 and the last ones in 2021. Herbarium samples of ferns were studied by I.M. Krasnoborov for the first volume of "Flora of Siberia" (Malyschev 2000), by A.I. Shmakov during the preparation of the monographs "Key for the Ferns of Russia" (Shmakov 2009) and "Ferns of North Asia" (Shmakov 2011), by L.I. Malyshev for the "Conspect of Asian Russia Flora" (Malyschev 2012) and others.

General description
Purpose: The purpose of this publication is to mobilise ferns biodiversity data, using as examples herbarium specimens stored at the Central Siberian Botanic Garden SB RAS collections (NS and NSK). One of our primary goals is to database and image these collections to make them web-accessible for researchers and to provide open online access to the CSBG SB RAS Digital Herbarium (http://herb.csbg.nsc.ru:8081) as a worldwide data resource for the study of biodiversity.

Project description
Title: Digitisation of vascular plants collections (NSK, NS) and creating the CSBG SB RAS Digital Herbarium.
Ilya Eremin -technical support of the CSBG SB RAS Digital Herbarium.

Sampling methods
Study extent: All ferns, stored in NS and NSK herbarium collections, were digitised by staff of the Digitisation group at the Vascular Plant Systematics Laboratory of the CSBG SB RAS. Step description: The digitisation process includes the following six steps: 1. Mounting of dry plant material on to a herbarium sheet, according to Skvortsov A. K. (Skvortsov 1977); 2. Checking the identification and nomenclature by a specialist using taxanomic databases, such as