VASCULAR FLORA OF TOSNENSKY DISTRICT (LENINGRAD REGION, EUROPEAN RUSSIA): COMPOSITION, STRUCTURE AND DYNAMICS

Abstract

The article presents the first comprehensive assessment of the vascular flora of Tosnensky district (Leningrad region, Northwestern European Russia). In this study, we made the first checklist of vascular plants for this area based on our field observations in 2016–2022, the literature, online sources and herbarium collections. The flora of Tosnensky district consists of 874 species, of which 706 are native, 36 are archaeophytes, 131 are neophytes, and one species has an uncertain status. The list contains information on 43 species new to the district and on one species (Euphrasia micrantha Rchb) new to the flora of Leningrad region. Results show that by the number of native species, Asteraceae, Cyperaceae, Poaceae are leading families; Brassicaceae is the largest in terms of the number of alien species. The native flora is dominated by forest-inhabiting species (55.3% of all species); the largest number of alien species is found on roadsides (42.7%). Most of the native species have a Eurasian range (30.5%), and 20.8% of all alien plants originate from North America. Perennial herbs dominate among both native and alien species (72.9% and 54.2%, respectively). In alien flora of Tosnensky district, there are 59 casual and 55 naturalized non-invasive species, while 14 species have been assigned as invasive. In addition, we provide information on the habitats of 42 species protected in Leningrad region, including three species that are listed in the Red Book of the Russian Federation, namely Isoetes echinospora Durieu, Dactylorhiza baltica (Klinge) Nevski and Lobelia dortmanna L. The flora of Tosnensky district is well listed compared to floras of neighboring territories, however our findings indicate a relatively low proportion of neophytes (15% of all species). This feature can be explained by the low level of development of the transport network that reduces the likelihood of the introduction and spread of neophytes.