Distribution of Bunias orientalis in Latvia [Bunias orientalis paplitimas Latvijoje]. – Bothanica Lithuanica, 12(2): 69–77

Bunias orientalis, the native of the European part of Russia, the Caucasus, western Siberia, and now also common in Central and some other parts of northern and western Europe, is among the most widespread alien species of Latvia. Studies on the Bunias orientalis, including the history of its advent, current patterns of distribution, migration routes, and tendencies, reveal significant regularities responsible for the spread of invasive species to new regions, which permit certain generalizations relevant also for other species. First recorded in Latvia in 1803, today the number of registered Bunias orientalis localities is 337 with the highest increase in the recent period. The distribution of this species, using the standard grid of 10 × 10 km for mapping, has been intensively studied in the last decades, and the most representative data are now available. Bunias orientalis is found mostly along the highways, railway lines, and in heavily disturbed habitats; to a lesser extent in grasslands, fallow lands, fields, orchards, on the riversides, forest edges, and others habitats. Most of the localities are in eastern Latvia, central part of eastern Latvia, in the vicinity of some biggest cities mostly in eastern Latvia, and the country’s capital; the species is less common on the seacoast, and even less in western Latvia. The lowest concentration of localities is in the central part of Latvia and the central part of western Latvia. Mapping of the registered Bunias orientalis localities in a historical sequence helps track down its migration routes in the east-west direction, which for the most part follow the highways, railways, and rivers. Limy soils and continental climatic conditions greatly facilitate the spread and establishment of Bunias orientalis in new localities. It is concluded that this alien species emerges mainly next to the arterial roads and rivers and migrates along them. In this respect the role of farming and gardening is less significant.

Keywords: Bunias orientalis, alien species, distribution, migration routes, Latvia.