Survey of invasive alien species in the flora of Lozenska Mountain, Bulgaria

Abstract

Th is study explores the invasive alien fl ora of Lozenska Mountain, southwestern Bulgaria (maximum height 1190 m, area 80 km 2 ). Th e aims were to (i) describe the taxonomic and ecological structure of the invasive alien fl ora in Lozenska Mountain, and (ii) provide data on the local distribution of the globally most widespread invasive species. Ten transects of diff erent lengths (from 4 to 12 km) in diff erent parts of the mountain covering the most characteristic habitats were surveyed between April 2017 and October 2018. Altogether, 27 invasive alien species (IAS) and 4 potentially invasive alien species (PIAS) belonging to 17 families of fl owering plants were encountered. Th ese represent 3.46% of the fl ora of Lozenska Mountain, and 45% of all the IAS in Bulgaria. Seven species (Acer negundo, Ailanthus altissima, Amorpha fr uticosa, Bidens fr ondosus, Fallopia × bohe mica, Opuntia humifusa and Robinia pseudoacacia) are highly aggressive. In the biological spectrum of IAS, therophytes predominate (29%), followed by hemicryptophytes (19.4%). Th e majority of IAS originates from America (65.6%) and Asia (19.5%). 64.5% of the IAS were deliberately introduced. Th e established invasive species on the territory of the mountain are predominantly heliophytes (90.3%); microthermophytes (71.0%); high humidity species (38.7%); mesophytes (54.8%), mesooligotrophs (58.1%) and basophilic species (80.6%). Th e most widespread species are Robinia pseudoacacia, Erigeron canadensis and Xanthium italicum. Most of the IAS were found in one transect only. Th e highest percentage of species cover (over 80%) was reached by plants adapted to specifi c habitats: aquatic (Elodea canadensis), riparian (Impatiens glan dulifera, Fallopia × bohemica) and anthropogenically heavily disturbed terrains (Sorghum halepen se). Th ere is a substantial threat of IAS irruption on the territory of Lozenska Mountain for the following habitat types (reference codes according to Annex I of the Directive 92/43/EEC): 3150 (Natural eutrophic lakes with Magnopotamion or Hydrocharition vegetation) and 3270 (Rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation) included in Natura 2000.

Effects of tree size and park maintenance on soil seed bank of Gleditsia triacanthos, an exotic tree in urban green areas

“…From some European countries, including Hungary, honey locust was reported as sporadically occurring alien tree (Balogh et al 2004;Pyšek et al 2012;Glišić et al 2014;Glogov et al 2019). However, its recent sporadic character does not rule out that it may be seriously invasive in the future.…”