The role of railway lines in the distribution of alien plant species in the territory of Daugavpils City (Latvia)

Abstract

The study was performed based on an inventory of alien flora in Daugavpils City. During the field studies all the alien species were recorded applying a regular grid consisting of 344 quadrats of 500 m × 500 m. Data of the 84 quadrats that cover all railway lines in the city were analysed to identify relationships between the distribution of alien plants and the location of railway lines. First the obtained data were compared with the first flora inventory in the city, which was conducted from 1975 to 1983. Comparison of data of the previous inventory and those obtained by us showed that the number of the recorded alien taxa along railways differed: 95 and 38 taxa, respectively. Secondly, some factors affecting the distribution of alien species along railway lines were analysed. Obtained results indicate that the highest concentrations of alien plants occurred in areas where railways are crossing or are located close to the adjacent cultivated and abandoned allotments, areas of private houses or cemeteries. Railway management measures such as topsoil disturbance and application of herbicides were found to be important human-induced factors affecting the distribution of annual alien taxa. The results of geospatial and statistical analyses demonstrated that the geographical distribution of alien species in general did not coincide with railway lines. However, the distribution of three species, i.e. Dracocephalum thymiflorum, Erysimum durum, and Lappula squarrosa, was associated only with railway lines, demonstrating the importance of railway infrastructure elements for the expansion of these species.

Analysis of some limiting ecological factors on the example of the distribution of the genusTiliaL. cultivated in Latvia

“…The coldest months are January and February, their average temperatures are -4.6 and -4.7 °C, respectively. The absolute maximum temperature, + 36.4 °C, and the absolute minimum temperature, -43.2 °C, in the whole territory of Latvia were observed only in Daugavpils; thus the range of extreme temperatures here is 79.6 °C Rutkovska et al, 2013). The average annual precipitation is 667 mm.…”

Lycopus lucidusTurcz. ex Benth.var.hirtusRegel (Lamiaceae) in Italy: a new naturalized alien species for the European flora

“…Abandoned areas such as railway embankments and freight yards, where plant species grow without control, can be important for their high floristic diversity (Zerbe et al 2003;Herbst and Herbst 2006). Moreover, highways and railways often act as ecological corridors for the spread and establishment of native (Penone et al 2012) and non-native (Hansen and Clevenger 2005;Wilkomirski et al 2012; Barina et al 2013;Rutkovska et al 2013) plant species, especially neophytes, with new arrivals almost every year (e.g. Ardenghi 2013).…”

Railway side mapping of alien plant distributions in Mpumalanga, South Africa

“…The disturbed area is particularly important during the early stage of invasion because it creates vacant niches that alien plants can colonise (Masters & Sheley 2001). Rutkovska et al (2013) found that some of the alien taxa in Latvia were associated with topsoil disturbance because of the construction and maintenance of railway lines. It is therefore possible that the development of railway networks in the study area may have promoted the distribution and spread of some of the alien plants.…”

“…The Southern African Plant Invaders Atlas (SAPIA) database (2016) provides information on railway side invasion in certain areas of South Africa, including parts of the Mpumalanga province. Woody alien plants along railway sides are a concern to railway infrastructure and rail operations because dense infestations often conceal railway crossings, endangering human life (Rutkovska et al 2013). Infestations along railways may also act as a starting point for the spread of species to the neighbouring agricultural or natural landscape.…”