Dynamics and occurence patterns of the Tatarian orache Atriplex tatarica L. (Chenopodiaceae) at the roadsides in Warsaw, Poland

Atriplex tatarica is an invasive annual plant from Central Asia. It is an early successional species of disturbed habitats, tolerant of a high content of NaCl. It grows also by the roadsides, on lawns by the streets and other places in cities sprayed with salt during snowfalls. The paper presents results of the analysis of abundance and patterns of occurrence of this invasive subhalophytic plant by the roadsides in the Warsaw city. We found that frequency and distribution of Atriplex tatarica increased significantly over the last few decades. The species grows chiefly along main streets which are de-iced. It forms monodominant patches of different length at the zone closest to the street verge. The NaCl concentration there is significantly higher than in the zones more distant from the street verge, although this parameter is very variable. The cover of other species increases with an increasing distance from the roadside verge