Ausbreitung und beginnende Einbürgerung von Spiraea japonica in Österreich

Abstract.

Essl F. 2005. Spread and incipient naturalization of Spiraea japonica in Austria. Bot. Helv. 115: 1–14.

The subspontaneous spread and incipient naturalization of the alien Japanese honeysuckle (Spiraea japonica) in Austria were studied by reviewing floristic literature and by surveying a 3-km² area in the alpine foothills of eastern Upper Austria between 1990 and 2004. The literature review shows that the abundance and range of Spiraea japonica have increased in Austria during the 20th century: Until 1945, the species had been recorded in only three map** units (c. 30 km²) of the floristic map** project of Austria. Between 1945 and 1990, it was found in seven map** units, and since 1991, in a total of 20 map** units. In the field survey, 50 individuals of Spiraea japonica were recorded in 1990, but 198 in 2004. The species mainly occurred in climax forests (Galio sylvatici-Carpinetum) and pioneer forests (Sambucetum racemosae) dominated by Betula pendula; it was less frequent in pine or spruce plantations. No detrimental effects on native plants could be observed. Nevertheless, the further expansion of Spiraea japonica in Central Europe should be monitored attentively as this species is considered invasive in parts of North America.