Invasion, dispersal and ecology of the South African neophyte Senecio inaequidens in The Netherlands: from wool alien to railway and road alien
Acta botanica neerlandica , Volume 47 - Issue 1 p. 131- 151
Senecio inaequidens, a perennial pioneer plant, invaded The Netherlands at Tilburg with sheep’s wool from South Africa in 1939, where it failed to establish a permanent population. In 1942 a new invasion from an expanding invader population at Liege occurred at Eijsden, establishing a new dispersal centre in southern Limburg, The Netherlands. In the 1980s a further dispersal throughout The Netherlands resulted in additional dispersal centres at the railway stations at Amsterdam and Hengelo. The dispersal along new railway lines in the Amsterdam region confirmed the importance of trains for occasional long-distance dispersal events because in general the majority of the anemochorous achenes remained in the vicinity of the parent plants. Expansion dynamics and ecology was studied in a new established population at the railway station in Hoofddorp. The species has a high selffertility. Adaptation to the Atlantic climate of The Netherlands was accompanied by the selection for flowering earliness from August to May and prolongation of the flowering period to end of December. Achene mass mostly declined from high values in July to 70% lower ones in December. Low dormancy of early summer achenes allowed establishment of a new generation in the same year; late autumn achenes had a high dormancy and germinated in next spring. Dormant achenes persisted for two winter periods and survived frost at 15°C. Caterpillars of Tyria jacobaeae were recorded as leaf herbivores on S. inaequidens. but had nearly no impact on a plant’s performance. The extinction or survival of the various founder populations as wool aliens in Europe is discussed in relation to founder effects, adaptation to winter temperature in western Europe, prolongation of the flowering period and the importance of modern traffic means and climatic changes for its rapid expansion after 1985.
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W.H.O. Ernst. (1998). Invasion, dispersal and ecology of the South African neophyte Senecio inaequidens in The Netherlands: from wool alien to railway and road alien. Acta botanica neerlandica, 47(1), 131–151.
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