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FP5

GIANT ALIEN Report Summary

Project ID: EVK2-CT-2001-00128
Funded under: FP5-EESD
Country: Czech Republic

Ecological, biological and demographical determinants of H. mantegazzianum invasion in relation to habitat and land use characteristics

Studies of Heracleum mantegazzianum in the Czech Republic and Germany revealed high seedling density, low mortality of established plants and fast population development. Flowering occurred in the 3rd year but was postponed up to 12 years under stress. Overlap between male and female phases allows for self-pollination and production of viable seed. This together with high fecundity allows single plants to start invasion after long-distance dispersal. A short-term persistent seed bank is formed; 90% of the seed germinate next spring but some survive longer. Morphophysiological dormancy is broken by cold stratification. These features, together with efficient dispersal by humans, water and wind, result in enormous invasion potential. At a local scale, populations increased by 1,260m2/year. Early in succession, life strategy accords with that of ruderal monocarpic plants, later with competitive perennials. Population growth rates of open stands depend on transition into next life-stages; generation time is ±3 years. In dense stands, stasis is more important and generation time exceeds 5 years. Productive human-disturbed habitats and inappropriate landscape management favoured invasion in Europe. Native diversity is adversely affected locally but not regionally. In its native region in the Caucasus, Heracleum is confined to disturbed sites and rare in natural subalpine meadows.

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Reported by

INSTITUTE OF BOTANY - ACADEMY OF SCIENCES OF THE CZECH REPUBLIC
145,Zamek 1
252 43 PRUHONICE
Czech Republic
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