Seed release by invasive thistles: The impact of plant and environmental factors

Eelke Jongejans, Nicholas M. Pedatella, Katriona Shea, Olav Skarpaas, Richard Randolph Auhl

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

Dispersal is a key process in biological studies of spatial dynamics, but the initiation of dispersal has often been neglected, despite strong indications that differential timing of dispersal can significantly affect dispersal distances. To investigate which plant and environmental factors determine the release of plumed seeds by the invasive thistles Carduus acanthoides and Carduus nutans, we exposed 192 flower heads of each species to increasing wind speeds in a full-factorial wind tunnel experiment with four air flow turbulence, three flower head wetness and two flower head temperature levels. The number of seed releases was highest under dry and turbulent conditions and from heads that had already lost a considerable number of seeds, but was not affected by flower head size, head angle or temperature. Inspection of the trials on video showed that higher wind speeds were needed to meet the seed release threshold in laminar flows and for C. acanthoides heads that had been wet for a longer time. Species differences were minimal, although seed release was more sensitive to lower levels of turbulence in the larger-headed and more open C. nutans heads. Knowledge of seed release biases towards weather conditions favourable for long-distance dispersal improves our understanding of the spread of invaders and allows managers to increase the efficiency of their containment strategies by applying them at crucial times.

Original languageEnglish (US)
Pages (from-to)2457-2464
Number of pages8
JournalProceedings of the Royal Society B: Biological Sciences
Volume274
Issue number1624
DOIs
Publication statusPublished - Oct 7 2007

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Medicine(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

Cite this