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

被引:43
作者
Jongejans, Eelke
Pedatella, Nicholas M.
Shea, Katriona
Skarpaas, Olav
Auhl, Richard
机构
[1] Penn State Univ, Dept Biol & IGDP Ecol, University Pk, PA 16802 USA
[2] Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA
[3] Norwegian Inst Nat Res, N-0349 Oslo, Norway
关键词
seed abscission; seed dispersal; seed release threshold; wind turbulence;
D O I
10.1098/rspb.2007.0190
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
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.
引用
收藏
页码:2457 / 2464
页数:8
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