Life-history plasticity of riparian annual plants adapted to extreme variations in water level: mesocosm experiments

Yu Song, Xuesha Ke, Wenzhi Liu, Anthony John Davy, Guihua Liu (Lead Author)

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Abstract

The riparian zones of reservoirs associated with regulated rivers in China experience annual fluctuations in water level of up to 30 m that may vary in timing from year to year. Few plant species can tolerate such hydrological perturbation but short-lived riparian annuals might be evolutionarily pre-adapted to such conditions. This study investigated plasticity of life history in four annual species: one typically associated with free-flowing rivers (Panicum bisulcatum) and three that colonize reservoir margins (Cyperus michelianus, Fimbristylis miliacea and Eclipta prostrata). We found that all four species produced non-dormant seeds that survived prolonged submergence; germination percentage was independent of the time of exposure by receding waters. Although growth was reduced as a result of shorter growing seasons, all four species completed their life cycles and produced seeds before winter. In addition, P. bisulcatum and C. michelianus allocated biomass to seed production, at the expense of roots and stems, in response to later establishment. All species responded to later establishment with a reduced vegetative growth period before seed production. C. michelianus, F. miliacea and E. prostrata could also delay the onset of flowering time by up to 2 months. P. bisulcatum, a plant that can flower only after exposure to short days, consequently had a fixed flowering time and could accommodate delayed establishment only with a progressively shorter period of vegetative growth. This lower flexibility might explain its absence from reservoir margins. The conceptual framework presented here offers a tool to predict the establishment of vegetation under hydrological disturbance in riparian environments and thereby provides insights into improved restoration practice.
Original languageEnglish
Pages (from-to)1311–1318
Number of pages8
JournalRiver Research and Applications
Volume31
Issue number10
Early online date29 Aug 2014
DOIs
Publication statusPublished - 8 Dec 2015

Keywords

  • life-history adaptation
  • flowering phenology
  • phenotypic plasticity
  • water-level fluctuation
  • riparian zone
  • regulated river

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