Seed banks in desert annuals: Implications for persistence and coexistence in variable environments

Catherine E. Pake, D. Lawrence Venable

Research output: Contribution to journalArticle

264 Scopus citations

Abstract

It is widely believed that desert annual plants maintain between-year seed banks, yet few field studies actually have measured the proportion of the viable seed bank that remains dormant through a season. Dormancy and germination fractions were quantified for a guild of winter annuals on a creosote flat in the Sonoran Desert for three years. Predictions from two types of theoretical models applicable to temporally variable environments were examined: (1) the evolution of life history traits promoting persistence in the face of temporal variation and (2) the role of temporal variation in mediating species coexistence. The density of ungerminated seeds was estimated by collecting soil samples after germination, but prior to new seed set. Seedlings were followed in nearby plots to estimate the density of germinated seedlings and their reproductive success. Long-term data collected from permanent plots over a 10-yr period were used to calculate temporal variation in reproductive success for each species. Species with higher temporal variation in reproductive success had lower germination fractions and smaller seeds, consistent with the theory that seed dormancy and large seed size are partially substitutable bet-hedging strategies. The data also suggested that this system possesses traits that are necessary for temporal variation to promote coexistence. First, between-year seed banks, necessary to buffer populations in unfavorable years, were documented for 17 species. Second, there was a strong tendency for year-to-year variation in germination fractions to vary among species. Finally, plants germinated more in years of higher reproductive success. We discuss how a correlation between germination and reproductive success enhances the role of temporal variance in success hierarchies in promoting species coexistence.

Original languageEnglish (US)
Pages (from-to)1427-1435
Number of pages9
JournalEcology
Volume77
Issue number5
DOIs
StatePublished - Jan 1 1996

Keywords

  • Desert annual plants
  • Dormancy
  • Field experiment
  • Life history traits
  • Predictive germination
  • Reproductive success
  • Seed banks
  • Sonoran Desert
  • Spatial variation
  • Species coexistence
  • Temporal variation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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