Dominant drivers of seedling establishment in a fire-dependent obligate seeder: Climate or fire regimes?

Annabel L. Smith, David Blair, Lachlan McBurney, Sam C. Banks, Philip S. Barton, Wade Blanchard, Don A. Driscoll, A. Malcolm Gill, David B. Lindenmayer

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Climate change is causing fire regime shifts in ecosystems worldwide. Plant species with regeneration strategies strongly linked to a fire regime, such as obligate seeders, may be particularly threatened by these changes. It is unclear whether changes in fire regimes or the direct effects of climate change will be the dominant threats to obligate seeders in future. We investigated the relative importance of fire-related variables (fire return interval andfire severity) and environmental factors (climate and topography) on seedling establishment in the world's tallest angiosperm, an obligate seeder, Eucalyptus regnans. Throughout its range, this species dominates the wet montane forests of south-eastern Australia and plays a keystone role in forest structure. Following major wildfires, we investigated seedling establishment in E. regnanswithin 1 year of fire as this is a critical stage in the regeneration niche of obligate seeders. Seedling presence and abundance were strongly related to the occurrence of fire but not to variation in fire severity (moderate vs. high severity). Seedling abundance increased with increasing fire return interval (range 26-300 years). First-year seedling establishment was also strongly associated with low temperatures and with high elevations, high precipitation and persistent soil water availability. Our results show that both climate and fire regimes are strong drivers of E. regnans seedling establishment. The predicted warming and drying of the climate might reduce the regeneration potential for some obligate seeders in future and these threats are likely to be compounded by changes in fire regimes, particularly increases in fire frequency.

Original languageEnglish
Pages (from-to)258-270
Number of pages13
JournalEcosystems
Volume17
Issue number2
Early online date10 Oct 2013
DOIs
Publication statusPublished - Mar 2014
Externally publishedYes

Keywords

  • Climate change
  • Disturbance
  • Fire return interval
  • Fire severity
  • Forest management
  • Plant functional type
  • Range shift
  • Regeneration niche

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