Dispersal: The Eighth Fire Seasonality Effect on Plants

Keith, David A.; Dunker, Bianca; Driscoll, Don A.

doi:10.1016/j.tree.2019.12.001

Cited by 13 publications

(12 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dewy pines represent a common form of such periodicity: adaptations to disturbance regimes (Brawn et al, 2001; Denslow, 1980; Pausas et al, 2004). Although many studies on disturbance‐adapted plants have shown strong effects of changes in the periodic pattern of these disturbance regimes on population dynamics (Evans et al, 2010; Keith et al, 2020; Miller et al, 2019), we found no differences in dewy‐pine stochastic growth rates among different fire regimes considered. Instead, dewy‐pine populations were negatively affected by introducing human perturbations in the form of heavy browsing after fires, especially when starting in the early post‐fire habitat states (Figure 3c; Paniw, Quintana‐Ascencio et al, 2017).…”

Section: Discussioncontrasting

confidence: 80%

Demographic consequences of changes in environmental periodicity

Eva

Özgül

Blumstein

et al. 2023

Ecology

View full text Add to dashboard Cite

show abstract

Section: Discussioncontrasting

confidence: 80%

Demographic consequences of changes in environmental periodicity

Eva

Özgül

Blumstein

et al. 2023

Ecology

View full text Add to dashboard Cite

show abstract

“…(2019) and Keith et al. (2020) surveyed the literature extensively and used a conceptual demographic framework to identify eight globally relevant mechanisms of fire seasonality effects on plant populations, seven of which are relevant to seedling recruitment. Here, we use an experimental approach to help isolate the effects of fire seasonality on two seedling recruitment mechanisms: (1) postfire seed persistence, and (2) postfire seedling establishment (emergence and survival).…”

Section: Introductionmentioning

confidence: 99%

“…Summer and autumn fires typically coincide with peak seed-bank abundance and strong propagule dispersal vectors, and cue seeds for germination close to the next available germination season (Bond 1984, C espedes et al 2012, Dunker et al 2019. Miller et al (2019) and Keith et al (2020) surveyed the literature extensively and used a conceptual demographic framework to identify eight globally relevant mechanisms of fire seasonality effects on plant populations, seven of which are relevant to seedling recruitment. Here, we use an experimental approach to help isolate the effects of fire seasonality on two seedling recruitment mechanisms: (1) postfire seed persistence, and (2) postfire seedling establishment (emergence and survival).…”

Section: Introductionmentioning

confidence: 99%

Experimental seed sowing reveals seedling recruitment vulnerability to unseasonal fire

Miller

Fontaine

Merritt

et al. 2021

Ecological Applications

View full text Add to dashboard Cite

Unseasonal fire occurrence is increasing globally, driven by climate change and other human activity. Changed timing of fire can inhibit postfire seedling recruitment through interactions with plant phenology (the timing of key processes, e.g., flower initiation, seed production, dispersal, germination), and therefore threaten the persistence of many plant species. Although empirical evidence from winter‐rainfall ecosystems shows that optimal seedling recruitment is expected following summer and autumn (dry season) fires, we sought experimental evidence isolating the mechanisms of poor recruitment following unseasonal (wet season) fire. We implemented a seed‐sowing experiment using nine species native to fire‐prone, Mediterranean‐climate woodlands in southwestern Australia to emulate the timing of postfire recruitment and test key mechanisms of fire seasonality effects. For seeds sown during months when fire is unseasonal (i.e., August–September: end of the wet winter season), seedling recruitment was reduced by up to 99% relative to seeds sown during seasonal fire months (i.e., May–June: end of the dry summer season) because of varying seed persistence, seedling emergence, and seedling survival. We found that up to 70 times more seedlings emerged when seeds were sown during seasonal fire months compared to when seeds were sown during unseasonal fire months. The few seedlings that emerged from unseasonal sowings all died with the onset of the dry season. Of the seeds that failed to germinate from unseasonal sowings, only 2% survived exposure on the soil surface over the ensuing hot and dry summer. Our experimental results demonstrate the potential for unseasonal fire to inhibit seedling recruitment via impacts on pregermination seed persistence and seedling establishment. As ongoing climate change lengthens fire seasons (i.e., unseasonal wildfires become more common) and managed fires are implemented further outside historically typical fire seasons, postfire seedling recruitment may become more vulnerable to failure, causing shifts in plant community composition towards those with fewer species solely dependent on seeds for regeneration.

show abstract

“…Fire seasonality (the time of year of fire occurrence) is a relatively understudied element of the fire regime ( Whelan, 1995 ) despite significant recent advances ( Miller et al, 2019 ; Keith et al, 2020 ). Historically, wildfires have been more prevalent in warmer or drier seasons, when fuel moisture and weather conditions are most conducive to ignition and fire spread ( Krawchuk and Moritz, 2011 ); however, global increases in annual fire weather due to climate change have led to fire seasons in many regions around the world beginning earlier and lasting longer ( Westerling et al, 2006 ; Jolly et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

“…In conjunction with greater anthropogenic ignitions, this is increasing the frequency of unseasonal fires (those outside the historical fire season) in the landscape ( Le Page et al, 2010 ; Balch et al, 2017 ; Bowman et al, 2020 ). Variation in fire seasonality can adversely affect plant populations through negative impacts on critical life history stages including adult survival and growth, propagule availability, dispersal, and post-fire seedling establishment ( Miller et al, 2019 ; Keith et al, 2020 ; and references therein). However, supporting evidence for these mechanisms is relatively limited across most climate and vegetation types—in particular, evidence of how altered fire seasonality affects recruitment from soil seed banks of species with innate seasonal germination requirements ( Miller et al, 2019 ; Cao et al, 2020 ; Tangney et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Fire Seasonality, Seasonal Temperature Cues, Dormancy Cycling, and Moisture Availability Mediate Post-fire Germination of Species With Physiological Dormancy

et al. 2021

Self Cite

View full text Add to dashboard Cite

Fire seasonality (the time of year of fire occurrence) has important implications for a wide range of demographic processes in plants, including seedling recruitment. However, the underlying mechanisms of fire-driven recruitment of species with physiological seed dormancy remain poorly understood, limiting effective fire and conservation management, with insights hampered by common methodological practices and complex dormancy and germination requirements. We sought to identify the mechanisms that regulate germination of physiologically dormant species in nature and assess their sensitivity to changes in fire seasonality. We employed a combination of laboratory-based germination trials and burial-retrieval trials in natural populations of seven species of Boronia (Rutaceae) to characterize seasonal patterns in dormancy and fire-stimulated germination over a 2-year period and synthesized the observed patterns into a conceptual model of fire seasonality effects on germination. The timing and magnitude of seedling emergence was mediated by seasonal dormancy cycling and seasonal temperature cues, and their interactions with fire seasonality, the degree of soil heating expected during a fire, and the duration of imbibition. Primary dormancy was overcome within 4–10 months’ burial and cycled seasonally. Fire-associated heat and smoke stimulated germination once dormancy was alleviated, with both cues required in combination by some species. For some species, germination was restricted to summer temperatures (a strict seasonal requirement), while others germinated over a broader seasonal range of temperatures but exhibited seasonal preferences through greater responses at warmer or cooler temperatures. The impacts of fires in different seasons on germination can vary in strength and direction, even between sympatric congeners, and are strongly influenced by moisture availability (both the timing of post-fire rainfall and the duration soils stay moist enough for germination). Thus, fire seasonality and fire severity (via its effect on soil heating) are expected to significantly influence post-fire emergence patterns in these species and others with physiological dormancy, often leading to “germination interval squeeze.” Integration of these concepts into current fire management frameworks is urgently required to ensure best-practice conservation. This is especially pertinent given major, ongoing shifts in fire seasonality and rainfall patterns across the globe due to climate change and increasing anthropogenic ignitions.

show abstract

Dispersal: The Eighth Fire Seasonality Effect on Plants

Cited by 13 publications

References 12 publications

Demographic consequences of changes in environmental periodicity

Demographic consequences of changes in environmental periodicity

Experimental seed sowing reveals seedling recruitment vulnerability to unseasonal fire

Fire Seasonality, Seasonal Temperature Cues, Dormancy Cycling, and Moisture Availability Mediate Post-fire Germination of Species With Physiological Dormancy

Contact Info

Product

Resources

About