Patterns in longevity of soil seedbanks in fire-prone communities of south-eastern Australia

2000 ◽  
Vol 48 (4) ◽  
pp. 539 ◽  
Author(s):  
Tony D. Auld ◽  
David A. Keith ◽  
Ross A. Bradstock
Keyword(s):  
Seed Dormancy ◽  
Seed Longevity ◽  
Dormant Seed ◽  
South Eastern ◽  
Secondary Dormancy ◽  
Seed Decay ◽  
Eastern Australia ◽  
Initial Seed ◽  
In Fire ◽  
Study Species

Seed burial in nylon mesh bags over a 2-year period was used to examine seed longevity patterns in 12 shrub and two graminoid species in fire-prone habitats around Sydney, south-eastern Australia. Most species released a large fraction of their annual seed-crop in a dormant state and all species showed evidence for some form of persistent seedbank. However, regressions of seed persistence over time were in most cases poor predictors of seed decay (9 of 14 study species). Considerable variation in the degree and pattern of seed longevity was apparent in the study species. Three functional groupings of species are suggested. (1) Seed half-lives in the soil predicted to be greater than 2 years and evidence of imposed secondary dormancy (continuous, Kunzea spp. or seasonal, Grevillea caleyi). Only Kunzea capitata and G. caleyi showed significant seed decay in this group. (2) Seed half-lives in the soil predicted to be greater than 2 years and no evidence of secondary dormancy (nine species). Six species had high seed dormancy at release (only two of which showed significant seed decay). Three species had initial seed dormancy of 40–57%—two (Asterolasia elegans and Zieria involucrata) with significant decay only for the non-dormant seed fraction, and one (Comesperma ericinum) with significant decay of both the dormant and non-dormant seed fractions. (3) Two species (Darwinia biflora and Persoonia pinifolia) showed evidence of very short mean half-lives of seeds in the soil (0.4–1.0 years). The threatened species, D. biflora, had a rapid initial seed decay over 6 months followed by little decay for 18 months, and the half-life of seeds is likely to be a poor predictor of seed longevity. For P. pinifolia, maintenance of a soil seedbank is predicted to be dependent on continual inputs of seeds locally or dispersal of seeds from other sites.

scholarly journals Reproductive trajectories over decadal time-spans after fire for eight obligate-seeder shrub species in south-eastern Australia

2014 ◽  
Vol 62 (5) ◽  
pp. 369 ◽  
Author(s):  
Annette M. Muir ◽  
Peter A. Vesk ◽  
Graham Hepworth
Keyword(s):  
Seed Storage ◽  
Fire Frequency ◽  
Reproductive Maturity ◽  
South Eastern ◽  
Reproductive Response ◽  
Eastern Australia ◽  
Maturity Period ◽  
Fire Planning ◽  
In Fire ◽  
South Eastern Australia

Intervals between fires are critical for the persistence of obligate-seeding shrubs, and are often used in planning fires for fuel reduction and biodiversity conservation in fire-prone ecosystems worldwide. Yet information about the trajectories of reproductive performance for such species is limited and information is often qualitative. To test existing assumptions about reproductive maturity periods for eight obligate-seeding shrubs (with both canopy and soil seedbanks) in foothill forests of south-eastern Australia, we used a chronosequence approach, with sites from 2 years to >40 years post-fire. Quantitative measurements of flowering and fruiting were used to fit models of reproductive response in relation to time-since-fire for each species. Inferred reproductive maturity for each species, based on modelled times to reach 80% of maximum flower production, varied from 5 to 18 years post-fire. For a subset of three species, models predicted 80% maximum seed production occurring 1–7 years later than flowering. Our results confirmed or extended assumptions about post-fire reproductive maturity for these species, and provided a basis for improved incorporation of plant life-history in ecological fire planning. We infer that increased fire frequency makes one of our study taxa, Banksia spinulosa var. cunninghamii (Sieber ex Rchb.) A.S.George, vulnerable to decline because of its long reproductive maturity period and serotinous seed storage.

scholarly journals Applying seed germination studies in fire management for biodiversity conservation in south-eastern Australia

Web Ecology ◽  
2008 ◽  
Vol 8 (1) ◽  
pp. 47-54 ◽  
Author(s):  
T. D. Auld ◽  
M. K. J. Ooi
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Fire Regimes ◽  
Functional Trait ◽  
Strong Response ◽  
South Eastern ◽  
Germination Response ◽  
Eastern Australia ◽  
The Impact ◽  
South Eastern Australia

Abstract. We examine the patterns of germination response to fire in the fire-prone flora of the Sydney basin, south-eastern Australia, using examples from several decades of research. The flora shows a strong response to fire-related germination cues. Most species show an interaction between heat and smoke, a number respond only to heat, whilst a few are likely to respond only to smoke. Many recruit in the first 12 months after fire and show no obvious seasonal patterns of recruitment, whilst several species have a strong seasonal germination requirement, even in this essentially aseasonal rainfall region. Key challenges remaining include designing future seed germination studies within the context of informing the germination response surface to smoke and heat interactions, and incorporation of the impact of varying soil moisture on seed germination post-fire, including its affect on resetting of seed dormancy. An understanding of the resilience of species to frequent fire also requires further work, to identify species and functional types most at risk. This work must ideally be integrated within the framework of the management of fire regimes that will change under a changing climate. We suggest that the functional classification of plant types in relation to fire could be enhanced by a consideration of both the type of germination response to fire (type of cues required) and the timing of the response (seasonally driven in response to seed dormancy characteristics, or independent of season). We provide a simplified version of such an addition to functional trait classification in relation to fire.

Variability and drivers of extreme fire weather in fire-prone areas of south-eastern Australia

2017 ◽  
Vol 26 (3) ◽  
pp. 177 ◽  
Author(s):  
Sarah Harris ◽  
Graham Mills ◽  
Timothy Brown
Keyword(s):  
Fire Risk ◽  
Weather Conditions ◽  
Time Of Day ◽  
Drought Indices ◽  
Fire Weather ◽  
South Eastern ◽  
Eastern Australia ◽  
In Fire ◽  
Extreme Fire ◽  
South Eastern Australia

Most of the life and property losses due to bushfires in south-eastern Australia occur under extreme fire weather conditions – strong winds, high temperatures, low relative humidity (RH) and extended drought. However, what constitutes extreme, and the values of the weather ingredients and their variability, differs regionally. Using a gridded dataset to identify the highest 10 fire weather days from 1972 to 2012, as defined by McArthur’s Forest Fire Danger Index (FFDI), for 24 sites across Victoria and nearby, we analyse the extent and variability of these highest 10 FFDI days, and of the contributing temperature, RH, wind speed, wind direction and drought indices. We document the occurrence of these events by time of day, month of occurrence and inter-annual variability. We find there is considerable variability among regions in the highest FFDI days and also the contributing weather and drought parameters, with some regional groupings apparent. Many major fire events occurred on these highest 10 fire weather days; however there are also days in which extreme fire weather occurred yet no known major fires are recorded. The results from this study will be an additional valuable resource to fire agencies in fire risk planning by basing fire management decisions on site-specific extreme fire weather conditions.

Unusual fire seasons in a changing climate - A Bayesian approach.

2020 ◽  
Author(s):  
Douglas Ian Kelley ◽  
Chantelle Burton ◽  
Rhys Whitley ◽  
Chris Huntingford ◽  
Ioannis Bistinas ◽  
...  
Keyword(s):  
Real Time ◽  
Fire Season ◽  
Model Parameters ◽  
Posterior Probability Distribution ◽  
South Eastern ◽  
Eastern Australia ◽  
Fire Activity ◽  
In Fire ◽  
Extreme Fire

<p>A series of fire events have captured the attention of the public and press in the last couple of years. South America, for example, saw the largest increase in fire count in nearly 10 years, mainly in areas historically associated with deforestation in Amazonia. Meanwhile, South Eastern Australia has seen a number of devastating bush fires in recent months, resulting in (at time of writing) 27 deaths and the destruction of over 2000 properties. These two fire events, in particular, have sparked debates about whether the levels of burning were unprecedented, and if so, whether they were driven by changes in human ignitions or land management, or if the fire season was drier than normal and whether climate change played a role. However, confidently determining the main drivers of fire events such as these often remains challenging. There is an ever-increasing availability of near-real-time meteorological and fire activity data that could be used to determine drivers, but the complex interplay of different fire controls makes teasing apart drivers of fire difficult from observations alone. Many coarse-scale fire-enabled terrestrial biosphere models account for some interplay of controls. However, most fail to reliably reproduce trends in fire, and often rely on inputs that are not available for some time after these fire seasons have passed.</p><p>Here, we have developed a Bayesian framework which addresses this by inferring fire drivers directly from observations and tracking uncertainty in a simple fire model. The model uses coarse resolution, monthly data that is available at near-real-time and emulates most fire-enabled land surface schemes by summarizing drivers as controls describing fuel continuity; moisture; lightning and human ignitions; and human suppression. The framework can be trained on different fire-related variables and finds a posterior probability distribution of both the model parameters and the expected fire activity from the model as a whole. This allows us to determine the probability of a particular fire season event within the context of the historical meteorological record, as well as the main drivers of unusual fire events.</p><p>This framework is first applied globally, identifying tropical forests and woodland ecosystems as key hotspots of long term fire regime shifts. In South Eastern Australian woodland, changes in fuel continuity and moisture point to a weak, long term decline in fire activity, but with increased variability, indicating a higher probability of extreme fire years. The arc of deforestation in the Amazon shows long-term increased susceptibility to fire due to drying conditions from changes in land cover. However, when focusing the framework specifically on Amazonia, we show lower meteorologically driven fire counts than we see in the observations for 2019, and that it is extremely likely (>95% probability) that the weather conditions have not triggered the very high levels of fire seen in the Amazon this last year. This demonstrates the potential of the framework for use in rapid attribution of drivers in future extreme fire seasons.</p>

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