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.

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.

Effects of fire frequency and mowing on a temperate, derived grassland soil in south-eastern Australia

2008 ◽  
Vol 17 (5) ◽  
pp. 586 ◽  
Author(s):  
Suzanne M. Prober ◽  
Ian D. Lunt ◽  
Kevin R. Thiele
Keyword(s):  
Biological Activity ◽  
Soil Surface ◽  
Fire Frequency ◽  
Biological Properties ◽  
Grassland Soil ◽  
Positive Feedbacks ◽  
South Eastern ◽  
Eastern Australia ◽  
Protective Cover ◽  
South Eastern Australia

Frequent disturbances such as fire are widely considered important drivers of plant composition and diversity in productive grassy ecosystems. Effects of fire frequency on grassland soils, however, are less well understood. We established replicated disturbance regimes in a high-quality, representative Themeda australis–Poa sieberiana-derived grassland in south-eastern Australia that had historically been burnt every 4–8 years. Effects on soil chemical, physical and biological properties were measured after 10 years of application of 2-, 4-, and 8-yearly burning, 2-yearly mowing and an undisturbed treatment. Contrary to other grassy ecosystems, there were no detectable effects of disturbance regime on total soil nitrogen and carbon, or a range of other soil chemical properties in the top 10 cm. However, a cumulative effect of burning on the grassland soil was evident from a suite of changes to soil surface properties, available nutrients and biological activity. In particular, on biennially burnt plots, reduced litter and plant protective cover were associated with increased soil surface compaction, decreased infiltration and decreased soil biological activity, which in turn were related to poor sward recovery after fire and drought. These relationships indicate potential for positive feedbacks whereby repeated removal of soil protective cover and changes to soil surface chemistry through very frequent burning ultimately lead to further reduction in soil protective cover through reduced productivity. However, this is only likely in extreme cases: data from unburnt plots indicated that soils that had historically been burnt every 4–8 years had not passed a threshold beyond which such soil changes were irreversible or damaging. Contrary to other predictions, cessation of burning for 13 years did not lead to detectable soil nutrient release through senescence of dominant grasses. Biennial mowing with slash retention was an effective alternative disturbance for maintaining sward vigour while avoiding soil surface damage.

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