Dry Eucalypt Forest Research Articles

Interactions of non-intersecting oblique lines of fire burning in surface fuels in a combustion wind tunnel with and without wind

Background High-intensity wildfires are often characterised by the interaction of multiple coalescing fires. Previously, results of investigation of obliquely intersecting lines of fire in a ‘V’ configuration in dry eucalypt forest litter were reported. Aim This article reports on investigation of the behaviour of separated non-intersecting lines of fire in the absence and presence of wind. Methods Experiments in the CSIRO Pyrotron combustion wind tunnel investigated interactions of lines of fire of 800 and 1500 mm lengths located at incident angles of 30° and 45° and separated at the closest point by 150 mm. Key results The behaviour of separated fires in wind was fundamentally different to that of fires burning in no wind and previous non-separated fires, sustaining separation for some time and distance before merging. Conclusions Although all fires showed evidence of interactions, the strength of interaction was greater in larger fires with more energetic flames, suggesting a key influence of the magnitude and rate of release and transfer of heat to unburnt fuels. Implications Future research should focus on quantifying contributions of aspects such as fuel combustibility and bulk density that contribute to and determine the convecto–radiative interactions of fires so such behaviour can be predicted a priori.

Fuel in Tasmanian Dry Eucalypt Forests: Prediction of Fuel Load and Fuel Hazard Rating from Fuel Age

This paper presents equations for fuel load and fuel hazard rating (FHR) models based on the time since last fire for dry eucalypt forests in eastern Tasmania. The fuel load equations predict the load of the surface/near-surface and elevated fine fuel. The FHR equations predict the surface, near-surface, combined surface and near-surface, bark, and overall FHR. The utility of the “Overall fuel hazard assessment guide” from Victoria, Australia, is assessed for Tasmanian dry eucalypt forests: we conclude that, when fuel strata components are weighted according to their influence on fire behaviour, the Victorian guide provides a rapid, robust, and effective methodology for estimating FHR. The equations in this paper will be used for operational planning and on-the-ground performing of hazard reduction burning, prediction of fire behaviour for fire risk assessments and bushfire control, and providing inputs into the new Australian Fire Danger Rating System.

Simulations of the Waroona fire using the coupled atmosphere–fire model ACCESS-Fire

The Waroona fire burned 69 000 ha south of Perth in January 2016. There were two fatalities and 170 homes were lost. Two evening ember storms were reported and pyrocumulonimbus (pyroCb) cloud developed on consecutive days. The extreme fire behaviour did not reconcile with the near- surface conditions customarily used to assess fire danger. A case study of the fire (Peace et al. 2017) presented the hypothesis that the evening ember storms resulted from interactions between the above-surface wind fields, local topography and the fire plume. The coupled fire–atmosphere model ACCESS-Fire has been run in order to explore this hypothesis and other aspects of the fire activity, including the pyroCb development. ACCESS-Fire incorporates the numerical weather prediction model ACCESS (Australian Community Climate and Earth System Simulator, described by Puri et al. 2013) and a fire spread component. In these simulations, the Dry Eucalypt Forest Fire (Vesta) fire spread model is used. In this study we first show that the reconstruction of surface fire spread and simulated fire spread are a good match for the first day; second, we show that the model produces deep moist convection as an indicator of pyrocumulonimbus cloud and, third, we show the fire–atmosphere interactions surrounding the ember showers provided an environment conducive to the observed mass spotting. The simulation results demonstrate that ACCESS-Fire is a tool that may be used to further explore the complex processes and potential impacts surrounding pyroCb development and short-distance ember transport.

Fire Regime Has a Greater Impact Than Selective Timber Harvesting on Vegetation in a Sub-Tropical Australian Eucalypt Forest

We compared selectively harvested and unharvested areas located among treatments of annual burning since 1952, triennial burning since 1973 and an area that had received no prescribed burning, but with a single wildfire in 2006 (one fire in 72 years), in a dry sclerophyll eucalypt forest, south-eastern Queensland, Australia. Historic fire regime, rather than low-intensity, selective timber harvesting (17% to 37% live tree basal area removed) had a greater impact on a range of vegetation and soil attributes. Plant taxa composition was influenced more by historic fire regime than recent harvesting; of the 25.5% of the variation in taxa composition explained, fire treatments alone accounted for 96.4% of the explained variation and harvesting alone accounted for just 4.8%. Selective harvesting of timber had a predictable influence associated with removal of tree cover and physical impacts associated with extraction of logs. In harvested areas there were increases (p < 0.05) in bare-ground cover and in coarse woody debris volumes and decreases in understorey vegetation height, particularly where woody understorey was present. However, overall, the combined effects of timber harvesting and fire regime were relatively minor. These sub-tropical dry eucalypt forests appear to be resilient to the impacts of combined, but low-intensity disturbances.

Patterns of flammability after a sequence of mixed‐severity wildfire in dry eucalypt forests of southern Australia

AbstractFire severity is the impact of a fire on the landscape, particularly the physical impact on vegetation. Previous studies have established that the severity of a fire can be influenced by the severity of previous fires. Many of these studies were conducted in mixed‐conifer forests, while little is known of this process in temperate eucalypt forests. Barker and Price in their 2018 publication (“Positive severity feedback between consecutive fires in dry eucalypt forests of southern Australia,” Ecosphere 9:e02110) found that high severity fire promotes high severity fire in eucalypt forests, but how is the severity of a fire in these systems affected by the severity of two sequential previous fires? This was investigated using remotely sensed and mapped fire severity data. We found that high severity fire is more likely after at least one previous high severity fire, regardless of its position in the sequence. A sequence of low or moderate severity fire followed by low severity fire resulted in the lowest proportion of high severity in the response fire. Our results suggest that low severity fire maintains the structure of forest fuels, so flammability remains relatively constant. A single high severity fire drives change, altering the structure and flammability of the vegetation and promoting more severe fire. However, the effects were small, so a cycle of high severity fire may be easily broken due to the influence of other variables, such as weather. Repeated high severity fire may also result in a decline in the ability of plants to recover from fire, leading to a compositional and structural change and potentially reducing the flammability of a forest.

Mechanical Mastication Reduces Fuel Structure and Modelled Fire Behaviour in Australian Shrub Encroached Ecosystems

Shrub encroachment of grassland and woodland ecosystems can alter wildfire behaviour and threaten ecological values. Australian fire managers are using mechanical mastication to reduce the fire risk in encroached ecosystems but are yet to evaluate its effectiveness or ecological impact. We asked: (1) How does fuel load and structure change following mastication?; (2) Is mastication likely to affect wildfire rates of spread and flame heights?; and (3) What is the impact of mastication on flora species richness and diversity? At thirteen paired sites (masticated versus control; n = 26), located in Victoria, Australia, we measured fuel properties (structure, load and hazard) and floristic diversity (richness and Shannon’s H) in 400 mP2 plots. To quantify the effects of mastication, data were analysed using parametric and non-parametric paired sample techniques. Masticated sites were grouped into two categories, 0–2 and 3–4 years post treatment. Fire behaviour was predicted using the Dry Eucalypt Forest Fire Model. Mastication with follow-up herbicide reduced the density of taller shrubs, greater than 50 cm in height, for at least 4 years. The most recently masticated sites (0–2 years) had an almost 3-fold increase in dead fine fuel loads and an 11-fold increase in dead coarse fuel loads on the forest floor compared with the controls. Higher dead coarse fuel loads were still evident after 3–4 years. Changes to fuel properties produced a reduction in predicted flame heights from 22 m to 5–6 m under severe fire weather conditions, but no change in the predicted fire rate of spread. Reductions in flame height would be beneficial for wildfire suppression and could reduce the damage to property from wildfires. Mastication did not have a meaningful effect on native species diversity, but promoted the abundance of some exotic species.

Darker, cooler, wetter: forest understories influence surface fuel moisture

The moisture content of dead leaves, twigs and bark on the forest floor is a key determinant of fire behaviour. The microclimate inside forests, which drive the moisture content of these dead fuel components, is typically measured at screen height (150 cm). However, in some forest types, the surface fuel at ground level may be subject to additional sheltering from low shrubs, ferns and grasses, which could alter the microclimate near the surface (hereafter near-surface). In such cases, screen height measurements may not adequately represent the near-surface conditions that determine dead fuel moisture contents.We sought to quantify the effect of understorey vegetation on near-surface microclimate. We measured in-forest temperature, relative humidity and solar radiation in eucalypt forests over two fire seasons at both screen height and the near-surface using weather stations at 25 sites. The sites encompassed wet eucalypt forest (n=18) with a dense, mesic understorey and dry eucalypt forest (n=7) with a sparser, scleromorphic understorey.Wet forests with dense understorey vegetation had near-surface air temperatures that averaged 1.3°C lower, relative humidities that averaged 13.1% higher and total solar radiation that was 0.84 MJ less per day compared with those measured at screen height. These microclimate differences led to predicted fuel moistures which averaged 4.7% higher at the near-surface compared with screen height – this was statistically significant. In contrast, dry forests with less understorey vegetation, had near-surface air temperatures that averaged 4.2°C higher, and relative humidities that averaged 3.1% lower compared to screen height. These differences were not large enough to translate into statistically significant differences in predicted fine fuel moisture between heights.Overall, these findings show that understorey vegetation plays an important role in moderating near-surface microclimate in some forest types and this needs to be taken into consideration when predicting fuel moisture.

Conservation status of common wombats in Tasmania II: population distribution and trends, and the incidence and significance of roadkill

Understanding species’ distribution, population trends, and the significance of threatening processes are central to the effective conservation and management of wildlife. The island state of Tasmania, Australia, is home to two of the three extant subspecies of common wombat Vombatus ursinus ursinus and V. u. tasmaniensis, both endemic to the state. We provide a comprehensive conservation assessment of both subspecies in Tasmania, providing information on distribution and habitat, population trends and incidence of roadkill. Wombats are widespread in Tasmania, occurring in most vegetation communities, but particularly in agricultural areas, dry eucalypt forests and woodlands, and grasslands. Wombat roadkills are widespread along most major roads, with the interaction of traffic speed and wombat density likely to be one of the main causes of wombat roadkill along roads with low traffic volume. Despite this, and other factors that impact wombats including sarcoptic mange and targeted culling, population indices from standardised spotlight surveys have increased by 2.6 times over the past 36 years for V. u. tasmaniensis on mainland Tasmania and by 4.2 times over the past 27 years for V. u. ursinus on Flinders Island. Based on IUCN criteria for distribution extent and population size and trends, neither subspecies qualifies for up-listing to Threatened. Nevertheless, because of risks to wombats (e.g. disease and roadkill) ongoing monitoring and research into effective mitigation is warranted.

Initial growth of fires in eucalypt litter, from ignition to steady-state rate of spread: laboratory studies

As part of an investigation of wildfire growth and acceleration, the initial growth of incipient fires burning in uniform dry eucalypt forest (Eucalyptus rossii, E. macrorhyncha) litter fuel of 1.2 kg m−2 was studied in a combustion wind tunnel with a fuel bed width of 1.5 m. Fifty-eight fires of three ignition patterns (point, 400-mm line and 800-mm line) were carried out at two air speeds (1.25 and 2.0 m s−1) and two dead fuel moisture content (FMC) groups for each air speed (≤7.5% and >7.5% oven-dry weight for the low air speed and ≤5% and >5% for the high air speed). The fraction of steady-state rate of spread reached as a function of time was determined and fitted to two theoretical fire growth models from the literature. The best model suggests the times for a point ignition fire to reach steady-state spread rate were ~38 and 50 min under the higher FMC for 2.0 m s−1 and 1.25 m s−1 air speeds, respectively, and ~25 min under the lower FMC for 2.0 m s−1. Future work will extend these results to field-scale fire behaviour, which will help improve operational response to wildfire outbreaks and planning of ignition patterns for prescribed burning.

Very frequent burning encourages tree growth in sub-tropical Australian eucalypt forest

Frequent fire often has a negative impact of tree recruitment and growth. Tree growth rates, density and recruitment were compared among treatments of annual burning since 1952, triennial burning since 1973 and no burning (1946 to 1996) or single wildfire (1996 to 2018), in a dry sclerophyll eucalypt forest, south-eastern Queensland, Australia. Tree diameter (at breast height, DBH) growth rates were greater in the annually burnt treatment than in the triennially burn and single wildfire treatments over the period from 1974 to 2018, and these differences were also apparent pre-wildfire (period from 1974 to 1996). In the period from 1996 to 2018, the annually burnt treatment had greater DBH growth relative to the single wildfire treatment, but the triennial treatment had intermediate growth rates. Competitive interactions between trees (assessed using plot basal area) also had a negative impact on individual tree growth rates. The impacts of different fire regimes at this site on tree crown health were not apparent (P > 0.05) and there was only limited evidence that differences in growth rates were due to differences in soil nutrients (marginally higher topsoil phosphorus in the frequently burnt treatments, P = 0.075). Greater tree growth rates in the annually burnt treatment may be related to the lower density of understorey woody plants in this treatment and potentially reduced competition for soil moisture. The density of trees (DBH ≥ 10 cm) in 2018 was surprisingly higher in the triennially burnt treatment (381 stems/ha) relative to both the annually burnt (192 stems/ha) and single wildfire (234 stems/ha) treatments. This was largely due a higher level of recruitment over time and a higher density of stems 10–20 cm DBH in triennially burnt plots. Concerns regarding the impacts of frequent prescribed fire on tree recruitment and growth may be unwarranted in these remarkably resilient dry eucalypt forests.

Two methods for calculating wildland fire rate of forward spread

Accurate estimation of a wildland fire’s progression is critical for the development of robust fire spread prediction models and their validation. Two methods commonly used to determine spread rate are the cumulative spread rate, calculated as the total distance travelled by a fire divided by the total time of travel, and the interval spread rate, calculated using the minimum time and maximum distance between observations. This paper analyses the differences between these two methods using experimental fires conducted in dry eucalypt forest leaf litter in either a combustion wind tunnel or large (4ha) field sites. Fires were ignited from a point, 400-mm and 800-mm line ignitions in the wind tunnel, and point and 120-m line ignitions in the field experiments. A total of 312 and 397 observations of distance travelled and time taken were made during the laboratory and field experiments respectively, along with associated environmental variables. Mean spread rates and standard deviations were significantly greater for the interval method than those of the cumulative method for all the laboratory data and the field point ignition fires, and the difference between them varied with distance and time since ignition. These findings have important implications for fire spread and acceleration model development.

The 10% wind speed rule of thumb for estimating a wildfire’s forward rate of spread in forests and shrublands

The collective analysis of a relatively large number of wildfire observations documented in conifer forests, dry eucalypt forests and temperate shrublands revealed that the forward rate of fire spread is roughly 10% of the average 10-m open wind speed, provided both are expressed in the same units (e.g. km h −1 ). Knowledge of a wildfire’s forward spread rate is a prerequisite for defining adequate fire suppression strategies and to ensure timely public warnings. We wanted to investigate the possibility that a simple relationship exists that could be used as a first approximation for quickly estimating a wildfire’s spread rate simply from the open wind speed alone. We analysed data from a number of high-intensity wildfire observations (n = 118) documented in temperate shrublands, Australian dry eucalypt forests and North American conifer forests to examine the suitability and soundness of a relationship between wind speed and rate of fire spread. We also contrasted the performance of the best function against established fire spread rate models for the three fuel types. The resulting rule of thumb is that the forward rate of spread of wildfires burning in forests and shrublands in relatively dry conditions is approximately equal to 10% of the average 10-m open wind speed, where both values are expressed in the same units. The rule of thumb gives the most accurate results for dry fuel and high wind speed conditions with reduced bias and mean relative errors lower than 50%. Under these conditions, the error statistics are comparable to those obtained by the established fire spread rate models. The rule is not applicable to grasslands.

Investigation of the effects of interactions of intersecting oblique fire lines with and without wind in a combustion wind tunnel

Quantification of the interaction of intersecting and non-intersecting fire perimeters over a range of shapes, sizes and orientations is essential to understanding the behaviour of high-intensity wildfires that have become discontiguous as a result of spot fires or effects of broken topography or fuels. One key configuration is that of the V-shaped fire where two individual lines of fire intersect at oblique angles. Previous work under calm conditions in pine needle litter and straw found the speed of propagation of the vertex of the intersection to increase non-linearly as the angle of intersection decreased. The present paper investigates this relation in dry eucalypt forest litter in both the absence and presence of wind (~1.0ms−1) and found that the increase in vertex speed under calm conditions was no greater than would be expected due to the geometry of the configuration. Conversely, in the presence of wind, the increase in the vertex propagation speed was substantially greater than explained by the geometry alone. Although these results suggest that fire line interactions can influence the behaviour and spread of coalescing fire fronts, further research is required to both identify the precise mechanisms driving this behaviour and quantify the resultant effects.

Mammal functional diversity increases with vegetation structural complexity in two forest types

Enhanced understanding of relationships between functional diversity (FD) and environmental gradients is crucial given accelerating rates of land-cover change and disturbance worldwide. Functional diversity measures the abundance, range and distribution of traits in a community, and links species diversity with ecosystem function. Several studies have related bird or invertebrate FD to environmental gradients, but information on the responses of mammal FD to vegetation structural diversity at scales of management relevance is scarce. We addressed this knowledge gap by examining responses of ground-dwelling mammal FD to vegetation structural complexity in wet (high-productivity) and dry (low-productivity) eucalypt forest in the Otway Ranges, southeast Australia. In dry forest, we expected a positive relationship between FD and vegetation structural complexity because more resources should enable species with a greater diversity of traits to co-exist. We expected negative correlations in wet forest, where competitive dominance may drive a decrease in FD as structural complexity increases. Ground-dwelling mammals were surveyed using camera traps, and we used five traits to construct four FD indices (richness, evenness, divergence, and dispersion). Six vegetation structure variables were used to calculate two indices of vegetation structure, and we used linear mixed models to relate functional diversity and species richness to vegetation structural complexity (the total abundance of structural attributes) and heterogeneity (the level of contrast or patchiness in structure), in wet and dry forest. Camera traps detected ten native ground-dwelling mammal species. All FD indices were positively correlated with vegetation structural complexity, but only functional dispersion responded to structural heterogeneity. Contrary to expectations, relationships between FD and structural complexity were consistent in both forest types, and we suggest that low levels of functional niche occupancy prevented competitive dominance in wet forest. Species richness did not respond to any predictor variables, and is unlikely to be a useful surrogate of ground-dwelling mammal FD. Our results indicate that forest managers may sustain ecosystem functions performed by ground-dwelling mammals by conserving structurally complex vegetation.

The influence of seed supply and seedbed on seedling recruitment in shelterwood-treated jarrah (Eucalyptus marginata) forest

Successful and adequate recruitment of seedlings is an essential ecological process in forest ecosystem dynamics and is a key principle underpinning sustainable timber harvesting. This is particularly so with the shelterwood silvicultural system used in the jarrah (Eucalyptus marginata) forest of south-west Australia where partial cuts of overstorey are made followed by prescribed burning to stimulate seed fall and seedling establishment. There have been concerns over the lack of seedling recruitment in some shelterwood-treated areas of the jarrah forest, and hence this study was implemented to explore the roles of seed supply and seedbed conditions in limiting recruitment of jarrah seedlings. Low seedling densities were recorded across all six burnt study sites and were strongly correlated (at both broad and fine scales) with both canopy seed store and seed fall. Ample levels of post-burn seed fall only resulted in low seedling numbers suggesting that adequate seed supply did not coincide with seedbed conditions suitable for mass seedling regeneration. Conditions favourable for seedling recruitment were highly variable within sites, since both seed supply and seedbed conditions were spatially heterogeneous. Fine-scale areas burnt to mineral soil showed an additive influence to the overwhelmingly dominant factor of seed supply on seedling recruitment. However, the capacity of low intensity burns to produce these seedbed conditions at a broad scale appears to be limited. Results suggest that successful stocking of shelterwood-treated jarrah forest is not always feasible following a single silvicultural event, such as post-harvest burning under mild conditions. The chances of ample seed supply coinciding with broad-scale seedbed conditions favourable for mass germination, emergence and establishment appear to be low. Successful stocking of shelterwood-treated jarrah forest is more likely to be a longer term outcome achieved through episodic recruitment, especially when favourable environmental conditions coincide with optimal seedbed conditions. Such episodic recruitment strategies may be common in resource-limited systems such as jarrah forest and other dry eucalypt forest systems, where conditions controlling the regeneration niche are often variable and unpredictable.

Assessing improvements in models used to operationally predict wildland fire rate of spread

The prediction of fire propagation across landscapes is necessary for safe and effective fire management. We analyzed the predictive accuracy of models currently used operationally in Australia for predicting fire spread rates in five different fuel types (grasslands, temperate and semi-arid shrublands, dry eucalypt and conifer forests) compared to their previous counterparts. We calculated error statistics and contrasted model predictions against observed spread rates of field observations of wildfires and prescribed fires. We then compared the changes in error metrics of older models to newer ones. Evaluation results show newer models to have improved prediction accuracy. Mean absolute errors were reduced by 56%, 68% and 70% in dry eucalypt forests, grasslands and crown fires in conifer forests, respectively. The most significant improvement was the reversion of under-prediction bias achieved with newer models. This study has highlighted the value of continuous improvement when it comes to developing operational wildland fire spread models.

Positive severity feedback between consecutive fires in dry eucalypt forests of southern Australia

AbstractFire regimes have long‐term effects on ecosystems which can be subtle, requiring study at a large spatial scale and temporal scale to fully appreciate. The way in which multiple fires interact to create a fire regime is poorly understood, and the relationship between the severities of consecutive fires has not been studied in Australia. By overlaying remotely sensed severity maps, our study investigated how the severity of a fire is influenced by previous fire severity. This was done by sampling points at 500‐m spacing across 53 fires in dry eucalypt forests of southeast Australia, over a range of time since fire spanning every major fire season for 30 yr. Generalized additive models were used to determine the influence of previous severity on the probability of crown fire and understory fire, controlling for differences in time since fire, topography, and weather. We found that a crown fire is more than twice as likely after a previous crown fire than previous understory fire, and understory fire is more likely after previous understory fire. Our findings are in line with the results of studies from North America and suggest that severe fire promotes further fire. This may be evidence of a runaway positive feedback, which can drive ecological change, and lead to a mosaic of divergent vegetation, but research into more than two consecutive fires is needed to explore this. Our results also suggest that a low‐severity prescribed fire may be a useful management option for breaking a cycle of crown fires.

The relationship between environmental variables, detection probability and site occupancy by Tasmanian nocturnal birds, including the Tasmanian masked owl (Tyto novaehollandiae castanops)

Knowledge of the habitat requirements of nocturnal birds is vital for the development of effective conservation strategies. This study is the first intensive systematic survey of the occurrence of the threatened Tasmanian masked owl (Tyto novaehollandiae castanops), the Tasmanian boobook (Ninox leucopsis) and the Australian owlet-nightjar (Aegotheles cristatus) in Tasmania using call playback, spotlighting and listening techniques. Occupancy models were created that explain the spatial distribution of the three species. Temperature and wind influenced the detectability of all species. Detectability of the Tasmanian boobook was also associated with nightlight. The Tasmanian masked owl was most often found in low-elevation mature dry eucalypt forest. This may be related to a combination of availability of nesting sites, food availability and accessibility, and physiological factors. The Australian owlet-nightjar also showed a broad preference for dry eucalypt forest and avoided open country. In contrast, the Tasmanian boobook was most often found in wet eucalypt forest with higher temperatures and fewer roads. We conclude that mature dry and wet forest types at low elevations need to be carefully managed to maintain populations of Tasmania’s nocturnal birds, particularly the threatened Tasmanian masked owl. Consideration should be given to retention of a network of contiguous areas of undisturbed mature forest across forested landscapes.

Impact of a moderate/high-severity prescribed eucalypt forest fire on soil phosphorous stocks and partitioning

This study examines the direct impact of a moderate/high-severity prescribed fire on phosphorous (P) stocks and partitioning in oligotrophic soils of a dry eucalypt forest within Sydney's water supply catchments, Australia. We also quantify and characterize the P present in the ash produced in this fire, and explore its relationships with the maximum temperatures recorded in the litter layer during the burn.In these oligotrophic soils, P concentrations were already relatively low before the fire (<130mgkg−1, mainly in organic forms). The fire consumed the entire litter layer and the thin Oa soil horizon, creating 6.3±3.1tha−1 of ash, and resulted into direct net P losses of ~7kgha−1. The P lost was mostly organic and there was a moderate net gain of inorganic and non-reactive P forms. Importantly, only a small proportion of the post-fire P was bioavailable (equivalent to ~3% of the total P lost during fire). Higher total P concentrations in ash corresponded with higher maximum temperatures (>650°C) recorded in the burning litter layer, but effects of fire temperature on ash P partitioning were not significant.Fire not only transformed P chemically, but also physically. Our results show that, immediately after fire, up to 2kgha−1 of P was present in the ash layer and, therefore, highly erodible and susceptible to be transported off-site by wind- and water erosion. Even if most of this P was, initially, of low bioavailability, its transfer to depositional environments with different geochemical conditions (e.g. anoxic sediments in water reservoirs) can alter its geochemical forms and availability. Further investigation of potential P transformations off-site is therefore essential, particularly given that SE-Australian water supply catchments are subject to recurrent perturbation by prescribed fire and wildfires. The latter have already resulted in major algal blooms in water supply reservoirs.

Fire Regimes and Environmental Gradients Shape Bird, Mammal and Plant Distributions in Temperate Forests

All photographs in this section are provided by authors of papers in our scientific journals and are used by permission.All copyrights reserved. Fire is a global driver of ecosystems. In a recent study published in Ecosphere, we tested six hypotheses relating to fire regimes and environmental gradients using data on birds (493 sites), mammals (175 sites), and vascular plants (615 sites) systematically collected in dry eucalypt forests in southern Australia. We showed that interacting fire regimes and environmental gradients influence the distribution of birds, small mammals, and plants, and that multiple components of the fire regime drive biotic distributions. These results underscore the important insights that can be gained by modeling how fire regimes, not just fire events, influence biota in forests. These photographs illustrate the article “Fire regimes and environmental gradients shape vertebrate and plant distributions in temperate eucalypt forests” by L. T. Kelly et al., published in Ecosphere 8(4):e01781. https://doi.org/10.1002/ecs2.1781