Post-fire Seedling Recruitment Research Articles

Plant life-history data as evidence of an historical mixed-severity fire regime in Banksia Woodlands

Context The concept of the fire regime is central to understanding and managing fire-prone ecosystems globally, and information on past regimes can provide useful insights into species disturbance adaptations. Although observations from satellite imagery or palaeoecological proxy data can provide direct evidence of past, pre-colonial fire regimes, they may be limited in temporal or spatial resolution and are not available for all ecosystems. However, fire-related plant-trait and demographic data offer an alternative approach to understand species–fire regime associations at the ecosystem scale. Aims We aimed to quantify the life-history strategies and associated fire regimes for six co-occurring shrub and tree species from fire-prone, Mediterranean-climate Banksia Woodlands in south-western Australia. Methods We collected static demographic data on size structure, seedling recruitment, and plant mortality across sites of varying time since last fire. We combined demographic data with key fire-related species traits to define plant life-history strategies. We then compared observed life histories with a priori expectations for surface, stand-replacing, and mixed-severity fire-regime types to infer historical fire-regime associations. Key results Fire-killed shrubs and weakly serotinous trees had abundant post-fire seedling recruitment, but also developed multi-cohort populations during fire-free periods via inter-fire seedling recruitment. Resprouting shrubs had little seedling recruitment at any time, even following fire, and showed no signs of decline in the long absence of fire, likely owing to their very long lifespans. Conclusions The variation in life-history strategies for these six co-occurring species is consistent with known ecological strategies to cope with high variation in fire intervals in a mixed-severity fire regime. Whereas resprouting and strong post-fire seedling recruitment indicate a tolerance of shorter fire intervals, inter-fire recruitment and weak serotiny are interpreted as a bet-hedging strategy to cope with occasional long fire-free periods that may otherwise exceed adult and seed-bank lifespans. Implications Our findings suggested that Banksia Woodlands have evolved with highly variable fire intervals in a mixed-severity fire regime. Further investigations of species adaptations to varying fire size and patchiness can help extend our understanding of fire-regime tolerances.

The morphological and ecological variation of Arctostaphylos (Ericaceae) fruit: A link between plant ecology and animal foraging behavior.

Persistent soil seed banks are characteristic of Arctostaphylos (Ericaceae) species in the Mediterranean-climate California Floristic Province. While most species are obligate seeders, regeneration of stands of all Arctostaphylos species ultimately depends on post-fire seedling recruitment. Arctostaphylos seed banks are created, in large part, by scatter-hoarding rodents. Variation in fruit morphology, therefore, is expected to impact the Arctostaphylos-rodent interaction. Seeds produce sufficient rewards (nutritious mature embryo) to entice rodents to disperse and ultimately bury seeds in the soil. Hard seed coats increase the time required to extract the embryo, encouraging rodents to choose storage over immediate predation, and nutlets are frequently empty. We assessed the variation of fruit nutlet fusion and seed viability among 38 Arctostaphylos taxa. Factors such as latitude, elevation, life history, ploidy, and phylogenetic position were also analyzed. Generalized mixed-effects models were used to determine the factors contributing to variation in fruit nutlet fusion and seed viability. Our results indicate that fruit volume and shape are the most important variables affecting nutlet fusion and seed viability. Additionally, other potential influences only show a weak correlation and are not predicted to significantly impact nutlet fusion or seed viability. These findings provide insights into evolved strategies used by plants to increase reproductive success via scatter-hoarding rodents. Our study benefits the conservation and restoration of Arctostaphylos stands by emphasizing the importance of animal-mediated dispersal and providing estimates of seed viability for different species. With the anticipated effects of climate change, such as departures from historic fire regimes, the preservation of the relationship between plants and animal foragers is crucial for the continued survival of Arctostaphylos and California's evergreen chaparral.

What Drives Reproductive Maturity and Efficiency in Serotinous Boreal Conifers?

In boreal North America, much of the landscape is covered by fire-adapted forests dominated by serotinous conifers. For these forests, reductions in fire return interval could limit reproductive success, owing to insufficient time for stands to reach reproductive maturity i.e., to initiate cone production. Improved understanding of the drivers of reproductive maturity can provide important information about the capacity of these forests to self-replace following fire. Here, we assessed the drivers of reproductive maturity in two dominant and widespread conifers, semi-serotinous black spruce and serotinous jack pine. Presence or absence of female cones were recorded in approximately 15,000 individuals within old and recently burned stands in two distinct ecozones of the Northwest Territories (NWT), Canada. Our results show that reproductive maturity was triggered by a minimum tree size threshold rather than an age threshold, with trees reaching reproductive maturity at smaller sizes where environmental conditions were more stressful. The number of reproductive trees per plot increased with stem density, basal area, and at higher latitudes (colder locations). The harsh climatic conditions present at these higher latitudes, however, limited the recruitment of jack pine at the treeline ecotone. The number of reproductive black spruce trees increased with deeper soils, whereas the number of reproductive jack pine trees increased where soils were shallower. We examined the reproductive efficiency i.e., the number of seedlings recruited per reproductive tree, linking pre-fire reproductive maturity of recently burned stands and post-fire seedling recruitment (recorded up to 4 years after the fires) and found that a reproductive jack pine can recruit on average three times more seedlings than a reproductive black spruce. We suggest that the higher reproductive efficiency of jack pine can explain the greater resilience of this species to wildfire compared with black spruce. Overall, these results help link life history characteristics, such as reproductive maturity, to variation in post-fire recruitment of dominant serotinous conifers.

Changes in the resilience of resprouting juvenile tree populations in temperate forests due to coupled severe drought and fire

Elevated tree mortality and reduced recruitment of new trees linked to drought and fires has been reported across a range of forests over the last few decades. Forests that resprout new foliage epicormically from buds beneath the bark are considered highly resilient to disturbance, but are potentially at risk of elevated mortality, demographic shifts and changes to species composition due to synergistic effects of drought and fire. Despite this, the effects of drought-fire interactions on such forests remain largely unknown. We assessed the effects of drought severity and fire frequency on juvenile mortality, post-fire seedling recruitment and replacement of juvenile trees (balance of recruitment minus mortality) following fire. We compared dry ridgetops and wet gullies (i.e. two forest types that inhabit different topographic positions in the landscape) across a temperate forest in southern Australia. Both forest types experienced higher rates of fire-induced juvenile mortality in areas that had experienced severe drought compared to moderate drought, though mortality rates were generally low across all drought and fire combinations (e.g. < 15%). This result indicated that topographic position did little to reduce juvenile mortality when exposed to severe drought plus fire. In wet forest, severe drought also reduced recruitment and replacement of dead juveniles by post-fire seedlings compared to moderate drought. In dry forest net-negative replacement increased with the severity of drought. Across both forest types, the total pool of juveniles was reduced under severe drought (by 16–79 in DSF; 5–11 in WSF). Future increases in the frequency of coupled severe drought and fire could potentially increase the susceptibility of resilient temperate forests to major changes in structure and function.

Postfire Seedling Establishment of Desert Peach (Prunus fasciculata) and Joshua Tree (Yucca brevifolia) from Simulated Seed Caches in the Mojave Desert

Desert rodents in the western USA cache enormous numbers of seeds. Seed caches represent a reliable, although highly variable, source of seedling recruitment for numerous desert plants. Prefire caching of refractory seeds (i.e., those capable of forming persistent seed banks) is an important source of postfire seedling recruitment, but it is likely that prefire caches of short-lived seeds also may contribute to postfire regeneration. The primary objective of this study was to quantify seedling recruitment from artificial caches of 2 species with short-lived seeds planted after a stand-replacing wildfire in a singleleaf pinyon (Pinus monophylla) forest. I investigated the survival of 180 artificial caches of Yucca brevifolia and Prunus fasciculata. Caches were composed of 2, 4, or 8 seeds. Also, because soils of the burned area have unusually high coarse fragment volumes (59%), I examined, in greenhouse trials, how soil coarse fragment volumes (CFVs) impacted seedling establishment of these 2 species from caches. In greenhouse trials, the number of P. fasciculata seedlings increased with increasing CFVs. In contrast, Y. brevifolia seedling numbers decreased with increasing CFVs. In field transects, 17% of cached P. fasciculata seeds produced seedlings, whereas 12% of Y. brevifolia seeds recruited seedlings in the first year postfire. The advantage of P. fasciculata in greenhouse CFV trials was not replicated in field seedling recruitment. Seedling mortality over the first 3 years postfire was not statistically different among the 3 cache sizes for either species, nor did seedling sizes differ significantly by cache size and survey date. I conclude that, although the overall recruitment from postfire caches was low (12%–17%), prefire caches of short-lived seeds probably recruit postfire seedlings, but only in specific circumstances.

Rainforest persistence and recruitment after Australia’s 2019–2020 fires in subtropical, temperate, dry and littoral rainforests

Interactions between rainforest plants and fire occur when fires encroach into rainforest and when rainforest pioneers colonise fire-prone open forests. Although numerous studies show that many rainforest plants survive fire by resprouting and postfire seedling recruitment, data is lacking for several major Australian rainforest types. In this study, we examine fire-resilience traits among 228 taxa of woody rainforest plants in four rainforest classes (subtropical, warm temperate, dry and littoral rainforest) less than 1 year after being burnt in the extensive wildfires of 2019–2020. Among taxa with ≥ 5 records of complete crown scorch (126), resprouting occurred in 63% of taxa overall and 61% of late-successional taxa. Fire-cued seedling recruitment occurred in 62% of taxa overall and 48% of late-successional taxa. Surprisingly, species richness of woody plants increased 22% postfire due to high rates of persistence and emergence of new taxa into standing plant populations as seedlings. Stem density increased ∼400% postfire due to high rates of resprouting and reproduction through suckering and seedling recruitment, although there was a significant redistribution from medium to smaller stem size classes. Larger stems (&gt;10 cm diameter at breast height) were not significantly reduced in rainforest stands. High resprouting rates in small rainforest plants (1 cm diameter at breast height, 1 m tall) suggests rapid attainment of resprouting capacity. Our findings demonstrate that most subtropical, dry, warm temperate and littoral rainforest plant taxa are resilient to rare fires, and suggest that rainforest plants that invade rarely-burnt open forests may quickly become resistant to removal by infrequent fires, with potential for increased populations through fire-enhanced seedling germination.

Experimental seed sowing reveals seedling recruitment vulnerability to unseasonal fire.

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.

Limited overall impacts of ectomycorrhizal inoculation on recruitment of boreal trees into Arctic tundra following wildfire belie species-specific responses.

We tested whether post-fire seedling establishment of common boreal tree and expanding shrub species at treeline and in Arctic tundra is facilitated by co-migration of boreal forest mycorrhizal fungi. Wildfires are anticipated to facilitate biome shifts at the forest-tundra ecotone by improving seedbed conditions for recruiting boreal species; at the same time fire alters the composition and availability of mycorrhizal fungi critical to seedling performance. To determine the role of root-associated fungi (RAF) in post-fire seedling recruitment and future biome shifts, we outplanted four dominant boreal tree and shrub species inoculated with one of three treatments at treeline and in tundra: burned boreal forest, unburned boreal forest, or a control treatment of sterilized inoculum. We compared survivorship, growth, and physiological performance of the seedlings in relation to mycorrhizal inoculum treatment and among host species, characterized the RAF communities based on ITS-rDNA sequencing of individual root tips sampled from surviving seedlings, and tested for correlations between RAF composition and the inoculation treatments, host species, and duration of the experiment. We explored correlations between RAF composition and seedling metrics. Both live and sterile autoclaved inoculation treatments had similar effects on seedling survivorship and growth for all species. RAF composition did not vary by treatment, suggesting that most colonization was due to local fungi. However, seedling traits and growth were correlated with RAF species composition, colonization, and the relative abundance of specific RAF taxa. Picea sp. performance in particular showed strong co-variation with RAF metrics. Our results suggest that mycorrhizal co-migration is not a primary limiting factor to boreal seedling recruitment because the experimental provision of inoculum did not affect seedling recruitment; yet, RAF did influence seedling performance, particularly resident RAF at treeline and in tundra, suggesting that mycorrhizal fungi are important to vegetation processes at the treeline-tundra ecotone.

Inability of fire to control vegetation dynamics in low-productivity mulga (Acacia aneura)-dominated communities of eastern Australia

Reduced fire frequency and severity associated with livestock grazing are cited as a cause of woody plant encroachment and thickening in rangelands, but such paradigms are difficult to test experimentally owing to limited opportunities to burn. Mulga (Acacia aneura) dominates 25% of the Australian continent and epitomises this quandary. We measured the effect of rare wildfires on tree and shrub mortality and subsequent regeneration in mulga-dominated communities to critically examine prevailing but unsubstantiated paradigms of vegetation structural change. Mortality of mature mulga trees was positively correlated with fire severity, which was negatively correlated with tree basal area per hectare. High-severity fires killed the majority of mulga, but only occurred in more open areas, whereas low-severity fires typical of many mulga communities did not kill substantial proportions of mature mulga. The majority of mulga saplings were killed across all sites regardless of fire severity. Seedling germination was stimulated by fire, but not dependent on it. Green turkey bush (Eremophila gilesii) was the only shrub species with &gt;50% mortality across all sites. Combined with the rarity of fire events in the historical record, our results, particularly limited fire mortality and enhanced post-fire seedling recruitment, suggest that the role of fire in shaping vegetation structure in mulga-dominated communities has been overstated. The decoupling of fire and vegetation structure is consistent with emerging regional studies in low-productivity semiarid environments.

Relationships between fire severity and recruitment in arid grassland dominated by the obligate-seeding soft spinifex (Triodia pungens)

Fire intensity is recognised as an important driver of regeneration dynamics in forest and shrubland vegetation types, but its effects on recruitment processes in arid grasslands are poorly understood. Here, we used fire severity as a surrogate measure of fire intensity, and compared post-fire seedling recruitment from arid Triodia pungens (soft spinifex) plots burnt by low-severity experimental fires against those burnt by a high-severity wildfire. To explain T. pungens recruitment patterns, we also: (1) conducted a longitudinal depth distribution study of soil seedbank densities, and (2) carried out a lethal-temperature experiment on T. pungens seeds. High-severity burning was associated with reduced T. pungens recruitment compared with low-severity fire, and this relationship was attributed to the low lethal temperature thresholds of seeds and the adverse impacts of elevated soil temperatures during high-severity fire on the shallow soil seedbank. Among other species in the community, there were varied recruitment responses to fire severity. Overall, our results indicate that a strong link exists between fire severity and recruitment in arid spinifex grassland, though the association is variable among species, and dependent on the seedbank attributes, germination biologies and lethal-temperature thresholds of seeds of individual species.

Post-Fire Seedling Recruitment and Morpho-Ecophysiological Responses to Induced Drought and Salvage Logging in Pinus halepensis Mill. Stands

Salvage logging is the commonest post-fire emergency action, but has unclear ecological effects. In the Mediterranean Basin, drought periods and fire regimes are changing and forest management should be adapted. In summer 2009, a mid-high severity fire burned 968 ha of Aleppo pine (Pinus halepensis Mill.) forest in southeast Spain, which was submitted to salvage logging six months later. In spring 2010, plots were set in untreated and logged areas to monitor the recruitment and survival of the main tree species and three companion species: Stipa tenacissima L. (resprouter), Cistus clusii Dunal and Rosmarinus officinalis L. (obligate seeders). We evaluated responses to different scenarios in relation to intensification of summer droughts and forest management to obtain differences in water stress, growth, and gas exchange to cope with summer drought. Drought was induced by using rain-exclusion shelters and recorded ecophysiological characteristics were obtained with a portable gas exchange system. The main tree species recruitment was poor, but companion species showed a high survival ratio. Lower water stress was found for obligate seeder seedlings, which was higher in logged areas with induced drought. The initial post-fire stage was similar for the studied areas. However, after two drought periods (2010 and 2011), significant differences were found in the morphological and ecophysiological responses. In the unmanaged area, the biggest size of individuals due to the most marked increases in height and coverage were observed mainly in resprouter S. tenacissima. In the area submitted to salvage logging, the growth ratios in plots with induced drought were lower, mainly for seeders. Greater productivity was related to higher transpiration, stomatal conductance, and net photosynthetic ratio, but lower water use efficiency was found in obligate seeders with no drought induction, and S. tenacissima obtained higher values in untreated areas. Our results confirm that both forest management and intensification of summer droughts influenced the resilience and productivity of the ecosystems in the short term. Adaptive forest management after fire can imply successful survival and recovery of plant communities in the mid to long term. This study provide a scientific basis to develop tools for the post-fire restoration of serotinous pine forests occurring in low-altitudinal areas of the Mediterranean Basin, prone to summer droughts and fire events.

Fire in Mediterranean Climate Ecosystems—A Comparative Overview

Four regions of the world share a similar climate and structurally similar plant communities with the Mediterranean Basin. These five areas, known collectively as mediterranean-type climate (MTC) regions, are dominated by evergreen sclerophyllous-leaved shrublands, semi-deciduous scrub, and woodlands, all of which are prone to widespread crown fires. Summer droughts produce an annual fire hazard that contributes to a highly predictable fire regime. Fire has been an important factor driving the convergence of these systems and is reflected in plant traits such as lignotubers in resprouting shrubs and delayed reproduction that restricts recruitment to a postfire pulse of seedlings. On fertile soils where postfire resprouting is very rapid, opportunities for postfire seedling recruitment are limited and thus these woody taxa have not opted for delaying reproduction. Such fire-independent recruitment is widespread in the floras of MTC regions of the Mediterranean Basin and California and postfire seeding te...

Little evidence for local adaptation to soils or microclimate in the post-fire recruitment of three Californian shrubs

Background: Seedling recruitment following fire is an infrequent yet critical demographic transition for woody plants in Mediterranean ecosystems.Aims: Here we examine whether post-fire seedling recruitment of three widespread Californian chaparral shrubs is affected by local adaptation within an edaphically and topographically complex landscape.Methods: We reciprocally transplanted 6-month-old seedlings of Adenostema fasciculatum, Ceanothus cuneatus and Eriodictyon californicum to serpentine and sandstone soils, and cool northerly and warm southerly slopes.Results: At the age of 2 years, none of the species manifested higher survival or growth on ‘home’ compared with ‘away’ soils or slopes, indicating an absence of local adaptation with respect to seedling recruitment in these environments. Seedlings of all species manifested lower survival and relative growth on serpentine soils regardless of seedling source, as well as a variety of other destination and source effects.Conclusions: The ability of these three species to recruit in new environments, such as in restoration settings or in response to shifting climates, is unlikely to be impeded by a need for seeds from sources that closely match their edaphic or topographic destination.

Postfire seedling recruitment at the southern limit of lichen woodland

Although fire is the primary mechanism driving regeneration in open black spruce ( Picea mariana (Mill.) BSP) lichen woodland, there are limited data concerning the sources of seedling mortality across the range of burn severity. We monitored planted seedlings in areas of high and low burn severity in Terra Nova National Park (Newfoundland, Canada) to determine sources and patterns of mortality of black spruce seedlings among burn treatments following a recent burn (2002). The importance of herbivory by small mammals as a source of seedling mortality was evaluated using small cages that excluded voles and non-native snowshoe hare. Overall seedling mortality was high (79%) in all areas; mortality was similar in areas of low (73%) and high (76%) burn severity, and highest in edge areas adjacent to closed-canopy forest (90%). Drought, rather than herbivory, was the most common cause of mortality during the first two seasons following germination. Seedling mortality at the southern edge of the lichen woodland was comparable to that found in other studies, but sources differed, emphasizing the spatially variable nature of mortality. Based on the level of seedling recruitment, our results suggest lichen woodland will return at this site.

Quantitative Evidence for Increasing Forest Fire Severity in the Sierra Nevada and Southern Cascade Mountains, California and Nevada, USA

Recent research has concluded that forest wildfires in the western United States are becoming larger and more frequent. A more significant question may be whether the ecosystem impacts of wildfire are also increasing. We show that a large area (approximately 120000 km2) of California and western Nevada experienced a notable increase in the extent of forest stand-replacing (“high severity”) fire between 1984 and 2006. High severity forest fire is closely linked to forest fragmentation, wildlife habitat availability, erosion rates and sedimentation, post-fire seedling recruitment, carbon sequestration, and various other ecosystem properties and processes. Mean and maximum fire size, and the area burned annually have also all risen substantially since the beginning of the 1980s, and are now at or above values from the decades preceding the 1940s, when fire suppression became national policy. These trends are occurring in concert with a regional rise in temperature and a long-term increase in annual precipitation. A close examination of the climate–fire relationship and other evidence suggests that forest fuels are no longer limiting fire occurrence and behavior across much of the study region. We conclude that current trends in forest fire severity necessitate a re-examination of the implications of all-out fire suppression and its ecological impacts.

The Biology of Corema conradii: Natural History, Reproduction, and Observations of a Post-fire Seedling Recruitment

Corema conradii (broom-crowberry, Ericaceae) is a rare dioecious shrub that reaches the southern extent of its range in New Jersey. A hot fire burned through one of the most extensive New Jersey populations of this state-endangered species during the summer of 2001, resulting in mortality of nearly all plants in the burned areas. Significant seedling recruitment occurred in the fall of 2002, followed by an even greater seedling emergence the following year. Fire is known to be an important stimulus for seed germination in this species, and fire events are an important component of the life cycle. We report data on seedling emergence as well as present ecological and biological observations of Corema conradii in the unusual coremal habitat of the New Jersey Pine Barrens, and suggest a life cycle model for this understudied species.

Post-fire Seedling Recruitment in Coastal Heathland in Relation to Regeneration Strategy and Habitat

Post-fire seedling recruitment was studied at six heathland sites near Evans Head, north-eastern NSW, in a range of habitats from dry to wet sand-heath. Species fire responses were recorded and seedling density, seedling survival and seedling shoot-growth rate were monitored for 3 years. There were marked differences in total seedling density and survivorship in different habitats, caused by several possible factors. Obligate seeders and facultative resprouters were found to have overlapping yet broadly distinctive patterns of seedling recruitment behaviour. Facultative resprouters as a group had significantly lower levels of seedling density and survival than obligate seeders. Six species exhibited ecotypic variation in mode of regeneration, five accompanied by marked changes in seedling density. Patterns of seedling recruitment behaviour in relation to fire response and habitat were consistent with the theory that resprouting is a stress-tolerant regeneration strategy and that for a given species regeneration strategy is linked with habitat quality.

Fire Studies in Mallee (Eucalyptus Spp.) Communities of Western New South Wales: Grass Fuel Dynamics and Associated Weather Patterns.

The probability of wildfires, or prescribed fires, occurring in mallee rangelands, is strongly dependent on availability of adequate grass fuel loads. Grass fuels comprise two major elements, a perennial component dominated by the hummock species Triodia scariosa (porcupine grass) and an ephemeral component dominated by the annual/biemial tussock species Stipa nitida (speargrass). Population dynamics and abundance of both fuel elements are, in turn, strongly influenced by rainfall regime, particularly during the seedling recruitment phase. This paper records data on the spatial distributions of different fuels, plant architecture and post-fire seedling recruitment and survivorship of T. scariosa, obtained during field studies on contrasting mallee sites in western New South Wales. In addition, rainfall data extending over c. 100 years were used in a water balance study at one mallee site (Pooncarie); while similar rainfall data were analysed for three mallee sites (Pooncarie, Ivanhoe and Mount Hope) using a filter technique to examine quasi- periodicities of rainfall and potential correlations with known wildfire seasons in the past. Precipitation records from the Meteorological Districts of western New South Wales, and from various towns in the area, were analysed as well. All data sets exhibited strong coherence and the resulting filter curves resembled each other closely, with peaks reflecting 'above-average rainfall' and troughs 'below-average rainfall or drought'- the latter often being associated with El NiiiolSouthern Oscillation events. The management implications of these phenomena, particularly as they relate to major drought events, are discussed in the context of vegetation manipulation based on prescribed fire.