Evolutionary history of fire‐stimulated resprouting,flowering, seed release and germination

Fire has shaped the evolution of many plant traits in fire‐prone environments: fire‐resistant tissues with heat‐insulated meristems, post‐fire resprouting or fire‐killed but regenerating from stored seeds, fire‐stimulated flowering, release of on‐plant‐stored seeds, and germination of soil‐stored seeds. Flowering, seed release and germination fit into three categories of response to intensifying fire: fire not required, weakly fire‐adapted or strongly fire‐adapted. Resprouting also has three categories but survival is always reduced by increasing fire intensity. We collated 286 records for 20 angiosperm and two gymnosperm families and 50 trait assignments to dated phylogenies. We placed these into three fire‐adapted trait types: those associated with the origin of their clade and the onset of fire‐proneness [primary diversification, contributing 20% of speciation events over the last 120 million years (My)], those originating much later coincident with a change in the fire regime (secondary diversification, 30%), and those conserved in the daughter lineage as already adapted to the fire regime (stabilisation, 50%). All four fire‐response types could be traced to >100 My ago (Mya) with pyrogenic flowering slightly younger because of its dependence on resprouting. There was no evidence that resprouting was always an older trait than either seed storage or non‐sprouting throughout this period, with either/both ancestral or derived in different clades and times. Fire‐adapted traits evolved slowly in the Cretaceous, 120–65 Mya, and rapidly but fitfully in the Cenozoic, 65–0 Mya, peaking over the last 20 My. The four trait‐types climaxed at different times, with the peak in resprouter speciation over the last 5 My attributable to fluctuating growing conditions and increasing savanna grasslands unsuitable for non‐sprouters. All experienced a trough in the 40–30‐Mya period following a reduction in world temperatures and oxygen levels and expected reduced fire activity. Thick bark and serotiny arose in the Mid‐Cretaceous among extant Pinaceae. Heat‐stimulated germination of hard seeds is ancestral in the 103‐My‐old Fabales. Smoke‐(karrikin)‐stimulated germination of non‐hard seeds is even older, and includes the 101‐My‐old Restionaceae–Anarthriaceae. A smoke/karrikin response is detectable in some fire‐free lineages that prove to have a fire‐prone ancestry. Among clades that are predominantly fire‐prone, absence of fire‐related traits is the advanced condition, associated either with increased fire frequency (loss of serotiny and soil storage), or migration to fire‐free habitats (loss of thick bark, pyrogenic flowering, serotiny or soil storage). Protea (Africa) and Hakea (Australia) illustrate the importance of stabilisation processes between resprouting/non‐sprouting in accounting for speciation events over the last 20 My and highlight the frequent interchange possible between these two traits. Apart from Pinus, most ancestral trait reconstruction relative to fire has been conducted on predominantly Southern Hemisphere clades and this needs to be redressed. Despite these limitations, it is clear that fire has had a profound effect on fire‐related trait evolution worldwide, and set the platform for subsequent evolution of many non‐fire‐related traits. Genetics of the triggering mechanisms remain poorly understood, except the karrikin system for smoke‐stimulated germination. We exhort biologists to include fire‐proneness and fire‐related traits in their thinking on possible factors controlling the evolution of plants.     

Shifting season of fire and its interaction with fire severity: Impacts on reproductive effort in resprouting plants

Fire regimes shape plant communities but are shifting with changing climate. More frequent fires of increasing intensity are burning across a broader range of seasons. Despite this, impacts that changes in fire season have on plant populations, or how they interact with other fire regime elements, are still relatively understudied. We asked (a) how does the season of fire affect plant vigor, including vegetative growth and flowering after a fire event, and (b) do different functional resprouting groups respond differently to the effects of season of fire? We sampled a total of 887 plants across 36 sites using a space‐for‐time design to assess resprouting vigor and reproductive output for five plant species. Sites represented either a spring or autumn burn, aged one to three years old. Season of fire had the clearest impacts on flowering in Lambertia formosa with a 152% increase in the number of plants flowering and a 45% increase in number of flowers per plant after autumn compared with spring fires. There were also season × severity interactions for total flowers produced for Leptospermum polygalifolium and L. trinervium with both species producing greater flowering in autumn, but only after lower severity fires. Severity of fire was a more important driver in vegetative growth than fire season. Season of fire impacts have previously been seen as synonymous with the effects of fire severity; however, we found that fire season and severity can have clear and independent, as well as interacting, impacts on post‐fire vegetative growth and reproductive response of resprouting species. Overall, we observed that there were positive effects of autumn fires on reproductive traits, while vegetative growth was positively related to fire severity and pre‐fire plant size.     

Fire interval effects on persistence of resprouter species in Mediterranean-type shrublands

The capacity of many plant species to resprout in fire-prone shrublands is thought to engender persistence, yet management concerns exist for the long-term persistence of some resprouting species given anthropogenic impacts including shortened fire intervals, long periods of fire exclusion, and/or fires of increasingly high severity. We explored the potential demographic effects of different fire interval regimes on lignotuberous resprouter species using the last fire interval for 36 sites (33 experimental fires, 3 wildfires) in biodiverse SW Australian shrublands, spanning an interval range of 3–42 years. Mortality and regrowth 1 year following the last fire was assessed for >7,000 tagged individuals from 20 shrub and sub-shrub species. Using generalized linear mixed effect models, we estimated the influence of fire interval (and selected fire and environmental covariates) on mortality and regrowth rates across all species, and individually for the four most common species. The overall model, as well as the models for three of the four most common species (Banksia attenuata, Melaleuca leuropoma, and M. systena, but not Hibbertia hypericoides) supported the hypothesis of increased mortality at short and long fire intervals, most likely due to total non-structural carbohydrate (TNC) and bud-bank limitation, respectively. However, no relationship between regrowth rate and fire interval was detected, suggesting that increased mortality at short (3–5 year) fire intervals may not be due solely to resource (TNC) limitation. Results show that lignotuberous resprouters are potentially vulnerable to population decline through attrition of mature plants under both shortened and lengthened fire interval regimes.     

Ecological divergence and evolutionary transition of resprouting types in Banksia attenuata

Resprouting is a key functional trait that allows plants to survive diverse disturbances. The fitness benefits associated with resprouting include a rapid return to adult growth, early flowering, and setting seed. The resprouting responses observed following fire are varied, as are the ecological outcomes. Understanding the ecological divergence and evolutionary pathways of different resprouting types and how the environment and genetics interact to drive such morphological evolution represents an important, but under‐studied, topic. In the present study, microsatellite markers and microevolutionary approaches were used to better understand: (1) whether genetic differentiation is related to morphological divergence among resprouting types and if so, whether there are any specific genetic variations associated with morphological divergence and (2) the evolutionary pathway of the transitions between two resprouting types in Banksia attenuata (epicormic resprouting from aerial stems or branch; resprouting from a underground lignotuber). The results revealed an association between population genetic differentiation and the morphological divergence of postfire resprouting types in B. attenuata. A microsatellite allele has been shown to be associated with epicormic populations. Approximate Bayesian Computation analysis revealed a likely evolutionary transition from epicormic to lignotuberous resprouting in B. attenuata. It is concluded that the postfire resprouting type in B. attenuata is likely determined by the fire's characteristics. The differentiated expression of postfire resprouting types in different environments is likely a consequence of local genetic adaptation. The capacity to shift the postfire resprouting type to adapt to diverse fire regimes is most likely the key factor explaining why B. attenuata is the most widespread member of the Banksia genus.     

How do drought and fire influence the patterns of resprouting in Australian deserts?

Rainfall is the key driver of woody cover and life-history attributes in arid grassy biomes where disturbance is mostly rare and of low intensity. However, relatively little is known about the causes of woody community assembly in arid systems that are subject to periodic intense fire disturbance. In the central Australian desert region, grassland and shrubland fire can occur following above average rainfall. Patterns of species regeneration response (resprouting vs. reseeding) are poorly documented in this region. We tested the effects of rainfall and fire on species’ resprouting response across the latitudinal rainfall–fire gradient using constrained ordination of 385 sites and general linear models. A resprouting response was significantly greater in grassland habitat as well as at the high end of the rainfall–fire gradient. The frequency of epicormic stem resprouting also increased along the rainfall–fire gradient. We attribute this pattern to the combined effects of frequent fire and rapid gap closure on seedlings of slow-growing, fire-killed woody species in higher rainfall grasslands. In addition, we also demonstrated that rapidly maturing fire-recruiting species are similarly favoured by high fire disturbance. In arid grassy ecosystems, unlike in mesic savanna, flammable grassland supports a mix of resprouting and recruitment functional types, and habitat membership cannot be predicted by resprouting capacity. Regions, such as central Australia, that are characterised by grassland–shrubland mosaics of high and low fuel biomass, respectively, pose specific challenges to fire ecology research that are possibly best dealt with by focussing modelling at the habitat scale.     

Effect of season of burn on shoot recovery and post‐fire flowering performance in the resprouter Stirlingia latifolia R. Br. (Proteaceae)

Abstract Stirlingia latifolia R. Br. is a proteaceous undershrub that is widespread in open woodlands and heathlands of the south‐west botanical province of Western Australia where it is subject to frequent fires, both natural and the result of fuel‐reduction burns. Shoots are completely destroyed by fire but regenerate rapidly by resprouting numerous new shoots from the root crown. Flowering is strongly triggered by fire with only sparse flowering in fire‐free periods. A study was undertaken to compare regrowth and flowering in populations of S. latifolia burnt in summer or autumn with populations burnt in spring as well as in unburnt population. Post‐fire flowering was recorded in 92% of plants burnt in summer/autumn compared with 73% of plants burnt in spring and less than 3% in populations that had not been burnt for more than 2 years. Plants burnt in summer/autumn resprouted an average of 8.5 shoots from their root crown, of which 93% developed an inflorescence. In contrast, spring‐burnt plants averaged only 5.9 shoots per plant with only 64% of these bearing an inflorescence. Ability to produce flowers was found to be related to plant age, with young individuals producing fewer or no inflorescences following spring burns in comparison with the more prolific flowering of similarly aged individuals following summer/autumn burns. Summer/autumn‐burnt plants also produced significantly longer inflorescence‐bearing shoots bearing a greater numbers of flower heads than those burnt in spring. Possible explanations for these results are given in the present report.     

Patterns of storage tissue and starch distribution in the young taproot of obligate seeders and resprouters of Australian Proteaceae (Juss.): Possible evidence of homoplastic evolution

The ancient Gondwanan family Proteaceae has its greatest speciation in fire‐prone environments of Australia. Fire response is either by seedling recruitment from parent plants that succumb to fire (obligate seeders), or survival and resprouting from protected buds (resprouters). Starch is the main source of energy for resprouting and in roots is restricted to parenchyma tissue. This study compared the size and distribution of storage parenchyma and the magnitude of starch reserves in roots of several proteaceous species from different genera in relation to their fire response and taxonomy. Cross‐sections (2 μm) of roots of 51 resprouter and 42 seeder species from 12 genera were stained for starch. Areas of cortex and ray parenchyma along with starch grain density were measured using image analysis software (Assess 2.0) and comparable samples of root tissue were assayed chemically for starch. Starch, where present, predominated in ray and cortex tissue with a greater percentage in resprouters (13.4 ± 1.03) than seeders (1.8 ± 0.26); these results correlated significantly with the chemical assay for starch (r = 0.93, P < 0.0001). Resprouters also had more storage parenchyma (56.9 ± 1.72%) than seeders (41.9 ± 1.91%) mostly due to broader rays (17.5 ± 1.22%) compared with seeders (8.2 ± 0.16%). Percentage of cortex tissue was similar for seeders and resprouters (39.4 ± 2.24 and 33.7 ± 2.04 respectively). Anatomical preferences for storage site were consistent within genera and broad suprageneric groupings. This study shows that histological analysis of root starch is a reliable predictor of resprouting capacity in Proteaceae and that patterns of storage tissue within genera, together with the persistence of parenchyma devoid of starch in seeders, are consistent with response to fire and suggests homoplastic evolution of this response within the family.     

Fitness and evolution of resprouters in relation to fire

There are many ways that plants may recover vegetatively from dieback caused by fires. Compared with fire-killed species, the presence of woody resprouters in fire-prone floras increases with fire frequency, though this is affected by site productivity that may have opposing correlates along different gradients. Population recovery is enhanced by resprouting when fecundity is low and/or seedling recruitment is not guaranteed. There is resource cycling between vegetative growth and storage but no clear trade-off between fecundity and storage, and more attention needs to be given to the role of somatic mutations in reducing fecundity. Seven fitness benefits of post-fire resprouting are noted that centre around the rapid return to adult growth rates and early flowering and seed set without the risks of recruitment failure. The extent of resprouting at the individual, population, and species levels varies greatly but it is under genetic control. Recent studies on the evolution of resprouting in fire-prone systems have shown that types of resprouting (clonality, rootstocks, epicormic bud strands) are derived from surrounding parent lineages lacking these traits and confined to non-fire-prone environments. The oldest lineages with fire-related resprouting date to at least 61 million years ago, indicating that seed plants have had a long evolutionary relationship with fire. Various genetic mechanisms, including beneficial somatic mutations, have been invoked to explain how speciation of resprouters may keep pace with non-sprouters.     

Does fire severity influence shrub resprouting after spring prescribed burning?

Prescribed burning is commonly used to reduce the risk of severe wildfire. However, further information about the associated environmental effects is required to help forest managers select the most appropriate treatment. To address this question, we evaluated if fire severity during spring prescribed burning significantly affects the resprouting ability of two common shrub species in shrubland under a Mediterranean climate in NW Spain. Fire behaviour and temperatures were recorded in tagged individuals of Erica australis and Pterospartum tridentatum during prescribed burning. The number and length of resprouted shoots were measured three times (6, 12 and 18 months) after the prescribed burning. The influence of a series of fire severity indicators on some plant resprouting vigour parameters was tested by canonical correlation analysis. Six months and one year after prescribed burning, soil burn severity (measured by the absolute reduction in depth of the organic soil layer, maximum temperatures in the organic soil layer and the mineral soil surface during burning and the post-fire depth of the organic soil layer) reduced the resprouting vigour of E. australis and P. tridentatum. In contrast, direct measurements of fire effects on plants (minimum branch diameter, duration of temperatures above 300 °C in the shrub crown and fireline intensity) did not affect the post-fire plant vigour.Soil burn severity during spring prescribed burning significantly affected the short-term resprouting vigour in a mixed heathland in Galicia. The lack of effects eighteen months after prescribed burning indicates the high resilience of these species and illustrates the need to conciliate fire prevention and conservation goals.     

Resprouting of saplings following a tropical rainforest fire in north‐east Queensland,Australia

Abstract In 2002, fire burnt areas of Mesophyll‐ and Notophyll Vine Forest in the Smithfield Conservation Park near Cairns, Australia. We assessed the ability of rainforest plant species to persist through fire via resprouting. Natural rates of mortality and resprouting in unburnt areas were assessed for all saplings (stems < 2 m) via 13, 2 × 50 m belt transects, and compared to estimates of mortality and resprouting in 26 transects in burnt areas. We also tested the resprouting ability per‐individual stem of each species against all other stems with which it co‐occurred. Totals of 1242 stems (138 species) were sampled in burnt transects and 503 stems (95 species) in unburnt transects (total number of unique species = 169). There was no difference in the number of stems existing prior to the fire in burnt and unburnt areas when expressed on a per‐sample area basis. Resprouting from basal shoots and root suckers was significantly greater in burnt than in unburnt areas, but rates of stem sprouting were not different. In burnt areas 72 species were tested for resprouting ability and most (65/72) resprouted at similar rates. All species analysed contained individuals that resprouted. The resprouting response of five species was significantly lower, and in two species was significantly higher. For these species especially, fire may act as a mechanism altering relative abundances. The fire coincided with an extreme El Niño event. Current predictions indicate El Niño conditions may become increasingly common, suggesting fire events within rainforest could become more frequent. Resprouting as a general phenomenon of rainforest species, and differential resprouting ability between species should therefore be an important consideration in assessing the potential path of vegetation change in rainforests after fire.     

Long-term post-fire resprouting dynamics and reproduction of woody species in a Brazilian savanna

Resprouting is an efficient life history strategy by which woody savanna species can recover their aboveground biomass after fire. However, resprouting dynamics after fire and the time it takes to start producing flowers and fruits are still poorly understood, especially for the Brazilian savanna (Cerrado biome), where fire is an important driver of vegetation structure and ecosystem functioning. We investigated the resprouting dynamics and production of flowers and fruits of 26 woody species (20 tree and 6 shrub species for a total of 485 individuals) that were burned and the production of flowers and fruits for a subset of 12 species (139 individuals) in an unburned area in a Brazilian savanna. We classified the species’ resprouting strategies as hypogeal (at the soil level, with main stem death), epigeal (on the main stem or crown), and hypogeal + epigeal. We used generalized linear mixed-effect models to identify the post-fire recovery patterns for five years. Individuals with basal resprouts (hypogeal and hypogeal + epigeal resprouting) produced an average of 6 basal resprouts, but only 33% of resprouts survived after five years. Individuals in burned areas produced fewer flowers and fruits than individuals in unburned areas. At least a subset of individuals in all the resprouting strategies started to produce flowers and fruits in the first-year post-fire. About 68% of the species with hypogeal resprouts produced flowers and fruits in the first-year post-fire, but the intensity of flowering and fruiting was lower compared to individuals with other resprouting strategies over time. Although woody species have invested in post-fire growth and sexual reproduction in all resprouting strategies, the long time needed to recover these processes can make these species more vulnerable to frequent fires.     

Drivers of post-fire resprouting success in restored Banksia woodlands

Disturbances can alter persistence trajectories of restored ecosystems. Resprouting is a common response of plants to disturbances such as fire or herbivory. Therefore, understanding a plant's resprouting response can inform successful restoration. We investigated patterns and drivers of resprouting following fire in fire-prone Banksia woodlands restored after sand mining in the Mediterranean-climate region of Western Australia. We applied experimental fire to samples of nine species with different resprouting types (rhizome, root crown, root sucker and lignotuber) across a 4- to 27-year-old restoration chronosequence. We investigated the influence of pre-fire plant size, restoration age and soil conditions on resprouting success, defined by: (i) the probability of resprouting (measured ~5 months after fire), (ii) the probability of surviving the first summer and, (iii) vigour (both measured ~12 months post-fire). We found that the probability of initial resprouting was high across most species, but summer survival was lower but comparable to that in other post-mining restored ecosystems following fire. Generally, pre-fire plant size did not influence probability of resprouting, while size and soil conditions were important for two species survival. Pre-fire plant size was a significant predictor of vigour for all species with soil conditions influencing four species. Restoration age significantly influenced survival of three species. However, as our models explained low amounts of variation in probabilities of resprouting and survival (R² = <0.11), other factors influencing resprouting success remain unidentified. Resprouting response to fire disturbance in restored Banksia woodlands are species and resprouter type specific, with plant size and soil conditions potentially more informative for understanding responses to disturbances than restoration age alone.     

Association of p53 codon 72 polymorphism with prostate cancer: a meta-analysis

Relationship of prostate cancer with the polymorphism of p53 codon 72 was reported with inconsistent results. The purpose of this study was to quantitatively evaluate the association between p53 codon 72 polymorphism and prostate cancer susceptibility. We performed an extensive search of relevant studies and made a meta-analysis, including 8 studies with 815 prostate cancer cases and 1047 controls. The combined results showed that there were no significant differences in genotype distribution between prostate cancer cases and control on the basis of all studies, CC/GC versus GG (OR = 1.24, 95% CI: 0.93–1.65), GG/GC versus CC (OR = 0.96, 95% CI: 0.60–1.55), GC versus GG (OR = 1.27, 95% CI: 0.91–1.77), CC versus GG (OR = 1.25, 95% CI:0.74–2.12), GC versus CC (OR = 1.09, 95% CI: 0.63–1.87). When stratifying for the race, there were also no statistically significant differences in genotype distribution between prostate cancer cases and controls. This meta-analysis did not provide an evidence of confirming association between p53 codon 72 polymorphism and prostate cancer.     

Post-fire regeneration strategies of Californian coastal sage shrubs

Summary Regeneration methods for coastal sage srub vegetation after fire were studied in the coastal Santa Monica Mountains of southern California. Six sites were sampled two years after a large fire of fall, 1978. The intensity of fire varied. Foliar cover and flowering incidence were recorded for individuals regenerating by resprouting or from seed. Resprouting plants contributed most to post-fire recovery, comprising 95% of the relative foliar shrub cover; 84% of resprout and 47% of seedling cover had flowered. An ANOVA of reproductive mode and fire intensity indicates that resprout total cover and individual size are significantly greater than those of seedlings, regardless of fire intensity. Among sites the average foliar cover of resprouts exceeded that of seedlings by factors ranging from 9 to 63. All coastal sage species examined resprout, although the potential vigor of resprouting appears to vary widely within genera (e.g. Encelia, Eriogonum, and Salvia) and even within species. In the second growing season following fire seedling density increased due to seeds shed by resprouted shrubs. Most of the cover on these stands of coastal sage scrub is destined to be either crown-sprouted individuals or their progeny.     

Comparative genet survival after fire in woody Mediterranean species

Summary Using data from three fires in northeastern Spain, we tested a condition necessary to support the idea that fire has been a factor in the evolution of the resprouting habit: populations of all resprouting species within a community should show high levels of genet survival after fires and show a low coefficient of variation. Species with high mean survival values were:Quercus ilex L.,Phillyrea latifolia L., andViburnum tinus L., with 88, 86 and 83% survival respectively; these groups had resprouts emerging from rootcrowns. Then followedArbutus unedo L. (75%),Pistacia lentiscus L. (73%),Erica arborea L. (77%),Erica multiflora L. (57%) andJuniperus oxycedrus L. (55%). This last group had resprouts from lignotubers or burls. These two groups also differed in the variability around the mean: the first showed a lower coefficient of variation, 6–12, and the second ranged from 19 to 26. Slope exposure had no significant influence on the process of resprouting, but soil depth did, with precipitation as a covariate. In the shallow soil category, the difference in genet survival between southern and northern exposures was 14% (71% vs. 57%); while the difference in the deep soil category was low, 5% (87% vs. 82%). There was no significant interaction. The component of variance for soils was larger than that for species-specific effects; substantial overlap of the within-species variance indicated that species responded as if they were a single hypothetical population, in which most of the variation in chances of survival was due to the soil conditions. The possession of the resprouting habit did not ensure a high performance. Hence, we find weak support for fire as a factor in the evolution of the resprouting habit.     

A six-year study of fire-related flowering cues and coexistence of two perennial grasses in a wet longleaf pine (<Emphasis Type="Italic">Pinus palustris</Emphasis>) savanna

Integrating population and community ecology can improve our understanding of the impacts of natural disturbances. Fire-stimulated flowering occurs in many long-lived herbaceous species of fire-maintained grasslands and savannas. Coexistence of these long-lived species may be affected in part by interspecific differences in the effect of fire-stimulated flowering on resource conservation, clonal growth, and longevity. This study comprised two parts. The first part investigated the effectiveness of different fire-related cues on fire-stimulated flowering in two cooccurring dominant grass species in a wet longleaf pine (Pinus palustris) savanna in southeastern Mississippi, USA. The second part investigated the immediate effects of the most important of these cues (damage and removal of aboveground vegetation and surface litter in May) along with nutrient addition on several measures of fitness and abundance over 6 years. Despite being a very effective inductive cue, when repeated frequently over 6 years, clipping plus surface litter removal significantly reduced flowering in both species. This negative effect was reduced to some extent by nutrient addition in Muhlenbergia expansa (which exhibited higher reproductive investment following clipping and fire than did Ctenium aromaticum). Frequent clipping resulted in an increasing numerical advantage of C. aromaticum over M. expansa with time. There was evidence of a modest release of C. aromaticum from competition with M. expansa in response to annual clipping. Responses suggest that suppressing flowering until after fire reduces the cost of flowering and maintains shoot densities, at least in M. expansa. Differences in the responses of these two species to repeated clipping and nutrient addition suggest that, despite their both exhibiting fire-stimulated flowering, each species is favored by slightly different fire frequencies. Moderate variation in fire frequency could maintain their coexistence in the long term.     

How does the fire regime change after creating a protected area in the Brazilian Cerrado?

Fire is a natural factor maintaining biodiversity and several ecological processes. The Brazilian Cerrado, considered the savanna with the highest biodiversity, is characterized by climatic seasonality, vegetation mosaics and topographic variations that together with fire determine its different plant physiognomies. The Chapada das Mesas National Park (CMNP), located in the south of the state of Maranhão (Brazil), has different savanna plant physiognomies with high ecological potential and archaeological and water wealth. The aim of the present study was to reconstruct the fire history over 28 years for the park and its surroundings (20 km buffer area), endeavouring to understand the impact of the creation of this National Park on its fire regime. Landsat satellite images were used from the TM, ETM + and OLI sensors to map the fire scars, which were identified and vectorized manually. The database created was used to analyze the total annual burned area, burned area percentage, density ignition, mean burn scar area and fire frequency during the mapped period. In total, 86 % of the CMNP was burn at least once between 1990 and 2017, while 72 % of the buffer area was burn. The creation of the park had significant effects on the density ignition when the periods before (1990–2005) and after (2006–2017) its creation were compared, and showed no significant effects on total annual area burned and average burn scar area. Despite the amount of burned area over time did not change significantly between the years before and after, the main change was observed in the fire seasonality after the creation of the park. In the park, 38 % of the area had a frequency of burn areas higher than ten times in the 28-year interval while 13 % of the buffer area was burn more than 10 times. In contrast, 23 % and 15 % had a fire frequency of 2 to 4 times on the buffer and the park respectively. Although the park was created to mitigate the human impacts of fire, the geographic isolation, the current occupation of the park by local populations and the pressure from agricultural expansion in the surroundings are influencing these conservation measures. Understanding the spatial–temporal distribution of fire in protected areas of the Cerrado contributes to improving management, preservation and conservation actions, so that in future studies other factors can be included to better understand the dynamic of fire occurrence in the region of the CMNP and in other protected areas of the Cerrado.     

Fire intensity and herbivory effects on postfire resprouting of Adenostoma fasciculatum in southern California chaparral

Summary Resprouting is the main regeneration mechanism after fire in Mediterranean-type ecosystems. Herbivores play an important role in controlling postfire seedling establishment, but their influence on regeneration by resprouting is less well known. To study the effects of fire intensity on resprouting of Adenostoma fasciculatum in southern California chaparral, and its interaction with herbivory, we conducted an experimental burn at three levels of fire intensity. We found that increasing fire intensity increased plant mortality, reduced the number of resprouts per plant, and delayed the time of resprouting. Herbivory increased with fire intensity, and was related to the time of resprouting. Plants resprouting later in the season and out of synchrony with the main flush were attacked more readily by herbivores. Post-resprouting mortality also increased with fire intensity and was significantly associated with herbivory in the higher fire intensity plots. Fire intensity effects on chaparral regeneration by resprouting may be farreaching through effects on the population structure, resprout production, and growth of Adenostoma fasciculatum.     

Fire, soil fertility and delayed seed release: a community analysis of the degree of serotiny

Delayed seed release (serotiny) is a convergent plant trait in fire-prone regions of the world but explaining the degree of serotiny has remained elusive because of the paucity of community data. Selective forces involving seed predators, fire and soil nutrients have been suggested as factors influencing serotiny. We tested whether protection of seeds and/or synchronized dispersal were associated with different levels of serotiny and if resprouting ability influences selection for strong serotiny. We compared the numbers and abundance of 146 woody species with delayed dispersal among five community types varying in combinations of fire severity, fire frequency, soil fertility and seed predators. The strength of the relationship between levels of serotiny and environmental factors was tested among community types ranging from rainforests to heathlands. Highest levels of serotiny were recorded in low nutrient shrublands with intermediate fire return intervals that burn at high severity, while the lowest were recorded in high nutrient, low flammability forests. Both protection of seeds and synchronized seed release were related to fire effects in nutrient-limited environments. Strong serotiny is prominent in species killed by fire whereas weak serotiny is more common in resprouting species. Recruitment failure in the inter-fire interval appears to drive selection for strong maternal care of seeds and synchronized seed dispersal in fire-prone environments. Weak serotiny is proposed as a bet-hedging strategy that relies on resprouting after fire for population persistence and higher probability of inter-fire recruitment. The spectrum of serotiny (weak to strong) in these communities is proposed to be driven by the interactive effect of both fire and soil nutrients on the selection for delayed seed dispersal.     

Effects of inter‐fire intervals on the reproductive output of resprouters and obligate seeders in the Proteaceae

Abstract Fire is often used as a management tool in fire‐prone communities to reduce fuel loads with the intention of reducing the severity and extent of unplanned fires, often resulting in the increased occurrence of fire in the dry sclerophyll vegetation of Australia. This study examined the effects of fire frequency (length of the inter‐fire interval) on the reproductive output of seven plant species in the Proteaceae, including obligate seeding shrubs (Hakea teretifolia, Petrophile pulchella), resprouting shrubs (Banksia spinulosa, Isopogon anemonifolius, Lambertia formosa) and resprouting trees (Banksia serrata, Xylomelum pyriforme). Reproductive output (measured as either number of confructescences or follicles) and relative size were estimated for 100 individuals at each of five sample sites, covering a range of past fire frequencies over 26 years including repeated short inter‐fire intervals. Patterns in reproductive output (after standardizing for size) were related to the life‐history attributes of the species. In areas that had experienced short inter‐fire intervals, obligate seeders had greater reproductive output compared with longer intervals, and the reproductive output of resprouting shrubs was less. Fire frequency did not affect reproductive output of the resprouting trees. The decreased reproductive output of the resprouting shrubs could be due to the allocation of resources to regrowth following fire rather than to reproduction. It is less clear what process resulted in the increased reproductive output of obligate seeders in high fire frequency areas, but it could be due to the most recent fires being more patchy in the areas experiencing shorter inter‐fire intervals, or it may have resulted from the selection for early reproduction in the high fire frequency areas. These results highlight the need to take into account past fire frequency at a site, in addition to time since the last fire, when planning prescribed fires.