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Author(s): Batllori, E; De Caceres, M; Brotons, L; Ackerly, DD; Moritz, MA; Lloret, F | Abstract: Understanding ecosystem responses to compound disturbance regimes and the influence of specific sequences of events in determining ecosystem shifts remains a challenge. We use a modelling framework for Mediterranean-type ecosystems to assess the effects of fire–drought interactions on long-term vegetation dynamics and to identify disturbance-driven changes in trait composition (tree seeder vs. tree resprouter prevalence) and ecosystem state (forest vs. non-forest). Changes in tree seeder and the tree resprouter dominance show nonlinear, threshold-type trends over gradients of increasing compound disturbance frequency. Vegetation composition thresholds mostly occur in a narrow range of the compound fire–drought disturbance space. Additionally, trait compositional switches and the likelihood of sudden changes in ecosystem state are promoted by fire-drought interactions. Distinct sequences of disturbance events cause vegetation transitions, disrupting ecosystem resilience, even under moderate recurrence of individual disturbances. An extreme drought year followed by one or two large fire events promotes shifts from resprouter- to seeder dominance. Contrastingly, a large crown fire followed by an extreme drought promotes changes from seeder to resprouter dominance. This disturbance sequence is also a mechanism strong enough to trigger sudden shifts in ecosystem state (from forest to non-forest). Synthesis. Thresholds of change in vegetation composition occur over a narrow range of the modelled gradients of compound fire-drought recurrence, and the loss of ecosystem resilience is contingent on particular sequences of disturbance events. Overall, our findings highlight that disturbance interactions define the relative location of tipping points in ecosystem state, and that effects and feedbacks of compound disturbance regimes increase the long-term likelihood of sudden ecosystem shifts and, therefore, uncertainty in predicting vegetation state.

Summary Understanding how drought affects seeder and resprouter plants during post-fire regeneration is important for the anticipation of Mediterranean vegetation vulnerability in a context of increasing drought and fire caused by climate change. A Mediterranean shrubland was subjected to various drought treatments (including 45% rainfall reduction, 7 months drought yr−1), before and after experimental burning, by means of a rainout–shelter system with an irrigation facility. Predawn shoot water potential (Ψpd), relative growth rate (RGR), specific leaf area (SLA) and bulk leaf carbon isotopic composition (δ13C) were monitored in the main woody species during the first 3 yr after fire. Cistus ladanifer seedlings showed higher Ψpd, RGR and SLA, and lower δ13C, than unburned plants during the first two post-fire years. Seedlings under drought maintained relatively high Ψpd, but suffered a decrease in Ψpd and RGR, and an increase in δ13C, relative to control treatments. Erica arborea, E. scoparia and Phillyrea angustifolia resprouts had higher Ψpd and RGR than unburned plants during the first post-fire year. Resprouters were largely unaffected by drought. Overall, despite marked differences between the two functional groups, post-fire environments were favourable for plant functioning of both seeder and resprouter shrubs, even under the most severe drought conditions implemented.

A higher frequency of natural selection is expected in populations of organisms with shorter generation times. In fire-prone ecosystems, populations of seeder plants behave as functionally semelparous populations, with short generation times compared to populations of resprouter plants, which are truly iteroparous. Therefore, a stronger signature of natural selection should be detected in seeder populations, favoured by their shorter generation times and higher rates of population turnover. Here we test this idea in Erica coccinea from the Cape Floristic Region, which is dimorphic for post-fire regeneration mode. We measured three floral traits supposedly subject to natural selection in seeder and resprouter populations. We then compared phenotypic trait variation with neutral genetic variation in each group of populations using PST–FST comparisons to detect signatures of natural selection in seeders and resprouters. We found a strong signature of selection in seeder populations, but not in resprouters. Furthermore, anthers of seeders were more exserted (and larger) than those of resprouters. These differences were maintained at sites where seeders and resprouters co-occurred, suggesting that phenotypic plasticity or adaptation to different growth environments are unlikely explanations for trait variation. These results provide empirical support for the hypothesis that the genetic signature of natural selection is certainly more intense in seeder than in resprouter populations, favoured by their comparatively faster generation turnovers. Increased frequency of natural selection would increase differentiation among populations, thus promoting speciation in pyrophytic seeder lineages of the Cape flora., J.G.S.-M. was supported by a ‘Ramón y Cajal’ postdoctoral contract from MICINN

The distribution limits of species are mainly related to climate but other environmental factors such as soil and fire may also play an important role in local population dynamics. Species that re-establish from seed after a severe disturbance (seeder species) should have different functional attributes from species that can survive a disturbance by vegetative regeneration (resprouters). The functional attributes will influence the establishment and survival of individuals and for trees, the stem size distributions provide a view of the history of the populations and may indicate the trajectories of the populations as they age. Two congeneric tree species – Allocasuarina fraseriana (a resprouter) and A. huegeliana (a seeder) are dominant to subdominant trees in forest and woodland vegetation of south western Australia and illustrate useful comparisons of functional attributes and population structures. Both species occupy fire prone vegetation, bear seeds in serotinous cones and are considered to regenerate new individuals after fire events. The seeder (Allocasuarina huegeliana) has smaller cones and seeds and more seeds cone-1 than the resprouter (A. fraseriana). The cones of the resprouter provide more protection against heat to the contained seeds than the seeder. It is generally considered that species in fire prone environments often rely on disturbance to provide suitable conditions for regeneration and recruitment between disturbances is poor. For a species killed by disturbance population structures years after the disturbance would be expected to be unimodal while a resprouter would have a multimodal structure, as adults would survive and remain in the population with the new recruits. Unexpectedly population structures for the two species we studied were very similar when compared at an overall landscape scale. We attribute this mainly to the ability of the species to recruit interfire. Best seedling recruitment does occur after fire, as this provides an environment with more nutrients and reduced competition for the seedlings. However interfire recruitment can be abundant in some habitats. The degree to which this occurs may vary in relation to co-occurring tree species and landscape position. In general, fuel reduction fires are being used to reduce the danger of high intensity fires as the climate becomes drier and hotter in parts of southern Australia and mild fires will influence recruitment of both species. Low intensity surface fires will remove interfire recruits of the seeder species, but may increase the density of small plants of the resprouter. Adults are unlikely to be damaged but size class structures will be different from those after stand replacing fires.

Eucalyptus delegatensis is native to the Australian Alps (subsp. delegatensis) and montane Tasmania (subsp. tasmaniensis). Post-fire regeneration mechanisms of the obligate-seeder subspecies on the Australian mainland are well-known, but less is known about the resprouter Tasmanian subspecies. In January 2016, large tracts of Eucalyptus delegatensis forests in central Tasmania, logged at different intensities, were burnt by low- and high-severity fire. We used statistical modelling to understand how tree survival, vegetative regeneration and seedling recruitment differed according to understorey type, fire severity, logging intensity and tree size (DBH). Fire severity, defined as unburnt, low-severity (fire scarring on the stem and/or lower canopy burnt) and high-severity (full canopy burnt), affected tree survival: 84% of trees were alive in unburnt transects, compared with 43% in low-severity transects and 36% in high-severity transects. Epicormic resprouting was the dominant mode of vegetative recovery, with

Spectral indices derived from optical remote sensing data have been widely used for fire-severity classification in forests from local to global scales. However, comparative analyses of multiple indices across diverse forest types are few. This represents an information gap for fire management agencies in areas like temperate south-eastern Australia, which is characterised by a diversity of natural forests that vary in structure, and in the fire-regeneration strategies of the dominant trees. We evaluate 10 spectral indices across eight areas burnt by wildfires in 1998, 2006, 2007, and 2009 in south-eastern Australia. These wildfire areas encompass 13 forest types, which represent 86% of the 7.9M ha region’s forest area. Forest types were aggregated into six forest groups based on their fire-regeneration strategies (seeders, resprouters) and structure (tree height and canopy cover). Index performance was evaluated for each forest type and forest group by examining its sensitivity to four fire-severity classes (unburnt, low, moderate, high) using three independent methods (anova, separability, and optimality). For the best-performing indices, we calculated index-specific thresholds (by forest types and groups) to separate between the four severity classes, and evaluated the accuracy of fire-severity classification on independent samples. Our results indicated that the best-performing indices of fire severity varied with forest type and group. Overall accuracy for the best-performing indices ranged from 0.50 to 0.78, and kappa values ranged from 0.33 (fair agreement) to 0.77 (substantial agreement), depending on the forest group and index. Fire severity in resprouter open forests and woodlands was most accurately mapped using the delta Normalised Burnt ratio (dNBR). In contrast, dNDVI (delta Normalised difference vegetation index) performed best for open forests with mixed fire responses (resprouters and seeders), and dNDWI (delta Normalised difference water index) was the most accurate for obligate seeder closed forests. Our analysis highlighted the low sensitivity of all indices to fire impacts in Rainforest. We conclude that the optimal spectral index for quantifying fire severity varies with forest type, but that there is scope to group forests by structure and fire-regeneration strategy to simplify fire-severity classification in heterogeneous forest landscapes.

International audience; In ecosystems subject to regular canopy fires, woody species have evolved two general strategies of post-fire regeneration. Seeder species are killed by fire and populations regenerate solely by post-fire recruitment from a seed bank. Resprouter species survive fire and regenerate by vegetative regrowth from protected organs. Interestingly, the abundance of these strategies varies along environmental gradients and across regions. Two main hypotheses have been proposed to explain this spatial variation: the gap dependence and the environmental variability hypotheses. The gap-dependence model predicts that seeders are favoured in sparse vegetation (vegetation gaps allowing effective post-fire recruitment of seedlings), while resprouters are favoured in densely vegetated sites (seedlings being outcompeted by the rapid crown regrowth of resprouters). The environmental-variability model predicts that seeders would prevail in reliable rainfall areas, whereas resprouters would be favoured in areas under highly variable rainfall that are prone to severe dry events (leading to high post-fire seedling mortality). We tested these two models using distribution data, captured at the scale of quarter-degree cells, for seeder and resprouter species of two speciose shrub genera (Aspalathus and Erica) common in fire-prone fyn-bos ecosystems of the mediterranean-climate part of the Cape Floristic Region. Contrary to the predictions of the gap-dependence model, species number of both resprouters and seeders increased with values of the Normalized Difference Vegetation Index (a widely used surrogate for vegetation density), with a more marked increase for seeders. The predictions of the environmental-variability hypothesis, by contrast, were not refuted by this study. Seeder and resprouter species of both genera showed highest richness in environments with high rainfall reliability. However, with decreasing reliability, seeder numbers dropped more quickly than those of resprou-ters. We conclude that the environmental-variability model is better able to explain the abundance of woody seeder and resprouter species in Southern Hemisphere fire-prone shrublands (fynbos and kwongan) than the gap-dependence model.

Soil enzymes are critical to soil nutrient cycling function but knowledge on the factors that control their response to major disturbances such as wildfires remains very limited. We evaluated the effect of fire-related plant functional traits (resprouting and seeding) on the resistance and resilience to fire of two soil enzyme activities involved in phosphorus and carbon cycling (acid phosphatase and β-glucosidase) in a Mediterranean shrublands in SE Spain. Using experimental fires, we compared four types of shrubland microsites: SS (vegetation patches dominated by seeder species), RR (patches dominated by resprouter species), SR (patches co-dominated by seeder and resprouter species), and IP (shrub interpatches). We assessed pre- and post-fire activities of the target soil enzymes, available P, soil organic C, and plant cover dynamics over three years after the fire. Post-fire regeneration functional groups (resprouter, seeder) modulated both pre- and post-fire activity of acid phosphatase and β-glucosidase, with higher activity in RR and SR patches than in SS patches and IP. However, we found no major differences in enzyme resistance and resilience between microsite types, except for a trend towards less resilience in SS patches. Fire similarly reduced the activity of both enzymes. However, acid phosphatase and β-glucosidase showed contrasting post-fire dynamics. While β-glucosidase proved to be rather resilient to fire, fully recovering three years after fire, acid phosphatase showed no signs of recovery in that period. Overall, the results indicate a positive influence of resprouter species on soil enzyme activity that is very resistant to fire. Long-lasting decrease in acid phosphatase activity probably resulted from the combined effect of P availability and post-fire drought. Our results provide insights on how plant functional traits modulate soil biochemical and microbiological response to fire in Mediterranean fire-prone shrublands. This work was supported by the research projects FEEDBACK (CGL2011-30515- C02-01), funded by the Spanish Ministry of Innovation and Science, and CASCADE (GA283068), funded by the European Union's Seventh Framework Programme (FP7/2007-2013).

This study aims to develop a method to estimate the recovery time of plant communities after high-severity wildfires. The designed methodology is based on map algebra and a geographical information system, which enabled calculation of the approximate time required to restore vegetation to conditions similar to pre-fire regarding plant height and canopy cover. The methodology considered, first, the vegetation in the territory, characterized by the structure of the dominant plant community (tree, shrub, or grassland) and its regeneration strategy (resprouter or seeder); and, second, two of the main factors determining recovery time – water availability and soil loss. We also considered the influence of observed rainfall trends over the past 50 years on these latter two factors. The methodology was applied to Spain to test its performance. The results suggest a period of 2 and approximately 100 years for grassland communities and tree communities with low germination, respectively. There are significant differences in plant communities between the two biogeographic regions (Euro-Siberian and Mediterranean) as well as within each community, directly linked to variability in terrain and climatic conditions.

Life-history attributes can impose differences on root system structures and properties related to nutrient and water uptake. Here, we assess whether plants with different post-fire regenerative strategies (resprouters, seeders and seeder-resprouters) differ in the topological and morphological properties of their root systems (external path, altitude, magnitude, topological index, specific root length, root length, root-to-shoot biomass ratio, length of the main axis of the root system and link length). To achieve these objectives, we sampled individuals from eight woody species in a shrubland located in the western Mediterranean Basin. We sampled the adult root systems using manual field excavation with the aid of an air compressor. The results indicate that resprouters have a higher root-to-shoot ratio, confirming their higher ability to store water, starch and nutrients and to invest in the belowground biomass. Moreover, this pattern would allow them to explore deeper parts of the soil layers. Seeder species would benefit from a higher specific root length, pointing to increased relative root growth and water uptake rates. This study confirms that seeders and resprouters may differ in nutrient and water uptake ability according to the characteristics of their root system. Species that can both resprout and establish seedlings after fire had different patterns of root system structure; in particular, root:shoot ratio was more similar to resprouters and specific root length was closer to seeders, supporting the distinct functional performance of this type of species.

Question: What are the short-term (first 4 yrs) dynamics of a Mediterraneanheathlandfollowingburningduringtheearly-vsthelate-fireseason?Location:SerradaLous~a, Central Portugal.Methods:Thevegetationstudiedwasa16-yearoldheathlandwithEricaaustra-lis (resprouter), Pterospartum tridentatum (resprouter/seeder) and Erica umbellata(seeder) among the dominant species. Four blocks, each with three 50 m 940 mplots,wereestablished.Oneplotperblockwasburnedduringtheearlysea-son(ES)andoneduringthe late season(LS),and thethirdremained unburned.Prior to, and during the first 4 yrs after burning, each burned plot was sampledforspeciesabundance,vigourandrichness.Theeffectsoffirethroughtimeweretested using random blocks repeated measures ANOVA. Recruitment was mod-elledasafunctionofpercentageofpost-firesoilcoveredbylitter(%).MANOVAwas used to test changes in the relative dominance of the woody species due tofire.CommunitydynamicswereassessedbyNMDSordinationanalysis.Results: Fire severity was higher and the percentage of post-fire soil covered bylitter lower in ES than LS burns. The post-fire plant dynamics were dominatedby the resprouting response. Resprouting was not affected by burning season,but ES fires resulted in higher seedling recruitment than LS fires, particularly inthe dominant seeder E. umbellata. Seedling recruitment was negatively relatedto post-fire soil covered by litter. Additionally, seedling emergence was delayedby nearly 1 yr in LS fires with respect to ES fires. Species richness was higher inES than LS fires. Fire did not globally affect the relative abundance of the domi-nant species, although the seeder E. umbellata decreased its relative cover withrespecttotheotherdominantspecies.Ordinationanalysisshowedthatthepost-fire dynamics of the vegetation were on a track of convergence with the com-munityexistingbeforefire.Conclusion: Burning season differentially affected regeneration, mainly by itseffectonseeding,withlittleeffectonresprouting.Burningseasonandassociatedchanges in fire severity and soil covered by litter could alter the short-termregeneration dynamics, which can have important implications for managingthishighlyflammablevegetation.IntroductionInseasonalclimates,firesatdifferenttimesduringtheyearcould affect the post-fire regenerating vegetation througha number of mechanisms. Plant and soil moisture contentvaryovertheyear,asdoesvegetationflammabilityandfireintensity(Hodgkinson1991).Furthermore,soilwatercon-tentmodifiesheatpenetrationintothesoil,duetowetsoilsbeing poor heat conductors (Frandsen & Ryan 1986).Hence, changes in fire intensity (sensu Keeley 2009) andin heat penetration could affect responses such as plantand seed mortality, time of resprouting and the number ofactive resprouting buds per plant (Malanson & Trabaud1988;Cruzet al.2003;Vesk&Westoby2004).Fire seasonality may affect plant responses related tophenological processes. First, the sensitivity of plant tissueto fire, notably of seeds, can change depending on level ofhydration (Parker 1987), which varies with the season.

The genus Erica represents the epitome of plant biodiversity in the South African Cape fynbos with over 700 species. This genus is composed of seeder and resprouter species, but both species diversity and endemism are strongly linked to the seeder habit and concentrated in the southwestern Cape Floristic Region (CFR). Erica coccinea is a relatively abundant and widespread fynbos species whose most remarkable morphological feature is the existence of distinct seeder and resprouter forms, frequently—but not always—in disjunct populations. Both higher within-population genetic diversity and among-population differentiation have been found in seeders, most likely as a consequence of the shorter generation times and faster population turnovers. Resprouters, despite being less diverse, are suspected to be ancestral. However, no solid evidence has yet been provided for the ancestrality of the resprouter form, or for the demographic processes that have determined the current distribution of genetic diversity in both regeneration forms. Here, we used microsatellites and sequences of the nuclear ribosomal internal transcribed spacers to describe the phylogeographic structure of seeder and resprouter E. coccinea populations and provide good evidence for the ancestral status of the resprouter form and the comparatively high rates of molecular evolution in derived seeder populations. We also reveal that mixed populations, where both seeder and resprouter individuals co-occur, were originated by secondary contacts. This study highlights the role of fire in driving accelerated diversification in seeder lineages of highly speciose CFR fynbos taxa., FO strongly thanks the Spanish Ministerio de Educación (travel Grant PR2010-0365) and the UCA Plan Propio de Investigación for providing travelling bursaries to do fieldwork. KBB acknowledges a PhD scholarship (FPI, BES-2009-015443) of the Spanish Ministry of Science and Innovation (MICINN). MH acknowledges a Ramón y Cajal fellowship (RYC2009-04537) from the Spanish Ministry of Science and Education (MICINN), and funding from the Research Council of Norway (203822/E40) and the Spanish Ministry of Economy and Competitiveness (CGL2012-40129-C02-02). SCGM and MH acknowledge the support of Marie Curie Intra European Fellowships within the 7th European Community Framework Programme (FP7-PEOPLE-2012-IEF, project nos. 328146 and 329088, respectively). JGS-M acknowledges a Ramón y Cajal fellowship (RYC2009-05164) from MICINN.

Question Do variations in fire intensity within a stand determine changes in fire intensity and plant demographics in a subsequent fire? Location San Diego (CA, USA); chaparral dominated by Adenostoma fasciculatum (resprouter) and Ceanothus greggii (seeder). Methods In 2003, a wildfire burned a young (16-yr-old) stand containing a set of experimental plots burned in 1987 with various levels of fire intensity. In 2004, all the 1987 plots were sampled for Adenostoma survival and the recruitment of both species. Similar measures were carried out in the adjacent old (75-yr) stand. Fire intensity in 2003 was estimated by a surrogate fire severity measure [minimum diameter of burned branches (branch diameter)]. Results In the young stand, branch diameter in 2003 was similar to the control plots in 1987, but lower than in the old stand. Fire intensity in 1987 did not significantly affect branch diameter in 2003. Survival of Adenostoma in the young stand was very low, much lower than after the 1987 burn and that in the old stand. Fire intensity in 1987 did not affect Adenostoma survival. Recruitment in Adenostoma increased, and in Ceanothus decreased, with increased fire intensity in 1987. Conclusions We demonstrate that there is a carry-over effect of fire intensity across a whole fire cycle on plant recruitment of the two dominant species. The 2003 fire partially reversed the relative effects on recruitment caused by elevated fire intensity in 1987. Arguably, this effect was driven by the contrasted relationships of the two species to fire intensity. Adenostoma survival in the young stand was much lower in 2003 than in 1987, despite similar branch diameter, and was also lower than in the old stand, despite higher branch diameter in this case. The causes of such mortality are unknown.

Plant communities are often composed of species belonging to different functional groups, but relatively few studies to date have explicitly linked their spatial structure to the outcome of the interaction among them. We investigated if mortality of seeder species during their establishment after fire is influenced by the proximity of the resprouter herb Brachypodium retusum . The study was conducted in a Mediterranean shrubland (00°39′ W; 38°43′ N), 40 km northwest of Alicante (Spain) with Ulex parviflorus , Cistus albidus , Helianthemum marifolium , and Ononis fruticosa as dominant obligate seeder species and a herbaceous layer is dominated by the resprouter B. retusum . We followed the fate of mapped seedlings and the biomass of B. retusum one, two, three and nine years after an experimental fire. We used point pattern analyses to evaluate the spatial pattern of mortality of seeder species at these years in relation to the biomass of B. retusum . We hypothesize that B. retusum may initially have a positive impact on seeder survival. We implemented this hypothesis as a point process model that maintains the overall number of dead seeder plants, but seeder survival varied proportionally to the biomass of B. retusum in its neighborhood. We then contrasted this hypothesis with a previous analysis based on a random mortality hypothesis. Our data were consistent with the hypothesis that proximity of B. retusum reduced the mortality of seeder plants at their establishment phase (i.e., 2 yrs after fire). However, we found no evidence that B. retusum influenced seeder mortality when plants grow to maturity. We also found that, under the more stressful conditions (fire + erosion scenario), B. retusum had a lower impact on the performance of seeder species. Our results suggest that B. retusum may reduce negative density-dependent effects among neighboring seeder plants during the first years after fire.

Many plants in fire-prone ecosystems produce seeds that are cued to germinate after fire. However, fire is not uniform in the landscape, and there are often refugia where fire does not reach, like rocky outcrops or moist valleys. Erica coccinea, a heath shrub from the South African fynbos, has two distinct pyrophyte forms (a resprouter and a seeder) as well as a ‘pyrofuge’ form that only occurs in fire refugia. We measured germination response to smoke and incubation temperature in seeds from pyrophyte (resprouter and seeder) and pyrofuge populations to determine whether these forms responded differently to a fire-cue (smoke) and a general germination cue (temperature). We found that seeds from pyrofuge plants had high germination success (80.9–92.0%) at the lowest incubation temperature (15/8°C 12h day/night cycle) regardless of smoke exposure. In contrast, seeds from pyrophytes (resprouters and seeders) responded strongly to the smoke cue (71.2–95.0%) and were not as limited by temperature. These results show that fire presence and absence is driving divergence of the primary germination cue in Erica coccinea. Given the patchiness of many natural fire regimes worldwide, we expect there may be pyrofuge populations exhibiting a similar divergence of traits in other species and other fire-prone ecosystems.

Many woody plant species in fire disturbed communities survive disturbance events by resprouting. The resprouting life history is predicted to be costly to plants as resources are diverted into storage for post-fire regrowth rather than allocated to current growth, and resprouting species typically grow more slowly than seeder species (species that do not resprout after disturbance events). Differences in allocation to current growth are also predicted to make resprouter species poorer competitors compared to seeder species. We tested the predictions that the evolution of a resprouter life history is associated with slow growth, increased allocation to storage, and low competitive ability in woody plant seedlings. We grew eight phylogenetically independent pairs of seeder and resprouter species in competition and no competition treatments in a field experiment near Sydney, Australia. The presence of competitors reduced plant growth rates across taxa and fire response life histories. However, relative to seeder species, resprouter species were not slower growing, they did not allocate more resources to storage, and they did not have lower competitive abilities. We propose that differences in resource allocation to storage are not responsible for differences in growth rate and competitive ability. Rather, growth rate and competitive ability in seedlings are associated with key aspects of plant life history such as life-span and body size at maturity. These traits that are sometimes, but not always, related to fire response life histories.

Question: Is post-fire, medium-term vegetation dynamics determined by land-use or fire history prior to fire? Location: South-facing slope in the Gallinera valley, Alicante province, eastern Spain. Methods: After mapping the land-use and fire history of the study site using photo-interpretation, we sampled vegetation structure on a set of plots representing the most frequent land-use and fire history combinations on an area burned six years before sampling. We studied the effects of land-use history, comparing the one-fire land-use trajectories. We analysed the effects of fire history; comparing one- and two-fire plots for both previously cropped and uncropped areas. Results: Most variables were not significantly different between the earliest abandoned plots (abandoned at least 38 years before the fire) and the uncropped plots. On the most recently abandoned plots (abandoned between one and four years before the fire), the therophyte richness and the ratio of seeder:resprouter richness were sign...

A range of reviews and technical reports have been presented in this volume that cover many components of the jarrah forest ecosystem and its restoration after bauxite mining in Western Australia. This synthesis reviews these papers and attempts to decide if the jarrah forest ecosystem has been restored. All ecosystem functions, including nutrient cycling and nutrient accumulation, appear to be successful or developing on an appropriate trajectory. Structural attributes of the restored vegetation are controlled by the floristic composition and growth of the vegetation and are developing favorably with time. Biodiversity measures show some deficiencies, which should be solved by time (e.g., lack of old rotting wood and tree hollows for fauna) or are the subject of ongoing research and development (e.g., imbalance of seeder/resprouter plant species). Various ways of measuring the success of Alcoa’s restoration are discussed and a numerical scorecard is presented. The overall scores were calculated as between 90 and 92% depending on the input parameters used. Such scores seem to agree with the overall subjective impression that Alcoa’s mine restoration is largely successful at restoring the jarrah forest ecosystem. A single measure of ecosystem restoration success, which acts as a surrogate for all others, does not exist, but the use of two such measures, soil organic carbon levels and floristic similarity, would adequately integrate all ecosystem components and could be used to determine the level of ecosystem restoration in this region.

10 páginas, 1 figura, 3 tablas., Mediterranean-type ecosystems are among the most remarkable plant biodiversity "hot spots" on the earth, and fire has traditionally been invoked as one of the evolutionary forces explaining this exceptional diversity. In these ecosystems, adult plants of some species are able to survive after fire (resprouters), whereas in other species fire kills the adults and populations are only maintained by an effective post-fire recruitment (seeders). Seeders tend to have shorter generation times than resprouters, particularly under short fire return intervals, thus potentially increasing their molecular evolutionary rates and, ultimately, their diversification. We explored whether seeder lineages actually have higher rates of molecular evolution and diversification than resprouters. Molecular evolutionary rates in different DNA regions were compared in 45 phylogenetically paired congeneric taxa from fire-prone Mediterranean-type ecosystems with contrasting seeder and resprouter life histories. Differential diversification was analyzed with both topological and chronological approaches in five genera (Banksia, Daviesia, Lachnaea, Leucadendron, and Thamnochortus) from two fire-prone regions (Australia and South Africa). We found that seeders had neither higher molecular rates nor higher diversification than resprouters. Such lack of differences in molecular rates between seeders and resprouters-which did not agree with theoretical predictions-may occur if (1) the timing of the switch from seeding to resprouting (or vice versa) occurs near the branch tip, so that most of the branch length evolves under the opposite life-history form; (2) resprouters suffer more somatic mutations and therefore counterbalancing the replication-induced mutations of seeders; and (3) the rate of mutations is not related to shorter generation times because plants do not undergo determinate germ-line replication. The absence of differential diversification is to be expected if seeders and resprouters do not differ from each other in their molecular evolutionary rate, which is the fuel for speciation. Although other factors such as the formation of isolated populations may trigger diversification, we can conclude that fire acting as a throttle for diversification is by no means the rule in fire-prone ecosystems., We thank R. Ree and B. R. Moore for their advice on the KIT and Sym- meTREE softwares and H. Dopazo for helping with the Phylemon server. B. Lamont provided fire-trait information on some Banksia species. We also thank T. Barraclough, P. Catalin, S. González-Martínez, B. Lamont, J. Pannell, X. Pic6, and R. Ree for helpful comments on the manuscript. This work has been partially financed by the PERSIST project (CGL2006- 07126/BOS) to JGP and by a research grant attached to a "Ramón y Cajal" contract to FO. JGS-M was granted a contract from the I3P program.

Several Cape species of the genus Erica are known to present seeder and resprouter phenotypes, and this variation seems to have a genetic basis. Therefore, this genus provides ideal model systems for using to elucidate the evolution of nonsprouting or seeder and resprouter life-histories in woody, fire-recruiting plants. A simple simulation model was developed to identify, under life-history optimality, the ecological conditions (viz. rainfall conditions and fire frequency) that conferred a selective advantage to the seeder phenotype over the resprouter in a given Cape Erica species. The model illustrated that the seeder life-history was able to invade and replace a resprouter population only under a mild mediterranean climate, with short, moderate summer droughts. This simulation approach will contribute to a better understanding of the biogeographical pattern of seeder and resprouter lineages of one of the paradigmatic fynbos woody taxa throughout the Cape floristic region.

Dominance-diversity curves have been previously constructed for a range of ecosystems around the world to illustrate the dominance of particular species and show how their relative abundances compare between communities separated in time or space. We investigate the usefulness of dominance-diversity curves in rehabilitated areas to compare the floristic composition and abundance of “undisturbed” areas with disturbed areas, using bauxite mining rehabilitation in Western Australia as an example. Rehabilitated pits (11–13 years old) subjected to prescribed fire in autumn and spring were compared with unburned rehabilitated areas and the native jarrah (Eucalyptus marginata) forest. Dominance diversity curves were constructed by ranking the log of the species density values from highest to lowest. Species were categorized according to a variety of functional responses: life form (trees, shrubs, subshrubs, and annuals), fire response syndrome (seeder or resprouter), nitrogen fixing capability, and origin (native or adventive). Exponential functions showed extremely good fits for all sites (r2 = 0.939–0.995). Dominance diversity graphs showed that after burning of rehabilitated areas, sites exhibited a more similar dominance-diversity curve than before burning. This was emphasized in a classification (UPGMA) of the regression equations from the dominance-diversity curves that showed that sites burned in spring were more similar to the native forest than sites burned in autumn. There was no significant segregation of the nitrogen-fixing and species origin categories, although the life form and fire response groupings showed significant segregation along the dominance-diversity curve. Resprouters tended to be over-represented in the lower quartiles and under-represented in the upper quartiles of post-burn sites. It is suggested that using dominance-diversity curves in the monitoring of rehabilitated areas may be a useful approach because it provides an easily interpretable visual representation of both species richness and abundance relationships and may be further utilized to emphasize categories of plants that are over- or under-represented in rehabilitated areas. This will assist in the post-rehabilitation management of these sites.

Post-fire sprouting of dormant buds in resprouter plants is facilitated by stored carbohydrate reserves, with starch being the critical reserve. Starch is mainly stored in xylem parenchyma ray tissue of woody underground organs, such as burls, lignotubers, and roots. We carried out a comparative analysis of the pattern of starch storage and the proportion of parenchymatic ray tissue in the upper root or cotyledonary region of seedlings from seeder and resprouter forms within two Cape Erica (Ericaceae) species: E. coccinea L. and E. calycina L., which were raised in the greenhouse under controlled irrigation. We also explored the root-to-shoot allocation patterns of seeder and resprouter seedlings in these two species. Resprouter seedlings of both species showed higher relative amounts of upper-root starch and upper-root storage tissue as well as a higher root-to-shoot allocation than their seeder counterparts. Pronounced swelling of the upper root region suggests ontogenetic development of a lignotuber in the resprouter forms of the two Erica species. The distinct allocation of starch in roots seems to be genetically determined and would account for the apparent differences in the root-to-shoot allocation patterns between both regeneration forms from the early seedling stage.

Concentrations of starch in roots of seeder species of Erica from the Cape Floristic Region, South Africa were found to be considerably less than in resprouters. Shoot starch was highly variable but mean values were similar in both seeder and resprouter species of Erica. Three distinct patterns of starch storage in roots were recognized. All seeder species fell within definitions of Categories 1 (narrow major and minor parenchymatous rays, one to two cells wide with no inter-ray storage) or 2 (thick major rays up to seven cells wide and thin minor rays with small amounts of inter-ray storage) whereas resprouter species were consistently within Categories 2 or 3 (broad major and minor rays, up to eight cells wide and conspicuous inter-ray starch storage). Results are discussed in light of similar studies of the related Epacridaceae. ‘Mixed’ species (i.e. with seeder or resprouter individuals present, often in distinct populations) were always classified as belonging to Category 2. Studies of populations of three ‘mixed’ species confirmed that seeder forms had consistently lower amounts of root starch than resprouters. Rays of xylem parenchyma were the main sites for starch storage in roots of both seeders and resprouters and greater proportions of cross-sectional area of roots were consistently devoted to such storage tissues in resprouter forms of the three ‘mixed’ species. Analyses of a number of seeder and resprouter Erica coccinea populations showed that differences in amounts of realised and potential root starch storage are best explained by the effect of regeneration behaviour rather than by among-population variability.

The genus Erica L., with more than 600 species, and a high number of endemics, represents the most remarkable example of floristic diversity in the Cape Floristic Region (CFR). It is largely confined to nutrient-poor, acidic, sandy soils, being one of the most characteristic element of fynbos. The ability to survive fires, resprouting from a lignotuber, is a common trait among Euro-mediterranean Erica species. In contrast, resprouting is fairly uncommon among ericas in the CFR (less than 10%). Most of them are killed by fire, regenerating only but readily by seed germination. An extensive survey on the resprouting ability of South African Erica species was carried out and the pattern of geographical distribution of resprouters and seeders in the CFR was determined. The geographical distribution of these two regeneration classes was related to a climatic gradient of seasonality along the CFR. A pattern of higher proportions of resprouter species towards the mediterranean, strongly seasonal northwestern CFR and the non-seasonal eastern CFR and summer rainfall area outside the CFR was identified. The number of resprouter species reaches a maximum in the eastern CFR and is lower in the southwestern CFR despite the overall higher concentration of species in this subregion. Summer drought strongly influences the effectiveness of post-fire regeneration and growth (i.e. new recruits plus survivors) of Erica species, and is the major selective force accounting for the pattern of distribution of seeders and resprouters in the CFR. A mild mediterranean climate with reliable autumn-winter rains and a short summer drought, typical of the mountain areas of the southwestern CFR, favours recruitment of seeders but hampers recruitment of resprouters. Resprouter species persist and become dominant under harsh conditions for recruitment (severe summer drought) and would coexist with seeders under situations of no summer stress. Diversification is associated with seeder lineages. Hence, number of seeder species will be higher than number of resprouters, especially in the southwestern CFR, where favourable conditions for recruitment allow a massive concentration of seeder species, many of them narrow endemics.

The influence of high temperatures (dry heat and hot water) on germination of seven Mediterranean Leguminosae species typical of fire-prone ecosystems in southern Spain is analyzed, in order to know the response of seeds to wildfires and the possible implications in their regeneration after this disturbance. Seeds were heated to a range of temperatures (50 °–150 °C) and exposure times (1–60 min) similar to those registered in the upper soil layers during wildfires. Germination tests were carried out in plastic Petri dishes over 60 days. In general, the degree of seed germination promotion by dry heat treatments showed a wide interspecific variation, although the final germination level was increased in all the studied species except for Scorpiurus muricatus. The thermal pretreatment of 50 °C, however, was not effective for germination in any species, and rising the temperature to 70 °C only slightly enhanced the germination in Cytisus patens. The preheatings of 90 °C (5 and 10 min), 120 °C (5 and 10 min), and 150 °C (1 min) were the most effective in promoting seed germination. Hot water (100 °C) scarification also increased the final germination level in all cases, with the exception of C. patens. The germination rates after preheating were much lower than in mechanically scarified seeds and closely resembled those of the untreated seeds, except for C. reverchonii, whose seed germination rate decreased with heat. The response of species to heat shock had no clear relationship with life trait or with the specific post-fire regeneration strategy (obligate seeder or facultative resprouter). Those species coexisting in the same habitats had different heat optimal requirements for seed germination, an strategy suggested by some authors as minimizing interspecific competition in the secondary succession started after fire.

High diversification of woody seeder lineages is characteristic of the south-western cape floristic region (CFR), South Africa, which has been explained as a consequence of its mild Mediterranean climate and reliable winter rainfall. Such climatic regime reduces the risk of post-fire recruitment failure, acting as an ecological filter that favours seeder populations, thus promoting genetic differentiation and diversification in seeder populations, as previously seen in the South African heath Erica coccinea. To explore this hypothesis further, genetic population structure was investigated in two Mediterranean Erica species, one seeder (Erica umbellata) and the other resprouter (Erica australis), using nuclear microsatellites. These two species are endemic to the western Mediterranean Basin and co-occur in heathlands of the Strait of Gibraltar region. Mean annual rainfall in this region is similar to that from the south-western CFR, but summer stress is more marked and winter rainfall is much less reliable. Contrary to what was found in E. coccinea, average genetic diversity levels were considerably lower in seeder populations (E. umbellata), regardless of an apparently higher gene flow among them. No differences in genetic differentiation among populations were found between the two species. The occurrence of less favourable climatic conditions for post-fire recruitment in the western Mediterranean compared to the south-western CFR may affect seeder populations more strongly than resprouter and may thus account for lower levels of within-population genetic diversity in the seeder E. umbellata. In addition, putatively higher migration rates in the seeder E. umbellata, may contribute to reduce its potential for genetic differentiation. This study provides evidence that high divergence of seeder populations is not a general rule in fire-prone, Mediterranean-type ecosystems. © 2012 Springer Science+Business Media B.V., Financial support for lab work has been provided by project VAMPIRO (CGL2008-05289-C02-01/BOS; Spanish Ministerio de Ciencia e Innovación), project P07-RNM-02869 (Junta de Andalucía, Spain) and project ACOMP09/073 (Generalitat Valenciana, Spain). JGS-M was supported by a ‘Ramón y Cajal’ (MICINN-RYC, Spain) postdoctoral contract. CT-D was supported by the Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía, Spain).

Selected epacrids (92 species in 15 genera) were examined with respect to fire response type, morphology, root anatomy and starch storage. Seeders, 75% of the species investigated, possessed a single main stem and a small root system with lateral roots which in most cases did not spread beyond the shoot canopy. Resprouter species were generally multi-stemmed with large lignotuberous root stocks. Certain seeder and resprouter species were intermediate in form and showed small root systems and basally branched main stems. Amounts of starch in roots of seeders (1‐9‡0‐5 mg starch g d. wt per root) were much less than in resprouters (14‐1‡3‐3) whereas amounts in shoots were similar (1‐9‡0‐5 and 1‐6‡0‐6 mg starch g d. wt per shoot, respectively). Starch storage in roots was mostly confined to rays of xylem parenchyma and inter-ray xylem parenchyma and the greater storage capacity of resprouters was generally due to broader rays. Growth zones in root xylem ranged from clear, verifiable annual rings, as in many seeder species, to indistinct growth zones, typical of many resprouter species. Shoot:root dry weight ratios were higher in seeders than resprouters. The study suggests that speciation within the Epacridaceae into seeder and resprouter forms involved divergent dierentiation in terms of morphology, shoot:root dry weight ratio root storage of starch. # 1996 Annals of Botany Company

Summary The synthesis and action of ethylene are absolute requirements for seed germination in Cyclopia intermedia (resprouter) and C. subternata (seeder). Stratification at 2 °C in the dark resulted in the breaking of dormancy in the resprouter and the stimulation of the initial rate of germination in the seeder. The dormancy-breaking effect of low temperatures could be substituted for by treatment with ethylene, GA 3 or BA. However, in the seeder, only ethylene could mimic the effect of stratification on the rate of seed germination. Inhibition of ethylene action by NBD inhibited the dormancy-breaking effect of stratification, ethylene, GA 3 and BA in the resprouter and suppressed germination in the seeder to the levels of the resprouter. Stratification or treatment with GA 3 and BA resulted in the suppression of ethylene production due to the suppression of the conversion of ACC to ethylene. The results of this study indicate that the effects of stratification, GA 3 and BA on dormancy-breaking and germination could be ascribed to the effects of these treatments on the ability of the seeds to react to ethylene.

Determining the location of buds and bud-forming meristems and hence the level of protection from heat is essential to understanding plant response to fire. Most eucalypts resprout readily from the stem (epicormic resprouting) and the base after felling or high intensity fire. In contrast, Eucalyptus regnans is one of the few eastern Australian fire-sensitive, obligate seeder eucalypts. Some authors have suggested that the relatively weak epicormic resprouting is due to a lack of bud-forming structures. Epicormic strands from the bark and outer xylem of three very large trees and two saplings were examined anatomically. Epicormic bud-forming structures were found in all samples examined. The bud-forming capacity consisted of narrow, radially elongated strips of cells of meristematic appearance. These strips were continuous from the outermost secondary xylem through to the outer bark. Bark was relatively thick at the base of the large trees, but remarkably thin above this basal skirt. Eucalyptus regnans was found to possess the apparently fire-adapted epicormic strands previously described in other eucalypts, thus showing its fire-adapted lineage. However, this fire-sensitive species apparently directs much of its resources to rapid height-growth rates in younger trees, rather than to vegetative fire survival.