Effects of repeated burning on Mediterranean communities of the northeastern Iberian Peninsula

Question: In relation to a single fire, do repeated wildfires in Mediterranean type ecosystems (1) reduce plant species richness or diversity; (2) modify patterns of abundance or dominance of plant species or (3) alter plant composition? Location: Pinus halepensis dominated communities of Catalonia, northeastern Iberian Peninsula, western Mediterranean Basin. Methods: Regional, paired design with 14 study sites, each consisting of a once burnt area (1994) and a twice burnt area (1975–1993 and 1994). Ten years after the last fire, we recorded all vascular plant species present in nested plots and quantified their relative abundances on transects. We compared species richness, diversity, dominance and relative abundance and species‐area correlations between paired once and twice burnt areas and assessed their floristic composition similarity. Results: No statistically significant differences were found in species richness or diversity. Slopes of species‐area correlations were higher in once burnt areas. In twice burnt areas, dominance by one or two species was higher. P. halepensis showed lower relative abundance and nanophanerophytes showed higher relative abundance. No differences were found for resprouter, seeder or resprouter‐seeder species. Floristic composition similarity between paired areas tended to be higher in less productive sites. Conclusions: Fire recurrence had contrasting effects on species richness at different spatial scales. Repeated burning reduced the relative abundance of the dominant tree species, which resulted in a higher relative abundance of shrubs. It also promoted the dominance of herbs, particularly Brachypodium retusum. However, it did not change the relative abundance of regenerative groups. Paired areas were more similar as they were more Mediterranean in terms of climatic conditions.     

Responses of reptiles to fire in transition zones are mediated by bioregion affinity of species

Fire has impact on reptile communities with marked shifts in community composition between burnt and unburnt areas. These shifts are often related to the preference of reptile species throughout early or late post-fire successional habitats. Areas located in transition zones between bioregions harbor complex reptile communities with a mixture of biogeographic affinities. In these biogeographic crossroads, since fire simplifies the habitat structure, we expected simpler (lower alpha diversity) and more similar (lower beta diversity) reptile communities within burnt than within unburnt localities. We have tested this hypothesis in a transition zone between the Atlantic and Mediterranean bioregions in northern Portugal. Reptiles were surveyed in five localities (8 times per locality) along fire edges in which each locality was composed of one burnt and one unburnt transect. In total, 588 reptiles from 10 species were recorded. Unburnt transects had higher alpha and beta diversity and higher relative abundance of non-Mediterranean individuals than did burnt transects. A redundancy analysis also showed contrasting responses of Mediterranean and non-Mediterranean species, the former increasing and the latter decreasing after fire. Our study demonstrates that fire reduced the complexity of the reptile community, with benefits towards Mediterranean species due to its environmental preferences and long evolutionary association to fire. In biogeographic crossroads such as the study area, the retention of long unburnt vegetation is expected to maintain more diverse reptile communities.     

Recurrent fires and environment shape the vegetation in Quercus suber L. woodlands and maquis

The effects of fire recurrence on vegetation patterns in Quercus suber L. and Erica-Cistus communities in Mediterranean fire-prone ecosystems of south-eastern France were examined on stands belonging to 5 fire classes, corresponding to different numbers of fires (from 0 to 4) and time intervals between fires since 1959. A common pool of species was identified among the plots, which was typical of both open and closed maquis. Fire recurrence reduced the abundance of trees and herbs, whereas it increased the abundance of small shrubs. Richness differed significantly between the most contrasting classes of fire recurrence, with maximal values found in control plots and minimal values in plots that had burned recurrently and recently. Equitability indices did not vary significantly, in contrast to Shannon's diversity index which mostly correlated with richness. Forest ecosystems that have burnt once or twice in the last 50 years were resilient; that is to say they recovered a biomass and composition similar to that of the pre-fire state. However, after more than 3-4 fires, shrubland communities displayed lower species richness and diversity indices than unburned plots. The time since the last fire and the number of fires were the most explanatory fire variables, governing the structure of post-fire plant communities. However, environmental factors, such as slope or exposure, also made a significant contribution. Higher rates of fire recurrence can affect the persistence or expansion of shrublands in the future, as observed in other Mediterranean areas.     

The response of cerambycid beetles (Coleoptera: Cerambycidae) to long‐term fire frequency regimes in subtropical eucalypt forest

Fire has a varied influence on plant and animal species through direct (e.g. fire‐induced mortality) and indirect (e.g. modification of habitat) effects. Our understanding of the influence of fire regime on invertebrates and their response to fire‐induced modifications to habitat is poor. We aimed to determine the response of a beetle family (Coleoptera: Cerambycidae) to varying fire treatments and hypothesised that the abundance of cerambycid beetles is influenced by fire frequency due to modifications in habitat associated with the fire treatments. Arthropods were sampled across 3 months in annually and triennially burnt areas (treatments starting in 1952 and 1973 respectively), an area unburnt since 1946, and a former unburnt treatment, burnt by wildfire in 2006. Eleven different cerambycid taxa were collected using flight intercept panel traps, dominated by three species (Ipomoria tillides, Adrium sp. and Bethelium signiferum) which made up 99% of individuals collected. Over the sampling period the long unburnt treatment had significantly lower species richness than the triennial and wildfire treatments. Cerambycid abundance was significantly higher in the triennially burnt treatment than in all other fire treatments. Ipomoria tillides was more abundant in both frequently burnt treatments, Adrium sp. was more common in triennially burnt areas, whereas B. signiferum, was more common in the wildfire affected treatment. Some, but not all, cerambycid beetles were more common in areas with a more open understorey (i.e. resulting from frequent burning), and lower tree basal area, as this likely influences their ability to fly easily between food sources. Cerambycid abundance was positively related to the volume of coarse woody debris and healthy tree crowns. Cerambycid beetles were clearly influenced by historic fire regime, suggesting that changes in fire regime can potentially have a profound influence on arthropod assemblages, and subsequent influences on ecosystem processes, which are currently poorly understood.     

Pollination of a core flowering shrub species in Mediterranean phrygana: variation in pollinator diversity, abundance and effectiveness in response to fire

Fire in Mediterranean-type ecosystems produces catastrophic changes in plant-pollinator systems; the recovery of which has been studied by comparing an unburnt mature forest habitat with that of an adjacent recently burnt area (eight years post-fire). The composition, visitation profiles, and effectiveness of the taxonomically diverse pollinator assemblages found on a core nectar providing species ( Satureja thymbra : Lamiaceae) were examined in these two contrasting habitats. S. thymbra in the freshly burnt area had low nectar standing crop and relatively less diverse bee community than an unburnt area which had twice the nectar standing crop and a higher bee diversity and abundance. Both sites supported bee assemblages dominated by the non-native bumblebee Bombus terrestris . Spatio-temporal heterogeneity of nectar standing crops and microclimatic conditions were sufficient to explain the form and magnitude of the diurnal foraging profiles at each site in relation to species specific foraging and flight abilities. B. terrestris, Apis mellifera and native solitary bees were the three primary guilds visiting S. thymbra and varied in the efficiency with which they delivered conspecific pollen grains to receptive stigmas. A pollinator effectiveness index for these three guilds was calculated based on floral visitation rates and pollen delivery efficiency and reflected the actual levels of effectiveness of each guild within and across the two habitat types. There was no overall inter-community difference in pollination effectiveness as the bee assemblages in both habitats were sufficient to produce maximum fruit set in S. thymbra, though the relative contribution of each guild varied intra-communally. Pollen limitation was not found to occur in either habitat.     

The role of environmental gradients in non-native plant invasion into burnt areas of Yosemite National Park, California

Fire is known to facilitate the invasion of many non-native plant species, but how invasion into burnt areas varies along environmental gradients is not well-understood. We used two pre-existing data sets to analyse patterns of invasion by non-native plant species into burnt areas along gradients of topography, soil and vegetation structure in Yosemite National Park, California, USA. A total of 46 non-native species (all herbaceous) were recorded in the two data sets. They occurred in all seven of the major plant formations in the park, but were least common in subalpine and upper montane conifer forests. There was no significant difference in species richness or cover of non-natives between burnt and unburnt areas for either data set, and environmental gradients had a stronger effect on patterns of non-native species distribution, abundance and species composition than burning. Cover and species richness of non-natives had significant positive correlations with slope (steepness) and herbaceous cover, while species richness had significant negative correlations with elevation, the number of years post-burn, and cover of woody vegetation. Non-native species comprised a relatively minor component of the vegetation in both burnt and unburnt areas in Yosemite (percentage species = 4%, mean cover < 6.0%), and those species that did occur in burnt areas tended not to persist over time. The results indicate that in many western montane ecosystems, fire alone will not necessarily result in increased rates of invasion into burnt areas. However, it would be premature to conclude that non-native species could not affect post-fire succession patterns in these systems. Short fire-return intervals and high fire severity coupled with increased propagule pressure from areas used heavily by humans could still lead to high rates of invasion, establishment and spread even in highly protected areas such as Yosemite.     

Effects of time since fire on birds in a plant diversity hotspot

Global changes are influencing fire regimes in many parts of the world. In the Fynbos plant diversity hotspot (Cape Floristic Region, South Africa), fire frequency has increased in protected areas where the mean fire interval went from 12–19 to 6–9 years between 1970 and 2000. Fire is one of the main drivers of plant diversity in the Cape Floristic Region. Too frequent fires threaten the persistence of slow-maturing plant species, and such insights have led to the adoption of fire management principles based on plant responses. The effects of fire on Fynbos fauna are much more poorly understood, and have not generally been considered in depth in Fynbos conservation policies, planning or management. We assessed the response of bird communities to long-term fire-induced vegetation changes using space-for-time substitution. We studied bird communities, vegetation structure and plant functional composition in 84 Fynbos plots burnt between two and 18 years before. Ten of the 14 bird species analysed showed a significant change in their abundance with time since fire. We observed a significant species turnover along the post-fire succession due to changes both in vegetation structure and plant functional composition, with a characteristic shift from non-Fynbos specialists and granivorous species to Fynbos specialists and nectarivorous species.If current trends of increasing fire frequency continue, Fynbos endemic birds such as nectarivores may become vulnerable. Conservation management should thus aim more carefully to maintain mosaics of Fynbos patches of different ages. Future research needs to estimate the proportion of vegetation of different ages and patch sizes needed to support dependent fauna, particularly endemics.     

Abundance and detection of feral cats decreases after severe fire on Kangaroo Island,Australia

Predation by feral cats (Felis catus) has caused the extinction of many native species in Australia and globally. There is growing evidence that the impacts of feral cats can be amplified in post-fire environments, as cats are drawn to hunt in or around recently burnt areas and are also more effective hunters in open habitats. In 2018–2019, we established arrays of camera traps to estimate the abundance of feral cats on Kangaroo Island, South Australia. Much of the island (including five of our seven survey sites) was subsequently burnt in a severe wildfire (December 2019–February 2020). We re-sampled the sites 3–8 months post-fire (seven sites) and 11–12 months post-fire (three sites). At two unburnt sites sampled post-fire, it was possible to produce density estimates of cats using a spatially explicit capture–recapture approach. Where estimating density was not possible (due to low detections or individual cats not being distinguishable), the number of individuals and percentage of trap nights with detections was compared between the sampling periods. Some low-level cat control occurred within 2 km of three of the seven arrays (all within the burn scar) within 3 months of the fire. Across the five burnt sites, there was a decline in cat detections post-fire (including those without post-fire cat control). At 3–8 months post-fire, there was, on average, a 57% reduction in the number of individual cats, and a 65% reduction in the number of nights with cat detections, relative to pre-fire levels. Although cat detections declined following the fire, reduced population sizes of prey species and reduced cover as a result of the fire might still mean that cat predation is a threat to some surviving prey species. Management that reduces feral cat predation pressure on wildlife following wildfire should enhance the likelihood of post-fire wildlife persistence and recovery.     

Burning grasses,poor seeds: post-fire reproduction of early-flowering Neotropical savanna grasses produces low-quality seeds

Fire is a key factor triggering ecological processes in old-growth grasslands and savannas and could have strong implications for reproduction via seeds for the herbaceous layer. In the Neotropical savannas, grasses show strong synchronous post-fire flowering, and their reproduction is often considered fire-dependent, with their massive post-fire seed production being suggested as a source of population maintenance. However, literature lacks studies to provide evidence of fire-dependent flowering and no study has assessed the quality of the post-fire seed production. Therefore, we aimed to describe a phenological pattern across early-flowering Neotropical savanna grasses in both recently burnt and unburnt cerrado communities addressing three questions: (1) Do the early-flowering species rely on fire for reproduction via seeds? (2) If no, what are the effects of fire on their reproductive phenology? (3) Does the massive seed production in post-fire cerrado communities lead to high-quality seeds? We recorded the reproductive phenology of nine early-flowering grasses for 17 weeks in unburnt and recently burnt cerrado communities. We collected the seeds, estimated the production of fertile seeds, and tested germination. No species showed a pattern of fire-dependent reproduction. Fire stimulated earlier flowering while reproduction in the unburnt community was related to continuous rainfall. Seed production following fire was of low quality, and no species produced?>?7% fertile seeds. Seed germination remained below 50% for most species. Post-fire seed production of early-flowering species led to poor seed quality, suggesting a constraint to the recruitment of new individuals of early-flowering Neotropical savanna grasses in recently burnt cerrados.

     

Flower visitor communities are similar on remnant and reconstructed tallgrass prairies despite forb community differences

One common goal of habitat restoration and reconstruction is to reinstate the biodiversity found at intact reference sites. However, few researchers have examined whether these practices reinstate communities of flower‐visiting insects. This is unfortunate, as anthropogenically mediated declines in flower visitors, including bees (the primary pollinators for most terrestrial ecosystems), beetles, flies, and butterflies, have been reported worldwide. Biodiversity declines may be especially severe in North America's tallgrass prairie, a once‐vast grassland that has experienced severe destruction and degradation due to agricultural conversion. As such, we assessed the structure of forb and flower‐visiting insect communities as a whole and two subsets of the flower visitor community—bees and phytophagous beetles—across five tallgrass prairie remnants and five reconstructed prairies (former crop fields) in Kansas from 2013 to 2015. Remnant prairies had significantly higher forb diversity and differed significantly in forb composition, compared to reconstructed prairies. Despite the dissimilarities in forb community structure, there were no differences in flower visitor diversity or abundance between remnants and reconstructed prairies. However, when considered separately, bee communities exhibited significantly greater variability in composition on reconstructed prairies, likely due to the abundance of generalist bee species visiting non‐native legumes at two reconstructed prairies. Our work provides evidence that prairie habitat reconstruction is a valuable tool for reestablishing flower‐visiting insect communities and also emphasizes the considerable role that non‐native species may play in structuring grassland plant–bee interactions.     

Evaluating the role of fire disturbance in structuring small reptile communities in temperate forests

Fire is an integral disturbance shaping forest community dynamics over large scales. However, understanding the relationship between fire induced habitat disturbance and biodiversity remain equivocal. Ecological theories including the intermediate disturbance hypothesis (IDH) and the habitat accommodation model (HAM) offer predictive frameworks that could explain faunal responses to fire disturbances. We used an 80 year post-fire chronosequence to investigate small reptile community responses to fires in temperate forests across 74 sites. First, we evaluated if changes in species richness, abundance and evenness post-fire followed trends of prior predictions, including the IDH. Second, using competing models of fine scale habitat elements we evaluated the specific ways which fire influenced small reptiles. Third, we evaluated support for the HAM by examining compositional changes of reptile community post-fire. Relative abundance was positively correlated to age post-fire while richness and evenness showed no associations. The abundance trend was as expected based on the prior prediction of sustained population increase post-disturbance, but the trend for richness contradicted the prediction of highest diversity at intermediate levels of disturbance (according to IDH). Abundance changes were driven mainly by changes in overstorey, ground layer, and shelter, while richness and evenness did not associate with any vegetation parameter. Community composition was not strongly correlated to age since fire, thus support for the HAM was weak. Overall, in this ecosystem, frequent fire disturbances can be detrimental to small reptiles. Future studies utilizing approaches based on species traits could enhance our understanding of biodiversity patterns post-disturbance.     

Effects of a short fire‐return interval on resources and assemblage structure of birds in a tropical savanna

Fire frequency is a key land management issue, particularly in tropical savannas where fire is widely used and fire recurrence times are often short. We used an extended Before‐After‐Control‐Impact design to examine the impacts of repeated wet‐season burning for weed control on bird assemblages in a tropical savanna in north Queensland, Australia. Experimentally replicated fire treatments (unburnt, singularly bunt, twice burnt), in two habitats (riparian and adjacent open woodland), were surveyed over 3 years (1 year before the second burn, 1 year post the second burn, 2 years post the second burn) to examine responses of birds to a rapid recurrence of fire. Following the second burn, species richness and overall bird abundance were lower in the twice‐burnt sites than either the unburnt or singularly burnt sites. Feeding group composition varied across year of survey, but within each year, feeding guilds grouped according to fire treatment. In particular, abundance of frugivores and insectivores was lower in twice‐burnt sites, probably because of the decline of a native shrub that produces fleshy fruits, Carissa ovata. Although broader climatic variability may ultimately determine overall bird assemblages, our results show that a short fire‐return interval will substantially influence bird responses at a local scale. Considering that fire is frequently used as a land management tool, our results emphasize the importance of determining appropriate fire‐free intervals.     

Soil seed bank,fire season,and temporal patterns of germination in a seeder-dominated Mediterranean shrubland

Soil seed banks play a major role in the post-fire regeneration of Mediterranean shrublands. They vary throughout the year in species composition, abundance, and readiness to germinate. After fire, germination occurs mainly during the following fall to spring. Time of germination can determine recruitment success. It is unclear what factors control post-fire germination and its timing. We tested the effects of season and fire on the readily germinable soil seed bank of a seeder-dominated shrubland. Plots were burned early and late in the summer season (ES, LS). Soil samples were collected before and after fire, and germinated in a chamber simulating successively autumn, winter, and spring conditions. Samples were kept moistened at all times. Fire intensity was similar between ES and LS. Several species of Cistus and herbs, mostly annuals, were dominant. Most germination occurred during the simulated-autumn period, with little subsequent germination during the following two periods. Germination speed (T ₅₀) during simulated-autumn was similar for shrubs and herbs, and independent of season or fire. Germination was lower for two shrubs (Rosmarinus officinalis, Cistus salvifolius) and higher for herbaceous dicots in LS than in ES soils. Fire reduced monocots and enhanced Cistus. Germination period significantly interacted with fire and season in some groups or species, altering the simulated-autumn germination peak. We demonstrate that the seed bank can germinate swiftly under simulated-autumn conditions. Hence, water availability is the main controlling factor of germination. Fire season differentially affected some species or groups, and could affect the post-fire regeneration.     

Effects of fire on vegetation and arthropods in a coastal heath,south‐east Queensland

Fire is an important part of many Australian ecosystems, and determining how it affects different vegetation communities and associated fauna is of particular interest to land managers. Here, we report on a study that used sites established during a 39‐year fire experiment in coastal heathland in southeastern Queensland to compare arthropod abundance and vegetation in 1.5–2.6 ha sites that were (i) long unburnt, (ii) burnt every 5 years and (iii) burnt every 3 years. We found that the abundance of ants was more than four times higher in the frequently burnt sites compared to long unburnt sits. Moreover, long unburnt sites had greater dominance of Xanthorrhoea johnsonii and Caustis recurvata, whereas burnt sites had greater cover of Lomandra filiformis, Leucopogon margarodes and Leucopogon leptospermoides. Our findings show that frequent fire can alter vegetation structure and composition, and this is matched by an increase in the relative dominance of ants in the arthropod community.     

Fire affects the occurrence of small mammals at distinct spatial scales in a neotropical savanna

Fire is a major disturbance event that affects biomes worldwide, altering vegetation structure and flora and fauna assemblages. Here, we investigated the effects of an extensive wildfire (~?6240 ha) on small mammal assemblages in savanna woodland (cerradão) at two spatial scales (meso- and macrohabitat) in a neotropical savanna (Brazilian Cerrado). At each spatial scale, we assessed relationships between habitat structure and small mammal species composition and abundance before and after the fire in four natural patches (one burned, three unburned) using partial redundancy analysis. From July 2009 to October 2013, we captured 1319 individuals belonging to 14 species. Our results showed that the fire had consequences for small mammal assemblage at both scales. After the fire, the burned patch differed from the other patches in vegetation attributes and species composition. At a fine scale, fire increased the herbaceous layer and decreased the litter layer and understory obstruction. On a larger scale, the main consequences of fire on vegetation structure were increased variation in litter depth, tree diameter, and distance to the nearest tree. We observed a relationship between mesohabitat structure and the abundance of species with different habitat requirements during the post-fire succession. Fire favored the invasion of generalist species from open Cerrado habitats (rodents Calomys tener, Calomys expulsus, Cerradomys scotti, and Necromys lasiurus) at the expense of more specialized forest species. Our results reinforce the relevance of incorporating multi-scale habitat heterogeneity in future studies assessing the effects of fire on wildlife.     

Electromagnetic radiation of mobile telecommunication antennas affects the abundance and composition of wild pollinators

The exponential increase of mobile telephony has led to a pronounced increase in electromagnetic fields in the environment that may affect pollinator communities and threaten pollination as a key ecosystem service. Previous studies conducted on model species under laboratory conditions have shown negative effects of electromagnetic radiation (EMR) on reproductive success, development, and navigation of insects. However, the potential effects that widespread mobile telecommunication antennas have on wild pollinator communities outside the laboratory microcosm are still unknown. Here we studied the effects of EMR from telecommunication antennas on key wild pollinator groups (wild bees, hoverflies, bee flies, remaining flies, beetles, butterflies, and wasps). We measured EMR at 4 distances (50, 100, 200 and 400 m) from 10 antennas (5 on Limnos Island and 5 on Lesvos Island, eastern Mediterranean, Greece), and correlated EMR values with insect abundance and richness (the latter only for wild bees and hoverflies). All pollinator groups except butterflies were affected by EMR. In both islands, beetle, wasp, and hoverfly abundance decreased with EMR, whereas the abundance of underground-nesting wild bees and bee flies unexpectedly increased with EMR. The effect of EMR on the abundance of remaining flies differed between islands. With respect to species richness, EMR only tended to have a negative effect on hoverflies in Limnos. As EMR affected the abundance of several insect guilds negatively, and changed the composition of wild pollinators in natural habitats, it might also have additional ecological and economic impacts on the maintenance of wild plant diversity, crop production and human welfare.     

Direct and indirect responses of tallgrass prairie butterflies to prescribed burning

Fire is an important tool in the conservation and restoration of tallgrass prairie ecosystems. We investigated how both the vegetation composition and butterfly community of tallgrass prairie remnants changed in relation to the elapsed time (in months) since prescribed fire. Butterfly richness and butterfly abundance were positively correlated with the time since burn. Habitat-specialist butterfly richness recovery time was greater than 70 months post-fire and habitat-specialist butterfly abundance recovery time was approximately 50 months post-fire. Thus, recovery times for butterfly populations after prescribed fires in our study were potentially longer than those previously reported. We used Path Analysis to evaluate the relative contributions of the direct effect of time since fire and the indirect effects of time since fire through changes in vegetation composition on butterfly abundance. Path models highlighted the importance of the indirect effects of fire on habitat features, such as increases in the cover of bare ground. Because fire return intervals on managed prairie remnants are often less than 5 years, information on recovery times for habitat-specialist insect species are of great importance.     

Ectomycorrhiza succession patterns in Pinus sylvestris forests after stand-replacing fire in the Central Alps

Fires shape fundamental properties of many forest ecosystems and climate change will increase their relevance in regions where fires occur infrequently today. In ecosystems that are not adapted to fire, post-fire tree recruitment is often sparse, a fact that might be attributed to a transient lack of mycorrhizae. Ectomycorrhizal (EcM) fungi play an important role for recruitment by enhancing nutrient and water uptake of their hosts. The questions arise whether and for how long the EcM community is transformed by fire. We investigated the resistance and resilience of EcM fungal communities on a chronosequence of 12 Pinus sylvestris stands in Valais (Switzerland) and Val d’Aosta (Italy) affected by fire between 1990 and 2006. Soil samples from burnt and non-burnt forests were analyzed with respect to EcM fungi by means of a bioassay. The number of EcM species was significantly lower in samples from recently (2–5 years) burnt sites than non-burnt forest, and increased with time since fire reaching levels of adjacent forests after 15–18 years. Community composition changed after fire but did not converge to that of non-burnt sites over the 18 year period. Only Rhizopogon roseolus and Cenococcum geophilum were abundant in both burnt sites and adjacent forest. Our data indicate fire resistance of some EcM fungal species as well as rapid resilience in terms of species number, but not in species composition. As long as the function of different EcM species for seedling establishment is unknown, the consequences of long-term shifts in EcM community composition for tree recruitment remain unclear.     

Secondary succession in coastal dune fynbos: variation due to site and disturbance

Succession after fire and bushcutting in coastal dune fynbos was monitored for two and a half years and comparisons were made with adjacent, mature (13 year-old) fynbos. Sixty-two to 68% of pre-disturbance species, including all the dominants, were found in the successional communities 1.5 yr after disturbance: the patterns thus fitted the initial floristic composition model. On the more mesic south facing slope, post-fire succession differed from the north-facing (burnt) and bushcut sites in that ordinations showed a clear separation between the mature and successional communities. This difference was due to the post-fire abundance on the southfacing slope site of short-and medium-lived species not present in the mature fynbos. One and a half years after disturbance, species richness and equitability had increased relative to mature vegetation. This increase was greatest for the south facing slope where short-and medium-lived species and juveniles of pre-disturbance dominants co-occurred. In general, successional patterns were consistent with those described for other fynbos and fire-prone mediterranean shrublands.     

Fire‐mediated niche‐separation between two sympatric small mammal species

Fire is a key ecological process influencing the population dynamics of small mammals. Whilst shifting competitive advantage amongst small mammal species following a single fire event is well‐documented, there has been little investigation of the potential influence of fire frequency on small mammal interspecific interactions. In this study, we investigated the effect of fire frequency on the abundance of two small dasyurid mammals, Antechinus stuartii and A. flavipes, which occur sympatrically in some parts of their range. The two antechinus species are known to have different habitat preferences, so it is possible that fire regimes may promote their coexistence in areas of sympatry by altering vegetation structure. To investigate this possibility, we estimated the abundance of both species using replicate sites which differed in the number of times burnt (1–4) during the last four decades, but with identical time‐since‐fire. Proportionally, we captured greater numbers of A. stuartii in less frequently burnt sites and greater numbers of A. flavipes in more‐frequently burnt sites. Hence, fire may mediate niche‐separation between these two species. To clarify further this pattern of response to fire frequency, we investigated which structural habitat variables differed between fire frequencies, and compared antechinus abundances with structural vegetation characteristics. We found a trend for lower ground cover density under higher fire frequencies. This offers one potential explanation of the patterns of abundance that we observed. Our study provided insights into the complexities of small mammal responses to fire, and strongly suggests that fire could mediate competitive interactions between species.