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Problems with Schurbon and Fauth's Test of Effects of Prescribed Burning on Amphibian Diversity
... When results were summarized, no research gaps were identified as having the highest priority (Platt et al. 1988, Waldrop and Lloyd 1991, White et al. 1991, Streng et al. 1993), but the long-term impacts to amphibian communities are unknown. Similarly, the response of amphibian communities and wetland ecology to annual or bi-annual burns versus longer fire frequencies has not been tested over a long period and is still debated (Schurbon and Fauth 2003, Means et al. 2004, Robertson and Ostertag 2004, Schurbon and Fauth 2004. ...
... Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Means et al. 2004, Robertson and Ostertag 2004. ...
Studies on the herpetofauna of ephemeral ponds have been conducted across the state. However, existing data on ephemeral pond-breeding amphibians are scattered and are not readily available to land managers, policy makers, scientists, and other interested stakeholders. This project was designed to synthesize existing information for these species in order to develop management strategies for ephemeral ponds, particularly as they pertain to amphibian conservation. Involving stakeholders during this process provided additional input as well as disseminated the information in a manner that facilitated discussion. Other project objectives included developing a geo-referenced database for ephemeral pond-breeding amphibian research and surveying ephemeral ponds. The project focused specifically on 5 Species of Greatest Conservation Need (SGCN): flatwoods salamander (now two species-Ambystoma bishopi and A. cingulatum), tiger salamander (A. tigrinum), striped newt (Notophthalmus perstriatus), ornate chorus frog (Pseudacris ornata), and gopher frog (Rana capito). This final report contains results from a 3-year project.
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency (Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... The Florida Comprehensive Wildlife Conservation Strategy ranked "incompatible fire" as one of the highest overall threats across all Florida's terrestrial habitat (FWC 2005). Most land managers recognize the necessity of fire to maintain the longleaf pine ecosystem, but there is debate regarding the importance of fire season versus fire frequency (Bishop and Haas 2005) and as to the appropriate fire frequency ( Schurbon and Fauth 2003, Robertson and Ostertag 2004. Additionally, many managers have to contend with managing units or entire properties that have heavy fuel loads resulting from long-term fire suppression. ...
... That claim was based on their finding higher amphibian species richness (i.e., all amphibians grouped together) in wetlands not burned for 3-7 years. Schurbon and Fauth's recommendation for increasing fire return interval was debated but has not been fully refuted (Means et al. 2004, Robertson and Ostertag 2004, Schurbon and Fauth 2004). One of the criticisms of the approach of Schurbon and Fauth (2003) was that species richness of all amphibians was too general a metric (i.e., it did not account for inherent differences in amphibian assemblages among wetlands with varying vegetation, elevation, or soils). ...
Available habitat within a landscape is often more limited for specialist species than for generalists. Therefore, specialists are potentially more vulnerable to extinction. The goal of our study was to better understand the ephemeral wetland habitat associations of specialist and generalist amphibians within a longleaf pine landscape in the southeastern United States. We also sought to determine specialist (e.g., oak toad [Anaxyrus quercicus], Mabee's salamander [Ambystoma mabeei], pine woods treefrog [Hyla femoralis], carpenter frog [Lithobates virgatipes]) and generalist (e.g., spotted salamander [Ambystoma maculatum], Cope's gray treefrog [Hyla chrysoscelis], southern leopard frog [Lithobates sphenocephalus]) species' responses to specific habitat restoration treatments. From 2005-2010, we examined the relationship between aquatic specialist and generalist amphibian species occupancy and wetland vegetation structure. We measured vegetation and amphibian responses to prescribed fire and vegetation mulching (a fire surrogate), plus a combination of mulching and burning. Untreated controls were wetlands that had not burned for 4-15 years. We combined data from this study and a previous study to elucidate patterns in amphibian assemblages in relation to fire history. Specialist relative species richness was highest when canopy openness was high and leaf litter depth was low, conditions best achieved by mulching plus burning. Some specialist species were not detected in wetlands with >8 years since fire, and some generalist species were not detected in wetlands with <2 years since fire, indicating that as vegetation structure changes with time since fire, there is a corresponding shift in the amphibian assemblage. Important patterns in species distributions can be overlooked if relationships to environment and responses to habitat change are too generalized and do not account for shifts in community composition. For conservation of longleaf pine specialist species, we recommend that uplands continue to be prescribed-burned on a 1-3-year return interval. Burning should occur during the early growing season when possible to maximize the probability that wetland basins burn. In cases where species of high conservation value are at imminent risk of extinction, we recommend a combination of mulching and burning to most quickly restore suitable habitat structure.
... The mean number of fires in the past 50 yr was 4.5 6 1.7 in ponds burned in the past 4 mo (not counting the most recent fire), 1.8 6 1.0 in ponds burned 3-4 yr ago, and 1.5 6 1.0 in ponds burned 11 yr ago. This means that our results may partly reflect how fire frequencies over long time periods affect Oak Toad larvae (Schurbon and Fauth, 2003;Means et al., 2004;Robertson and Ostertag, 2004;Schurbon and Fauth, 2004), although the results still indicate that either recent burning, more-frequent fires, or both are better for recruitment. Greenberg and Tanner (2005) found higher Oak Toad recruitment in ponds within hardwoodinvaded upland matrices than in ponds within fire-maintained pine flatwoods. ...
The direct and indirect effects of fire on different life stages of amphibians are poorly understood and difficult to predict given interspecific variation in physiology and life history. We investigated how time-since-fire (TSF) of seasonal ponds embedded within Florida scrub habitat affected growth, development, and survival of larval Oak Toads (Anaxyrus quercicus). We selected 12 ponds at Archbold Biological Station on the southern Lake Wales Ridge, Florida: four burned within the last 4 mo, four burned 3–4 yr ago, and four burned 11 yr ago. We hatched and reared three clutches of Oak Toads in the laboratory for 2 wk and then sorted larvae into groups of 24 having equal representation from each clutch. We randomly assigned groups of larvae to 0.22-m 3 mesh field enclosures in each pond (n = 2–3 enclosures per pond) and measured environmental variables that might contribute to observed amphibian responses including pH, temperature, and periphyton growth. After 15 d, when larvae began metamorphosing, mean survival was significantly higher in the most-recently burned ponds. The TSF did not have a significant effect on developmental stage or tadpole size, although Oak Toad larvae tended to develop faster in the most-recently burned ponds. Although all ponds were acidic (pH < 4.3), there was a trend toward higher pH in the more-recently burned ponds, and survival was significantly positively correlated with pH. Overall our results suggest that performance and recruitment of larval Oak Toads are higher in recently burned ponds.
... In terrestrial systems, fire is an important restoration tool but is also a natural stressor that occurs at variable intervals and in varying intensities across a landscape (Bunnell 1995;Bergeron et al. 1998). While herpetofauna have widely been proposed as ideal indicators of environmental stress, the stochastic nature of fire has historically made discussions of its effects on particular speciesand their full application as indicator organisms -difficult and often debatable (Petranka et al. 1993;Ash & Bruce 1994;Means et al. 2004;Robertson & Ostertag 2004;. Our choice of a study system illustrates an important caveat of the ABC method that has rarely been discussed, especially when used as an indicator of disturbance within the framework of ecological restoration. ...
... Interestingly, Schurbon and Fauth [18,20] documented negative effects of prescribed burning on the overall amphibian assemblage of longleaf pine forests and advocated burning on intervals longer than typically recommended for this forest type (e.g. [21,22]). However, hardwood vegetation can encroach quickly into longleaf pine forests from which fire has been excluded [23], altering the habitat from one that favors taxa adapted to open pine stands to one that favors taxa adapted to hardwood forests. ...
In the future, land stewards are expected to increase their use of fire surrogates to manage longleaf pine forests. Varying land management strategies may have disparate effects on wildlife and the strength of these effects may depend upon the degree to which each target species is associated with the longleaf pine forest. To determine how amphibian and reptile assemblages respond to prescribed burns and fire surrogates, we sampled these animals within plots of land managed under four common management practices (burning, thinning, thinning and burning, and application of herbicide) and on unmanaged reference plots. We analyzed these data first by examining the entire herpetofauna and then by repeating all analyses for only taxa exhibiting some evidence of an evolutionary association with longleaf pine forests. We found that estimates of species richness of all amphibians did not differ significantly among treatments. These trends were altered when the pool of taxa was restricted to amphibian species known to be associated with longleaf pine forests. For associated amphibians, species richness was elevated on plots that were exposed to herbicide and burn, hardwood thinning, and hardwood thinning plus prescribed fire, relative to reference plots. No significant trends were identified for squamates in general or those squamate species known to be associated with longleaf forests. Fire surrogates may facilitate conservation for individual species of the ancestral biota of longleaf pine forests, but these trends may be obscured when entire assemblages are considered.
... In terrestrial systems, fire is an important restoration tool but is also a natural stressor that occurs at variable intervals and in varying intensities across a landscape (Bunnell 1995;Bergeron et al. 1998). While herpetofauna have widely been proposed as ideal indicators of environmental stress, the stochastic nature of fire has historically made discussions of its effects on particular speciesand their full application as indicator organisms -difficult and often debatable (Petranka et al. 1993;Ash & Bruce 1994;Means et al. 2004;Robertson & Ostertag 2004;. Our choice of a study system illustrates an important caveat of the ABC method that has rarely been discussed, especially when used as an indicator of disturbance within the framework of ecological restoration. ...
... Interestingly, Schurbon and Fauth [18,20] documented negative effects of prescribed burning on the overall amphibian assemblage of longleaf pine forests and advocated burning on intervals longer than typically recommended for this forest type (e.g. [21,22]). However, hardwood vegetation can encroach quickly into longleaf pine forests from which fire has been excluded [23], altering the habitat from one that favors taxa adapted to open pine stands to one that favors taxa adapted to hardwood forests. ...
In the future, land stewards are expected to increase their use of fire surrogates to manage longleaf pine forests. Varying land management strategies may have disparate effects on wildlife and the strength of these effects may depend upon the degree to which each target species is associated with the longleaf pine forest. To determine how amphibian and reptile assemblages respond to prescribed burns and fire surrogates, we sampled these animals within plots of land managed under four common management practices (burning, thinning, thinning and burning, and application of herbicide) and on unmanaged reference plots. We analyzed these data first by examining the entire herpetofauna and then by repeating all analyses for only taxa exhibiting some evidence of an evolutionary association with longleaf pine forests. We found that estimates of species richness of all amphibians did not differ significantly among treatments. These trends were altered when the pool of taxa was restricted to amphibian species known to be associated with longleaf pine forests. For associated amphibians, species richness was elevated on plots that were exposed to herbicide and burn, hardwood thinning, and hardwood thinning plus prescribed fire, relative to reference plots. No significant trends were identified for squamates in general or those squamate species known to be associated with longleaf forests. Fire surrogates may facilitate conservation for individual species of the ancestral biota of longleaf pine forests, but these trends may be obscured when entire assemblages are considered.
The Florida Scrub ecosystem depends on fire to sustain ecosystem function and to support resident plant and animal species. A recent study addressed the relationship between the time since last fire (TSF) and resident amphibians and reptiles in rosemary bald, one Florida Scrub habitat type. This is a parallel study in another Florida Scrub habitat type, scrubby flatwoods, at Archbold Biological Station (ABS), Lake Placid, Florida, USA. We installed 36 400-m(2) enclosures (four burn units within each of three TSF categories X 3 replicates per burn unit) at ABS. Bucket trap sampling, within and outside the enclosures, occurred during the spring and late summer in 2007 and 2008. Ten environmental variables that reflect differences in the biotic and abiotic conditions of the microhabitats associated with different TSF were surveyed. Eleven species of reptiles and six species of amphibians were captured. Three lizard species together accounted for > 95% of the reptile captures, and two toad species together accounted for > 96% of the amphibian captures. Abundance of the Florida Sand Skink (Plestiodon reynoldsi Stejneger) was highest in long-unburned areas, probably because of the accumulated litter; but abundances of the other two lizard species did not show a relationship with TSF. Differences in relative abundances of species between sampling years may be a function of the difference in rainfall. Despite substantial variation in sampling methods between this study and the previous one, the herpetofaunal composition of the two habitat types were found to be similar; differences in diversity between them was attributable mostly to differences in relative abundances. Species inhabiting the Florida Scrub ecosystem respond differently to TSF: the federally-listed Florida Scrub Jay (Aphelocoma coerulescens Bosc), for example, requires more frequent burning than appears to be the case for the Florida Sand Skink. A land management plan of stochastic return intervals and spatial variation of high-intensity fires to maintain a mosaic landscape would be ideal; but management options for maintaining the diversity of all species inhabiting the Florida scrub ecosystem are limited, because of the generally small size of remaining habitat patches.
Amphibian Biology, Volume 10, Conservation and Decline of Amphibians: Ecological Aspects, Effects of Humans, and Management. Harold Heatwole, and John W. Wilkinson, editors. Surrey Beatty & Sons, Baulkham Hills, NSW, Australia, 2012, 436 pp. (ISBN 978-0-9803113-72, $137.50)
The specific objectives for the Southeast Region TER-S Workshop were to: (1) assess TER-S management needs within a regional context, with an emphasis on system-level and cross-boundary approaches; (2) assess these approaches for their potential to keep common species common while recovering or enhancing TER-S populations; (3) examine the current state of the science and practice within DoD for such holistic approaches; (4) identify potential partners and existing partnership structures whose focus is, at least in part, meeting TER-S conservation objectives; (5) identify gaps in knowledge, technology, management, and partnerships that, if addressed, could improve implementation of system-level and cross-boundary approaches; and (6) prioritize investment opportunities to address these gaps. To achieve these objectives, workshop sponsors and organizers assembled a broad spectrum of discipline experts from the research and management communities, including federal and state agencies, academia, and the non-governmental conservation community.
Herpetofauna are frequently cited as ideal indicators for environmental and restoration monitoring due to their importance to ecological functioning, dominance of vertebrate biomass, and sensitivity to environmental change. Despite this relevance, herpetofauna have yet to be fully integrated into comprehensive, community-scale restoration monitoring methodologies. We tested the applicability of one such method, abundance–biomass comparisons (ABCs), to monitoring restoration success in a longleaf pine ecosystem currently undergoing restoration via prescribed burning. W statistics (a metric of environmental perturbation) for herpetofaunal assemblages in longleaf pine stands managed under varying fire intervals closely tracked forest succession from recently burned longleaf pine stands to those characterized by longer times since last burn and high levels of hardwood encroachment. Our results suggest that ABCs may be an applicable method for terrestrial restoration monitoring that encompasses entire faunal assemblages and allows for generality in restoration or disturbance response. We emphasize, however, that applications of this method and others need to take into account the specific ecological characteristics of study organisms and the natural history of study sites to avoid incorrect interpretations of disturbance response and inappropriate management recommendations.
With the increasing concerns for healthy forests and enhanced habitat for wildlife, private landowner involvement has become a critical component of biodiversity conservation in the US. Since biodiversity conservation is largely a public good, landowners have little incentive to promote it at their own cost. Strategies to develop socially optimal policies for biodiversity conservation should however consider three aspects—identifying forest practices that best promote habitat for a wide range of species at landscape level, estimating the costs associated with adoption of identified practices, and assessing the adoption potential of the identified practices among landowners. In this paper, we developed a framework to achieve these three tasks, applying an analytical hierarchy process, a dynamic optimization model, and an attribute based contingent valuation technique, respectively. The framework was applied to the context of enhancing habitat for biodiversity on private forests in Florida.
Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2007. O fogo é um agente natural de perturbação nas savanas tropicais, modifica a estrutura d comunidades animais e vegetais e transforma a paisagem. Como agente intermediário d perturbação as queimadas podem contribuir para manutenção da diversidade no Cerrado Utilizando armadilhas de interceptação e queda, foram investigados os efeitos do fogo sobre estrutura de taxocenoses de lagartos no Cerrado do Brasil Central; os efeitos de diferente regimes de queima sobre a riqueza, abundância e eqüidade de lagartos; e como a abundâncias das espécies de lagartos se relacionam com as mudanças nas características d hábitat que são induzidas pelo fogo. Foram utilizadas cinco parcelas de cerrado sensu strict submetidas a diferentes regimes de queima: queimadas quadrienais, queimadas bienais n início, meio e final da estação seca, e o controle (sem queima). Os lagartos foram amostrado durante cinco dias por mês de dezembro de 2005 a novembro de 2006 totalizando 60 armadilhas*dias por parcela. As eqüidades foram menores em parcelas nos extremos d perturbação, em acordo com a Hipótese da Perturbação Intermediária no âmbito local Quando riquezas foram contrastadas, o mesmo não aconteceu. As espécies de lagarto sobrevivem aos efeitos diretos das queimadas, mas possuem diferentes níveis de sensibilidad aos efeitos subseqüentes. Contudo, ambientes sob perturbações periódicas, a eqüidade pod ser muito mais informativa que a riqueza de espécies. É possível que uma alta riqueza d lagartos no Cerrado seja conduzida por uma combinação entre especializações de nicho redução da competição e pressões de predação nos extremos do gradiente de perturbação. Da 14 espécies observadas, seis demonstraram maior sensibilidade aos diferentes regimes ocorreram somente sob um tratamento específico (Enyalius aff. bilineatus, Tropiduru torquatus, Polychrus acutirostris, Mabuya guaporicola, Bachia bresslaui, e Tupinambi duseni), mas duas espécies generalistas (Tr. itambere e Ameiva ameiva) não ocorreram apenas sob regimes extremos. Tropidurus itambere e Micrablepharus atticolus apresentaram forte dominância sob regimes de queima mais severos e Ma. frenata e Ma. nigropunctata na ausência do fogo. A abundância total de lagartos não variou ao longo do ano, mas eqüidades maiores foram observadas no verão. Os efeitos sobre a estrutura da taxocenose de lagartos foram significativamente relacionados com mudanças na estrutura do hábitat induzidas pelo fogo, mas tiveram pouca relação com a variação temporal nos parâmetros climáticos. As características do hábitat, contrastantes entre as manchas submetidas a diferentes regimes de queima, e a presença de espécies de lagartos exclusivas em cada fragmento, sugerem que as paisagens heterogeneizadas pela passagem do fogo devam sustentar uma taxocenose de lagartos mais rica no contexto regional do que quando sujeitas aos efeitos homogeneizadores das queimadas antrópicas, ou da completa ausência de queima. O padrão encontrado para os lagartos pode ser recorrente em outros grupos animais. Queimadas antrópicas em alta freqüência e curta periodicidade bem como a completa supressão das queimadas devem ser evitadas. A manutenção destes regimes artificiais pode conduzir a uma grande perda de diversidade local e regional. _______________________________________________________________________________ ABSTRACT The fire is a natural agent of disturbance in tropical savannas, modifying the structure of animal and plant communities and transforming the landscape. As intermediate agent of disturbance the burns can contribute for maintenance of the diversity in the Cerrado. The effects of fire on the structure of lizard assemblages in the Cerrado of Central Brazil had been investigated using pit-fall traps. Throughout the different effects of burning regimes upon lizard richness, abundance and evenness; and how are the connections between lizard abundance and the changes in habitat characteristics induced by fire. Five plots of Cerrado sensu stricto under different burning regimes were sampled: quadrennial fires, biennial fires at early, modal and late dry-season and the control, without fire. Lizards had been surveyed during five days by month, December of 2005 the November of 2006, totalizing 600 trap*days by plot. The abundance and evenness had been lower under extremer disturbance, in agreement with intermediate disturbance hypothesis in the local level. Such result was conversely for richness contrasts. Lizard species survive well to direct effects off burns but they have varied sensitivity to subsequent effect and under periodic disturbances, evenness must to be much more informative. In addition, It is suggested that high lizard richness can be lead by a combination between niche specializations, competition reduction and predation pressures in the extremities of the disturbance gradient in Cerrado. Fourteen lizard species were surveyed, six shown fire-regimes sensibility and only occurred under a specific treatment (Enyalius aff. bilineatus, Tropidurus torquatus, Polychrus acutirostris, Mabuya guaporicola, Bachia bresslaui, and Tupinambis duseni), but two generalists species (Tr. itambere and Ameiva ameiva) had not occurred only under extreme regimes. Tropidurus itambere and Micrablepharus atticolus had presented strong dominance under more severe regimes and Ma. frenata and Ma. nigropunctata in the absence of the fire. The total abundance of lizards did not vary throughout the year, but higher evenness had been observed in the summer. The effects on the lizard assemblage structure had been significantly related with changes in the habitat structure induced by fire, but they had little relation with the variability of climate parameters throughout the year. Particularities of habitat structure in plots under different fire regimes, and the presence of exclusive species of lizards in each one plot, suggest that if natural burns lead to heterogenic landscape it can either drive to richer lizard fauna in regional context, rather than anthropogenic burns or the complete absence of fire. This pattern must be recurrent in other animal taxa and the anthropogenic fires, with high-frequency and low periodicity as well as the complete suppression of burns must be avoiding. The maintenance of these artificial regimes can drive great loss of local and regional diversity.
Southeastern United States habitats dominated by longleaf pine (Pinus palustris P. Miller) have declined precipitously in area and extent. Conservation of diverse ground-layer vegetation in these endangered habitats depends on prescribed fire. While the need for prescribed fire is now generally accepted, there is disagreement concerning the most appropriate fire regime. One of the more important variables is frequency of fire. Several hypothetical relationships between fire frequency and vascular plant richness and composition are suggested by the existing literature. Results of two long-term prescribed fire studies support the hypothesis that burning as frequently as fuels permit is optimal for maintaining the largest number of native ground-layer plant species. However, fire frequency effects on species composition differed between the two studies. Increasing fire frequency in South Carolina Ultisol flatwoods and wet savannas was associated with a distinct shift from woody to herbaceous-dominated communities. Herbs, particularly bunchgrasses and perennial forbs, dominated annual- and biennial-burn treatment plots, whereas triennial- and quadrennial-burn plots were shrub-dominated. In contrast, annual and biennial fires did not produce herbaceous dominated ground-layer vegetation in North Florida Spodosol flatwoods. Reduced dominance of saw palmetto and somewhat increased importance of forbs and grasses, particularly rhizomatous grasses, distinguished the annually burned plots. However, biennial- and quadrennial-burn plots were similar in composition and did not differ significantly in species richness at the largest spatial scale.
Woody plants in fire-frequented ecosystems commonly resprout from underground organs after fires. Responses to variation in characteristics of fire regimes may be a function of plant physiological status or fire intensity. Although these hypotheses have been explored for trees in southeastern longleaf pine (Pinus palustris) savannas, responses of other life forms and stages have not been studied. We examined effects of fire season and frequency, geography, habitat, and underground organ morphology on resprouting of shrubs. In 1994, we located replicated sites, each containing two habitats, upslope savannas and downslope seepages, in Louisiana and Florida. Each site, which contained quadrats located along transects within a 30 x 60 m plot, was burned either during the dormant or growing season and then reburned similarly two years later. Maximum fire temperatures were measured, and densities of shrub stems were censused in quadrats before and after fires. Shrubs collectively resprouted more following dormant than growing-season fires, regardless of habitat or geographic region. After repeated dormant-season fires, collective densities in seepages of both regions and densities of root-crown-bearing shrubs in Florida seepages were greater than those initially and after repeated growing-season fires. Shrub responses were generally unrelated to fire temperatures, supporting the hypothesis that resprouting of shrubs may be more dependent on their physiological status at the time of fires. There was, nonetheless, an inverse relationship between collective and root-crown-bearing shrub densities following repeated fires and maximum fire temperatures in Florida seepages. Anthropogenic dormant-season fires over many decades may have resulted in increases in shrub densities in longleaf pine savannas, especially seepages. Repeated growing-season fires, however, neither increased nor reduced densities of established shrubs. Long-term shifts in characteristics of fire regimes, even in fire-frequented habitats, may produce effects that are not reversible in the short term (<10 yr) by simply reintroducing prescribed fires that resemble those that occurred naturally during the growing season.
In six 8- to 11-year-old plantations of longleaf pine (Pinus palustris Mill.) near Aiken, S.C., responses of understory vegetation, light, and soil water availability and litterfall were studied in relation to pine thinning (May 1994), herbicidal treatment of nonpine woody vegetation (1995-1996), or the combined treatments (treatment responses described below are in absolute units). Treatment differences in fifth-year (1998) herbaceous species density were as follows: pine thinning > woody control = combined treatments > untreated (33, 30, 30, and 25 species per 40 m(2), respectively). Forb and grass covers were 13 and 8% greater, respectively, after pine thinning and 7 and 9% greater after woody control. Pine thinning stimulated a large increase in third-year gap fraction (0.26), short-term increases in soil water content (1%), and a reduction in pine litterfall by half (-120 g.m(-2) per year). Woody control had no effect on gap fraction, decreased litterfall of nonpine woody vegetation (-32 g.m(-2) per year), and stimulated season-long increases in soil water content (1-2%). The ranking of factors affecting herbaceous vegetation responses was as follows: light > soil water > herbicides > litterfall. Herbaceous species density and cover can be promoted in longleaf pine plantations by intensive thinning of pines and herbicidal control of non-pine woody vegetation.
Fire and insects are natural disturbance agents in many forest ecosystems, often interacting to affect succession, nutrient cycling, and forest species composition. We review literature pertaining to effects of fire-insect interactions on ecological succession, use of prescribed fire for insect pest control, and effects of fire on insect diversity from northern and boreal forests in North America. Fire suppression policies implemented in the early 1900s have resulted in profound changes in forest species composition and structure. Associated with these changes was an increased vulnerability of forest stands to damage during outbreaks of defoliating insects. Information about the roles that both fire and insects play in many northern forests is needed to increase our understanding of the ecology of these systems and to develop sound management policies.
Loss of over 98% of the original extent of longleaf pine (Pinus palustris Mill.) systems has resulted in the need for development of understory restoration techniques. In natural longleaf pine systems recruitment of understory dominant species like wiregrass (Aristida stricta Michx.) likely occurs following opening of the canopy by fire or other localized disturbances. We investigated site preparation and sowing methods for reestablishing dominant understory species in heavily disturbed xeric sandhills. Wiregrass establishment was significantly higher in burned and irrigated plots than in plots that were only burned or were burned and had soil disturbance. However, without irrigation, burned and disturbed sites showed greater establishment than did either treatment alone. Overall, species richness and cover showed the same patterns when irrigation was present, but were higher in disturbed soils without fire when not irrigated. We recommend sowing native seed mix with a hayblower onto areas with light soil disturbance if irrigation is not possible. Subsequent rolling of seed into soil will increase seedling establishment. Mechanical re-establishment of native groundcover in xeric longleaf pine systems is clearly possible.
Structure was assessed in uneven-aged stands of loblolly (Pinus taeda) and shortleaf pine (P. echinata) that were subjected to prescribed winter burns on cycles of 0, 3, 6, and 9 years. Vegetation assessments were made in late summer of 1990, 10 years after a single hardwood control treatment (basal injection of nonpine woody plants >2.5 cm in ground- line diameter with TordorP 101 R); 1 year after the fourth 3-year burn cycle; 4 years after the second 6-year burn cycle; and 1 year after the second g-year burn cycle. Compared to unburned controls, prescribed burning tended to increase (P < 0.008) percent ground cover from graminoids and composites. For understory woody plants that were >l m tall but ~2.5 cm diameter breast height (dbh), American beautyberry (Callicarpa americana) had the greatest percent ground cover on burned and unburned plots. Horizontal cover between 0- and 3-m height tended to average less (P I 0.002) with more frequent pre- scribed burning and with shorter time since burning. There were no burn treatment dif- ferences in density (P = 0.199, p = 0.853) or basal area (P = 0.477, fi = 0.898) for sapling-size stems (2.5-8.9 cm dbh), but species diversity of saplings was lower (P = 0.002) on plots prescribe burned at 3-year intervals as compared to other treatments. burning cycle, cutting cycle, Pinus echinata, Pinus taeda, plant diversity, prescribed burn- ing, selection silviculture
Fire alters the abundance and diversity of many species, but its effects on amphibians are poorly known. We tested whether prescribed burning affected amphibian abundance and diversity within the Francis Marion National Forest, South Carolina, by monitoring assemblages at 15 temporary ponds with five different burn histories: 0, 1, 3, 5, and 12 years after burns. We also monitored terrestrial and aquatic environmental variables likely to influence amphibian diversity, such as leaf-litter depth, pond water chemistry, and distance to neighboring ponds. Fire had significant negative effects. Immediate effects ( burning during the study ) explained 12.8% and 10.8% of the variation in anuran and amphibian abundance, respectively, whereas short-term effects explained 31.8% and 24.6% of variation in amphibian species richness and evenness, respectively. Species richness increased and evenness decreased with time since burn, primarily because salamanders were rarely encountered at sites burned within 2 years. These sites had the shallowest leaf litter and highest soil temperature variances. Environmental factors unrelated to burning also significantly influenced amphibian diversity. Water chemistry explained 31.1% of variation in species richness, 32.2% of evenness, and>25% of anuran, salamander, and total amphibian abundances. Salamanders were most sensitive to water chemistry factors, particularly pH. Our results suggest that decreasing the frequency of prescribed burns from the current 2–3 years to 3–7 years will better maintain diverse amphibian and plant assemblages. Substituting growing-season burns for the current practice of winter and spring burns would avoid repeatedly interrupting amphibian breeding and would maintain the desired longleaf pine community.
Four combinations of season and frequency of burning were applied in Coastal Plain loblolly pine stands over a 43-year period. Overstory species composition and growth were unaffected by treatment. Above-ground portions of small hardwoods (less than 12.5 cm d.b.h.) were killed and replaced by numerous sprouts under periodic summer, periodic winter, and annual winter burning regimes. With annual summer burning, small hardwoods and shrubs were killed and replaced by vegetation typical of grassland communities. Grasses and forbs also dominated the understory of annual winter burns but numerous hardwood sprouts survived. Study results emphasize that frequent burning over a long period is needed to create and maintain the pine-grassland community observed by the first European settlers of the southeast.
The short- and long-term post-fire response patterns of small mammals, reptiles and amphibians inhabiting mallee woodlands and heathlands in temperate Australia are reviewed with respect to species' life history parameters in a search for unifying trends. Pyric response patterns of small mammal species are closely tied to their shelter, food and breeding requirements. There is a trend of increased specificity and reduced flexibility in life history traits concomitant with increased impact of fire and later post-fire recolonization. For reptiles there appears to be a strong relationship between the shelter and foraging requirements of species and their abundance in various successional states. The high incidence of burrowing in the mallee/heath amphibian fauna imparts considerable resilience to fire, and most species' abundance and distribution patterns seem more closely linked to moisture regimes than to fire per se.The high degree of consistency between species' postfire response patterns and their life history parameters points to the feasibility of developing a model to predict the impact of fire on small vertebrates. Such a model is currently being developed.
Thirty-five year results from the Stoddard fire plots: a study of fire frequency in the Red Hills of North Florida and South Georgia
- S M Hermann
Hermann, S. M. 2000. Thirty-five year results from the Stoddard fire plots: a study of fire frequency in the Red Hills of North Florida and South Georgia. Page 31 in Proceedings of the 21st Tall Timbers Fire Ecology Conference.
The land manager's guide to the amphibians and reptiles of the South. The Nature Conservancy, Southeastern Region, Chapel Hill
- L A Wilson
Wilson, L. A. 1995. The land manager's guide to the amphibians and reptiles of the South. The Nature Conservancy, Southeastern Region, Chapel Hill, North Carolina. Conservation Biology Volume 18, No. 4, August 2004