The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Walter C. Oechel - One of the best experts on this subject based on the ideXlab platform.
-
Changes in Fire Intensity have carry-over effects on plant responses after the next Fire in southern California chaparral
Journal of Vegetation Science, 2012Co-Authors: José M. Moreno, Walter C. Oechel, Iván Torres, Belén Luna, Jon E. KeeleyAbstract: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.
-
Demography of Adenostoma fasciculatum after Fires of different intensities in southern California chaparral.
Oecologia, 1993Co-Authors: José M. Moreno, Walter C. OechelAbstract:Changes in the population structure of the lignotuberous resprouter Adenostoma fasciculatum were investigated by experimentally burning at various intensities an old stand in southern California chaparral. Survival after Fire, time of resprouting, herbivory, and survival after resprouting were monitored for more than 1 year after the Fire. Greater Fire Intensity increased plant mortality and the size of plants that died as a consequence of the Fire. Time from the Fire until resprouting increased with increasing Fire Intensity and was related to plant size: the larger the plants the earlier they resprouted. Post-resprouting mortality also increased with Fire Intensity and was related to time of resprouting. Herbivory increased with Fire Intensity and the size of plants affected by it changed with the Intensity of the Fire. Fire Intensity had profound direct and indirect effects on the population structure of Adenostoma fasciculatum. Plant size strongly determined the direct and indirect lethal effects of Fire.
-
Fire Intensity Effects on Germination of Shrubs and Herbs in Southern California Chaparral
Ecology, 1991Co-Authors: José M. Moreno, Walter C. OechelAbstract:The study reported here investigates the effects of Fire Intensity and com- bustion products (ash and char) on shrub and herbaceous seedling emergence in the field in a mixed southern California chaparral, which was dominated by a facultative seeder, Adenostoma fasciculatum, and by an obligate seeder, Ceanothus greggii. Fire effects were studied in two winter bums, one of which was manipulated by adding brush to experimental plots to increase Fire Intensity. Adenostoma was very sensitive to increasing Fire Intensity, with decreasing seedling production as Fire Intensity increased. This was detected within the normal range of Fire intensities of a winter bum, and to a greater extent when intensities were experimentally modified. Ceanothus germination was either stimulated by, or very resistant to, increasing Fire Intensity. Increasing Fire Intensity also promoted earlier germination of Ceanothus. Herb species were also differentially affected by increasing Fire intensities. Among the abundant herbs, Fire annuals like Phacelia brachyloba were more resistant to increasing Fire Intensity than opportunistic annuals like Cryptantha muricata. Seedling production of one opportunistic annual, Lotus strigosus, was, however, stimulated by all levels of increased Fire Intensity. In most cases, ash and char did not affect field germination. Fire Intensity can profoundly modify seedling production of shrubs and herbs after a Fire. By substantially altering post-Fire seedling populations, Fire Intensity may represent a major factor in controlling species composition and diversity in chaparral.
-
Fire Intensity and herbivory effects on postFire resprouting of Adenostoma fasciculatum in southern California chaparral.
Oecologia, 1991Co-Authors: José M. Moreno, Walter C. OechelAbstract:Resprouting is the main regeneration mechanism after Fire in Mediterranean-type ecosystems. Herbivores play an important role in controlling postFire seedling establishment, but their influence on regeneration by resprouting is less well known. To study the effects of Fire Intensity on resprouting of Adenostoma fasciculatum in southern California chaparral, and its interaction with herbivory, we conducted an experimental burn at three levels of Fire Intensity. We found that increasing Fire Intensity increased plant mortality, reduced the number of resprouts per plant, and delayed the time of resprouting. Herbivory increased with Fire Intensity, and was related to the time of resprouting. Plants resprouting later in the season and out of synchrony with the main flush were attacked more readily by herbivores. Post-resprouting mortality also increased with Fire Intensity and was significantly associated with herbivory in the higher Fire Intensity plots. Fire Intensity effects on chaparral regeneration by resprouting may be farreaching through effects on the population structure, resprout production, and growth of Adenostoma fasciculatum.
José M. Moreno - One of the best experts on this subject based on the ideXlab platform.
-
Changes in Fire Intensity have carry-over effects on plant responses after the next Fire in southern California chaparral
Journal of Vegetation Science, 2012Co-Authors: José M. Moreno, Walter C. Oechel, Iván Torres, Belén Luna, Jon E. KeeleyAbstract: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.
-
Demography of Adenostoma fasciculatum after Fires of different intensities in southern California chaparral.
Oecologia, 1993Co-Authors: José M. Moreno, Walter C. OechelAbstract:Changes in the population structure of the lignotuberous resprouter Adenostoma fasciculatum were investigated by experimentally burning at various intensities an old stand in southern California chaparral. Survival after Fire, time of resprouting, herbivory, and survival after resprouting were monitored for more than 1 year after the Fire. Greater Fire Intensity increased plant mortality and the size of plants that died as a consequence of the Fire. Time from the Fire until resprouting increased with increasing Fire Intensity and was related to plant size: the larger the plants the earlier they resprouted. Post-resprouting mortality also increased with Fire Intensity and was related to time of resprouting. Herbivory increased with Fire Intensity and the size of plants affected by it changed with the Intensity of the Fire. Fire Intensity had profound direct and indirect effects on the population structure of Adenostoma fasciculatum. Plant size strongly determined the direct and indirect lethal effects of Fire.
-
Fire Intensity Effects on Germination of Shrubs and Herbs in Southern California Chaparral
Ecology, 1991Co-Authors: José M. Moreno, Walter C. OechelAbstract:The study reported here investigates the effects of Fire Intensity and com- bustion products (ash and char) on shrub and herbaceous seedling emergence in the field in a mixed southern California chaparral, which was dominated by a facultative seeder, Adenostoma fasciculatum, and by an obligate seeder, Ceanothus greggii. Fire effects were studied in two winter bums, one of which was manipulated by adding brush to experimental plots to increase Fire Intensity. Adenostoma was very sensitive to increasing Fire Intensity, with decreasing seedling production as Fire Intensity increased. This was detected within the normal range of Fire intensities of a winter bum, and to a greater extent when intensities were experimentally modified. Ceanothus germination was either stimulated by, or very resistant to, increasing Fire Intensity. Increasing Fire Intensity also promoted earlier germination of Ceanothus. Herb species were also differentially affected by increasing Fire intensities. Among the abundant herbs, Fire annuals like Phacelia brachyloba were more resistant to increasing Fire Intensity than opportunistic annuals like Cryptantha muricata. Seedling production of one opportunistic annual, Lotus strigosus, was, however, stimulated by all levels of increased Fire Intensity. In most cases, ash and char did not affect field germination. Fire Intensity can profoundly modify seedling production of shrubs and herbs after a Fire. By substantially altering post-Fire seedling populations, Fire Intensity may represent a major factor in controlling species composition and diversity in chaparral.
-
Fire Intensity and herbivory effects on postFire resprouting of Adenostoma fasciculatum in southern California chaparral.
Oecologia, 1991Co-Authors: José M. Moreno, Walter C. OechelAbstract:Resprouting is the main regeneration mechanism after Fire in Mediterranean-type ecosystems. Herbivores play an important role in controlling postFire seedling establishment, but their influence on regeneration by resprouting is less well known. To study the effects of Fire Intensity on resprouting of Adenostoma fasciculatum in southern California chaparral, and its interaction with herbivory, we conducted an experimental burn at three levels of Fire Intensity. We found that increasing Fire Intensity increased plant mortality, reduced the number of resprouts per plant, and delayed the time of resprouting. Herbivory increased with Fire Intensity, and was related to the time of resprouting. Plants resprouting later in the season and out of synchrony with the main flush were attacked more readily by herbivores. Post-resprouting mortality also increased with Fire Intensity and was significantly associated with herbivory in the higher Fire Intensity plots. Fire Intensity effects on chaparral regeneration by resprouting may be farreaching through effects on the population structure, resprout production, and growth of Adenostoma fasciculatum.
Tony D. Auld - One of the best experts on this subject based on the ideXlab platform.
-
Persistence of obligate-seeding species at the population scale: effects of Fire Intensity, Fire patchiness and long Fire-free intervals
International Journal of Wildland Fire, 2006Co-Authors: Mark K. J. Ooi, Robert J. Whelan, Tony D. AuldAbstract:Understanding how a species persists under a particular Fire regime requires knowledge of the response to Fire of individual plants. However, categorising the Fire response of a species solely based on known responses of individual plants can be misleading when predicting a population response. In the present study, we sought to determine the Fire responses of several Leucopogon species at the population level, including the threatened L. exolasius. We found that, whilst all species studied were obligate seeders, the population responses of species to Fire were dependent upon Fire Intensity and patchiness. Results showed first that low Intensity Fires were significantly patchier than higher Intensity Fires. Second, the proportion of plants killed within a population decreased with increased Fire patchiness. We also assessed how populations were structured and found that stands were multi-aged at most sites, and did not have a single-aged structure, which is often assumed for obligate seeders. Both spatial complexity within the Fire regime leading to adult plant persistence, and inter-Fire recruitment, contributed to the multi-aged structure. It is possible that these Leucopogon species are gap recruiters, and may tolerate Fire rather than be specifically adapted to it. Inter-Fire recruitment may enable L. exolasius populations to persist for a much longer Fire-free period than many other species in the region.
-
Soil Temperatures During Experimental BushFires in Relation to Fire Intensity: Consequences for Legume Germination and Fire Management in South-Eastern Australia
The Journal of Applied Ecology, 1995Co-Authors: R. A. Bradstock, Tony D. AuldAbstract:1. Experimental Fires were used to determine the influence of Fire Intensity and subcomponents of Intensity (fuel consumption and rate of spread) on soil temperatures (at 0-10 cm depth) in shrub/woodland communities in the Sydney region of south-eastern Australia. 2. Temperatures > 60°C were achieved at depths of 0-3 cm. Such temperatures are sufficient to break seed dormancy in local legume species. 3. Maximum change in soil temperature was not significantly affected by Byram Fire Intensity. However, at 0-4 cm depth, maximum temperature change was significantly affected by the amount of fine fuel (particles < 6 mm thick) consumed on the ground (mainly litter, twigs and herbs). Fine fuel above the ground (shrub canopies), coarse fuel (6-25 mm thick) on the ground and rate of spread did not significantly affect maximum change in temperature in the top 4 cm of the soil. 4. The results indicate that 0.6-2.0 kg m −2 of fine fuel burnt on the ground is likely to stimulate germination of buried seeds of local legumes (seed dormancy broken at ≥ 60° C). 5. At the upper end of this fuel consumption range, germination is predicted to occur down to 3-cm depth, while consumption at the lower end of the range will stimulate germination to a depth of 1 cm. Post-Fire germination in Acacia suaveolens was in accordance with these predictions. 6. These results are discussed in relation to the use of prescribed Fire for hazard reduction. Prescribed Fires with maximum potential for germination (maximum fuel consumption in the target range) will be close to, or in excess of, the limit for control unless the rate of spread is very low (< 0.10 M S −1 ), thereby imposing constraints on the use of prescribed Fire to achieve both protection and conservation objectives
Jon E. Keeley - One of the best experts on this subject based on the ideXlab platform.
-
Changes in Fire Intensity have carry-over effects on plant responses after the next Fire in southern California chaparral
Journal of Vegetation Science, 2012Co-Authors: José M. Moreno, Walter C. Oechel, Iván Torres, Belén Luna, Jon E. KeeleyAbstract: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.
-
Fire Intensity, Fire severity and burn severity: a brief review and suggested usage
International Journal of Wildland Fire, 2009Co-Authors: Jon E. KeeleyAbstract:Several recent papers have suggested replacing the terminology of Fire Intensity and Fire severity. Part of the problem with Fire Intensity is that it is sometimes used incorrectly to describe Fire effects, when in fact it is justifiably restricted to measures of energy output. Increasingly, the term has created confusion because some authors have restricted its usage to a single measure of energy output referred to as Fireline Intensity. This metric is most useful in understanding Fire behavior in forests, but is too narrow to fully capture the multitude of ways Fire energy affects ecosystems. Fire Intensity represents the energy released during various phases of a Fire, and different metrics such as reaction Intensity, Fireline Intensity, temperature, heating duration and radiant energy are useful for different purposes. Fire severity, and the related term burn severity, have created considerable confusion because of recent changes in their usage. Some authors have justified this by contending that Fire severity is defined broadly as ecosystem impacts from Fire and thus is open to individual interpretation. However, empirical studies have defined Fire severity operationally as the loss of or change in organic matter aboveground and belowground, although the precise metric varies with management needs. Confusion arises because Fire or burn severity is sometimes defined so that it also includes ecosystem responses. Ecosystem responses include soil erosion, vegetation regeneration, restoration of community structure, faunal recolonization, and a plethora of related response variables. Although some ecosystem responses are correlated with measures of Fire or burn severity, many important ecosystem processes have either not been demonstrated to be predicted by severity indices or have been shown in some vegetation types to be unrelated to severity. This is a critical issue because Fire or burn severity are readily measurable parameters, both on the ground and with remote sensing, yet ecosystem responses are of most interest to resource managers.
Otilia Reyes - One of the best experts on this subject based on the ideXlab platform.
-
Fire affects soil organic matter and the emergence of Pinus radiata seedlings
Annals of Forest Science, 2015Co-Authors: Otilia Reyes, Juan García-duro, Josefa SalgadoAbstract:AbstractKey messageThese results present great interest for the knowledge of Fire effects and the regeneration capacity of the ecosystems, which is essential to minimise the long-term Fire impacts.ContextThis study integrates thermal analysis of soil with tests of Fire effects on Pinus radiata seeds germination and field seedling emergence in P. radiata plantations. The consequences of Fire Intensity P. radiata plantation regeneration can be predicted from the results.AimsThis study aims to identify the effects of Fire on soil organic matter and emergence of P. radiata seedlings in a stand in NW Spain and to test the response of seeds from two provenances of P. radiata to smoke and heat.MethodsBurnt, unburnt and laboratory-heated samples of dry soil were analysed in a differential scanning calorimeter. Based on the comparison between heat released during the combustion of the organic matter of these samples, we estimated the Fire severity. Early emergence of P. radiata seedlings was recorded in the field after Fire. Finally, the effects of Fire on seeds germination were tested in the laboratory.ResultsThe limited loss of soil organic matter indicated that the Fire had been of low severity and that the temperatures reached during the Fire remained below the ignition temperatures of soil organic matter. The germination rate was high in controls and the lowest Fire severities but decreased with Fire Intensity. The two provenances differed in their response to Fire Intensity. Seedling emergence was moderate and varied over time.ConclusionThe Intensity of the investigated Fire remained moderate, with a limited loss of soil organic matter. It limited seedling germination and emergence. Nevertheless, despite the scarce seedling emergence observed in the field, re-establishment of the population was possible.
-
regeneration models and plant regenerative types related to the Intensity of Fire in atlantic shrubland and woodland species
Journal of Vegetation Science, 2008Co-Authors: Otilia Reyes, Mercedes CasalAbstract:Abstract Question: Is it possible to model the germinative and resprouting behaviour of plant species in Atlantic shrublands and woodlands in relation to Fire Intensity? Is it possible to recognise different functional regenerative types in these plant species? Location: Galicia, NW Iberian Peninsula. Methods: We explored the patterns of germination and resprouting plant responses in relation to different intensities of Fire using data from 37 trees, shrubs and herbaceous species growing in Atlantic shrublands and woodlands. Results: Synthesizing their germinative and resprouting behaviour, we created two graphical models: the Functional Germinative Model (FGM) and the Functional Sprouting Model (FSM). Integrating the germinative and resprouting responses, and taking into account Fire Intensity, we created the Functional Regenerative Model (FRM), which predicts the post-Fire recuperation of the populations of each species. The FRM has been validated with data from four Atlantic communities. We identified ...