The Experts below are selected from a list of 17409 Experts worldwide ranked by ideXlab platform
Bruce Shindler - One of the best experts on this subject based on the ideXlab platform.
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Fuel reduction strategies in Forest Communities
Journal of Forestry, 2003Co-Authors: Bruce Shindler, Elizabeth TomanAbstract:This study uses panel data from a mail survey administered to the same individuals in 1996 and 2000 to measure change in public attitudes toward fire management programs on federal lands in eastern Oregon and Washington. Findings were generally similar between 1996 and 2000, but three noteworthy changes occurred over the four-year interval. First, the number of citizens who view smoke as a problem has risen. Second, citizens gave Forest Service information programs lower ratings and considered other sources of information more reliable. And finally, the relationship between the Forest Service and residents in the region appears to have eroded. Nevertheless, respondents continued to support prescribed fire and mechanized thinning for fuel reduction purposes in local Forests. [References: 24]
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Fuel Reduction Strategies in Forest Communities : A Longitudinal Analysis
Journal of Forestry, 2003Co-Authors: Bruce ShindlerAbstract:This study uses panel data from a mail survey administered to the same individuals in 1996 and 2000 to measure change in public attitudes toward fire management programs on federal lands in eastern Oregon and Washington. Findings were generally similar between 1996 and 2000; however, some noteworthy changes over the study period include: a) lower ratings of Forest Service information programs, b) an increase in citizens who view smoke as a problem, and c) an eroding relationship between the Forest Service and residents in the region. Overall, respondents continued specifically to support prescribed fire and mechanized thinning for fuel reduction purposes in local Forests.
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Fuel Reduction Strategies in Forest Communities: A Longitudinal Analysis of Public Support
Journal of Forestry, 2003Co-Authors: Bruce Shindler, Elizabeth TomanAbstract:This study uses panel data from a mail survey administered to the same individuals in 1996 and 2000 to measure change in public attitudes toward fire management programs on federal lands in eastern Oregon and Washington. Findings were generally similar between 1996 and 2000, but three noteworthy changes occurred over the four-year interval. First, the number of citizens who view smoke as a problem has risen. Second, citizens gave Forest Service information programs lower ratings and considered other sources of information more reliable. And finally, the relationship between the Forest Service and residents in the region appears to have eroded. Nevertheless, respondents continued to support prescribed fire and mechanized thinning for fuel reduction purposes in local Forests.
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Forest Communities: New frameworks for assessing sustainability
Forestry Chronicle, 1999Co-Authors: Solange Nadeau, Bruce Shindler, Christina KakoyannisAbstract:In both Canada and the United States, there has been a growing interest in the sustainability of Forests and Forest Communities. Policy makers and scientists have attempted to understand how Forest management practices can enhance or harm the future of such Communities. Although many studies have historically used economic indicators as measures of community stability, more recently researchers have demonstrated that the relationship between Communities and Forests goes far beyond simple economic dependency. Thus, recent frameworks for assessing Forest Communities have also addressed the need for broader social and institutional components. In this article, we briefly review three of these recent concepts — community capacity, community well-being and community resiliency — and examine what each of these terms has to contribute to the assessment of Forest Communities. Key words: Forest community, community stability, community capacity, community well-being, community resilience
Elizabeth Toman - One of the best experts on this subject based on the ideXlab platform.
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Fuel reduction strategies in Forest Communities
Journal of Forestry, 2003Co-Authors: Bruce Shindler, Elizabeth TomanAbstract:This study uses panel data from a mail survey administered to the same individuals in 1996 and 2000 to measure change in public attitudes toward fire management programs on federal lands in eastern Oregon and Washington. Findings were generally similar between 1996 and 2000, but three noteworthy changes occurred over the four-year interval. First, the number of citizens who view smoke as a problem has risen. Second, citizens gave Forest Service information programs lower ratings and considered other sources of information more reliable. And finally, the relationship between the Forest Service and residents in the region appears to have eroded. Nevertheless, respondents continued to support prescribed fire and mechanized thinning for fuel reduction purposes in local Forests. [References: 24]
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Fuel Reduction Strategies in Forest Communities: A Longitudinal Analysis of Public Support
Journal of Forestry, 2003Co-Authors: Bruce Shindler, Elizabeth TomanAbstract:This study uses panel data from a mail survey administered to the same individuals in 1996 and 2000 to measure change in public attitudes toward fire management programs on federal lands in eastern Oregon and Washington. Findings were generally similar between 1996 and 2000, but three noteworthy changes occurred over the four-year interval. First, the number of citizens who view smoke as a problem has risen. Second, citizens gave Forest Service information programs lower ratings and considered other sources of information more reliable. And finally, the relationship between the Forest Service and residents in the region appears to have eroded. Nevertheless, respondents continued to support prescribed fire and mechanized thinning for fuel reduction purposes in local Forests.
Antoine Guisan - One of the best experts on this subject based on the ideXlab platform.
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improving generalized regression analysis for the spatial prediction of Forest Communities
Journal of Biogeography, 2006Co-Authors: Ramona Maggini, Anthony Lehmann, Niklaus E Zimmermann, Antoine GuisanAbstract:Aim This study used data from temperate Forest Communities to assess: (1) five different stepwise selection methods with generalized additive models, (2) the effect of weighting absences to ensure a prevalence of 0.5, (3) the effect of limiting absences beyond the environmental envelope defined by presences, (4) four different methods for incorporating spatial autocorrelation, and (5) the effect of integrating an interaction factor defined by a regression tree on the residuals of an initial environmental model. Location State of Vaud, western Switzerland. Methods Generalized additive models (GAMs) were fitted using the grasp package (generalized regression analysis and spatial predictions, http://www.cscf.ch/grasp). Results Model selection based on cross-validation appeared to be the best compromise between model stability and performance (parsimony) among the five methods tested. Weighting absences returned models that perform better than models fitted with the original sample prevalence. This appeared to be mainly due to the impact of very low prevalence values on evaluation statistics. Removing zeroes beyond the range of presences on main environmental gradients changed the set of selected predictors, and potentially their response curve shape. Moreover, removing zeroes slightly improved model performance and stability when compared with the baseline model on the same data set. Incorporating a spatial trend predictor improved model performance and stability significantly. Even better models were obtained when including local spatial autocorrelation. A novel approach to include interactions proved to be an efficient way to account for interactions between all predictors at once. Main conclusions Models and spatial predictions of 18 Forest Communities were significantly improved by using either: (1) cross-validation as a model selection method, (2) weighted absences, (3) limited absences, (4) predictors accounting for spatial autocorrelation, or (5) a factor variable accounting for interactions between all predictors. The final choice of model strategy should depend on the nature of the available data and the specific study aims. Statistical evaluation is useful in searching for the best modelling practice. However, one should not neglect to consider the shapes and interpretability of response curves, as well as the resulting spatial predictions in the final assessment.
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improving generalized regression analysis for the spatial prediction of Forest Communities
Science & Engineering Faculty, 2006Co-Authors: Ramona Maggini, Anthony Lehmann, Niklaus E Zimmermann, Antoine GuisanAbstract:Aim: This study used data from temperate Forest Communities to assess: (1) five different stepwise selection methods with generalized additive models, (2) the effect of weighting absences to ensure a prevalence of 0.5, (3) the effect of limiting absences beyond the environmental envelope defined by presences, (4) four different methods for incorporating spatial autocorrelation, and (5) the effect of integrating an interaction factor defined by a regression tree on the residuals of an initial environmental model. Location: State of Vaud, western Switzerland. Methods: Generalized additive models (GAMs) were fitted using the grasp package (generalized regression analysis and spatial predictions, http://www.cscf.ch/grasp). Results: Model selection based on cross-validation appeared to be the best compromise between model stability and performance (parsimony) among the five methods tested. Weighting absences returned models that perform better than models fitted with the original sample prevalence. This appeared to be mainly due to the impact of very low prevalence values on evaluation statistics. Removing zeroes beyond the range of presences on main environmental gradients changed the set of selected predictors, and potentially their response curve shape. Moreover, removing zeroes slightly improved model performance and stability when compared with the baseline model on the same data set. Incorporating a spatial trend predictor improved model performance and stability significantly. Even better models were obtained when including local spatial autocorrelation. A novel approach to include interactions proved to be an efficient way to account for interactions between all predictors at once. Main conclusions: Models and spatial predictions of 18 Forest Communities were significantly improved by using either: (1) cross-validation as a model selection method, (2) weighted absences, (3) limited absences, (4) predictors accounting for spatial autocorrelation, or (5) a factor variable accounting for interactions between all predictors. The final choice of model strategy should depend on the nature of the available data and the specific study aims. Statistical evaluation is useful in searching for the best modelling practice. However, one should not neglect to consider the shapes and interpretability of response curves, as well as the resulting spatial predictions in the final assessment. © 2006 The Authors.
Sarayudh Bunyavejchewin - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic turnover along local environmental gradients in tropical Forest Communities
Oecologia, 2016Co-Authors: Claire A Baldeck, Kyle E Harms, Joseph B Yavitt, Robert John, Benjamin L Turner, Steven W Kembel, Sumedha Madawala, Nimal Gunatilleke, Savitri Gunatilleke, Sarayudh BunyavejchewinAbstract:While the importance of local-scale habitat niches in shaping tree species turnover along environmental gradients in tropical Forests is well appreciated, relatively little is known about the influence of phylogenetic signal in species' habitat niches in shaping local community structure. We used detailed maps of the soil resource and topographic variation within eight 24-50 ha tropical Forest plots combined with species phylogenies created from the APG III phylogeny to examine how phylogenetic beta diversity (indicating the degree of phylogenetic similarity of two Communities) was related to environmental gradients within tropical tree Communities. Using distance-based redundancy analysis we found that phylogenetic beta diversity, expressed as either nearest neighbor distance or mean pairwise distance, was significantly related to both soil and topographic variation in all study sites. In general, more phylogenetic beta diversity within a Forest plot was explained by environmental variables this was expressed as nearest neighbor distance versus mean pairwise distance (3.0-10.3 % and 0.4-8.8 % of variation explained among plots, respectively), and more variation was explained by soil resource variables than topographic variables using either phylogenetic beta diversity metric. We also found that patterns of phylogenetic beta diversity expressed as nearest neighbor distance were consistent with previously observed patterns of niche similarity among congeneric species pairs in these plots. These results indicate the importance of phylogenetic signal in local habitat niches in shaping the phylogenetic structure of tropical tree Communities, especially at the level of close phylogenetic neighbors, where similarity in habitat niches is most strongly preserved.
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temporal variability of Forest Communities empirical estimates of population change in 4000 tree species
Ecology Letters, 2014Co-Authors: Sarayudh Bunyavejchewin, Ryan A Chisholm, Richard Condit, Abd K Rahman, Patrick J Baker, Yuyun Chen, George B Chuyong, H S Dattaraja, Stuart J DaviesAbstract:Long-term surveys of entire Communities of species are needed to measure fluctuations in natural populations and elucidate the mechanisms driving population dynamics and community assembly. We analysed changes in abundance of over 4000 tree species in 12 Forests across the world over periods of 6–28 years. Abundance fluctuations in all Forests are large and consistent with population dynamics models in which temporal environmental variance plays a central role. At some sites we identify clear environmental drivers, such as fire and drought, that could underlie these patterns, but at other sites there is a need for further research to identify drivers. In addition, cross-site comparisons showed that abundance fluctuations were smaller at species-rich sites, consistent with the idea that stable environmental conditions promote higher diversity. Much community ecology theory emphasises demographic variance and niche stabilisation; we encourage the development of theory in which temporal environmental variance plays a central role.
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habitat filtering across tree life stages in tropical Forest Communities
Proceedings of The Royal Society B: Biological Sciences, 2013Co-Authors: Claire A Baldeck, Kyle E Harms, Joseph B Yavitt, Robert John, Benjamin L Turner, Renato Valencia, Hugo Navarrete, Sarayudh Bunyavejchewin, Somboon KiratiprayoonAbstract:Tropical tree Communities are shaped by local-scale habitat heterogeneity in the form of topographic and edaphic variation, but the life-history stage at which habitat associations develop remains poorly understood. This is due, in part, to the fact that previous studies have not accounted for the widely disparate sample sizes (number of stems) that result when trees are divided into size classes. We demonstrate that the observed habitat structuring of a community is directly related to the number of individuals in the community. We then compare the relative importance of habitat heterogeneity to tree community structure for saplings, juveniles and adult trees within seven large (24–50 ha) tropical Forest dynamics plots while controlling for sample size. Changes in habitat structuring through tree life stages were small and inconsistent among life stages and study sites. Where found, these differences were an order of magnitude smaller than the findings of previous studies that did not control for sample size. Moreover, community structure and composition were very similar among tree sub-Communities of different life stages. We conclude that the structure of these tropical tree Communities is established by the time trees are large enough to be included in the census (1 cm diameter at breast height), which indicates that habitat filtering occurs during earlier life stages.
Kyle E Harms - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic turnover along local environmental gradients in tropical Forest Communities
Oecologia, 2016Co-Authors: Claire A Baldeck, Kyle E Harms, Joseph B Yavitt, Robert John, Benjamin L Turner, Steven W Kembel, Sumedha Madawala, Nimal Gunatilleke, Savitri Gunatilleke, Sarayudh BunyavejchewinAbstract:While the importance of local-scale habitat niches in shaping tree species turnover along environmental gradients in tropical Forests is well appreciated, relatively little is known about the influence of phylogenetic signal in species' habitat niches in shaping local community structure. We used detailed maps of the soil resource and topographic variation within eight 24-50 ha tropical Forest plots combined with species phylogenies created from the APG III phylogeny to examine how phylogenetic beta diversity (indicating the degree of phylogenetic similarity of two Communities) was related to environmental gradients within tropical tree Communities. Using distance-based redundancy analysis we found that phylogenetic beta diversity, expressed as either nearest neighbor distance or mean pairwise distance, was significantly related to both soil and topographic variation in all study sites. In general, more phylogenetic beta diversity within a Forest plot was explained by environmental variables this was expressed as nearest neighbor distance versus mean pairwise distance (3.0-10.3 % and 0.4-8.8 % of variation explained among plots, respectively), and more variation was explained by soil resource variables than topographic variables using either phylogenetic beta diversity metric. We also found that patterns of phylogenetic beta diversity expressed as nearest neighbor distance were consistent with previously observed patterns of niche similarity among congeneric species pairs in these plots. These results indicate the importance of phylogenetic signal in local habitat niches in shaping the phylogenetic structure of tropical tree Communities, especially at the level of close phylogenetic neighbors, where similarity in habitat niches is most strongly preserved.
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habitat filtering across tree life stages in tropical Forest Communities
Proceedings of The Royal Society B: Biological Sciences, 2013Co-Authors: Claire A Baldeck, Kyle E Harms, Joseph B Yavitt, Robert John, Benjamin L Turner, Renato Valencia, Hugo Navarrete, Sarayudh Bunyavejchewin, Somboon KiratiprayoonAbstract:Tropical tree Communities are shaped by local-scale habitat heterogeneity in the form of topographic and edaphic variation, but the life-history stage at which habitat associations develop remains poorly understood. This is due, in part, to the fact that previous studies have not accounted for the widely disparate sample sizes (number of stems) that result when trees are divided into size classes. We demonstrate that the observed habitat structuring of a community is directly related to the number of individuals in the community. We then compare the relative importance of habitat heterogeneity to tree community structure for saplings, juveniles and adult trees within seven large (24–50 ha) tropical Forest dynamics plots while controlling for sample size. Changes in habitat structuring through tree life stages were small and inconsistent among life stages and study sites. Where found, these differences were an order of magnitude smaller than the findings of previous studies that did not control for sample size. Moreover, community structure and composition were very similar among tree sub-Communities of different life stages. We conclude that the structure of these tropical tree Communities is established by the time trees are large enough to be included in the census (1 cm diameter at breast height), which indicates that habitat filtering occurs during earlier life stages.