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Thomas W. Gillespie - One of the best experts on this subject based on the ideXlab platform.
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Dry Forests of the galapagos a comparative assessment of a world heritage site
Pacific Conservation Biology, 2020Co-Authors: Thomas W. Gillespie, Gunnar Keppel, Chelsea Robinson, Gonzalo RivastorresAbstract:Despite worldwide knowledge of the importance of the Galapagos archipelago, there is little comparative plot data from the Forests in the Dry regions. We examined patterns of woody plant (≥2.5 cm diameter at breast height (DBH)) species richness and structure using Gentry’s transect method (0.1 ha) on the three largest islands in the Galapagos. We identified the conservation status of woody plants within the Dry forest region, assessed forest cover and change in the region, and compared field results to other tropical Dry Forests in the Pacific. Of the 22 species encountered (11 native, 11 endemic), there were no non-native species and only one threatened species. Isabela, Santa Cruz and San Cristobal have similar overall levels of species, genera, family and liana richness per site, but significantly different tree species richness, density and tree height per transect. Geospatial databases identified 51 species (native 40%, endemic 60%) of woody plants (≥2.5 cm DBH) within the Dry forest region of the Galapagos and 13 species (10 from the genus Scalesia) on the IUCN Red List. There is an estimated 551.97 km2 of Dry forest in the Galapagos and there has been little change (<0.01%) in forest cover from 2000 to 2015. Dry Forests of the Galapagos have similar levels of species richness to Hawaii and the Marquesas but contain lower densities, basal areas and tree heights than other Dry Forests in the Pacific. These Dry Forests appear to be the best preserved and protected tropical Dry forest in the Pacific.
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Dry Forests of the Galápagos: a comparative assessment of a World Heritage Site
Pacific Conservation Biology, 2020Co-Authors: Thomas W. Gillespie, Gunnar Keppel, Chelsea Robinson, Gonzalo Rivas-torresAbstract:Despite worldwide knowledge of the importance of the Galapagos archipelago, there is little comparative plot data from the Forests in the Dry regions. We examined patterns of woody plant (≥2.5 cm diameter at breast height (DBH)) species richness and structure using Gentry’s transect method (0.1 ha) on the three largest islands in the Galapagos. We identified the conservation status of woody plants within the Dry forest region, assessed forest cover and change in the region, and compared field results to other tropical Dry Forests in the Pacific. Of the 22 species encountered (11 native, 11 endemic), there were no non-native species and only one threatened species. Isabela, Santa Cruz and San Cristobal have similar overall levels of species, genera, family and liana richness per site, but significantly different tree species richness, density and tree height per transect. Geospatial databases identified 51 species (native 40%, endemic 60%) of woody plants (≥2.5 cm DBH) within the Dry forest region of the Galapagos and 13 species (10 from the genus Scalesia) on the IUCN Red List. There is an estimated 551.97 km2 of Dry forest in the Galapagos and there has been little change (
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Prioritizing conservation of tropical Dry Forests in the Pacific
Oryx, 2014Co-Authors: Thomas W. Gillespie, Kristin O'neill, Gunnar Keppel, Stephanie Pau, Jean-yves Meyer, Jonathan P. Price, Tanquy JaffréAbstract:AbstractTo identify Forests of high priority for conservation in tropical Dry Forests of New Caledonia, Fiji, the Marquesas and Hawaii, we examined patterns of woody plant species richness (total, native and endemic) and threatened species (IUCN categorization and density) at the stand level, using Gentry's transect method. There were associations between total, native and endemic plant species richness in all four Pacific Dry forest regions but we found no significant association with the presence or density of species listed on the IUCN Red List. Dry Forests in New Caledonia and Hawaii merit the highest conservation priority in the Pacific, based on level of endemism and number of threatened species. The study sites that merit high conservation priority are Metzdorf, Nekoro and Pindai, in New Caledonia, Kokee and Kaupulehu, in Hawaii, and Vatia, in Fiji. New Caledonia and Fiji have a small Dry forest extent and protected area extent compared with other Dry Forests in biodiversity hotspots. Although we identified priority areas for Dry forest conservation, more comparative plot data, presence/absence data in fragments and regional geographical data are needed to adequately manage and protect Dry Forests in the Pacific.
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Scaling species richness and endemism of tropical Dry Forests on oceanic islands
Diversity and Distributions, 2013Co-Authors: Thomas W. Gillespie, Gunnar Keppel, Stephanie Pau, Jonathan P. Price, Tanguy Jaffré, Kristin O'neillAbstract:Aim We examine variation in woody plant species richness and endemism within tropical Dry forest on oceanic islands and determine what climatic and biogeographic metrics best explain native species richness and endemism across archipelagos, islands and plots. Location Oceanic islands in the Pacific. Methods Stand-level sampling (0.1 ha) at 35 different Dry forest sites across 16 islands, and five archipelagos (New Caledonia, Fiji, Marquesas, Marianas and Hawaii). Descriptors of native species richness and endemism were calculated at the plot, island and archipelago level. Biogeographic and climate metrics at the archipelago, island and plot level were drawn from the literature and computer databases. The effects of biogeographic and climate metrics were investigated using linear mixed-effects models. Results Dry Forests of New Caledonia and Fiji had the highest native species richness, while New Caledonia and Hawaii had the highest endemism. Native species richness and endemism within tropical Dry Forests on oceanic islands are primarily influenced by biogeographic metrics, especially isolation of the archipelago, and not climatic metrics. Most variance in native species richness and endemism (60% and 64%) is at the archipelago level compared with the island (8%, 16%) and plot (32%, 15%) level. At the island level, species richness in tropical Dry forest is affected by precipitation, while island area significantly affects endemism. The area of forest fragments is an important predictor of native species richness and endemism in plots. Main conclusions Although Dry Forests in the Pacific have been exceptionally deforested and degraded, high native species richness and endemism remains in a number of forest fragments. Biogeographic metrics explain most of the variance in native species richness and endemism across scales, while climatic metrics are important at the island level. First-order assessments of native richness and endemism at the archipelago, island and stand-level are possible for forest types on oceanic archipelagos.
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Floristic Composition and Natural History Characteristics of Dry Forests in the Pacific
Pacific Science, 2011Co-Authors: Thomas W. Gillespie, Gunnar Keppel, Stephanie Pau, Jean-yves Meyer, Jonathan P. Price, Tanguy Jaffré, Kristin O'neillAbstract:We compare the floristic composition of tropical Dry Forests at the stand level using Gentry’s transect method (0.1 ha) in some of the largest and highest-quality remaining fragments in the Pacific (Hawai‘i, 15 sites; Fiji, 9; the Marianas, 3; the Marquesas, 6; New Caledonia, 7) and compare results with neotropical Dry Forests. A total of 299 species or morphospecies ≥2.5 cm diameter at breast height were identified from all 40 sites in the Pacific. Rubiaceae (28 spp.), Euphorbiaceae (25 spp.), Fabaceae (23 spp.), Sapindaceae (18 spp.), and Myrtaceae (17 spp.) were the most speciose families in Pacific Dry forest; however, no family dominated across regions in the Pacific. The most common species by frequency and density in each region were native with the exception of Hawai‘i, which contains a high number of nonnative species. Observed and estimated (Chao 2) levels of native species richness show that New Caledonia and Fiji contain the highest species richness followed by Hawai‘i, the Marianas, and the Marquesas. There is very little overlap at the native species level among regions, with Hawaiian Dry Forests the most dissimilar at the native species, genus, and family level and New Caledonia and Fiji the most similar. Unlike mainland neotropical Dry forest, Dry Forests in the Pacific contain very few deciduous species and a low proportion of wind-dispersed species. There is a high proportion of dioecious species in Hawai‘i, which is similar to the neotropics; however, other Pacific regions have fewer dioecious species.
Jennifer S Powers - One of the best experts on this subject based on the ideXlab platform.
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Will tropical Dry Forests be vulnerable to climate change, and what will be their social effects?
UNED Research Journal, 2019Co-Authors: Jennifer S PowersAbstract:Tropical Dry Forests provide societies with many valuable ecosystem services. These Forests are characterized by alternating rainy and Dry seasons. Changes to rainfall regimes are likely to negatively impact the internal dynamics of Dry Forests; at longer timescales, climate change may shift the geographical borders of Dry Forests. Society should establish policies and management practices such as reforestation with drought tolerant tree species to adapt to these changes now.
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unraveling the mechanisms underlying pulse dynamics of soil respiration in tropical Dry Forests
Environmental Research Letters, 2016Co-Authors: Bonnie G. Waring, Jennifer S PowersAbstract:Tropical Dry Forests are already undergoing changes in the quantity and timing of rainfall, but there is great uncertainty over how these shifts will affect belowground carbon (C) cycling. While it has long been known that Dry soils quickly release carbon dioxide (CO2) upon rewetting, the mechanisms underlying the so-called 'Birch effect' are still debated. Here, we quantified soil respiration pulses and their biotic predictors in response to simulated precipitation events in a regenerating tropical Dry forest in Costa Rica. We also simulated the observed rewetting CO2 pulses with two soil carbon models: a conventional model assuming first-order decay rates of soil organic matter, and an enzyme-catalyzed model with Michaelis–Menten kinetics. We found that rewetting of Dry soils produced an immediate and dramatic pulse of CO2, accompanied by rapid immobilization of nitrogen into the microbial biomass. However, the magnitude of the rewetting CO2 pulse was highly variable at fine spatial scales, and was well correlated with the size of the dissolved organic C pool prior to rewetting. Both the enzyme-catalyzed and conventional models were able to reproduce the Birch effect when respiration was coupled directly to microbial C uptake, although models differed in their ability to yield realistic estimates of SOC and microbial biomass pool sizes and dynamics. Our results suggest that changes in the timing and intensity of rainfall events in tropical Dry Forests will exert strong influence on ecosystem C balance by affecting the dynamics of microbial biomass growth.
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resilience of tropical Dry Forests a meta analysis of changes in species diversity and composition during secondary succession
Oikos, 2016Co-Authors: Géraldine Derroire, Patricia Balvanera, Carolina Castellanoscastro, Guillaume Decocq, Deborah Kennard, Edwin Lebrijatrejos, Jorge A Leiva, Per Christer Oden, Jennifer S PowersAbstract:Assessing the recovery of species diversity and composition after major disturbance is key to understanding the resilience of tropical Forests through successional processes, and its importance for biodiversity conservation. Despite the specific abiotic environment and ecological processes of tropical Dry Forests, secondary succession has received less attention in this biome than others and changes in species diversity and composition have never been synthesised in a systematic and quantitative review. This study aims to assess in tropical Dry Forests 1) the directionality of change in species richness and evenness during secondary succession, 2) the convergence of species composition towards that of old-growth forest and 3) the importance of the previous land use, precipitation regime and water availability in influencing the direction and rate of change. We conducted meta-analyses of the rate of change in species richness, evenness and composition indices with succession in 13 tropical Dry forest chronosequences. Species richness increased with succession, showing a gradual accumulation of species, as did Shannon evenness index. The similarity in species composition of successional Forests with old-growth Forests increased with succession, yet at a low rate. Tropical Dry Forests therefore do show resilience of species composition but it may never reach that of old-growth Forests. We found no significant differences in rates of change between different previous land uses, precipitation regimes or water availability. Our results show high resilience of tropical Dry Forests in term of species richness but a slow recovery of species composition. They highlight the need for further research on secondary succession in this biome and better understanding of impacts of previous land-use and landscape-scale patterns.
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Resilience of tropical Dry Forests – a meta‐analysis of changes in species diversity and composition during secondary succession
Oikos, 2016Co-Authors: Géraldine Derroire, Patricia Balvanera, Guillaume Decocq, Deborah Kennard, Jorge A Leiva, Per Christer Oden, Jennifer S Powers, Carolina Castellanos-castro, Edwin Lebrija-trejos, Victor Rico-grayAbstract:Assessing the recovery of species diversity and composition after major disturbance is key to understanding the resilience of tropical Forests through successional processes, and its importance for biodiversity conservation. Despite the specific abiotic environment and ecological processes of tropical Dry Forests, secondary succession has received less attention in this biome than others and changes in species diversity and composition have never been synthesised in a systematic and quantitative review. This study aims to assess in tropical Dry Forests 1) the directionality of change in species richness and evenness during secondary succession, 2) the convergence of species composition towards that of old-growth forest and 3) the importance of the previous land use, precipitation regime and water availability in influencing the direction and rate of change. We conducted meta-analyses of the rate of change in species richness, evenness and composition indices with succession in 13 tropical Dry forest chronosequences. Species richness increased with succession, showing a gradual accumulation of species, as did Shannon evenness index. The similarity in species composition of successional Forests with old-growth Forests increased with succession, yet at a low rate. Tropical Dry Forests therefore do show resilience of species composition but it may never reach that of old-growth Forests. We found no significant differences in rates of change between different previous land uses, precipitation regimes or water availability. Our results show high resilience of tropical Dry Forests in term of species richness but a slow recovery of species composition. They highlight the need for further research on secondary succession in this biome and better understanding of impacts of previous land-use and landscape-scale patterns.
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scale dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical Dry Forests
New Phytologist, 2016Co-Authors: Bonnie G. Waring, Rachel I Adams, Sara Branco, Jennifer S PowersAbstract:Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical Dry Forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling.
Géraldine Derroire - One of the best experts on this subject based on the ideXlab platform.
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resilience of tropical Dry Forests a meta analysis of changes in species diversity and composition during secondary succession
Oikos, 2016Co-Authors: Géraldine Derroire, Patricia Balvanera, Carolina Castellanoscastro, Guillaume Decocq, Deborah Kennard, Edwin Lebrijatrejos, Jorge A Leiva, Per Christer Oden, Jennifer S PowersAbstract:Assessing the recovery of species diversity and composition after major disturbance is key to understanding the resilience of tropical Forests through successional processes, and its importance for biodiversity conservation. Despite the specific abiotic environment and ecological processes of tropical Dry Forests, secondary succession has received less attention in this biome than others and changes in species diversity and composition have never been synthesised in a systematic and quantitative review. This study aims to assess in tropical Dry Forests 1) the directionality of change in species richness and evenness during secondary succession, 2) the convergence of species composition towards that of old-growth forest and 3) the importance of the previous land use, precipitation regime and water availability in influencing the direction and rate of change. We conducted meta-analyses of the rate of change in species richness, evenness and composition indices with succession in 13 tropical Dry forest chronosequences. Species richness increased with succession, showing a gradual accumulation of species, as did Shannon evenness index. The similarity in species composition of successional Forests with old-growth Forests increased with succession, yet at a low rate. Tropical Dry Forests therefore do show resilience of species composition but it may never reach that of old-growth Forests. We found no significant differences in rates of change between different previous land uses, precipitation regimes or water availability. Our results show high resilience of tropical Dry Forests in term of species richness but a slow recovery of species composition. They highlight the need for further research on secondary succession in this biome and better understanding of impacts of previous land-use and landscape-scale patterns.
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Secondary succession in tropical Dry Forests
2016Co-Authors: Géraldine DerroireAbstract:Secondary succession is a complex process involving numerous factors acting across scales. Understanding secondary succession in tropical Dry Forests is important for the conservation and restoration of this highly threatened biome. My research aims to improve knowledge of the trajectories and drivers of secondary succession in this biome, and the underlying mechanisms. I used a combination of literature synthesis, observational and experimental approaches to study plant-plant interactions and community changes during succession. Through review of published studies, I showed that established trees have a mainly positive effect on the seed dispersal, survival and germination of the subsequent generation of woody plants. However, the balance between positive and negative effects is more complex at the seedling establishment stage and can be influenced by the precipitation regime. Meta-analyses of chronosequence studies showed an increase in tree and shrub species richness with succession and a slow convergence of successional forest species composition with that of old-growth Forests. Using survey of young woody plants establishing under isolated trees in pastures, I showed that the attributes of the trees influence the functional composition of the regeneration assemblages but are only weakly related to their taxonomic composition. The position of isolated trees in the landscape is also influential, but this is complex and site-specific. Through extensive sampling of leaf functional traits of sapling communities in secondary Forests of different successional age, I found that community functional composition shifts from conservative towards acquisitive strategies of resource economics, through both species turnover and intraspecific variation of trait values. Five of the measured traits also showed directional changes with tree ontogeny. Lastly, an experimental test of seed fate showed that leaf litter reduced seed removal in successional Forests. Seed germination rate was higher in successional Forests compared with open sites and generally benefited from the presence of litter. Overall, this research suggests a higher predictability of successional trajectories when studied through functional rather than taxonomic composition. It also shows heterogeneity in successional trajectories among tropical Dry Forests that require further study.
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Resilience of tropical Dry Forests – a meta‐analysis of changes in species diversity and composition during secondary succession
Oikos, 2016Co-Authors: Géraldine Derroire, Patricia Balvanera, Guillaume Decocq, Deborah Kennard, Jorge A Leiva, Per Christer Oden, Jennifer S Powers, Carolina Castellanos-castro, Edwin Lebrija-trejos, Victor Rico-grayAbstract:Assessing the recovery of species diversity and composition after major disturbance is key to understanding the resilience of tropical Forests through successional processes, and its importance for biodiversity conservation. Despite the specific abiotic environment and ecological processes of tropical Dry Forests, secondary succession has received less attention in this biome than others and changes in species diversity and composition have never been synthesised in a systematic and quantitative review. This study aims to assess in tropical Dry Forests 1) the directionality of change in species richness and evenness during secondary succession, 2) the convergence of species composition towards that of old-growth forest and 3) the importance of the previous land use, precipitation regime and water availability in influencing the direction and rate of change. We conducted meta-analyses of the rate of change in species richness, evenness and composition indices with succession in 13 tropical Dry forest chronosequences. Species richness increased with succession, showing a gradual accumulation of species, as did Shannon evenness index. The similarity in species composition of successional Forests with old-growth Forests increased with succession, yet at a low rate. Tropical Dry Forests therefore do show resilience of species composition but it may never reach that of old-growth Forests. We found no significant differences in rates of change between different previous land uses, precipitation regimes or water availability. Our results show high resilience of tropical Dry Forests in term of species richness but a slow recovery of species composition. They highlight the need for further research on secondary succession in this biome and better understanding of impacts of previous land-use and landscape-scale patterns.
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Secondary succession in tropical Dry Forests : drivers and mechanisms of forest regeneration
2016Co-Authors: Géraldine DerroireAbstract:Secondary succession is a complex process involving numerous factors acting across scales. Understanding secondary succession in tropical Dry Forests is important for the conservation and restoration of this highly threatened biome. My research aims to improve knowledge of the trajectories and drivers of secondary succession in this biome, and the underlying mechanisms. I used a combination of literature synthesis, observational and experimental approaches to study plant-plant interactions and community changes during succession. Through review of published studies, I showed that established trees have a mainly positive effect on the seed dispersal, survival and germination of the subsequent generation of woody plants. However, the balance between positive and negative effects is more complex at the seedling establishment stage and can be influenced by the precipitation regime. Metaanalyses of chronosequence studies showed an increase in tree and shrub species richness with succession and a slow convergence of successional forest species composition with that of old-growth Forests. Using survey of young woody plants establishing under isolated trees in pastures, I showed that the attributes of the trees influence the functional composition of the regeneration assemblages but are only weakly related to their taxonomic composition. The position of isolated trees in the landscape is also influential, but this is complex and sitespecific. Through extensive sampling of leaf functional traits of sapling communities in secondary Forests of different successional age, I found that community functional composition shifts from conservative towards acquisitive strategies of resource economics, through both species turnover and intraspecific variation of trait values. Five of the measured traits also showed directional changes with tree ontogeny. Lastly, an experimental test of seed fate showed that leaf litter reduced seed removal in successional Forests. Seed germination rate was higher in successional Forests compared with open sites and generally benefited from the presence of litter. Overall, this research suggests a higher predictability of successional trajectories when studied through functional rather than taxonomic omposition. It also shows heterogeneity in successional trajectories among tropical Dry Forests that require further study.
G. Arturo Sánchez-azofeifa - One of the best experts on this subject based on the ideXlab platform.
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Phyllostomid bat occurence in successional stages of neotropical Dry Forests
PLoS ONE, 2014Co-Authors: Luis Daniel Avila-cabadilla, Jafet M. Nassar, Kathryn E. Stoner, Mariana Yolotl Alvarez-añorve, Mário M. Espírito-santo, Carla I. Aranguren, Mickaël Henry, José A. Gonzalez-carcacia, Luiz A. Dolabela Falcao, G. Arturo Sánchez-azofeifaAbstract:Tropical Dry Forests (TDFs) are highly endangered tropical ecosystems being replaced by a complex mosaic of patches of different successional stages, agricultural fields and pasturelands. In this context, it is urgent to understand how taxa playing critical ecosystem roles respond to habitat modification. Because Phyllostomid bats provide important ecosystem services (e.g. facilitate gene flow among plant populations and promote forest regeneration), in this study we aimed to identify potential patterns on their response to TDF transformation in sites representing four different successional stages (initial, early, intermediate and late) in three Neotropical regions: México, Venezuela and Brazil. We evaluated bat occurrence at the species, ensemble (abundance) and assemblage level (species richness and composition, guild composition). We also evaluated how bat occurrence was modulated by the marked seasonality of TDFs. In general, we found high seasonal and regional specificities in phyllostomid occurrence, driven by specificities at species and guild levels. For example, highest frugivore abundance occurred in the early stage of the moistest TDF, while highest nectarivore abundance occurred in the same stage of the driest TDF. The high regional specificity of phyllostomid responses could arise from: (1) the distinctive environmental conditions of each region, (2) the specific behavior and ecological requirements of the regional bat species, (3) the composition, structure and phenological patterns of plant assemblages in the different stages, and (4) the regional landscape composition and configuration. We conclude that, in tropical seasonal environments, it is imperative to perform long-term studies considering seasonal variations in environmental conditions and plant phenology, as well as the role of landscape attributes. This approach will allow us to identify potential patterns in bat responses to habitat modification, which constitute an invaluable tool for not only bat biodiversity conservation but also for the conservation of the key ecological processes they provide.
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Succession and management of tropical Dry Forests in the Americas: review and new perspectives.
Forest Ecology and Management, 2009Co-Authors: Mauricio Quesada, G. Arturo Sánchez-azofeifa, Kathryn E. Stoner, Alicia Castillo, Julio Calvo-alvarado, Mariana Yolotl Alvarez-añorve, Luis Daniel Avila-cabadilla, Mário M. Espírito-santo, Marcílio Fagundes, Geraldo Wilson FernandesAbstract:Understanding tropical forest succession is critical for the development of tropical forest conservation strategies worldwide, given that tropical secondary Forests can be considered the Forests of the future. Tropical Dry Forests (TDF) are among the most threatened tropical ecosystems, there are more secondary Forests and forest restoration efforts that require a better understanding of successional processes. The main goal of this synthesis for this special issue on the ecology and management of tropical Dry Forests in the Americas is to present a summarized review of the current knowledge of the ecology and management implications associated to TDF succession. We explore specific issues associated to tropical Dry forest succession with emphasis on the use of chronosequences, plant diversity and composition, plant phenology and remote sensing, pollination, and animal-plant interactions; all under the integrating umbrella of ecosystem succession. We also emphasize the need to conduct socio-ecological research to understand changes in land-use history and its effects on succession and forest regeneration of TDF. We close this paper with some thoughts and ideas associated with the strong need for an integrating dimension not considered until today: the role of cyberinfrastructure and eco-informatics as a tool to support sound conservation, management and understanding of TDF in the Americas.
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Ecology and regeneration of tropical Dry Forests in the Americas: Implications for management
Forest Ecology and Management, 2009Co-Authors: Kathryn E. Stoner, G. Arturo Sánchez-azofeifaAbstract:Abstract Dry Forests represent the most endangered ecosystem in tropical regions and continue to be one of the most sought after environments for human colonization, development and production. In spite of this, Dry Forests are one of the least well studied tropical habitats. This special issue is dedicated to reviewing much of the information that exists about tropical Dry forest in the Americas. The introduction summarizes the articles presented herein, highlighting management strategies that are suggested throughout the special issue that may be useful for conserving tropical Dry forest environments.
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Research priorities for neotropical Dry Forests
Biotropica, 2005Co-Authors: G. Arturo Sánchez-azofeifa, Mauricio Quesada, Jon Paul Rodríguez, Jafet M. Nassar, Kathryn E. Stoner, Alicia Castillo, Theresa Garvin, Egleé L. Zent, Julio Calvo-alvarado, Margaret KalacskaAbstract:Our understanding of the human and biophysical dimensions of tropical Dry forest change and its cumulative effects is still in the early stages of academic discovery. The papers in this special section on Neotropical Dry Forests cover a wide range of sites and problems ranging from the use of multispectral and hyperspectral remote sensing platforms to the impact of hurricanes on tropical Dry forest regeneration. Here, we present to the scientific community the results of a workshop on which research priorities for tropical Dry Forests were discussed. This discussion focuses on the need to develop linkages between remote sensing, ecological, and social science research. The incorporation of social sciences into ecological research could contribute dramatically to our understandings of tropical Dry Forests by providing important contextual information to ecologists, and by helping to develop an important science–policy–public nexus on which environmental management can succeed. RESUMEN El conocimiento actual de las dimensiones humanas y biofisicas de los cambios en los bosque secos tropicales y sus efectos acumulativos esta en las etapas iniciales del descubrimiento academico. En este articulo, introducimos una serie de articulos cientificos asociados a este numero especial sobre bosques secos en los Neotropicos. Estos articulos provienen de una distribucion muy variada de sitios en las Americas y van desde las aplicaciones de sensores multi- e hiperspectrales, hasta el estudio del efecto que los huracanes causan en la regeneracion de los bosques secos. Presentamos a la comunidad cientifica los resultados de un taller dirigido a la discusion de aquellas prioridades de investigacion en bosques secos. La discusion se enfoca a lo largo de los vinculos que se necesitan entre percepcion remota, ecologia y ciencias sociales. La incorporacion las ciencias sociales dentro de la investigacion ecologica podria contribuir dramaticamente al entendimiento de los bosque secos tropicales, asi como tienen len a posibilidad de ayudar en el desarrollo de vinculos importantes entre ciencia y politica dirigida al manejo de los recursos presentes en este importante ecosistema.
William L Baker - One of the best experts on this subject based on the ideXlab platform.
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spatially extensive reconstructions show variable severity fire and heterogeneous structure in historical western united states Dry Forests
Global Ecology and Biogeography, 2012Co-Authors: Mark A Williams, William L BakerAbstract:Aim Wildfire is often considered more severe now than historically in Dry Forests of the western United States. Tree-ring reconstructions, which suggest that historical Dry Forests were park-like with large, old trees maintained by low-severity fires, are from small, scattered studies. To overcome this limitation, we developed spatially comprehensive reconstructions across 927,000 ha in four landscapes, using a new method based on land surveys from c. 1880. Location Dry Forests of the western United States. Methods We reconstructed forest structure for four large Dry-forest landscapes using forest descriptions and tree data from historical land surveys. Using multiple elements of historical forest structure from this study along with corroborating information from tree-ring studies, we were able to interpret past forest dynamics. Hypotheses concerning historical structure and dynamics were then tested. Results These reconstructions show that Dry Forests were structurally variable, containing from 20 to over 1000 trees ha -1 and some dense understoreys of shrubs and small trees. Park-like stands of large trees maintained by low-severity fire predominated only in parts of the study landscapes. Only 3, 12, 40 and 62% of the four landscapes fit a low-severity fire model; 38‐97% had evidence of higherseverity (mixed- and high-severity) fire. Some large modern wildfires (e.g. RodeoChediski), perceived as catastrophic, had fire severity congruent with historical variability.
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implications of spatially extensive historical data from surveys for restoring Dry Forests of oregon s eastern cascades
Ecosphere, 2012Co-Authors: William L BakerAbstract:Dry western Forests (e.g., ponderosa pine and mixed conifer) were thought to have been historically old and park-like, maintained by low-severity fires, and to have become denser and more prone to high-severity fire. In the Pacific Northwest, early aerial photos (primarily in Washington), showed that Dry Forests instead had variable-severity fires and forest structure, but more detail is needed. Here I used pre-1900 General Land Office Surveys, with new methods that allow accurate reconstruction of detailed forest structure, to test eight hypotheses about historical structure and fire across about 400,000 ha of Dry Forests in Oregon's eastern Cascades. The reconstructions show that only about 13.5% of these Forests had low tree density. Forests instead were generally dense (mean = 249 trees/ha), but density varied by a factor of 2–4 across about 25,000-ha areas. Shade-tolerant firs historically were 17% of trees, dominated about 12% of forest area, and were common in forest understories. Understory trees and shrubs dominated on 83.5%, and were dense across 44.8% of forest area. Small trees (10–40 cm dbh) were >50% of trees across 72.3% of forest area. Low-severity fire dominated on only 23.5%, mixed-severity fire on 50.2%, and high-severity fire on 26.2% of forest area. Historical fire included modest-rotation (29–78 years) low-severity and long-rotation (435 years) high-severity fire. Given historical variability in fire and forest structure, an ecological approach to restoration would restore fuels and manage for variable-severity fires, rather than reduce fuels to lower fire risk. Modest reduction in white fir/grand fir and an increase in large snags, down wood, and large trees would enhance recovery from past extensive logging and increase resiliency to future global change. These Forests can be maintained by wildland fire use, coupled, near infrastructure, with prescribed fires that mimic historical low-severity fires.
