The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
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.
Mark D Bertness - One of the best experts on this subject based on the ideXlab platform.
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small mammal herbivore control of Secondary Succession in new england tidal marshes
Ecology, 2009Co-Authors: Keryn B Gedan, Caitlin M Crain, Mark D BertnessAbstract:Secondary Succession is impacted by both biotic and abiotic forces, but their relative importance varies due to environmental drivers. Across estuarine salinity gradients, physical stress increases with salinity, and biotic stresses are greater at lower salinities. In southern New England tidal marshes spanning a landscape-scale salinity gradient, we experimentally examined the effects of physical stress and consumer pressure by mammalian herbivores on Secondary Succession in artificially created bare patches. Recovery was slower in marshes exposed to full-strength seawater, where physical stress is high. Compared to full-strength salt marshes, recovery in low-salinity marshes was much faster and was influenced by small-mammal consumers. At lower salinities, small mammals selectively ate and prevented the establishment of several native and two invasive, nuisance species (Typha angustifolia and Phragmites australis) but were unable to control the expansion of established P. australis stands. By controlling the establishment of competitively dominant species and the trajectory of Secondary Succession in low-salinity marshes, small mammals may play a cryptic keystone role in estuarine plant communities and are a critical, overlooked consideration in the conservation and management of estuarine marshes.
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Secondary Succession dynamics in estuarine marshes across landscape scale salinity gradients
Ecology, 2008Co-Authors: Caitlin M Crain, Lindsey K Albertson, Mark D BertnessAbstract:Secondary Succession plays a critical role in driving community structure in natural communities, yet how Succession dynamics vary with environmental context is generally unknown. We examined the importance of seedling and vegetative recruitment in the Secondary Succession of coastal marsh vegetation across a landscape-scale environmental stress gradient. Replicate bare patches were initiated in salt, brackish, and oligohaline marshes in Narragansett Bay, Rhode Island, USA, and allowed to recover unmanipulated or with colonizing seedlings or vegetative runners removed for three years. Seed dispersal and seed bank studies were conducted at the same sites. We found that rates of recovery were 3-10 times faster in brackish and oligohaline marshes than in salt marshes. The fast pace of recovery in oligohaline marshes was driven by seedling colonization, while recovery was dominated by vegetative runners in brackish marshes and by both seedlings and runners in salt marshes. Seed and seedling availability was much greater in oligohaline marshes with up to 24 times the seed bank density compared with salt marshes. In contrast to the facilitated Succession generally found in salt marshes, oligohaline marshes follow the tolerance model of Succession where numerous species colonize from seed and are slowly displaced by clonal grasses whose recovery is slowed by preemptive competition from seedlings, contributing to the higher species diversity of oligohaline marshes. These findings reveal fundamental differences in the dynamics and assembly of marsh plant communities along estuarine salinity gradients that are important for conceptually understanding wetlands and for guiding the management and restoration of various types of coastal marshes.
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Secondary Succession DYNAMICS IN ESTUARINE MARSHES ACROSS LANDSCAPE‐SCALE SALINITY GRADIENTS
Ecology, 2008Co-Authors: Caitlin M Crain, Lindsey K Albertson, Mark D BertnessAbstract:Secondary Succession plays a critical role in driving community structure in natural communities, yet how Succession dynamics vary with environmental context is generally unknown. We examined the importance of seedling and vegetative recruitment in the Secondary Succession of coastal marsh vegetation across a landscape-scale environmental stress gradient. Replicate bare patches were initiated in salt, brackish, and oligohaline marshes in Narragansett Bay, Rhode Island, USA, and allowed to recover unmanipulated or with colonizing seedlings or vegetative runners removed for three years. Seed dispersal and seed bank studies were conducted at the same sites. We found that rates of recovery were 3-10 times faster in brackish and oligohaline marshes than in salt marshes. The fast pace of recovery in oligohaline marshes was driven by seedling colonization, while recovery was dominated by vegetative runners in brackish marshes and by both seedlings and runners in salt marshes. Seed and seedling availability was much greater in oligohaline marshes with up to 24 times the seed bank density compared with salt marshes. In contrast to the facilitated Succession generally found in salt marshes, oligohaline marshes follow the tolerance model of Succession where numerous species colonize from seed and are slowly displaced by clonal grasses whose recovery is slowed by preemptive competition from seedlings, contributing to the higher species diversity of oligohaline marshes. These findings reveal fundamental differences in the dynamics and assembly of marsh plant communities along estuarine salinity gradients that are important for conceptually understanding wetlands and for guiding the management and restoration of various types of coastal marshes.
Jennifer S Powers - 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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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.
Yosio Edemir Shimabukuro - One of the best experts on this subject based on the ideXlab platform.
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assessing the extent of agriculture pasture and Secondary Succession forest in the brazilian legal amazon using spot vegetation data
Remote Sensing of Environment, 2006Co-Authors: Joao M B Carreiras, Jose M C Pereira, Manuel L Campagnolo, Yosio Edemir ShimabukuroAbstract:Abstract There has been growing concern about land use/land cover change in tropical regions, as there is evidence of its influence on the observed increase in atmospheric carbon dioxide concentration and consequent climatic changes. Mapping of deforestation by the Brazil's National Space Research Institute (INPE) in areas of primary tropical forest using satellite data indicates a value of 587,727 km 2 up to the year 2000. Although most of the efforts have been concentrated in mapping primary tropical forest deforestation, there is also evidence of large-scale deforestation in the cerrado savanna, the second most important biome in the region. The main purpose of this work was to assess the extent of agriculture/pasture and Secondary Succession forest in the Brazilian Legal Amazon (BLA) in 2000, using a set of multitemporal images from the 1-km SPOT-4 VEGETATION (VGT) sensor. Additionally, we discriminated primary tropical forest, cerrado savanna, and natural/artificial waterbodies. Four classification algorithms were tested: quadratic discriminant analysis (QDA), simple classification trees (SCT), probability-bagging classification trees (PBCT), and k -nearest neighbors (K-NN). The agriculture/pasture class is a surrogate for those areas cleared of its original vegetation cover in the past, acting as a source of carbon. On the contrary, the Secondary Succession forest class behaves as a sink of carbon. We used a time series of 12 monthly composite images of the year 2000, derived from the SPOT-4 VGT sensor. A set of 19 Landsat scenes was used to select training and testing data. A 10-fold cross validation procedure rated PBCT as the best classification algorithm, with an overall sample accuracy of 0.92. High omission and commission errors occurred in the Secondary Succession forest class, due to confusion with agriculture/pasture and primary tropical forest classes. However, the PBCT algorithm generated the lower misclassification error in this class. Besides, this algorithm yields information about class membership probability, with ∼80% of the pixels with class membership probability greater or equal than 0.8. The estimated total area of agriculture/pasture and Secondary Succession forest in 2000 in the BLA was 966 × 10 3 and 140 × 10 3 km 2 , respectively. Comparison with an existing land cover map indicates that agriculture/pasture occurred primarily in areas previously occupied by primary tropical forest (46%) and cerrado savanna (33%), and also in transition forest (19%), and other vegetation types (2%). This further confirms the existing evidence of extensive cerrado savanna conversion. This study also concludes that SPOT-4 VGT data are adequate for discriminating several major land cover types in tropical regions. Agriculture/pasture was mapped with errors of about 5%. Very high classification errors were associated with Secondary Succession forest, suggesting that a different methodology/sensor has to be used to address this difficult land cover class (namely with the inclusion of ancillary data). For the other classes, we consider that accurate maps can be derived from SPOT-4 VGT data with errors lower than 20% for the cerrado savanna, and errors lower than 10% for the other land cover classes. These estimates may be useful to evaluate impacts of land use/land cover change on the carbon and water cycles, biotic diversity, and soil degradation.
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Assessing the extent of agriculture/pasture and Secondary Succession forest in the Brazilian Legal Amazon using SPOT VEGETATION data
Remote Sensing of Environment, 2006Co-Authors: Joao M B Carreiras, Jose M C Pereira, Manuel L Campagnolo, Yosio Edemir ShimabukuroAbstract:Abstract There has been growing concern about land use/land cover change in tropical regions, as there is evidence of its influence on the observed increase in atmospheric carbon dioxide concentration and consequent climatic changes. Mapping of deforestation by the Brazil's National Space Research Institute (INPE) in areas of primary tropical forest using satellite data indicates a value of 587,727 km 2 up to the year 2000. Although most of the efforts have been concentrated in mapping primary tropical forest deforestation, there is also evidence of large-scale deforestation in the cerrado savanna, the second most important biome in the region. The main purpose of this work was to assess the extent of agriculture/pasture and Secondary Succession forest in the Brazilian Legal Amazon (BLA) in 2000, using a set of multitemporal images from the 1-km SPOT-4 VEGETATION (VGT) sensor. Additionally, we discriminated primary tropical forest, cerrado savanna, and natural/artificial waterbodies. Four classification algorithms were tested: quadratic discriminant analysis (QDA), simple classification trees (SCT), probability-bagging classification trees (PBCT), and k -nearest neighbors (K-NN). The agriculture/pasture class is a surrogate for those areas cleared of its original vegetation cover in the past, acting as a source of carbon. On the contrary, the Secondary Succession forest class behaves as a sink of carbon. We used a time series of 12 monthly composite images of the year 2000, derived from the SPOT-4 VGT sensor. A set of 19 Landsat scenes was used to select training and testing data. A 10-fold cross validation procedure rated PBCT as the best classification algorithm, with an overall sample accuracy of 0.92. High omission and commission errors occurred in the Secondary Succession forest class, due to confusion with agriculture/pasture and primary tropical forest classes. However, the PBCT algorithm generated the lower misclassification error in this class. Besides, this algorithm yields information about class membership probability, with ∼80% of the pixels with class membership probability greater or equal than 0.8. The estimated total area of agriculture/pasture and Secondary Succession forest in 2000 in the BLA was 966 × 10 3 and 140 × 10 3 km 2 , respectively. Comparison with an existing land cover map indicates that agriculture/pasture occurred primarily in areas previously occupied by primary tropical forest (46%) and cerrado savanna (33%), and also in transition forest (19%), and other vegetation types (2%). This further confirms the existing evidence of extensive cerrado savanna conversion. This study also concludes that SPOT-4 VGT data are adequate for discriminating several major land cover types in tropical regions. Agriculture/pasture was mapped with errors of about 5%. Very high classification errors were associated with Secondary Succession forest, suggesting that a different methodology/sensor has to be used to address this difficult land cover class (namely with the inclusion of ancillary data). For the other classes, we consider that accurate maps can be derived from SPOT-4 VGT data with errors lower than 20% for the cerrado savanna, and errors lower than 10% for the other land cover classes. These estimates may be useful to evaluate impacts of land use/land cover change on the carbon and water cycles, biotic diversity, and soil degradation.
Gonzalo Castillocampos - One of the best experts on this subject based on the ideXlab platform.
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bat diversity and abundance associated with the degree of Secondary Succession in a tropical forest mosaic in south eastern mexico
Animal Conservation, 2007Co-Authors: Alejandro A Castroluna, Vinicio J Sosa, Gonzalo CastillocamposAbstract:Under the hypothesis that bat diversity would be lower in the early stages of Secondary Succession and that species affected negatively by habitat modification would be more frequent in later Successional stages, we evaluated how bats use 12 vegetation stands representing four stages of Secondary Succession, following disturbance caused by slash-and-burn agriculture and selective logging. We compared bat richness, abundance and diversity, and found that none of these variables was different among stages or rainy seasons. However, of the 10 most common bat species, two were significantly more abundant in stands at the early stages of Secondary Succession, while the opposite was true for three other species. Canopy cover mainly explains these patterns. Rainy season had no effect on the abundance of the common species. The results of this study indicate that although some frugivorous species were very abundant in the younger stands, the majority of the rare species were captured in older stands. The absence of rare and habitatspecialized species from young Successional stages close to primary forest suggests that, for effective bat conservation in landscapes modified by human activity, areas with original vegetation should be maintained to ensure the survivorship of sensitive-to-deforestation species.
