Philosophical Transactions of the Royal Society B: Biological Sciences, 2013
A mosaic of protected areas, including indigenous lands, sustainable-use production forests and r... more A mosaic of protected areas, including indigenous lands, sustainable-use production forests and reserves and strictly protected forests is the cornerstone of conservation in the Amazon, with almost 50 per cent of the region now protected. However, recent research indicates that isolation from direct deforestation or degradation may not be sufficient to maintain the ecological integrity of Amazon forests over the next several decades. Large-scale changes in fire and drought regimes occurring as a result of deforestation and greenhouse gas increases may result in forest degradation, regardless of protected status. How severe or widespread these feedbacks will be is uncertain, but the arc of deforestation in south-southeastern Amazonia appears to be particularly vulnerable owing to high current deforestation rates and ecological sensitivity to climate change. Maintaining forest ecosystem integrity may require significant strengthening of forest conservation on private property, which can in part be accomplished by leveraging existing policy mechanisms.
ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. ... more ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. The sensitivity of this system to natural and anthropogenic disturbances therefore has important implications for the global climate. Some global models have predicted large-scale forest dieback and the savannization of Amazonia over the next century [Meehl et al., 2007]. While several studies have demonstrated the sensitivity of dynamic global vegetation models to changes in temperature, precipitation, and dry season length [e.g. Galbraith et al., 2010; Good et al., 2011], the ability of these models to accurately reproduce ecosystem dynamics of present-day transitional or low biomass tropical forests has not been demonstrated. A model-data intercomparison was conducted with four state-of-the-art terrestrial ecosystem models to evaluate the ability of these models to accurately represent structure, function, and long-term biomass dynamics over a range of Amazonian ecosystems. Each modeling group conducted a series of simulations for 14 sites including mature forest, transitional forest, savannah, and agricultural/pasture sites. All models were run using standard physical parameters and the same initialization procedure. Model results were compared against forest inventory and dendrometer data in addition to flux tower measurements. While the models compared well against field observations for the mature forest sites, significant differences were observed between predicted and measured ecosystem structure and dynamics for the transitional forest and savannah sites. The length of the dry season and soil sand content were good predictors of model performance. In addition, for the big leaf models, model performance was highest for sites dominated by late successional trees and lowest for sites with predominantly early and mid-successional trees. This study provides insight into tropical forest function and sensitivity to environmental conditions that will aid in predictions of the response of the Amazonian rainforest to future anthropogenically induced changes.
As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivit... more As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivity. Precipitation across the basin is predicted to decline as global climate change and regional land transformation continue through this century. This study evaluated predictions of site-level gross, net and component ecosystem C-fluxes by five land-surface models (ED2, IBIS, JULES, CLM3. 5, SiB3) and one site-specific carbon and hydrodynamic model (SPA) for two Brazilian Amazon rainforests (Tapajos and Caxiuana National ...
Determining whether the terrestrial biosphere will act as a sink or source of carbon in the futur... more Determining whether the terrestrial biosphere will act as a sink or source of carbon in the future is crucial for understanding the feedbacks that will affect future global warming. To this end, a growing number of GCMs now include interactive global carbon cycle models (Friedlingstein et al., J. Clim. 19, 2006). To allow for the prediction of net CO2 fluxes
ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. ... more ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. The sensitivity of this system to natural and anthropogenic disturbances therefore has important implications for the global climate. Some global models have predicted large-scale forest dieback and the savannization of Amazonia over the next century [Meehl et al., 2007]. While several studies have demonstrated the sensitivity of dynamic global vegetation models to changes in temperature, precipitation, and dry season length [e.g. Galbraith et al., 2010; Good et al., 2011], the ability of these models to accurately reproduce ecosystem dynamics of present-day transitional or low biomass tropical forests has not been demonstrated. A model-data intercomparison was conducted with four state-of-the-art terrestrial ecosystem models to evaluate the ability of these models to accurately represent structure, function, and long-term biomass dynamics over a range of Amazonian ecosystems. Each modeling group conducted a series of simulations for 14 sites including mature forest, transitional forest, savannah, and agricultural/pasture sites. All models were run using standard physical parameters and the same initialization procedure. Model results were compared against forest inventory and dendrometer data in addition to flux tower measurements. While the models compared well against field observations for the mature forest sites, significant differences were observed between predicted and measured ecosystem structure and dynamics for the transitional forest and savannah sites. The length of the dry season and soil sand content were good predictors of model performance. In addition, for the big leaf models, model performance was highest for sites dominated by late successional trees and lowest for sites with predominantly early and mid-successional trees. This study provides insight into tropical forest function and sensitivity to environmental conditions that will aid in predictions of the response of the Amazonian rainforest to future anthropogenically induced changes.
The ICESAT mission has acquired lidar measurements of land surface vertical structure for several... more The ICESAT mission has acquired lidar measurements of land surface vertical structure for several years. Although these have severely limited spatio-temporal resolutions and coverages, they nonetheless are the only consistent, global data of this kind. Our earlier work has linked airborne lidar measurements with a height-structured ecosystem model, the Ecosystem Demography (ED) model for modeling local (10's of kilometers) carbon
... large portion of the landscape enabling the georeferencing of the landscape with remote ... i... more ... large portion of the landscape enabling the georeferencing of the landscape with remote ... importance of these factors at la Selva. We first examined the potential effects of slope ... height sensitivity at La Selva (Peterson 2000) and was thus difficult to evaluate in terms of importance. ...
As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivit... more As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivity. Precipitation across the basin is predicted to decline as global climate change and regional land transformation continue through this century. This study evaluated predictions of site-level gross, net and component ecosystem C-fluxes by five land-surface models (ED2, IBIS, JULES, CLM3. 5, SiB3) and one site-specific carbon and hydrodynamic model (SPA) for two Brazilian Amazon rainforests (Tapajos and Caxiuana National ...
Philosophical Transactions of the Royal Society B: Biological Sciences, 2013
A mosaic of protected areas, including indigenous lands, sustainable-use production forests and r... more A mosaic of protected areas, including indigenous lands, sustainable-use production forests and reserves and strictly protected forests is the cornerstone of conservation in the Amazon, with almost 50 per cent of the region now protected. However, recent research indicates that isolation from direct deforestation or degradation may not be sufficient to maintain the ecological integrity of Amazon forests over the next several decades. Large-scale changes in fire and drought regimes occurring as a result of deforestation and greenhouse gas increases may result in forest degradation, regardless of protected status. How severe or widespread these feedbacks will be is uncertain, but the arc of deforestation in south-southeastern Amazonia appears to be particularly vulnerable owing to high current deforestation rates and ecological sensitivity to climate change. Maintaining forest ecosystem integrity may require significant strengthening of forest conservation on private property, which can in part be accomplished by leveraging existing policy mechanisms.
ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. ... more ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. The sensitivity of this system to natural and anthropogenic disturbances therefore has important implications for the global climate. Some global models have predicted large-scale forest dieback and the savannization of Amazonia over the next century [Meehl et al., 2007]. While several studies have demonstrated the sensitivity of dynamic global vegetation models to changes in temperature, precipitation, and dry season length [e.g. Galbraith et al., 2010; Good et al., 2011], the ability of these models to accurately reproduce ecosystem dynamics of present-day transitional or low biomass tropical forests has not been demonstrated. A model-data intercomparison was conducted with four state-of-the-art terrestrial ecosystem models to evaluate the ability of these models to accurately represent structure, function, and long-term biomass dynamics over a range of Amazonian ecosystems. Each modeling group conducted a series of simulations for 14 sites including mature forest, transitional forest, savannah, and agricultural/pasture sites. All models were run using standard physical parameters and the same initialization procedure. Model results were compared against forest inventory and dendrometer data in addition to flux tower measurements. While the models compared well against field observations for the mature forest sites, significant differences were observed between predicted and measured ecosystem structure and dynamics for the transitional forest and savannah sites. The length of the dry season and soil sand content were good predictors of model performance. In addition, for the big leaf models, model performance was highest for sites dominated by late successional trees and lowest for sites with predominantly early and mid-successional trees. This study provides insight into tropical forest function and sensitivity to environmental conditions that will aid in predictions of the response of the Amazonian rainforest to future anthropogenically induced changes.
As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivit... more As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivity. Precipitation across the basin is predicted to decline as global climate change and regional land transformation continue through this century. This study evaluated predictions of site-level gross, net and component ecosystem C-fluxes by five land-surface models (ED2, IBIS, JULES, CLM3. 5, SiB3) and one site-specific carbon and hydrodynamic model (SPA) for two Brazilian Amazon rainforests (Tapajos and Caxiuana National ...
Determining whether the terrestrial biosphere will act as a sink or source of carbon in the futur... more Determining whether the terrestrial biosphere will act as a sink or source of carbon in the future is crucial for understanding the feedbacks that will affect future global warming. To this end, a growing number of GCMs now include interactive global carbon cycle models (Friedlingstein et al., J. Clim. 19, 2006). To allow for the prediction of net CO2 fluxes
ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. ... more ABSTRACT The Amazonian rainforests play a vital role in global water, energy and carbon cycling. The sensitivity of this system to natural and anthropogenic disturbances therefore has important implications for the global climate. Some global models have predicted large-scale forest dieback and the savannization of Amazonia over the next century [Meehl et al., 2007]. While several studies have demonstrated the sensitivity of dynamic global vegetation models to changes in temperature, precipitation, and dry season length [e.g. Galbraith et al., 2010; Good et al., 2011], the ability of these models to accurately reproduce ecosystem dynamics of present-day transitional or low biomass tropical forests has not been demonstrated. A model-data intercomparison was conducted with four state-of-the-art terrestrial ecosystem models to evaluate the ability of these models to accurately represent structure, function, and long-term biomass dynamics over a range of Amazonian ecosystems. Each modeling group conducted a series of simulations for 14 sites including mature forest, transitional forest, savannah, and agricultural/pasture sites. All models were run using standard physical parameters and the same initialization procedure. Model results were compared against forest inventory and dendrometer data in addition to flux tower measurements. While the models compared well against field observations for the mature forest sites, significant differences were observed between predicted and measured ecosystem structure and dynamics for the transitional forest and savannah sites. The length of the dry season and soil sand content were good predictors of model performance. In addition, for the big leaf models, model performance was highest for sites dominated by late successional trees and lowest for sites with predominantly early and mid-successional trees. This study provides insight into tropical forest function and sensitivity to environmental conditions that will aid in predictions of the response of the Amazonian rainforest to future anthropogenically induced changes.
The ICESAT mission has acquired lidar measurements of land surface vertical structure for several... more The ICESAT mission has acquired lidar measurements of land surface vertical structure for several years. Although these have severely limited spatio-temporal resolutions and coverages, they nonetheless are the only consistent, global data of this kind. Our earlier work has linked airborne lidar measurements with a height-structured ecosystem model, the Ecosystem Demography (ED) model for modeling local (10's of kilometers) carbon
... large portion of the landscape enabling the georeferencing of the landscape with remote ... i... more ... large portion of the landscape enabling the georeferencing of the landscape with remote ... importance of these factors at la Selva. We first examined the potential effects of slope ... height sensitivity at La Selva (Peterson 2000) and was thus difficult to evaluate in terms of importance. ...
As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivit... more As the largest tropical forest in the world, Amazonia accounts for 15% of terrestrial productivity. Precipitation across the basin is predicted to decline as global climate change and regional land transformation continue through this century. This study evaluated predictions of site-level gross, net and component ecosystem C-fluxes by five land-surface models (ED2, IBIS, JULES, CLM3. 5, SiB3) and one site-specific carbon and hydrodynamic model (SPA) for two Brazilian Amazon rainforests (Tapajos and Caxiuana National ...
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