The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
David D. Breshears - One of the best experts on this subject based on the ideXlab platform.
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Continental-scale consequences of tree Die-offs in North America: identifying where forest loss matters most
Environmental Research Letters, 2018Co-Authors: Abigail L. S. Swann, David D. Breshears, Marysa M. Laguë, Elizabeth S. Garcia, Jason P. Field, David J. P. Moore, Scott R. Saleska, Scott C. Stark, Juan Camilo Villegas, Darin J. LawAbstract:Regional-scale tree Die-off events driven by drought and warming and associated pests and pathogens have occurred recently on all forested continents and are projected to increase in frequency and extent with future warming. Within areas where tree mortality has occurred, ecological, hydrological and meteorological consequences are increasingly being documented. However, the potential for tree Die-off to impact vegetation processes and related carbon dynamics in areas remote to where Die-off occurs has rarely been systematically evaluated, particularly for multiple distinct regions within a given continent. Such remote impacts can occur when climate effects of local vegetation change are propagated by atmospheric circulation—the phenomena of 'ecoclimate teleconnections'. We simulated tree Die-off events in the 13 most densely forested US regions (selected from the 20 US National Ecological Observatory Network [NEON] domains) and found that tree Die-off even for smaller regions has potential to affect climate and hence Gross Primary Productivity (GPP) in disparate regions (NEON domains), either positively or negatively. Some regions exhibited strong teleconnections to several others, and some regions were relatively sensitive to tree loss regardless of what other region the tree loss occurred in. For the US as a whole, loss of trees in the Pacific Southwest—an area undergoing rapid tree Die-off—had the largest negative impact on remote US GPP whereas loss of trees in the Mid-Atlantic had the largest positive impact. This research lays a foundation for hypotheses that identify how the effects of tree Die-off (or other types of tree loss such as deforestation) can ricochet across regions by revealing hot-spots of forcing and response. Such modes of connectivity have direct applicability for improving models of climate change impacts and for developing more informed and coordinated carbon accounting across regions.
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Ecosystem dynamics and management after forest die‐off: a global synthesis with conceptual state‐and‐transition models
Ecosphere, 2017Co-Authors: Richard Cobb, Francisco Lloret, Katinka X. Ruthrof, David D. Breshears, Henry D Adams, Tuomas Aakala, William R L Anderegg, B E Ewers, Lucia Galiano, José M. GrünzweigAbstract:Broad-scale forest Die-off associated with drought and heat has now been reported from every forested continent, posing a global-scale challenge to forest management. Climate-driven Die-off is frequently compounded with other drivers of tree mortality, such as altered land use, wildfire, and invasive species, making forest management increasingly complex. Facing similar challenges, rangeland managers have widely adopted the approach of developing conceptual models that identify key ecosystem states and major types of transitions between those states, known as “state-and-transition models” (S&T models). Using expert opinion and available research, the development of such conceptual S&T models has proven useful in anticipating ecosystem changes and identifying management actions to undertake or to avoid. In cases where detailed data are available, S&T models can be developed into probabilistic predictions, but even where data are insufficient to predict transition probabilities, conceptual S&T models can provide valuable insights for managing a given ecosystem and for comparing and contrasting different ecosystem dynamics. We assembled a synthesis of 14 forest Die-off case studies from around the globe, each with sufficient information to infer impacts on forest dynamics and to inform management options following a forest Die-off event. For each, we developed a conceptual S&T model to identify alternative ecosystem states, pathways of ecosystem change, and points where management interventions have been, or may be, successful in arresting or reversing undesirable changes. We found that our diverse set of mortality case studies fit into three broad classes of ecosystem trajectories: (1) single-state transition shifts, (2) ecological cascading responses and feedbacks, and (3) complex dynamics where multiple interactions, mortality drivers, and impacts create a range of possible state transition responses. We integrate monitoring and management goals in a framework aimed to facilitate development of conceptual S&T models for other forest Die-off events. Our results highlight that although forest Die-off events across the globe encompass many different underlying drivers and pathways of ecosystem change, there are commonalities in opportunities for successful management intervention.
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ecosystem dynamics and management after forest die off a global synthesis with conceptual state and transition models
Ecosphere, 2017Co-Authors: Richard C Cobb, Francisco Lloret, Katinka X. Ruthrof, David D. Breshears, Henry D Adams, Tuomas Aakala, William R L Anderegg, B E Ewers, Lucia GalianoAbstract:Broad-scale forest Die-off associated with drought and heat has now been reported from every forested continent, posing a global-scale challenge to forest management. Climate-driven Die-off is frequently compounded with other drivers of tree mortality, such as altered land use, wildfire, and invasive species, making forest management increasingly complex. Facing similar challenges, rangeland managers have widely adopted the approach of developing conceptual models that identify key ecosystem states and major types of transitions between those states, known as “state-and-transition models” (S&T models). Using expert opinion and available research, the development of such conceptual S&T models has proven useful in anticipating ecosystem changes and identifying management actions to undertake or to avoid. In cases where detailed data are available, S&T models can be developed into probabilistic predictions, but even where data are insufficient to predict transition probabilities, conceptual S&T models can provide valuable insights for managing a given ecosystem and for comparing and contrasting different ecosystem dynamics. We assembled a synthesis of 14 forest Die-off case studies from around the globe, each with sufficient information to infer impacts on forest dynamics and to inform management options following a forest Die-off event. For each, we developed a conceptual S&T model to identify alternative ecosystem states, pathways of ecosystem change, and points where management interventions have been, or may be, successful in arresting or reversing undesirable changes. We found that our diverse set of mortality case studies fit into three broad classes of ecosystem trajectories: (1) single-state transition shifts, (2) ecological cascading responses and feedbacks, and (3) complex dynamics where multiple interactions, mortality drivers, and impacts create a range of possible state transition responses. We integrate monitoring and management goals in a framework aimed to facilitate development of conceptual S&T models for other forest Die-off events. Our results highlight that although forest Die-off events across the globe encompass many different underlying drivers and pathways of ecosystem change, there are commonalities in opportunities for successful management intervention.
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Recent tree die‐off has little effect on streamflow in contrast to expected increases from historical studies
Water Resources Research, 2015Co-Authors: Joel A. Biederman, David D. Breshears, Peter Troch, Andrew J. Somor, Adrian A. Harpold, Ethan Gutmann, David Gochis, Russell L. Scott, Arjan J. H. Meddens, Paul D. BrooksAbstract:Recent bark beetle epidemics have caused regional-scale tree mortality in many snowmelt-dominated headwater catchments of western North America. Initial expectations of increased streamflow have not been supported by observations, and the basin-scale response of annual streamflow is largely unknown. Here we quantified annual streamflow responses during the decade following tree Die-off in eight infested catchments in the Colorado River headwaters and one nearby control catchment. We employed three alternative empirical methods: (i) double-mass comparison between impacted and control catchments, (ii) runoff ratio comparison before and after Die-off, and (iii) time-trend analysis using climate-driven linear models. In contrast to streamflow increases predicted by historical paired catchment studies and recent modeling, we did not detect streamflow changes in most basins following Die-off, while one basin consistently showed decreased streamflow. The three analysis methods produced generally consistent results, with time-trend analysis showing precipitation was the strongest predictor of streamflow variability (R2 = 74–96%). Time-trend analysis revealed post-Die-off streamflow decreased in three catchments by 11–29%, with no change in the other five catchments. Although counter to initial expectations, these results are consistent with increased transpiration by surviving vegetation and the growing body of literature documenting increased snow sublimation and evaporation from the subcanopy following Die-off in water-limited, snow-dominated forests. The observations presented here challenge the widespread expectation that streamflow will increase following beetle-induced forest Die-off and highlight the need to better understand the processes driving hydrologic response to forest disturbance.
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How drought-induced forest Die-off alters microclimate and increases fuel loadings and fire potentials
2015Co-Authors: Katinka X. Ruthrof, Joseph B. Fontaine, George Matusick, David D. Breshears, Darin J. Law, Giles E. St. J. Hardy, S. PowellAbstract:Forest Die-offs associated with drought and heat have recently occurred across the globe, raising concern that associated changes in fuels and microclimate could link initial Die-off disturbance to subsequent fire disturbance. Despite widespread concern, little empirical data exist. Following forest Die-off in the Northern Jarrah Forest, southwestern Australia, we quantified fuel dynamics and associated microclimate for Die-off and control plots. Sixteen months post-Die-off, Die-off plots had significantly elevated 1-hr fuels (11.8 vs. 9.8 tons ha-1) but not larger activity fuel classes (10-hr and 100-hr fuels). Due to stem mortality, Die-off plots had significantly greater standing dead wood mass (100 vs. 10 tons ha-1), visible sky (hemispherical images analysis: 31% vs. 23%) and potential near-ground solar radiation input (measured as Direct Site Factor: 0.52 vs. 0.34). Supplemental, mid-summer microclimate measurements (temperature, relative humidity and wind speed) were combined with long-term climatic data and fuel load estimates to parameterize fire behaviour models. Fire spread rates were predicted to be 30% greater in Die-off plots with relatively equal contributions from fuels and microclimate, highlighting need for operational consideration by fire managers. Our results underscore potential for drought-induced tree Die-off to interact with subsequent fire under climate change.
Francisco Lloret - One of the best experts on this subject based on the ideXlab platform.
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Relationship between heatwave‐induced forest die‐off and climatic suitability in multiple tree species
Global change biology, 2020Co-Authors: Jordi Margalef-marrase, Maria Angeles Perez‐navarro, Francisco LloretAbstract:In recent decades, many forest Die-off events have been reported in relation to climate-change-induced episodes, such as droughts and heat waves. To understand how these extreme climatic events induce forest Die-off, it is important to find a tool to standardize the climatic conditions experienced by different populations during a specific climatic event, taking into account the historic climatic conditions of the site where these populations live (bioclimatic niche). In this study, we used estimates of climatic suitability calculated from species distribution models (SDMs) for such purpose. We studied forest Die-off across France during the 2003 heatwave that affected Western Europe, using 2,943 forest inventory plots dominated by 14 single tree species. Die-off severity was estimated by Normalized Difference Vegetation Index (NDVI) loss using Moderate-resolution Imaging Spectroradiometer remote sensor imagery. Climatic suitability at the local level during the historical 1979-2002 period (HCS), the episode time (2003; ECS) and suitability deviance during the historical period (HCS-SD) were calculated for each species by means of boosted regression tree models using the CHELSA climate database and occurrences extracted from European forest inventories. Low HCS-SD and high mean annual temperature explained the overall regional pattern of vulnerability to Die-off across different monospecific forests. The combination of high historical and low episode climatic suitability also contributed significantly to overall forest Die-off. Furthermore, we observed different species-specific relationships between Die-off vulnerability and climatic suitability: Sub-Mediterranean and Mediterranean species tended to be vulnerable in historically more suitable localities (high HCS), whereas Euro-Siberian species presented greater vulnerability when the hot drought episode was more intense. We demonstrated that at regional scale, past climatic legacy plays an important role in explaining NDVI loss during the episode. Moreover, we demonstrated that SDMs-derived indexes, such as HCS, ECS and HCS-SD, could constitute a tool for standardizing the ways that populations and species experience climatic variability across time and space.
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Ecosystem dynamics and management after forest die‐off: a global synthesis with conceptual state‐and‐transition models
Ecosphere, 2017Co-Authors: Richard Cobb, Francisco Lloret, Katinka X. Ruthrof, David D. Breshears, Henry D Adams, Tuomas Aakala, William R L Anderegg, B E Ewers, Lucia Galiano, José M. GrünzweigAbstract:Broad-scale forest Die-off associated with drought and heat has now been reported from every forested continent, posing a global-scale challenge to forest management. Climate-driven Die-off is frequently compounded with other drivers of tree mortality, such as altered land use, wildfire, and invasive species, making forest management increasingly complex. Facing similar challenges, rangeland managers have widely adopted the approach of developing conceptual models that identify key ecosystem states and major types of transitions between those states, known as “state-and-transition models” (S&T models). Using expert opinion and available research, the development of such conceptual S&T models has proven useful in anticipating ecosystem changes and identifying management actions to undertake or to avoid. In cases where detailed data are available, S&T models can be developed into probabilistic predictions, but even where data are insufficient to predict transition probabilities, conceptual S&T models can provide valuable insights for managing a given ecosystem and for comparing and contrasting different ecosystem dynamics. We assembled a synthesis of 14 forest Die-off case studies from around the globe, each with sufficient information to infer impacts on forest dynamics and to inform management options following a forest Die-off event. For each, we developed a conceptual S&T model to identify alternative ecosystem states, pathways of ecosystem change, and points where management interventions have been, or may be, successful in arresting or reversing undesirable changes. We found that our diverse set of mortality case studies fit into three broad classes of ecosystem trajectories: (1) single-state transition shifts, (2) ecological cascading responses and feedbacks, and (3) complex dynamics where multiple interactions, mortality drivers, and impacts create a range of possible state transition responses. We integrate monitoring and management goals in a framework aimed to facilitate development of conceptual S&T models for other forest Die-off events. Our results highlight that although forest Die-off events across the globe encompass many different underlying drivers and pathways of ecosystem change, there are commonalities in opportunities for successful management intervention.
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ecosystem dynamics and management after forest die off a global synthesis with conceptual state and transition models
Ecosphere, 2017Co-Authors: Richard C Cobb, Francisco Lloret, Katinka X. Ruthrof, David D. Breshears, Henry D Adams, Tuomas Aakala, William R L Anderegg, B E Ewers, Lucia GalianoAbstract:Broad-scale forest Die-off associated with drought and heat has now been reported from every forested continent, posing a global-scale challenge to forest management. Climate-driven Die-off is frequently compounded with other drivers of tree mortality, such as altered land use, wildfire, and invasive species, making forest management increasingly complex. Facing similar challenges, rangeland managers have widely adopted the approach of developing conceptual models that identify key ecosystem states and major types of transitions between those states, known as “state-and-transition models” (S&T models). Using expert opinion and available research, the development of such conceptual S&T models has proven useful in anticipating ecosystem changes and identifying management actions to undertake or to avoid. In cases where detailed data are available, S&T models can be developed into probabilistic predictions, but even where data are insufficient to predict transition probabilities, conceptual S&T models can provide valuable insights for managing a given ecosystem and for comparing and contrasting different ecosystem dynamics. We assembled a synthesis of 14 forest Die-off case studies from around the globe, each with sufficient information to infer impacts on forest dynamics and to inform management options following a forest Die-off event. For each, we developed a conceptual S&T model to identify alternative ecosystem states, pathways of ecosystem change, and points where management interventions have been, or may be, successful in arresting or reversing undesirable changes. We found that our diverse set of mortality case studies fit into three broad classes of ecosystem trajectories: (1) single-state transition shifts, (2) ecological cascading responses and feedbacks, and (3) complex dynamics where multiple interactions, mortality drivers, and impacts create a range of possible state transition responses. We integrate monitoring and management goals in a framework aimed to facilitate development of conceptual S&T models for other forest Die-off events. Our results highlight that although forest Die-off events across the globe encompass many different underlying drivers and pathways of ecosystem change, there are commonalities in opportunities for successful management intervention.
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strong resilience of soil respiration components to drought induced die off resulting in forest secondary succession
Oecologia, 2016Co-Authors: Josep Barba, Jorge Curiel Yuste, Rafael Poyatos, Ivan A Janssens, Francisco LloretAbstract:How forests cope with drought-induced perturbations and how the dependence of soil respiration on environmental and biological drivers is affected in a warming and drying context are becoming key questions. The aims of this study were to determine whether drought-induced Die-off and forest succession were reflected in soil respiration and its components and to determine the influence of climate on the soil respiration components. We used the mesh exclusion method to study seasonal variations in soil respiration (R S) and its components: heterotrophic (R H) and autotrophic (R A) [further split into fine root (R R) and mycorrhizal respiration (R M)] in a mixed Mediterranean forest where Scots pine (Pinus sylvestris L.) is undergoing a drought-induced Die-off and is being replaced by holm oak (Quercus ilex L.). Drought-induced pine Die-off was not reflected in R S nor in its components, which denotes a high functional resilience of the plant and soil system to pine Die-off. However, the succession from Scots pine to holm oak resulted in a reduction of R H and thus in an important decrease of total respiration (R S was 36 % lower in holm oaks than in non-defoliated pines). Furthermore, R S and all its components were strongly regulated by soil water content-and-temperature interaction. Since Scots pine Die-off and Quercus species colonization seems to be widely occurring at the driest limit of the Scots pine distribution, the functional resilience of the soil system over Die-off and the decrease of R S from Scots pine to holm oak could have direct consequences for the C balance of these ecosystems.
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Effects of drought-induced forest Die-off on litter decomposition
Plant and Soil, 2015Co-Authors: Josep Barba, Francisco Lloret, Jorge Curiel YusteAbstract:Aims Drought-induced forest Die-off and subsequent species replacement may modify environmental conditions and eventually affect litter decomposition. We aimed to disentangle the effects of tree species and Die-off state on litter decomposition in a mixed forest where Pinus sylvestris populations experiencing severe drought-induced Die-off are being replaced by Quercus ilex.
Neil S. Cobb - One of the best experts on this subject based on the ideXlab platform.
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precipitation thresholds and drought induced tree die off insights from patterns of pinus edulis mortality along an environmental stress gradient
New Phytologist, 2013Co-Authors: Michael J Clifford, David D. Breshears, Neil S. Cobb, Patrick D Royer, Paulette L FordAbstract:Summary � Recent regional tree Die-off events appear to have been triggered by a combination of drought and heat – referred to as ‘global-change-type drought’. To complement experiments focused on resolving mechanisms of drought-induced tree mortality, an evaluation of how patterns of tree Die-off relate to highly spatially variable precipitation is needed. � Here, we explore precipitation relationships with a Die-off event of pinyon pine (Pinus edulis Engelm.) in southwestern North America during the 2002–2003 global-change-type drought. Pinyon Die-off and its relationship with precipitation was quantified spatially along a precipitation gradient in north-central New Mexico with standard field plot measurements of Die-off combined with canopy cover derived from normalized burn ratio (NBR) from Landsat imagery. � Pinyon Die-off patterns revealed threshold responses to precipitation (cumulative 2002– 2003) and vapor pressure deficit (VPD), with little to no mortality (< 10%) above 600 mm and below warm season VPD of c. 1.7 kPa. [Correction added after online publication 17 June 2013; in the preceding sentence, the word ’below’ has been inserted.] � Our results refine how precipitation patterns within a region influence pinyon Die-off, revealing a precipitation and VPD threshold for tree mortality and its uncertainty band where other factors probably come into play – a response type that influences stand demography and landscape heterogeneity and is of general interest, yet has not been documented.
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Precipitation thresholds and drought‐induced tree die‐off: insights from patterns of Pinus edulis mortality along an environmental stress gradient
The New phytologist, 2013Co-Authors: Michael J Clifford, David D. Breshears, Neil S. Cobb, Patrick D Royer, Paulette L FordAbstract:Summary � Recent regional tree Die-off events appear to have been triggered by a combination of drought and heat – referred to as ‘global-change-type drought’. To complement experiments focused on resolving mechanisms of drought-induced tree mortality, an evaluation of how patterns of tree Die-off relate to highly spatially variable precipitation is needed. � Here, we explore precipitation relationships with a Die-off event of pinyon pine (Pinus edulis Engelm.) in southwestern North America during the 2002–2003 global-change-type drought. Pinyon Die-off and its relationship with precipitation was quantified spatially along a precipitation gradient in north-central New Mexico with standard field plot measurements of Die-off combined with canopy cover derived from normalized burn ratio (NBR) from Landsat imagery. � Pinyon Die-off patterns revealed threshold responses to precipitation (cumulative 2002– 2003) and vapor pressure deficit (VPD), with little to no mortality (< 10%) above 600 mm and below warm season VPD of c. 1.7 kPa. [Correction added after online publication 17 June 2013; in the preceding sentence, the word ’below’ has been inserted.] � Our results refine how precipitation patterns within a region influence pinyon Die-off, revealing a precipitation and VPD threshold for tree mortality and its uncertainty band where other factors probably come into play – a response type that influences stand demography and landscape heterogeneity and is of general interest, yet has not been documented.
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Decreased streamflow in semi-arid basins following drought-induced tree Die-off: A counter-intuitive and indirect climate impact on hydrology
Journal of Hydrology, 2011Co-Authors: Maite Guardiola-claramonte, David D. Breshears, Travis E Huxman, Peter Troch, Matthew B. Switanek, Matej Durcik, Neil S. CobbAbstract:Drought- and infestation-related tree Die-off is occurring at regional scales and is projected to increase with global climate change. These large-scale changes in vegetation are expected to influence hydrological responses, but the ecohydrological consequences of Die-off have rarely been studied empirically and consequently remain uncertain. Here we evaluate observed hydrologic responses to recent regional-scale Die-off of pinon pine (Pinus edulis) in Southwestern USA. Basins with the most tree Die-off showed a significant decrease in streamflow over several years following Die-off, and this decrease was not attributable to climate variability alone. The results are counterintuitive compared to responses to reductions in tree cover by harvest that have shown an increase in streamflow, although such increases are more substantial for locations with higher precipitation than where the pinon pine Die-off occurred. We are unable to isolate the cause of the increase, but note that it is consistent with a reported increase in understory herbaceous cover post-Die-off and associated increase in solar radiation reaching near-ground (below the tree canopy overstory), which together would be expected to reduce overland flow. Our study highlights the need to more fully evaluate hydrological responses to drought-induced tree Die-off empirically, in addition to modelling studies. More generally, the result illustrate potential indirect effects of climate on hydrological responses mediated through ecohydrological changes in vegetation, which will need to be considered in future water resources assessments.
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regional vegetation die off in response to global change type drought
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: David D. Breshears, Craig D Allen, Neil S. Cobb, Paul M Rich, Kevin P Price, Randy G Balice, William H Romme, Jude H Kastens, Lisa M Floyd, Jayne BelnapAbstract:Future drought is projected to occur under warmer temperature conditions as climate change progresses, referred to here as global-change-type drought, yet quantitative assessments of the triggers and potential extent of drought-induced vegetation Die-off remain pivotal uncertainties in assessing climate-change impacts. Of particular concern is regional-scale mortality of overstory trees, which rapidly alters ecosystem type, associated ecosystem properties, and land surface conditions for decades. Here, we quantify regional-scale vegetation Die-off across southwestern North American woodlands in 2002-2003 in response to drought and associated bark beetle infestations. At an intensively studied site within the region, we quantified that after 15 months of depleted soil water content, >90% of the dominant, overstory tree species (Pinus edulis, a pinon) died. The Die-off was reflected in changes in a remotely sensed index of vegetation greenness (Normalized Difference Vegetation Index), not only at the intensively studied site but also across the region, extending over 12,000 km2 or more; aerial and field surveys confirmed the general extent of the Die-off. Notably, the recent drought was warmer than the previous subcontinental drought of the 1950s. The limited, available observations suggest that Die-off from the recent drought was more extensive than that from the previous drought, extending into wetter sites within the tree species' distribution. Our results quantify a trigger leading to rapid, drought-induced Die-off of overstory woody plants at subcontinental scale and highlight the potential for such Die-off to be more severe and extensive for future global-change-type drought under warmer conditions.
Stijn Temmerman - One of the best experts on this subject based on the ideXlab platform.
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spatio temporal development of vegetation die off in a submerging coastal marsh
Limnology and Oceanography, 2017Co-Authors: Lennert Schepers, Matthew L Kirwan, Glenn R Guntenspergen, Stijn TemmermanAbstract:In several places around the world, coastal marsh vegetation is converting to open water through the formation of pools. This is concerning, as vegetation Die-off is expected to reduce the marshes' capacity to adapt to sea level rise by vegetation-induced sediment accretion. Quantitative analyses of the spatial and temporal development of marsh vegetation Die-off are scarce, although these are needed to understand the bio-geomorphic feedback effects of vegetation Die-off on flow, erosion, and sedimentation. In this study, we quantified the spatial and temporal development of marsh vegetation Die-off with aerial images from 1938 to 2010 in a submerging coastal marsh along the Blackwater River (Maryland, U.S.A). Our results indicate that Die-off begins with conversion of marsh vegetation into bare open water pools that are relatively far (> 75 m) from tidal channels. As vegetation Die-off continues, pools expand, and new pools emerge at shorter and shorter distances from channels. Consequently larger pools are found at larger distances from the channels. Our results suggest that the size of the pools and possibly the connection of pools with the tidal channel system have important bio-geomorphic implications and aggravate marsh deterioration. Moreover, we found that the temporal development of vegetation Die-off in moderately degraded marshes is similar as the spatial Die-off development along a present-day gradient, which indicates that the contemporary Die-off gradient might be considered a chronosequence that offers a unique opportunity to study vegetation Die-off processes.
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Spatio‐temporal development of vegetation die‐off in a submerging coastal marsh
Limnology and Oceanography, 2016Co-Authors: Lennert Schepers, Matthew L Kirwan, Glenn R Guntenspergen, Stijn TemmermanAbstract:In several places around the world, coastal marsh vegetation is converting to open water through the formation of pools. This is concerning, as vegetation Die-off is expected to reduce the marshes' capacity to adapt to sea level rise by vegetation-induced sediment accretion. Quantitative analyses of the spatial and temporal development of marsh vegetation Die-off are scarce, although these are needed to understand the bio-geomorphic feedback effects of vegetation Die-off on flow, erosion, and sedimentation. In this study, we quantified the spatial and temporal development of marsh vegetation Die-off with aerial images from 1938 to 2010 in a submerging coastal marsh along the Blackwater River (Maryland, U.S.A). Our results indicate that Die-off begins with conversion of marsh vegetation into bare open water pools that are relatively far (> 75 m) from tidal channels. As vegetation Die-off continues, pools expand, and new pools emerge at shorter and shorter distances from channels. Consequently larger pools are found at larger distances from the channels. Our results suggest that the size of the pools and possibly the connection of pools with the tidal channel system have important bio-geomorphic implications and aggravate marsh deterioration. Moreover, we found that the temporal development of vegetation Die-off in moderately degraded marshes is similar as the spatial Die-off development along a present-day gradient, which indicates that the contemporary Die-off gradient might be considered a chronosequence that offers a unique opportunity to study vegetation Die-off processes.
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Coastal marsh Die-off and reduced attenuation of coastal floods: A model analysis
Global and Planetary Change, 2012Co-Authors: Stijn Temmerman, Mindert De Vries, Tjeerd J. BoumaAbstract:Global climate change is expected to increase the risks of coastal flood disasters due to accelerating sea level rise and increasing intensity and frequency of storm surges. Coastal marsh vegetation is considered, on the one hand, to increase resistance to a landward propagating flood wave, such as a storm surge, and hence to protect against flood disasters. On the other hand, coastal marsh vegetation is dying off at several places around the world due to accelerating sea level rise. Here we present hydrodynamic model simulations of flood attenuation by a tidal marsh, with particular focus on the effects of spatial patterns of vegetation Die-off. It is shown that a same percentage of marsh Die-off but occurring as different spatial patterns of marsh break-up has largely different effects on flood attenuation. Patches of Die-off that are directly connected to tidal channels have a much greater effect on increased landward flood propagation, while a same percentage of marsh Die-off, but occurring at inner marsh locations disconnected from tidal channels, has only a minor effect. This implies that a random pattern of up to 50% of marsh Die-off still provides a considerable flood attenuating effect. However with increasing percentage of random marsh Die-off the flood attenuating effect decreases exponentially, since the chance for vegetation Die-off occurring directly adjacent to tidal channels increases. This study demonstrates that tidal marsh Die-off, which may increase with ongoing global change, is expected to have non-linear effects on reduced coastal protection against flood waves.
Paulette L Ford - One of the best experts on this subject based on the ideXlab platform.
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precipitation thresholds and drought induced tree die off insights from patterns of pinus edulis mortality along an environmental stress gradient
New Phytologist, 2013Co-Authors: Michael J Clifford, David D. Breshears, Neil S. Cobb, Patrick D Royer, Paulette L FordAbstract:Summary � Recent regional tree Die-off events appear to have been triggered by a combination of drought and heat – referred to as ‘global-change-type drought’. To complement experiments focused on resolving mechanisms of drought-induced tree mortality, an evaluation of how patterns of tree Die-off relate to highly spatially variable precipitation is needed. � Here, we explore precipitation relationships with a Die-off event of pinyon pine (Pinus edulis Engelm.) in southwestern North America during the 2002–2003 global-change-type drought. Pinyon Die-off and its relationship with precipitation was quantified spatially along a precipitation gradient in north-central New Mexico with standard field plot measurements of Die-off combined with canopy cover derived from normalized burn ratio (NBR) from Landsat imagery. � Pinyon Die-off patterns revealed threshold responses to precipitation (cumulative 2002– 2003) and vapor pressure deficit (VPD), with little to no mortality (< 10%) above 600 mm and below warm season VPD of c. 1.7 kPa. [Correction added after online publication 17 June 2013; in the preceding sentence, the word ’below’ has been inserted.] � Our results refine how precipitation patterns within a region influence pinyon Die-off, revealing a precipitation and VPD threshold for tree mortality and its uncertainty band where other factors probably come into play – a response type that influences stand demography and landscape heterogeneity and is of general interest, yet has not been documented.
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Precipitation thresholds and drought‐induced tree die‐off: insights from patterns of Pinus edulis mortality along an environmental stress gradient
The New phytologist, 2013Co-Authors: Michael J Clifford, David D. Breshears, Neil S. Cobb, Patrick D Royer, Paulette L FordAbstract:Summary � Recent regional tree Die-off events appear to have been triggered by a combination of drought and heat – referred to as ‘global-change-type drought’. To complement experiments focused on resolving mechanisms of drought-induced tree mortality, an evaluation of how patterns of tree Die-off relate to highly spatially variable precipitation is needed. � Here, we explore precipitation relationships with a Die-off event of pinyon pine (Pinus edulis Engelm.) in southwestern North America during the 2002–2003 global-change-type drought. Pinyon Die-off and its relationship with precipitation was quantified spatially along a precipitation gradient in north-central New Mexico with standard field plot measurements of Die-off combined with canopy cover derived from normalized burn ratio (NBR) from Landsat imagery. � Pinyon Die-off patterns revealed threshold responses to precipitation (cumulative 2002– 2003) and vapor pressure deficit (VPD), with little to no mortality (< 10%) above 600 mm and below warm season VPD of c. 1.7 kPa. [Correction added after online publication 17 June 2013; in the preceding sentence, the word ’below’ has been inserted.] � Our results refine how precipitation patterns within a region influence pinyon Die-off, revealing a precipitation and VPD threshold for tree mortality and its uncertainty band where other factors probably come into play – a response type that influences stand demography and landscape heterogeneity and is of general interest, yet has not been documented.