Tree Mortality Patterns and Processes Active
Dying piñon pine (Pinus edulis) with orange needles, due to drought stress and associated bark beetle outbreak, Jemez Mtns., NM. October 2002.
The same view, with grey skeletons of dead piñon pines (Pinus edulis) after the needles have dropped, with surviving green junipers. May 2004.
Natural climatic variability, including episodic droughts, has long been known to trigger accelerated tree mortality in forests worldwide, including in the Southwest U.S. Scientific understanding of the process drivers and spatial patterns of tree mortality is surprisingly limited, constraining our ability to model forest responses to projected climate changes. The onset of regional drought since the late 1990s has resulted in extensive die-off episodes of multiple tree species across millions of acres in the Southwest, fostering substantial collaborative tree mortality research in this region. Ongoing tree mortality research in northern New Mexico includes: reconstruction of historic forest dieback patterns; monitoring of forest and woodland demographies (tree mortality and regeneration); experimental determination of physiological thresholds of drought- and heat-induced tree mortality; relationships between tree growth, drought stress, insects/diseases, and mortality; remote-sensing of landscape-scale patterns of forest stress and die-off; documentation of regional, national, and global patterns of forest die-off; and efforts to improve models of tree mortality processe
Forest responses to increasing aridity and warmth in the southwestern United States
Climate-induced forest dieback: An escalating global phenomenon?
Tree die-off in response to global change-type drought: Mortality insights from a decade of plant water potential measurements
Mechanisms of plant survival and mortality during drought: Why do some plants survive while others succumb to drought?
Bark beetle outbreaks in western North America: Causes and consequences
Nonlinear dynamics in ecosystem response to climatic change: Case studies and policy implications
Regional vegetation die-off in response to global-change-type drought
Cross scale interactions, nonlinearities, and forecasting catastrophic events
The importance of rapid, disturbance-induced losses in carbon management and sequestration
Drought-induced shift of a forest-woodland ecotone: Rapid landscape response to climate variation
- Overview
Natural climatic variability, including episodic droughts, has long been known to trigger accelerated tree mortality in forests worldwide, including in the Southwest U.S. Scientific understanding of the process drivers and spatial patterns of tree mortality is surprisingly limited, constraining our ability to model forest responses to projected climate changes. The onset of regional drought since the late 1990s has resulted in extensive die-off episodes of multiple tree species across millions of acres in the Southwest, fostering substantial collaborative tree mortality research in this region. Ongoing tree mortality research in northern New Mexico includes: reconstruction of historic forest dieback patterns; monitoring of forest and woodland demographies (tree mortality and regeneration); experimental determination of physiological thresholds of drought- and heat-induced tree mortality; relationships between tree growth, drought stress, insects/diseases, and mortality; remote-sensing of landscape-scale patterns of forest stress and die-off; documentation of regional, national, and global patterns of forest die-off; and efforts to improve models of tree mortality processe
- Science
- Publications
Filter Total Items: 22
Forest responses to increasing aridity and warmth in the southwestern United States
In recent decades, intense droughts, insect outbreaks, and wildfires have led to decreasing tree growth and increasing mortality in many temperate forests. We compared annual tree-ring width data from 1,097 populations in the coterminous United States to climate data and evaluated site-specific tree responses to climate variations throughout the 20th century. For each population, we developed a clAuthorsA.P. Williams, Craig D. Allen, C. I. Millar, T.W. Swetnam, J. Michaelsen, C.J. Still, Steven W. LeavittClimate-induced forest dieback: An escalating global phenomenon?
Forests, which today cover 30 percent of the world’s land surface (FAO, 2006), are being rapidly and directly transformed in many areas by the impacts of expanding human populations and economies. Less evident are the pervasive effects of ongoing climatic changes on the condition and status of forests around the world. Recent examples of drought and heat-related forest stress and dieback (definedAuthorsCraig D. AllenTree die-off in response to global change-type drought: Mortality insights from a decade of plant water potential measurements
Global climate change is projected to produce warmer, longer, and more frequent droughts, referred to here as “global change-type droughts”, which have the potential to trigger widespread tree die-off. However, drought-induced tree mortality cannot be predicted with confidence, because long-term field observations of plant water stress prior to, and culminating in, mortality are rare, precluding tAuthorsD.D. Breshears, O.B. Myers, Clifton W. Meyer, F.J. Barnes, C.B. Zou, Craig D. Allen, N.G. McDowell, W. T. PockmanMechanisms of plant survival and mortality during drought: Why do some plants survive while others succumb to drought?
Severe droughts have been associated with regional-scale forest mortality worldwide. Climate change is expected to exacerbate regional mortality events; however, prediction remains difficult because the physiological mechanisms underlying drought survival and mortality are poorly understood. We developed a hydraulically based theory considering carbon balance and insect resistance that allowed devAuthorsNate G. McDowell, William T. Pockman, Craig D. Allen, David D. Breshears, Neil Cobb, Thomas Kolb, Jennifer Plaut, John Sperry, Adam West, David G. Williams, Enrico A. YepezBark beetle outbreaks in western North America: Causes and consequences
Since 1990, native bark beetles have killed billions of trees across millions of acres of forest from Alaska to northern Mexico. Although bark beetle infestations are a regular force of natural change in forested ecosystems, several of the current outbreaks, which are occurring simultaneously across western North America, are the largest and most severe in recorded history.AuthorsBarbara Bentz, Jesse Logan, James A. MacMahon, Craig D. Allen, Matt Ayres, Edward E Berg, Allan Carroll, Matt Hansen, Jeff H. Hicke, Linda A. Joyce, Wallace Macfarlane, Steve Munson, Jose Negron, Tim Paine, Jim Powell, Kenneth Raffa, Jacques Regniere, Mary Reid, Bill Romme, Steven J. Seybold, Diana Six, Jim Vandygriff, Tom Veblen, Mike White, Jeff WitcoskyNonlinear dynamics in ecosystem response to climatic change: Case studies and policy implications
Many biological, hydrological, and geological processes are interactively linked in ecosystems. These ecological phenomena normally vary within bounded ranges, but rapid, nonlinear changes to markedly different conditions can be triggered by even small differences if threshold values are exceeded. Intrinsic and extrinsic ecological thresholds can lead to effects that cascade among systems, precludAuthorsVirginia R. Burkett, Douglas A. Wilcox, Robert Stottlemyer, Wylie Barrow, Dan Fagre, Jill Baron, Jeff Price, Jennifer L. Nielsen, Craig D. Allen, David L. Peterson, Greg Ruggerone, Thomas DoyleRegional vegetation die-off in response to global-change-type drought
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 rapAuthorsD.D. Breshears, N.S. Cobb, P.M. Rich, K. P. Price, Craig D. Allen, R.G. Balice, W.H. Romme, J.H. Kastens, M. Lisa Floyd, J. Belnap, J. J. Anderson, O.B. Myers, Clifton W. MeyerCross scale interactions, nonlinearities, and forecasting catastrophic events
Catastrophic events share characteristic nonlinear behaviors that are often generated by cross-scale interactions and feedbacks among system elements. These events result in surprises that cannot easily be predicted based on information obtained at a single scale. Progress on catastrophic events has focused on one of the following two areas: nonlinear dynamics through time without an explicit consAuthorsDebra P. C. Peters, Roger A. Pielke, Brandon T. Bestelmeyer, Craig D. Allen, Stuart Munson-McGee, Kris M. HavstadThe importance of rapid, disturbance-induced losses in carbon management and sequestration
Management of terrestrial carbon fluxes is being proposed as a means of increasing the amount of carbon sequestered in the terrestrial biosphere. This approach is generally viewed only as an interim strategy for the coming decades while other longer-term strategies are developed and implemented — the most important being the direct reduction of carbon emissions. We are concerned that the potentialAuthorsD.D. Breshears, Craig D. AllenDrought-induced shift of a forest-woodland ecotone: Rapid landscape response to climate variation
In coming decades, global climate changes are expected to produce large shifts in vegetation distributions at unprecedented rates. These shifts are expected to be most rapid and extreme at ecotones, the boundaries between ecosystems, particularly those in semiarid landscapes. However, current models do not adequately provide for such rapid effects—particularly those caused by mortality—largely becAuthorsCraig D. Allen, David D. Breshears