Widespread, rapid aspen (Populus tremuloides) mortality since the beginning of the 21st century, sometimes called sudden aspen decline (SAD), has been documented in many locations across North America, but it has been particularly pronounced in the southwestern U.S. We investigated the relationship between aspen growth, mortality, and climate across three forest types in northern Arizona using crossdated tree-ring samples from 126 live and 132 dead aspen. Aspen growth was negatively correlated with warm temperatures and positively associated with higher precipitation. Using survival analysis techniques to investigate the links between aspen mortality, tree traits, and climatic conditions, we found that tree traits played a larger role in mortality risk than climate factors. Trees with larger diameters, older trees, and trees with faster growth rates over the past 50 years had a reduced risk of mortality. Management actions aimed at maintaining the most vigorous, fastest growing aspen in the region could help mitigate the impacts of a warmer, drier future.
Webinar series registration.
This online seminar series will cover the breadth of wildland fire research relevant to California and introduce researchers to new topics and research groups across the state. Topics will include fire weather, wildfire risk, fire ecology, remote sensing, emissions, fire dynamics, fire modeling and public health. Featuring many early-career researchers, this series is aimed at a highly interdisciplinary academic audience but is open to anyone interested in these topics.
View an up-to-date schedule here: https://frg.berkeley.edu/california-fire-science-seminar-series/
Drought can exacerbate wildfire frequency, intensity, and severity. This webinar explores wildfire management approaches based on ecological principles, including those that embed traditional ecological knowledge.
Presenters: Dr. Jeremy Littell, Research Ecologist, Alaska Climate Adaptation Science Center, USGS
Bill Tripp, Deputy Director of Eco-Cultural Revitalization, Department of Natural Resources, Karuk Tribe
This webinar focuses on planning, restoration, and recovery actions that strengthen ecosystem resilience, mitigate the impacts of natural disasters, and realize co-benefits.
Presenters: Dr. Jennifer Cartwright, Lower Mississippi-Gulf Water Science Center, USGS
Rachel M. Gregg, Senior Scientist, EcoAdapt
Hannah Panci, Climate Change Scientist and Robert Croll, Climate Change Program Coordinator, Great Lakes Indian Fish and Wildlife Commission
Introducing ecological drought as a scientific concept distinct from other definitions of drought, this webinar explores recent research on the topic, including transformational drought impacts and ecological tipping points.
Presenters: Dr. Shelley Crausbay, Senior Scientist, Conservation Science Partners; Dr. Amanda Cravens, Research Social Scientist, USGS
This report found that records across the western US now show declines, of which 33% are significant (vs. 5% expected by chance) and 2% are significant and positive (vs. 5% expected by chance). Declining trends are observed across all months, states, and climates, but are largest in spring, in the Pacific states, and in locations with mild winter climate.
This study found that cross-validated results generally indicate a higher occurrence of smaller fires when months preceding fire season are wet, while larger fires are more frequent when soils are dry. This is consistent with the concept of increased fuel accumulation under wet conditions in the pre-season. These results demonstrate the fundamental strength of the relationship between soil moisture and fire activity at long lead-times and are indicative of that relationship’s utility for the future development of national-scale predictive capability.