1,214 research outputs found
Recommended from our members
Historical forest succession and disturbance dynamics in Coastal Douglas-fir forests in the southern western Cascades of Oregon
No full textCoastal Douglas-fir (Pseudotsuga menziesii var menziesii) forests are extensive west of the crest of the Cascade Mountains in Oregon and Washington and are renowned for their productivity, biodiversity, and the ecosystem services they provide. Increasing wildfire activity in recent years including the extensive 2020 Labor Day fires, and a warming climate have raised concerns about the resistance and resilience of Coastal Douglas-fir forests. At the same time federal land managers are now tasked with restoration of natural successional and disturbance processes including fire to maintain biodiversity and ecosystem services given natural and anthropogenic stressors. However, we lack information that precisely describes historical fire regimes and successional dynamics in Coastal Douglas-fir forests sufficient to guide reintroduction of wildfire, in the context of restoration and adaptation of forest conditions and successional dynamics that are resilient to climate change. This gap in information exists because rigorous dendrochronological research methods have been sparsely used in Coastal Douglas-fir forests due to the challenges of sampling intact fire-scarred trees and the expectation that historical fires were infrequent and often severe. This dissertation provides the first extensive annually resolved dendrochronological reconstruction of historical (1600-1910 CE) fires and forest development in Douglas-fir forests of the southern western Oregon Cascades. Reconstruction sites covered an ecological gradient where Douglas-fir is the dominant tree species from low elevation warm-dry Douglas-fir forests to high elevation cool-wet Pacific silver fir (Abies amabilis) forests.
In Chapter 2, I used multiple lines of evidence to reconstruct historical fire events. A frequent mixed-severity fire regime historically influenced tree establishment and successional dynamics across the broad warm-dry to cool-moist climatic gradient that I sampled. The majority of fire intervals prior to the early 19th century were 50 years long in both warm-moist and cool-moist microclimates, predominantly in the 19th century. Fire extent and frequency varied at fine spatial and temporal scales with small isolated fires occurring at approximately the same frequency as extensive fires. Most (94%) of historical fires were reconstructed from crossdated fire scars. Although the majority of tree establishment cohorts (90%) were associated with fire, tree establishment cohorts provided evidence of only 26% of historical fires evidenced by fire scars because historical fires did not always provide an opportunity for tree establishment or tree cohorts were killed by subsequent fires. Chapter 2 demonstrates the importance of crossdated fire records for quantifying fire history in these forest types, providing more nuanced and precise understanding of tree establishment and the development of old-growth forest conditions than previously known in Douglas-fir forests with a mixed-severity fire regime..
In Chapter 3, I quantified annual fire-climate relationships, identified variability in fire frequency over time, and evaluated how fire occurrence and frequency are related to climate, biophysical setting, people, and forest succession. I found no evidence that historical fires occurred preferentially in drought conditions prior to European settlement in 1830. After 1830 fires were significantly associated with drought. The increased fidelity of fire to drought years occurred at approximately the same time that fire frequency declined at most sites in my study area, and these declines in fire frequency occurred 50 - 100 years before fire suppression efforts began in the early 20th century. These unexpected results suggest that Native America traditional burning and changes in the flammability of Douglas-fir forests that occur with succession may have historically been important drivers of fire frequency. For example, there was strong evidence of traditional burning at one of my reconstruction sites where extremely frequent historical fires (mean fire interval 2.9 years) regularly occurred in years with wet spring and summer conditions. Declines in fire frequency in warm-dry forests coincided with disease epidemics and the disruption of Native America lifeways brought by European settlement. Decreases in fire frequency occurred several decades earlier across cool-moist western hemlock and Pacific silver fir forests at two of my study sites. These decreases in fire at cool-moist forest sites coincided with a cool-wet climatic period in the early 19th century and the development of mature Douglas-fir forest structure that resists burning. Younger early successional Douglas-fir forests developing after high-severity fire in the 19th century continued to burn frequently until fire suppression in the early 20th century. Chapter 3 demonstrates that fires historically burned under a broader range of climatic conditions, and this means that fire occurrence and frequency were likely mediated by fine scale endogenous drivers including topography, fuel moisture and structure, and the timing and distribution of ignitions.
In Chapter 4, I use forest structure and composition, tree establishment records, and fire records to identify forest types and fire-mediated development types and precisely illustrate how fire frequency and severity historically contributed to diversity in forest development, structure, and composition. I identify how forest types and fire-mediated development types are uniquely related to biophysical environment to determine if forest types are indicative of a distinct historical fire regime, and to refine our understanding of how fire influenced forest development in different parts of the landscape. Old-growth forest conditions (composition and structure; forest type) varied at broad scales with microclimate. In contrast, forest development history (development types) varied at finer scales with slope and heatload, and even-aged, two-aged, many-aged, and multi-aged development types occurred across xeric, warm-dry, and cool-moist microclimates. Many-aged stands with continuous tree establishment over several decades to centuries developed almost exclusively on gentle slopes. Even-aged, two-aged, and multi-aged forests with distinct tree establishment cohorts that establish after moderate- to high-severity fire were usually located on steep slopes. Overall, the influence of fire on forest successional dynamics was partitioned at fine scales by topography, and this created a mosaic of distinct forest ages and development histories across warm-dry to cool-moist forest types in Douglas-fir forests in the southern western Cascades.
This dissertation provides a uniquely detailed and precise characterization of frequent mixed-severity fire regimes in Douglas-fir forests in the southern western Cascades. A mixture of frequent low-, moderate-, and high-severity fire created the mature and old-growth forests that land management aims to protect today. Removing fire from these Douglas-fir forests has altered successional dynamics, forest structure and composition, and may have intensified drought and wildfire effects at the same time as drought severity and frequency are increasing across forests of the western United States. This research can inform future dendroecological reconstruction in Douglas-fir forests, guide reintroduction of fire, contribute to conservation and land planning, and inform response to contemporary wildfires as we adapt to a warmer and drier climate in the Pacific Northwest
An Oral History Interview with Meg Leta Jones
No full textAn Oral History Interview with Meg Leta Jones conducted by Gerardo Con DiazThis oral history interview is sponsored by NSF 2202484, “Mining a Usable Past: Perspectives, Paradoxes, and Possibilities with Security and Privacy,” at the Charles Babbage Institute, University of Minnesota. The interview is with Meg Leta Jones, Provost’s Distinguished Associate Professor in the Communication, Culture, and Technology program at Georgetown University. Jones discusses her upbringing in rural Illinois, her education in engineering, law, and communication studies, and her path to interdisciplinary privacy scholarship. She reflects on her work on the right to be forgotten, data deletion, and comparative privacy regimes. Then she discusses her engagement with design, infrastructure, and information ethics, as well as her roles as author, mentor, and public scholar.National Science FoundationLeta Jones, Meg. (2025). An Oral History Interview with Meg Leta Jones. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/274361
Faces and Places in Fashion: Meg Flather, Home Shopping Diva
No full textMeg Flather has spent decades building a multi-faceted career in performance, cosmetics and media. As author of Lessons, Lyrics and Lipstick, Meg performs entertaining and inspirational seminars for men and women embarking on similar vocations. As national makeup artist for OLAY, Meg worked closely with public relations, marketing and product development. As a home shopping brand ambassador, Meg has grown sales for PERLIER on TSC, Canada, Aloette on Shop NBC, PRAI on TVSN, Australia, StriVectin on QVC, and TSC, Canada. In December, 2015, Meg became the New York based Director of Education for TATCHA skincare.Meg began her cosmetic career in New York City. She was special events captain for all metropolitan accounts for Clinique, resident make-up artist for Yves St. Laurent at Bergdorf Goodman, held the highest national sales record for both Stila and Body and Soul at Barney’s, and raised customer service and artistry standards at all Face Stockholm locations. As an expert in her field, Meg has been featured on The Discovery Channel, in 15 national publications and her artistry credits include People Magazine, NBC Daytime, CNN, 20/20, The View, documentary films and numerous private clients.Part presentation, part Q&A, the "Faces & Places in Fashion" lecture series is an opportunity to connect students and the public alike to the pulse of the fashion industry in an open and conversational setting
Recommended from our members
Drivers and Impacts of a Recent Annual Grass Invasion: Ventenata dubia and Fire in the Inland Northwest
No full textBiological invasions threaten native biodiversity, alter ecosystem function, and are a major cause of economic losses across the planet. The most impactful invaders alter disturbance regimes and initiate state shifts to outside the historical range of variability of the ecosystem. Concern for ecological and economic losses has prompted a rapid expansion of invasion ecology research. However, the continual arrival of new invaders with unknown ecological impacts demands further research to help close the ever-growing knowledge gap. In the Pacific Northwest, a recently introduced, rapidly spreading Eurasian annual grass, Ventenata dubia (ventenata) is poised to alter fire behavior and ecosystem function across forest-mosaic landscapes of the Inland Northwest, USA. This dissertation aims to: 1) determine the biotic and abiotic factors associated with the V. dubia invasion, 2) characterize the relationship between invasion and plant community diversity in burned and unburned areas, 3) examine how biotic and environmental factors interact to influence community invasion resistance, and 4) evaluate the influence of V. dubia on fuel characteristics and fire behavior at multiple scales.
I used field data, statistical analyses, and landscape fire simulations to determine the drivers and impacts of the V. dubia invasion at community and landscape-scales in the Blue Mountains Ecoregion of the Inland Northwest. In Chapter 2, I identified V. dubia’s unique niche in forested ecosystems of the region, including historically invasion and fire-resistant dwarf shrublands imbedded within the larger forested landscape. I demonstrated that V. dubia expands invasion impacts in these ecosystems rather than occurring in areas already impacted by other invasive annual grasses (Bromus tectorum and Taeniatherum caput-medusae), increasing the overall invasion footprint. Chapter 2 also examined the relationship between V. dubia and plant community diversity with and without fire. I found that V. dubia was weakly related to community diversity in unburned areas but was strongly negatively related to diversity and abundance of functionally similar species in burned areas. These results suggest that V. dubia may fill an otherwise seemingly unoccupied niche in unburned areas but may outcompete functionally similar species for post-fire resources.
In Chapter 3, I explored interacting drivers of community invasion resistance using an in-situ manipulation experiment across three vegetation types. I found that community biomass and some traits (specific leaf area, fine-to-total root volume, and height) may confer invasion resistance of existing communities to V. dubia. However, this was only the case in the most productive wet meadow vegetation types. I found no evidence that biomass or community trait composition contributed to invasion resistance in less productive and more stressful low sage-steppe or scab-flat vegetation types, indicating that environmental and biotic factors interact to influence invasion resistance. To assess the potential influence of V. dubia invasion on fire behavior across the region, I evaluated the influence of V. dubia on fuels and fire in Chapter 4 using a novel application of the landscape-scale Large Fire Simulator, FSim. I show that invasion increased fire spread, burn probabilities, and fire intensity across forest-mosaic landscapes by increasing fuels and fire occurrence in invaded non-forested areas adjacent to fuel rich forests.
Overall, this dissertation provides some of the first documentation of V. dubia’s niche and invasion dynamics in forested landscapes, and characterizes how this invasion differs from other problematic species in this region. My work demonstrates that V. dubia may initiate a grass-fire cycle in historically fire- and invasion-resistant scabland ecosystems and that annual grass invasion can have substantial impacts on fire behavior in uninvaded forests – ecosystems thought to be resistant to annual grass impacts. Together, these chapters provide valuable information from the invasion front to aid the management of this rapidly spreading species
Recommended from our members
Multipartner Planning for Sustainability: The Pittsburgh Urban Forest
No full textThe City of Pittsburgh, formerly the capital of the American steel industry, suffered economic and social collapse in the late 1980s and 1990s. Since then, it has experienced an economic renaissance supported by the tech and medical care industries. However, despite the surprising recovery of the city, collapsed tax bases and changing public priorities have meant that some peripheral functions, such as the maintenance of parks and street trees have fallen by the wayside. Fortunately, citizen groups, partnering with independent consulting agencies and the city government have been able to band together to help drive a truly collaborative process to improve the health and benefits of the urban forest while creating local jobs. The City of Pittsburgh Urban Forest Master Plan is part of a constellation of management tools and synergistic organizations which draw upon the expertise of a diverse set of stakeholders to create a robust and innovative forest management atmosphere that could well serve as a model for other recovering rust belt cities in the region
Recommended from our members
A Climate of Risk: Modeled Vegetation, Carbon, Fire, and Biomass Loss Risk in Western Oregon and Washington under Climate Change
No full textManaging wildlands to protect species and ecosystem services in response to climate change is challenging. To develop effective long-term strategies, natural resource managers need to account for the projected effects of climate change as well as the uncertainty inherent in those projections. Vegetation models are one important source of projected climate impacts. Interpreting those model results can be difficult due to both uncertainty in results and model limitations. Factors contributing to uncertainty include embedded assumptions about atmospheric CO2 levels, uncertain climate projections driving models, and model algorithm selection. Limitations include processes excluded by models, such as mortality from maladaptation and succession, as well as algorithmic simplifications such as assumptions about wildfire ignitions.
To understand the potential impacts of climate change on vegetation and wildfire in 21st century, I used the MC2 dynamic global vegetation model (DGVM) to simulate vegetation for the Northwest conterminous United States using results from 20 different Climate Model Intercomparison Project Phase 5 (CMIP5) models downscaled using the MACA algorithm. Results were generated for representative concentration pathways (RCP) 4.5 and 8.5 under vegetation modeling scenarios with and without fire suppression for a total of 80 model runs for future projections. For analysis, results were aggregated by three subregions: the western Northwest (WNW), from the crest of the Cascade Mountains west; Northwest plains and plateau (NWPP), the non-mountainous areas east of the Cascade Mountains; and eastern Northwest mountains (ENWM), the mountainous areas east of the Cascade Mountains.
To understand MC2 sensitivity to model assumptions, I further explored results and associated uncertainties from the MC2 Dynamic Global Vegetation Model for the WNW subregion. I compared model results for vegetation cover and carbon dynamics over the period 1895-2100 assuming: 1) unlimited wildfire ignitions versus stochastic ignitions, 2) no fire, and 3) a moderate CO2 fertilization effect versus no CO2 fertilization effect.
Finally, I implemented an Environmental Evaluation Modeling System (EEMS) decision support model using MC2 DGVM results to characterize biomass loss risk for the WNW subregion. Risk was based on biomass present, fire occurrence and severity, and mortality of climate-maladapted vegetation as indicated by modeled vegetation type change. I characterized the uncertainty due to RCP, fire suppression, and climate projection choice, and I evaluated whether fire or climate maladaptation mortality was the dominant driver of risk.
In the 21st century, in the WNW, mean fire interval (MFI) averaged over all climate projections decreases by up to 48%. By the end of the 21st century, potential vegetation shifts from conifer to mixed forest under RCP 4.5 and 8.5 with and without fire suppression. In the NWPP, MFI averaged over all climate projections decreases by up to 82% without fire suppression and increases by up to 14% with fire suppression resulting in woodier vegetation cover. In the ENWM, MFI averaged across all climate projections decreases by up to 81%, subalpine communities are lost, but conifer forests continue to dominate the subregion in the future.
In evaluating the effects of ignition and CO2 fertilization assumptions, the greatest carbon stock loss in the WNW, approximately 23% of historical levels, occurs with unlimited ignitions and no CO2 fertilization effect. With stochastic ignitions and a CO2 fertilization effect, carbon stocks are more stable than with unlimited ignitions. For all scenarios, the dominant vegetation type shifts from pure conifer to mixed forest, indicating that vegetation cover change is driven solely by climate and that significant mortality due climate-maladapted vegetation as indicated by modeled vegetation shifts are likely through the 21st century regardless of fire regime changes.
The risk of biomass loss in the WNW generally increases in current high biomass areas within the study region through time. The pattern of increased risk is generally south to north and upslope into the Coast and Cascade mountain ranges and along the coast. Uncertainty from climate future choice is greater than that attributable to RCP or +/- fire suppression. Fire dominates as the driving factor for biomass loss risk in more model runs than mortality due to climate maladaptation. This method of interpreting DGVM results and the associated uncertainty provides managers with data in a form directly applicable to their concerns and could prove helpful in adaptive management planning at regional to local scales
Recommended from our members
Historical frequent fire in the culturally modified landscape of the McDonald-Dunn Forest
No full textThe existence and condition of old-growth Douglas-fir (Pseudotsuga menziesii var menziesii) forests in the McDonald and Dunn Research Forest of the Willamette Valley, Oregon, are inextricably tied to the occurrence and reoccurrence of fire. Fire, in turn, is the result of both people and natural elements. Frequent cultural burning by Indigenous People in the Valley has been widely reported by different disciplines and ways of knowing, but few studies have attempted to describe its spatial or temporal qualities over time for any particular part of the Valley. It is understood that the immense diversity of ecosystems and vegetation types present in the Valley prior to settlement, including old forests, is the result of sophisticated cultural burning and land stewardship by Indigenous Peoples. An investigation into the fire history of the Research Forest offers insights into both Indigenous cultural groups and ways of living in fire-prone ecosystems. Unique characteristics of Willamette Valley old-growth, characteristics of ecological and cultural significance, have yet to be explored or explained.
In Chapter 2, I sampled fire-scarred cross sections across different biophysical settings within the Research Forest, in order to better understand relationships between fire history and observed phenomena, and to begin to document fire, including cultural burning that is attributed to the region by other sources. I detected frequent fire from 1725-1850, with fire occurring somewhere in the study area almost every year. Fire intervals at watershed scales ranged from one to more than 10 years and typically occurred at subdecadal frequencies. Fires during this time were typically small and spatially complex, although larger fire events also occurred at lower frequencies. Fires most often occurred during August, September, and October. After roughly the year 1850, fires became less frequent, more localized, and occurred more often outside of the months of August, September, and October. These changes coincided with known settlement activities before and after 1850, including widespread disease epidemics among Indigenous Peoples, permanent settlement by white farmers, and the forced removal of Indigenous Peoples to reservations.
In Chapter 3, I used tree-aging and forest-mapping techniques to determine stand age, structure, and composition of old-growth Douglas-fir forests within the forest reserves of the McDonald-Dunn Forest. Prior to settlement around 1850, these forests were composed of an all-aged component of large, well-spaced Douglas-fir, along with a more minor component of grand fir, bigleaf maple, and Pacific yew of more unknown ages and densities. Today, these old forests have become substantially more dense, due to infilling by a largely even-aged cohort of Douglas-fir established in the decades following settlement and more gradual establishment of grand fir, bigleaf maple, and Pacific yew. I determined that the immediate cause of these major changes was the drastic decrease in fire after the mid-1840s, with the root cause being fire suppression and the loss of Indigenous fire stewardship. The old forest reserves of the McDonald-Dunn have since been shaped by a broad assortment of human activities operating under a very different worldview.
My research provides the first modern fire history for the Research Forest, and the first within the eastern Coast Range to employ rigorous dendrochronological techniques combined with an assessment of existing forest structure and composition. In a local context, this study provides ecological and historical context to past, present, and future research on the McDonald-Dunn, and is an important contribution to any endeavor that considers changing landscapes, including management. More broadly, my work has contributed to the growing understanding of forest disturbance and succession dynamics of old forests in the Douglas-fir region of the Pacific Northwest
Recommended from our members
The Effects of Disturbance History on Ground-Layer Plant Community Composition in British Columbia
No full textPlant communities are sensitive to perturbations and may display alternative recovery pathways depending on disturbance history. In sub-boreal lodgepole pine forests of central interior British Columbia, Canada, fire and logging are two widespread landscape disturbances that overlap in many regions. We asked whether cumulative, short-interval disturbance from logging and fire resulted in different ground-layer plant communities than resulted from fire alone. Using field-collected data, we compared the taxonomic composition and functional traits of 3-year old plant communities that were either harvested 6-to-13 years prior, or not harvested prior to being burned in a large stand-replacing fire. The taxonomic composition diverged between the two treatments, driven primarily by differences in a few key indicator species such as Petasites frigidus and Vaccinium membranaceum. Analysis of individual species’ morphological traits indicated that only a few species vary in size in relation to disturbance history. Our data suggest that a history of forest harvest leaves a subtle footprint on post-fire ground-layer plant communities at early stages of succession.Keywords: multiple disturbance effects, wildfire, understory species composition, forest harvest, clearcut logging, plant functional traits, disturbance histor
Fire refugia
No full textThis site serves as the data repository for the paper entitled "Drivers, spatial patterns, and biogeography of fire refugia and severity in the context of extreme fire growth events"
Authors: Cameron E. Naficy, Garrett W. Meigs, Matthew J. Gregory, Ray Davis, David M. Bell, Meg A. Krawchuk
Journal information: Ecological Application
- …
