Research Database
Displaying 21 - 40 of 62
The Economic Value of Fuel Treatments: A Review of the Recent Literature for Fuel Treatment Planning
Year: 2022
This review synthesizes the scientific literature on fuel treatment economics published since 2013 with a focus on its implications for land managers and policy makers. We review the literature on whether fuel treatments are financially viable for land management agencies at the time of implementation, as well as over the lifespan of fuel treatment effectiveness. We also review the literature that considers the broad benefits of fuel treatments across multiple sectors of society. Most studies find that fuel treatments are not financially viable for land management agencies based on revenue…
Publication Type: Journal Article
Tree mortality response to drought-density interactions suggests opportunities to enhance drought resistance
Year: 2022
1. The future of dry forests around the world is uncertain given predictions that rising temperatures and enhanced aridity will increase drought-induced tree mortality. Using forest management and ecological restoration to reduce density and competition for water offers one of the few pathways that forests managers can potentially minimize drought-induced tree mortality. Competition for water during drought leads to elevated tree mortality in dense stands, although the influence of density on heat-induced stress and the durations of hot or dry conditions that most impact mortality remain…
Publication Type: Journal Article
Fire and Forests in the 21st Century: Managing Resilience Under Changing Climates and Fire Regimes in USA Forests
Year: 2021
Higher temperatures, lower snowpacks, drought, and extended dry periods have contributed to increased wildfire activity in recent decades. Climate change is expected to increase the frequency of large fires, the cumulative area burned, andfire suppression costs and risks in many areas of the USA. Fire regimes are likely to change due to interactions among climate, fire, and other stressors and disturbances; resulting in persistent changes in forest structure and function. The remainder of the twenty-first century will present substantial challenges, as natural resource managers are faced with…
Publication Type: Book Chapter
The importance of Indigenous cultural burning in forested regions of the Pacific West, USA
Year: 2021
Indigenous communities in the Pacific West of North America have long depended on fire to steward their environments, and they are increasingly asserting the importance of cultural burning to achieve goals for ecological and social restoration. We synthesized literature regarding objectives and effects of cultural burning in this region within an ecosystem services framework. Much scholarly literature focuses on why various species harvested from burned areas were important historically, while tribes and recent research increasingly stress a wide range of ecological and cultural benefits…
Publication Type: Journal Article
Expansion of the invasive European mistetoe in California, USA
Year: 2020
The horticulturist Luther Burbank introduced the European mistletoe (Viscum album L.) to Sebastopol, Sonoma County, California, USA, around 1900 to grow as a Christmas ornament crop and tincture for medicinal use. The mistletoe has since spread from the point of introduction on apple to other hardwood trees, especially non-native hardwoods in yards and farms of the region. Mistletoe surveys were previously conducted in 1971,1986, and 1991. We re-surveyed the region in 2019, with emphasis on the 1991 perimeter, and documented the current farthest distribution of V. album. This represents a 120…
Publication Type: Journal Article
Transformation of western hemlock (Tsuga heterophylla) tree crowns by dwarf mistletoe (Arceuthobium tsugense, Viscaceae)
Year: 2020
Dwarf mistletoes (Arceuthobium species) are arboreal, hemiparasitic plants of conifers that can change the structure and function of the tree crown. Hemlock dwarf mistletoe (Arceuthobium tsugense subsp. tsugense) principally parasitizes western hemlock (Tsuga heterophylla) and effects 10.8% of all western hemlock trees in Oregon, USA. In this study, we climbed 16 western hemlock trees (age 97–321 years, height 33–54.7 m) across a gradient of infection (0%–100% of branches infected) and measured occurrence of all dwarf mistletoe infections, dwarf mistletoe caused deformities, foliage, branch…
Publication Type: Journal Article
Riparian and adjacent upland forests burned synchronously during dry years in eastern Oregon (1650-1900 CE), USA
Year: 2020
Riparian forests link terrestrial and freshwater communities and therefore understanding the landscape context of fire regimes in these forests is critical to fully understanding the landscape ecology. However, few direct studies of fire regimes exist for riparian forests, especially in the landscape context of adjacent upland forests or studies of long-term climate drivers of riparian forest fires. We reconstructed a low-severity fire history from tree rings in 38 1-ha riparian plots and combined them with existing fire histories from 104 adjacent upland plots to yield 2633 fire scars…
Publication Type: Journal Article
Crowded and Thirsty: Fire exclusion leads to greater drought sensitivity in mixed-conifer forests
Year: 2020
Wildfires were a frequent source of disturbance in forests of the Western United States prior to Euro-American settlement. Following a series of catastrophic wildfires in the Northern Rockies in 1910, the U.S. Forest Service adopted a broad wildfire suppression policy that has resulted in forests thick with small trees. These crowded trees compete for nutrients and water and experience increased drought stress in summer.In recent decades, many trees have died following drought, bark beetle outbreaks, and severe wildfire. A link between this mortality and increasing susceptibility to drought…
Publication Type: Report
Washington State 2020 Forest Action Plan
Year: 2020
Washington has more than 22 million acres of forestland. From the lush rainforests on our coasts, to the rugged sub-alpine forests along the Cascade Crest, to the pine-dominated hillsides surrounding the Columbia Plateau, forests are an integral part of our landscapes and communities, and they provide a wealth of benefits to Washingtonians and the planet. They provide us with sustainable timber and jobs, produce clean air and water, sequester carbon, and support world-class outdoor recreation. Our forests, however, face unprecedented threats that require bold action. Climate change is…
Publication Type: Government Report
Tamm Review: Reforestation for resilience in dry western U.S. forests
Year: 2019
The increasing frequency and severity of fire and drought events have negatively impacted the capacity and success of reforestation efforts in many dry, western U.S. forests. Challenges to reforestation include the cost and safety concerns of replanting large areas of standing dead trees, and high seedling and sapling mortality rates due to water stress, competing vegetation, and repeat fires that burn young plantations. Standard reforestation practices have emphasized establishing dense conifer cover with gridded planting, sometimes called 'pines in lines', followed by shrub control and pre-…
Publication Type: Journal Article
Fire deficits have increased drought‐sensitivity in dry conifer forests; fire frequency and tree‐ring carbon isotope evidence from Central Oregon
Year: 2019
A century of fire suppression across the Western US has led to more crowded forests and increased competition for resources. Studies of forest thinning or stand conditions after mortality events have provided indirect evidence for how competition can promote drought stress and predispose forests to severe fire and/or bark beetle outbreaks. Here we demonstrate linkages between fire deficits and increasing drought stress through analyses of annually resolved tree‐ring growth, fire scars, and carbon isotope discrimination (Δ13C) across a dry mixed‐conifer forest landscape. Fire deficits across…
Publication Type: Journal Article
Disequilibrium of fire-prone forests sets the stage for a rapid decline in conifer dominance during the 21st century
Year: 2018
The impacts of climatic changes on forests may appear gradually on time scales of years to centuries due to the long generation times of trees. Consequently, current forest extent may not reflect current climatic patterns. In contrast with these lagged responses, abrupt transitions in forests under climate change may occur in environments where alternative vegetation states are influenced by disturbances, such as fire. The Klamath forest landscape (northern California and southwest Oregon, USA) is currently dominated by high biomass, biodiverse temperate coniferous forests, but climate change…
Publication Type: Journal Article
It takes a few to tango: changing climate and fire regimes can cause regeneration failure of two subalpine conifers
Year: 2018
Environmental change is accelerating in the 21st century, but how multiple drivers may interact to alter forest resilience remains uncertain. In forests affected by large high-severity disturbances, tree regeneration is a resilience linchpin that shapes successional trajectories for decades. We modeled stands of two widespread western U.S. conifers, Douglas-fir (Pseudotsuga menziesii var. glauca), and lodgepole pine (Pinus contorta var. latifolia), in Yellowstone National Park (Wyoming, USA) to ask (1) What combinations of distance to seed source, fire return interval, and warming-drying…
Publication Type: Journal Article
Regional and local controls on historical fire regimes of dry forests and woodlands in the Rogue River Basin, Oregon, USA
Year: 2018
Fire regimes structure plant communities worldwide with regional and local factors, including anthropogenic fire management, influencing fire frequency and severity. Forests of the Rogue River Basin in Oregon, USA, are both productive and fire-prone due to ample winter precipitation and summer drought; yet management in this region is strongly influenced by forest practices that depend on fire exclusion. Regionally, climate change is increasing fire frequency, elevating the importance of understanding historically frequent-fire regimes. We use cross-dated fire-scars to characterize historical…
Publication Type: Journal Article
Drought, Tree Mortality, and Wildfire in Forests Adapted to Frequent Fire
Year: 2018
Massive tree mortality has occurred rapidly in frequent-fire-adapted forests of the Sierra Nevada, California. This mortality is a product of acute drought compounded by the long-established removal of a key ecosystem process: frequent, low- to moderate-intensity fire. The recent tree mortality has many implications for the future of these forests and the ecological goods and services they provide to society. Future wildfire hazard following this mortality can be generally characterized by decreased crown fire potential and increased surface fire intensity in the short to intermediate term.…
Publication Type: Journal Article
Wildfires managed for restoration enhance ecological resilience
Year: 2018
Expanding the footprint of natural fire has been proposed as one potential solution to increase the pace of forest restoration programs in fire‐adapted landscapes of the western USA. However, studies that examine the long‐term socio‐ecological trade‐offs of expanding natural fire to reduce wildfire risk and create fire resilient landscapes are lacking. We used the model Envision to examine the outcomes that might result from increased area burned by what we call “restoration” wildfire in a landscape where the ecological benefits of wildfire are known, but the need to suppress high‐risk fires…
Publication Type: Journal Article
Review of broad-scale drought monitoring of forests: Toward an integrated data mining approach
Year: 2016
Efforts to monitor the broad-scale impacts of drought on forests often come up short. Drought is a direct stressor of forests as well as a driver of secondary disturbance agents, making a full accounting of drought impacts challenging. General impacts can be inferred from moisture deficits quantified using precipitation and temperature measurements. However, derived meteorological indices may not meaningfully capture drought impacts because drought responses can differ substantially among species, sites and regions. Meteorology-based approaches also require the characterization of current…
Publication Type: Journal Article
Wildfire, climate, and perceptions in Northeast Oregon
Year: 2016
Wildfire poses a rising threat in the western USA, fueled by synergies between historical fire suppression, changing land use, insects and disease, and shifts toward a drier, warmer climate. The rugged landscapes of northeast Oregon, with their historically forest- and resource-based economies, have been one of the areas affected. A 2011 survey found area residents highly concerned about fire and insect threats, but not about climate change. In 2014 we conducted a second survey that, to explore this apparent disconnect, included questions about past and future summertime (fire season)…
Publication Type: Journal Article
Effects of Drought on Forests and Rangelands in the United States: A Comprehensive Science Synthesis
Year: 2016
This assessment provides input to the reauthorized National Integrated Drought Information System (NIDIS) and the National Climate Assessment (NCA), and it establishes the scientific foundation needed to manage for drought resilience and adaptation. Focal areas include drought characterization; drought impacts on forest processes and disturbances such as insect outbreaks and wildfire; and consequences for forest and rangeland values. Drought can be a severe natural disaster with substantial social and economic consequences. Drought becomes most obvious when large-scale changes are observed;…
Publication Type: Report
Does prescribed fire promote resistance to drought in low elevation forests of the Sierra Nevada, California, USA?
Year: 2016
Prescribed fire is a primary tool used to restore western forests following more than a century of fire exclusion, reducing fire hazard by removing dead and live fuels (small trees and shrubs). It is commonly assumed that the reduced forest density following prescribed fire also reduces competition for resources among the remaining trees, so that the remaining trees are more resistant (more likely to survive) in the face of additional stressors, such as drought. Yet this proposition remains largely untested, so that managers do not have the basic information to evaluate whether prescribed…
Publication Type: Journal Article