Research Database
Displaying 21 - 40 of 44
Ventenata ( Ventenata dubia ) Response to Grazing and Prescribed Fire on the Pacific Northwest Bunchgrass Prairie
Year: 2022
The exotic annual grass ventenata ( Ventenata dubia L.) is raising concern as it rapidly invades multiple ecosystem types within the United States, including sagebrush steppe, ponderosa pine forests, woodlands, and much of the Palouse and Pacific Northwest Bunchgrass Prairie (PNB). Despite increasing attention, little is known about the invasion dynamics of ventenata, especially its response to disturbances such as grazing and fire. In this study, we examined how cattle grazing and prescribed fire affect the abundance (standing crop, cover, frequency, and density) of ventenata and other plant…
Publication Type: Journal Article
Historical Fire and Ventenata dubia Invasion in a Temperate Grassland
Year: 2021
Ventenata (Ventenata dubia L.) is an invasive annual grass that has rapidly expanded its range across temperate grassland and shrub-steppe ecosystems in western North America. However, there is little published regarding its ecology, especially its relationship with fire on rangelands. The objective of this study was to examine the effect of fire on ventenata invasion in the Pacific Northwest Bunchgrass (PNB) Prairie. Given the influence of fire on the invasion of other annual grasses such as cheatgrass ( Bromus tectorum L.), we expected that fire would facilitate the spread and increase in…
Publication Type: Journal Article
Expanding the invasion footprint: Ventenata dubia and relationships to wildfire, environment, and plant communities in the Blue Mountains of the Inland Northwest, USA
Year: 2020
Questions: A recently introduced non-native annual grass, Ventenata dubia, is challenging previous conceptions of community resistance in forest mosaic communities in the Inland Northwest. However, little is known of the drivers and potential ecological impacts of this rapidly expanding species. Here we (1) identify abiotic and biotic habitat characteristics associated with the V. dubia invasion and examine how these differ between V. dubia and other problematic non-native annual grasses, Bromustectorum and Taeniatherum caput-medusae; and (2) determine how burning influences relationships…
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
Invasive grasses: A new perfect storm for forested ecosystems?
Year: 2020
Exotic grasses are a widespread set of invasive species that are notable for their ability to significantly alter key aspects of ecosystem function. Understanding the role and importance of these invaders in forested landscapes has been limited but is now rising, as grasses from Eurasia and Africa continue to spread through ecosystems of the Americas, Australia, and many Pacific islands, where they threaten biodiversity and alter various aspects of the fire regime. The ecological, social and economic impacts of the grass-fire cycle associated with species such as cheatgrass (Bromus tectorum)…
Publication Type: Journal Article
Short- and long-term effects of ponderosa pine fuel treatments intersected by the Egley Fire Complex, Oregon, USA
Year: 2019
Background Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after…
Publication Type: Journal Article
The emergence of network governance in U.S. National Forest Administration: Causal factors and propositions for future research
Year: 2019
Since its establishment in the early twentieth century, the U.S. Forest Service has periodically evolved its approach to decision-making and management for the millions of hectares of national forest under its authority. Starting in the 1990s, a complex governance regime emerged in which non-Forest Service entities—such as state and other federal agencies, non-governmental organizations, public utilities, rural communities, and others—contribute resources and legitimacy to processes that include decision-making, project funding and implementation, monitoring, and changes to management rules…
Publication Type: Journal Article
Wildfire, climate, and invasive grass interactions negatively impact an indicator species by reshaping sagebrush ecosystems
Year: 2016
Iconic sagebrush ecosystems of the American West are threatened by larger and more frequent wildfires that can kill sagebrush and facilitate invasion by annual grasses, creating a cycle that alters sagebrush ecosystem recovery post disturbance. Thwarting this accelerated grass–fire cycle is at the forefront of current national conservation efforts, yet its impacts on wildlife populations inhabiting these ecosystems have not been quantified rigorously. Within a Bayesian framework, we modeled 30 y of wildfire and climatic effects on population rates of change of a sagebrush-obligate species,…
Publication Type: Journal Article
Ecosystem resilience is evident 17 years after fire in Wyoming big sagebrush ecosystems
Year: 2016
Recent policy has focused on prevention of wildfire in the sagebrush steppe in an effort to protect habitat for the greater sage grouse (Centrocercus urophasianus). Historically, fire return intervals in Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) ecosystems were 50–100 yr or more, but invasive species, climate change, and a legacy of intensive grazing practices have led to degraded rangeland condition, altered fire regimes and fire effects, and declines in sagebrush cover. Little is known about the long-term impacts of fire in this ecosystem in areas where grazing pressure…
Publication Type: Journal Article
Seasonal burning of juniper woodlands and spatial recovery of herbaceous vegetation
Year: 2016
Decreased fire activity has been recognized as a main cause of expansion and infilling of North American woodlands. Piñon-juniper (Pinus-Juniperus) woodlands in the western United States have expanded in area 2–10-fold since the late 1800s. Woodland control measures using chainsaws, heavy equipment and prescribed fire are used to restore big sagebrush (Artemisia tridentata Nutt.) steppe plant communities and reduce woody fuel loading. Immediate objectives in the initial control of piñon-juniper are; (1) recovery of perennial herbaceous species to restore site composition, structure and…
Publication Type: Journal Article
Restoration impacts on fuels and fire potential in a dryland tropical ecosystem dominated by the invasive grass Megathyrsus maximus
Year: 2015
Ecological restoration often attempts to promote native species while managing for disturbances such as fire and non-native invasions. The goal of this research was to investigate whether restoration of a non-native, invasive Megathyrsus maximus (guinea grass) tropical grassland could simultaneously promote native species and reduce fire potential. Megathyrsus maximus was suppressed with herbicide, and three suites of native species—each including the same groundcover and shrub, and one of three tree species—were outplanted in a randomized, complete block design that also included herbicide…
Publication Type: Journal Article
Fire and non-native grass invasion interact to suppress tree regeneration in temperate deciduous forests
Year: 2015
While many ecosystems depend on fire to maintain biodiversity, non-native plant invasions can enhance fire intensity, suppressing native species and generating a fire–invasion feedback. These dynamics have been observed in arid and semi-arid ecosystems, but fire–invasion interactions in temperate deciduous forests, where prescribed fires are often used as management tools to enhance native diversity, have rarely been investigated. Here we evaluated the effects of a widespread invasive grass on fire behaviour in eastern deciduous forests in the USA and the potential effects of fire and…
Publication Type: Journal Article
Management of cheatgrass fuel loading in the shrub-steppe
Year: 2013
The fire risk experiment was in plant communities that spanned the range of B. tectorum cover. Bromus tectorum cover was grouped into five classes. Each replicate is comprised of 8 to 18 plots in the three lowest B. tectorum cover classes and 2 to 6 plots at the two highest cover classes. A replicate is a collection of plots where the risk of fire was determined as the proportion of plots that burned. Each class has four replicates. We used 176 square plots, 10 m on a side. Two hundred twenty six plots, 10 m on a side, were used to related B. tectorum cover…
Publication Type: Presentation
Does seeding after wildfires in rangelands reduce erosion or invasive species?
Year: 2013
Mitigation of ecological damage caused by rangeland wildfires has historically been an issue restricted to the western United States. It has focused on conservation of ecosystem function through reducing soil erosion and spread of invasive plants. Effectiveness of mitigation treatments has been debated recently. We reviewed recent literature to conduct a meta-analysis of seeding after wildfires to determine if seedings may (1) protect ecosystems against soil erosion and (2) reduce invasion or abundance of undesirable nonnative plant species. Effectiveness of postfire seedings was examined in…
Publication Type: Journal Article
Conditions favouring Bromus tectorum dominance of endangered sagebrush steppe ecosystems
Year: 2013
Ecosystem invasibility is determined by combinations of environmental variables, invader attributes, disturbance regimes, competitive abilities of resident species and evolutionary history between residents and disturbance regimes. Understanding the relative importance of each factor is critical to limiting future invasions and restoring ecosystems. We investigated factors potentially controlling Bromus tectorum invasions into Artemisia tridentata ssp. wyomingensis communities across 75 sites in the Great Basin. We measured soil texture, cattle grazing intensity, gaps among perennial plants…
Publication Type: Journal Article
Sagebrush steppe recovery after fire varies by development phase of Juniperus occidentalis woodland
Year: 2013
Woodland ecosystems of the world have been changed by land use demands, altered fire regimes, invasive species and climate change. Reduced fire frequency is recognised as a main causative agent for Pinus–Juniperus L. (piñon–juniper) expansion in North American woodlands. Piñon–juniper control measures, including prescribed fire, are increasingly employed to restore sagebrush steppe communities. We compared vegetation recovery following prescribed fire on Phase 2 (mid-succession) and Phase 3 (late-succession) Juniperus occidentalis Hook. (western juniper) woodlands in Oregon. The herbaceous…
Publication Type: Journal Article
Management of Cheatgrass Fuel Loading in the Shrub-Steppe
Year: 2013
The Columbia Basin Natural Wildlife Refuge (CNWR) had been periodically grazed until the Refuge was established in 1944. Cheatgrass became a prominent plant in the area. In 1986 a fire occurred near the study area. The area was reseeded with Elymus wawawaiensis (Snake River Wheatgrass, Secar cultivar). This grass has established reducing cheatgrass cover to very low levels. The study area was established in 2002 to test hypotheses on the effects of herbicides on plant community structure and establishment of Elymus wawawaiensis. In 2002 study plots were established and characterized before…
Publication Type: Report
Preemergent Control of Medusahead on California Annual Rangelands with Aminopyralid
Year: 2012
Medusahead (Taeniatherum caput-medusae [L.] Nevski), the most problematic invasive grass on many California rangelands, is difficult to control selectively in grasslands. Prescribed burning, grazing, and herbicides have been tested with some success but are not practical in all situations. The selective herbicide aminopyralid, normally used for control of certain broadleaf species such as thistles, suppresses some annual grasses when applied pre- or early postemergence. In 2009–2010, we tested the efficacy of aminopyralid for medusahead control in preemergence applications at three foothill…
Publication Type: Journal Article
Predicting the Occurrence of Downy Brome (Bromus tectorum) in Central Oregon
Year: 2012
Where the nonnative annual grass downy brome proliferates, it has changed ecosystem processes, such as nutrient, energy, and water cycles; successional pathways; and fire regimes. The objective of this study was to develop a model that predicts the presence of downy brome in Central Oregon and to test whether high presence correlates with greater cover. Understory data from the U.S. Department of Agriculture (USDA) Forest Service's Current Vegetation Survey (CVS) database for the Deschutes National Forest, the Ochoco National Forest, and the Crooked River National Grassland were compiled, and…
Publication Type: Journal Article
Cheating Cheatgrass: New research to combat a wily invasive weed
Year: 2012
Cheatgrass and its cousin, red brome, are exotic annual grasses that have invaded and altered ecosystem dynamics in more than 41 million acres of desert shrublands between the Rockies and the Cascade-Sierra chain. A fungus naturally associated with these Bromus species has been found lethal to the plants’ soil-banked dormant seeds. Supported by the Joint Fire Science Program (JFSP), researchers Susan Meyer, Phil Allen, and Julie Beckstead cultured this fungus, Pyrenophora semeniperda, in the laboratory and developed an experimental field application that, in some trials, killed all the…
Publication Type: Report