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This study examines tree growth and mortality associated with spring and fall burning repeated at five (5 yr) and fifteen-year (15 yr) intervals in six previously thinned ponderosa pine stands in the southern Blue Mountain Ecoregion near Burns, Oregon, USA. Each stand consisted of an unburned control, and four season-by-burn interval treatments: spring 5 yr, spring 15 yr, fall 5 yr, and fall 15 yr. Burning was initiated in fall 1997 and spring 1998. Pine height and diameter growth was evaluated in 2013, 15 years following initial treatment. Mortality was assessed annually from 2002 to 2017, when these stands experienced severe defoliation from pine butterfly (PB, Neophasia menapia), followed by a moderate outbreak of western pine beetle (WPB, Dendroctonus brevicomis), allowing us to examine resistance to these disturbances. Pine in the 5 yr fall treatments added more diameter than spring 15 yr and marginally more than spring 5 yr, while fall 15 yr added marginally more diameter than spring 15 yr. In addition, the fall 5 yr treatments had lower mortality associated with prescribed fire, PB, WPB, Ips spp., red turpentine beetle (RTB, D. valens), and mountain pine beetle (MPB, D. ponderosae), but the effect was not always significant. Annosus root disease (ARD, caused by Heterobasidion irregulare) and black stain root disease (BSRD, caused by Leptographium wagneri var. ponderosum) appear to be unaffected by burning. However, BSRD occurrence dramatically declined in all treatments, probably a result of thinning prior to study initiation. Results from this study demonstrate that repeated fall burning, especially at 5-year intervals, improves ponderosa pine diameter growth and may provide resistance to future biotic and abiotic disturbances while spring burning, regardless of frequency, does not.
The Nature Conservancy and the Forest Service, Department of Agriculture have long-term goals to reintroduce fire into U.S. ecosystems at ecologically relevant spatial and temporal scales. Building on decades of collaborative work, a Master Participating Agreement was signed in March 2017 to increase overall fire management capacity through training and education. In October 2017, The Nature Conservancy hosted a cross-boundary fire training, education, research, and restoration-related event for 2 weeks at Sycan Marsh Preserve in Oregon. Eighty people from 15 organizations applied prescribed fire on over 1,200 acres (490 ha). Managers and scientists participated
in the applied learning and training exercise. The exercise was a success; operational and research objectives were met, as indicated by multiagency, multidisciplinary fire research, and effectiveness monitoring. This paper describes a paradigm shift of fire-adapted, cross-boundary, multiagency landscape-scale restoration. Participants integrated adaptive management and translational ecology so that applied controlled burning incorporated
the most up-to-date scientifically informed management decisions. Scientists worked with practitioners to advance their understanding of the challenges being addressed by managers. The model program has stimulated an exponential increase in landscape scale and ecologically relevant dry forest restoration in eastern Oregon. Collaboration between managers and scientists is foundational in the long-term success of fire-adapted restoration. Examples of effects of prescribed fire on ecosystem services in the project area, such as increased resilience of trees in drought years, are also provided.
The relative influence of climate change and fire exclusion vary with soil moisture, which itself is influenced by climate and local topography:
- Burn probability along a soil aridity gradient for Trail Creek and Johnson Creek, with and without climate change, and with and without fire exclusion. Climate change increased burn probability by drying fuels in the most mesic locations (i.e., locations where temporally averaged soil moisture was high; see difference between blue and orange lines, highlighted by the upward pointing arrow). In the most arid locations, climate change promoted drought stress and reduced fine fuel loads, which in turn reduced burn probability.
- Climate change increased burn probability and led to larger, more frequent fires in locations where soil aridity was relatively low (i.e., time-averaged soil moisture >35%).
- In the most arid locations (i.e., time-averaged soil moisture <25%), climate change promoted drought stress and reduced fine fuel loads, which in turn reduced burn probability.
- In locations with intermediate soil aridity (25-35%), the effects of climate change and fire suppression varied in response to local trade-offs between aridity (which makes fuels more flammable) and productivity (which increases fuel loads).
Even within watersheds, at fine scales, risk management must be spatially and temporally explicit to optimize effects
Severity of fungal disease did not result in measurable reductions of populations of a non‐native, invasive host species, cheatgrass, which suggests that natural enemies may not strongly regulate cheatgrass in its introduced range. Landscape heterogeneity associated with disturbance and weather limited population‐level infection of hosts by the fungal pathogen. Disturbance (specifically wildfire) and variable weather are key components of this and similar invasion systems, and likely need to be considered when evaluating disease dynamics and potential for natural enemies to influence invasion potential.
Top-down and bottom-up factors affecting invasive populations are rarely considered simultaneously, yet their interactive responses to disturbances and management interventions can be essential to understanding invasion patterns. We evaluated post-fire responses of the exotic perennial forb Chondrilla juncea (rush skeletonweed) and its biocontrol agents to landscape factors and a post-fire combined herbicide (imazapic) and bacteria (Pseudomonas fluorescens strain MB906) treatment that targeted invasive annual grasses in a sagebrush steppe ecosystem. Biocontrol agents released against C. juncea in previous decades included Cystiphora schmidti (gall midge), Aceria chondrillae (gall mite), and Puccinia chondrillina (rust fungus). C. juncea abundance was greater in sprayed than unsprayed plots, and where soils were coarser, slopes faced southwest, solar heat loads and topographic water accumulation were greater, and cover of deep-rooted native perennials was lower. Mite infestation was greater in unsprayed plots, midge infestation was greater at higher elevations on steeper slopes, and midges were more abundant while rust was less abundant on gravelly soils. Biocontrol infestation levels varied considerably between years and could not be predicted in 2019 from 2018 infestation levels. Multiple biocontrol species were often present at the same plots but were rarely present on the same C. juncea individuals. These results suggest that spatial patterns of invasion by C. juncea are related to deep-soil water availability, warmer conditions, and alleviation of competition. Treatments designed to reduce invasive annual grasses may inadvertently release C. juncea by both reducing plant competition for soil resources and affecting biocontrol agent (mite) abundance.
Think of a floodplain as a sponge: Each spring, floodplains in the West soak up snow melting from the mountains. The sponge is then wrung out during summer and fall, when the snow is gone and rainfall is scarce. The more water that stays in the sponge, the longer streams can flow and plants can thrive. A full sponge makes the landscape better equipped to handle natural disasters, since wet places full of green vegetation can slow floods, tolerate droughts or stall flames.
The Pinyon Jay is a highly social, year-round inhabitant of pinyon-juniper and other coniferous woodlands in the western United States. Range-wide, Pinyon Jays have declined ~ 3-4% per year for at least the last half-century. Occurrence patterns and habitat use of Pinyon Jays have not been well characterized across much of the species’ range, and obtaining this information is necessary for better understanding the causes of ongoing declines and determining useful conservation strategies. Additionally, it is important to better understand if and how targeted removal of pinyon-juniper woodland, a common and widespread vegetation management practice, affects Pinyon Jays. The goal of this study was to identify the characteristics of areas used by Pinyon Jays for several critical life history components in the Great Basin, which is home to nearly half of the species’ global population, and to thereby facilitate the inclusion of Pinyon Jay conservation measures in the design of vegetation management projects. To accomplish this, we studied Pinyon Jays in three widely separated study areas using radio telemetry and direct observation and measured key attributes of their locations and a separate set of randomly-selected control sites using the U. S. Forest Service’s Forest Inventory Analysis protocol. Data visualizations, principle components analysis, and logistic regressions of the resulting data indicated that Pinyon Jays used a distinct subset of available pinyon-juniper woodland habitat, and further suggested that Pinyon Jays used different but overlapping habitats for seed caching, foraging, and nesting. Caching was concentrated in low-elevation, relatively flat areas with low tree cover; foraging occurred at slightly higher elevations with generally moderate but variable tree cover; and nesting was concentrated in slightly higher areas with high tree and vegetation cover. All three of these Pinyon Jay behavior types were highly concentrated within the lower-elevation band of pinyon-juniper woodland close to the woodland-shrubland ecotone. Woodland removal projects in the Great Basin are often concentrated in these same areas, so it is potentially important to incorporate conservation measures informed by Pinyon Jay occurrence patterns into existing woodland management paradigms, protocols, and practices.
A treatment targeting a single plant functional group did not achieve lasting success in these diversely invaded communities. Spraying alone did not release native perennials sufficiently to counteract the simultaneous release of secondary invaders and the return of target invaders. Planting or seeding may also be needed to achieve management goals.
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Wildland fires in 1999 and 2000 were the worst in 50 years and burned millions of acres of public lands. A shortage of native plant materials substantially increased the cost of rehabilitation and restoration efforts on the burned lands. Ecosystem restoration with native plants, in many cases, is the best option for restoring land health for multiple resource values and minimizing the establishment of invasive weeds.
This analysis reveals that outcomes are often predicated on complex process pathways over which humans have limited control. Consequently, expectations often shift through the course of projects, suggesting that a more useful paradigm for evaluating process-based restoration would be to identify relevant processes and to rigorously document how projects do or do not proceed along expected process pathways using both quantitative and qualitative data.