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Wildfire refugia are forest patches that are minimally-impacted by fire and provide critical habitats for fire-sensitive species and seed sources for post-fire forest regeneration. Wildfire refugia are relatively understudied, particularly concerning the impacts of subsequent fires on existing refugia. We opportunistically re-visited 122 sites classified in 1994 for a prior fire refugia study, which were burned by two wildfires in 2012 in the Cascade mountains of central Washington, USA. We evaluated the fire effects for historically persistent fire refugia and compared them to the surrounding non-refugial forest matrix. Of 122 total refugial (43 plots) and non-refugial (79 plots) sites sampled following the 2012...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/hyp.11144/full): The extensive forests that cover the mountains of the Pacific Northwest, USA, modify snow processes and therefore affect snow water storage as well as snow disappearance timing. However, forest influences on snow accumulation and ablation vary with climate, topography, and land cover and are therefore subject to substantial temporal and spatial variability. We utilize multiple years of snow observations from across the region to assess forest-snow interactions in the relatively warm winter conditions characteristic of the maritime and maritime-continental climates. We (1) quantify the difference in snow magnitude and disappearance timing...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2015WR017873/abstract): Spatially distributed snow depth and snow duration data were collected over two to four snow seasons during water years 2011–2014 in experimental forest plots within the Cedar River Municipal Watershed, 50 km east of Seattle, Washington, USA. These 40 × 40 m forest plots, situated on the western slope of the Cascade Range, include unthinned second-growth coniferous forests, variable density thinned forests, forest gaps in which a 20 m diameter (approximately equivalent to one tree height) gap was cut in the middle of each plot, and old-growth forest. Together, this publicly available data set includes snow depth and density observations...
Abstract (from http://www.publish.csiro.au/WF/WF16165): Interannual variability in burn severity is assessed across forested ecoregions of the western United States to understand how it is influenced by variations in area burned and climate during 1984–2014. Strong correlations (|r| > 0.6) between annual area burned and climate metrics were found across many of the studied regions. The burn severity of individual fires and fire seasons was weakly, but significantly (P < 0.05), correlated with burned area across many regions. Interannual variability in fuel dryness evaluated with fuel aridity metrics demonstrated weak-to-moderate (|r| >0.4) relationships with regional burn severity, congruent with but weaker than...
Greater sage-grouse (Centrocercus urophasianus) is a candidate for listing under the Endangered Species Act because of population and habitat fragmentation coupled with inadequate regulatory mechanisms to control development in critical areas. In addition to the current threats to habitat, each 1 degree celsius increase due to climate change is expected to result in an additional 87,000 km2 of sagebrush (Artemisia spp.) that will be converted to unsuitable habitat for sage-grouse. Thus, the future distribution and composition of sagebrush landscapes is likely to differ greatly from today’s configuration. We conducted a large, multi-objective project to identify: (1) characteristics of habitats required by sage-grouse,...
Abstract (from http://www.hydrol-earth-syst-sci.net/21/1/2017/): The phase of precipitation when it reaches the ground is a first-order driver of hydrologic processes in a watershed. The presence of snow, rain, or mixed-phase precipitation affects the initial and boundary conditions that drive hydrological models. Despite their foundational importance to terrestrial hydrology, typical phase partitioning methods (PPMs) specify the phase based on near-surface air temperature only. Our review conveys the diversity of tools available for PPMs in hydrological modeling and the advancements needed to improve predictions in complex terrain with large spatiotemporal variations in precipitation phase. Initially, we review...
Abstract (from http://jcom.sissa.it/archive/15/01/JCOM_1501_2016_A01): Whereas the evolution of snow cover across forested mountain watersheds is difficult to predict or model accurately, the presence or absence of snow cover is easily observable and these observations contribute to improved snow models. We engaged citizen scientists to collect observations of the timing of distributed snow disappearance over three snow seasons across the Pacific Northwest, U.S.A. . The primary goal of the project was to build a more spatially robust dataset documenting the influence of forest cover on the timing of snow disappearance, and public outreach was a secondary goal. Each year's effort utilized a different strategy, building...
Abstract (from http://www.bioone.org/doi/abs/10.3955/046.089.0305): It is hypothesized that climate impacts forest mosaics through dynamic ecological processes such as wildfires. However, climate-fire research has primarily focused on understanding drivers of fire frequency and area burned, largely due to scale mismatches and limited data availability. Recent datasets, however, allow for the investigation of climate influences on ecological patch metrics across broad regions independent of area burned and at finer scale. One area of particular interest is the distribution of fire refugia within wildfire perimeters. Although much recent research emphasis has been placed on high-severity patches within wildfires,...
Abstract (from http://www.sciencedirect.com/science/article/pii/S0378112716308532): Across the western United States, the three primary drivers of tree mortality and carbon balance are bark beetles, timber harvest, and wildfire. While these agents of forest change frequently overlap, uncertainty remains regarding their interactions and influence on specific subsequent fire effects such as change in canopy cover. Acquisition of pre- and post-fire Light Detection and Ranging (LiDAR) data on the 2012 Pole Creek Fire in central Oregon provided an opportunity to isolate and quantify fire effects coincident with specific agents of change. This study characterizes the influence of pre-fire mountain pine beetle (MPB; Dendroctonus...
Abstract (from http://iopscience.iop.org/article/10.1088/1748-9326/aa6f94/meta): High temperatures and severe drought contributed to extensive tree mortality from fires and bark beetles during the 2000s in parts of the western continental United States. Several states in this region have greenhouse gas (GHG) emission targets and would benefit from information on the amount of carbon stored in tree biomass killed by disturbance. We quantified mean annual tree mortality from fires, bark beetles, and timber harvest from 2003–2012 for each state in this region. We estimated tree mortality from fires and beetles using tree aboveground carbon (AGC) stock and disturbance data sets derived largely from remote sensing. We...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/eap.1396/full): Extensive mortality of whitebark pine, beginning in the early to mid-2000s, occurred in the Greater Yellowstone Ecosystem (GYE) of the western US, primarily from mountain pine beetle but also from other threats such as white pine blister rust. The climatic drivers of this recent mortality and the potential for future whitebark pine mortality from mountain pine beetle are not well understood, yet are important considerations in whether to list whitebark pine as a threatened or endangered species. We sought to increase the understanding of climate influences on mountain pine beetle outbreaks in whitebark pine forests, which are less well understood...
When the Earth experiences changes in climate, wildlife respond by moving – species adjust their ranges to stay within climatically suitable habitat, moving out of areas that become too hot or otherwise inhospitable, and moving into areas that become newly hospitable. However, climate change is now proceeding so quickly that it is becoming difficult for species to move fast enough to keep pace. In addition, today’s landscapes feature significant barriers to wildlife movement due to human land use (e.g., highways, cities, agriculture). Such is the case in the region surrounding the border of Washington state, USA, and British Columbia, Canada, where increasing development pressure and limited coordination of land...
Climate responses of sagebrush are needed to inform land managers of the stability and restoration of sagebrush ecosystems, which are an important but threatened habitat type. We evaluated climate responses of sagebrush using two approaches: (1) experimental manipulations of temperature and precipitation for natural plants in the field, and (2) assessment of how climate adaptation and weather have affected sagebrush seeding efforts on nearly 25 large-scale sagebrush seeding projects done over the past several decades. Experimental warming increased growth of sagebrush in high-elevation meadows in the Teton Mountains, but had marginal or no effect at lower elevations sites (near Twin Falls and Boise, Idaho, respectively)....
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/9781119011705.ch10/summary): This chapter discusses an approach that uses MC1 results to create climate-informed state-and-transition simulation model (cSTSMs) in two contrasting landscapes: dry forests in central Oregon and wet forests in western Washington. The studies presented here examine trends in different socioecological values under different climate and management assumptions using a dynamic global vegetation model/STSM approach. The authors found that simulated management actions did not prevent climate-induced vegetation change. Simulated management did in some cases promote desired forest structures and increase resilience to climate change....
Abstract (from http://www.sciencedirect.com/science/article/pii/S0034425716303261): Wildfires shape the distribution and structure of vegetation across the inland northwestern United States. However, fire activity is expected to increase given the current rate of climate change, with uncertain outcomes. A fire impact that has not been widely addressed is the development of unburned islands; areas within the fire perimeter that do not burn. These areas function as critical ecological refugia for biota during or following wildfires, but they have been largely ignored in methodological studies of remote sensing assessing fire severity under the assumption that they will be detected by algorithms for delineating fire...
Abstract (from http://www.sciencedirect.com/science/article/pii/S0034425716305016): Measuring post-fire effects at landscape scales is critical to an ecological understanding of wildfire effects. Predominantly this is accomplished with either multi-spectral remote sensing data or through ground-based field sampling plots. While these methods are important, field data is usually limited to opportunistic post-fire observations, and spectral data often lacks validation with specific variables of change. Additional uncertainty remains regarding how best to account for environmental variables influencing fire effects (e.g., weather) for which observational data cannot easily be acquired, and whether pre-fire agents of...
Aspen forests are “biological hotspots” in the western United States that support numerous wildlife species. Aspen ecosystems are also economically and socially important, providing high quality forage for livestock and game species (e.g. elk), as well as drawing tourists and improving local economies. Aspen ecosystems are in decline across portions of the western U.S., which is thought to be partly due to drought, and recent research suggests that future climate projected for the western U.S. will be even less capable of supporting aspen. We used different research methods to investigate key controls on aspen growth and survivability in the northern Great Basin and central Rockies. Specifically, we projected the...
Unburned islands are areas within wildfire perimeters that did not burn. These islands are important because they serve as a refuge both during and after the fire for plants and animals to survive and subsequently repopulate adjacent burned areas. This project sought to better understand how and why these islands occur – what makes some areas of the landscape fireproof, even as everything around them burns? How can we use that information to manage forests and rangelands in a way that supports continued development of unburned islands and fire refugia, even under climate change? To answer these questions, we developed a historical atlas of unburned islands across the Northwest (Washington, Oregon, and Idaho) and...
Habitat loss and climate change constitute two of the greatest threats to biodiversity worldwide, and theory predicts that these factors may act synergistically to affect population trajectories. Recent evidence indicates that structurally complex old-growth forest can be cooler than other forest types during spring and summer months, thereby offering potential to buffer populations from negative effects of warming. Old growth may also have higher food and nest-site availability for certain species, which could have disproportionate fitness benefits as species approach their thermal limits. We predicted that negative effects of climate change on 30-year population trends of old-growth-associated birds should be...
Abstract (from http://www.sciencedirect.com/science/article/pii/S0168192315002142): Physically-based models are a powerful tool to help understand interactions of vegetation, atmospheric dynamics, and hydrology, and to test hypotheses regarding the effects of land cover, management, hydrometeorology, and climate variability on ecosystem processes. The purpose of this paper is to evaluate recent modifications and further refinements to a multi-layer plant canopy model for simulating temperature and water vapor within three diverse forest canopies: a 4.5-m tall aspen thicket, a 15-m tall aspen canopy, and a 60-m tall Douglas fir canopy. Performance of the model was strongly related to source strength and profile stability...