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Folders: ROOT > ScienceBase Catalog > National and Regional Climate Adaptation Science Centers > Northwest CASC > FY 2014 Projects > Disappearing Refugia: Identifying Trends and Resilience in Unburned Islands under Climate Change ( Show direct descendants )

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_____Disappearing Refugia: Identifying Trends and Resilience in Unburned Islands under Climate Change
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A warming climate, fire exclusion, and land cover changes are altering the conditions that produced historical fire regimes and facilitating increased recent wildfire activity in the northwestern United States. Understanding the impacts of changing fire regimes on forest recruitment and succession, species distributions, carbon cycling, and ecosystem services is critical, but challenging across broad spatial scales. One important and understudied aspect of fire regimes is the unburned area within fire perimeters; these areas can function as fire refugia across the landscape during and after wildfire by providing habitat and seed sources. With increasing fire activity, there is speculation that fire intensity and...
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://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...
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...
We established a Landsat-derived geospatial database of unburned islands within 2,298 fires across the Inland Northwestern US (including eastern Washington, eastern Oregon, and Idaho) from 1984-2014. The detection of unburned areas within these fires is based upon a classification tree approach that uses two pre- and post-fire Landsat image pairs (see Meddens et al 2016 for details). The data set consist of unburned patches within each fire that are two pixels or larger. This database will be useful for identifying fire refugia, seed sources, and can be used as an overall metric of fire impacts across the northwestern US. (Meddens, A.J., Kolden, C.A., & Lutz, J.A. (2016). Detecting unburned areas within wildfire...
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 Oxford Academic): Fire refugia are landscape elements that remain unburned or minimally affected by fire, thereby supporting postfire ecosystem function, biodiversity, and resilience to disturbances. Although fire refugia have been studied across continents, scales, and affected taxa, they have not been characterized systematically over space and time, which is crucial for understanding their role in facilitating resilience in the context of global change. We identify four dichotomies that delineate an overarching conceptual framework of fire refugia: unburned versus lower severity, species-specific versus landscape-process characteristics, predictable versus stochastic, and ephemeral versus persistent....
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Composite Burn Index (CBI) Plot Data from 2015 field campiagn. These data are used in the detection of unburned areas using Landsat imagery, see for more info: Meddens, A. J., C. A. Kolden, and J. A. Lutz. 2016. Detecting unburned areas within wildfire perimeters using Landsat and ancillary data across the northwestern United States. Remote Sensing of Environment 186:275-285. Note that the data are entered into the jFiremon database management tool and outputted as a Microsoft Access database. Most plot locations are recorded in the UTM_zone11 with NAD83 datum, although some are recorded in zone 10. See spreadsheets for more info. A total of 380 plots were recorded.
Abstract (from esa): Western U.S. wildfire area burned has increased dramatically over the last half‐century. How contemporary extent and severity of wildfires compare to the pre‐settlement patterns to which ecosystems are adapted is debated. We compared large wildfires in Pacific Northwest forests from 1984 to 2015 to modeled historic fire regimes. Despite late twentieth‐century increases in area burned, we show that Pacific Northwest forests have experienced an order of magnitude less fire over 32 yr than expected under historic fire regimes. Within fires that have burned, severity distributions are disconnected from historical references. From 1984 to 2015, 1.6 M ha burned; this is 13.3–18.9 M ha less than expected....
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...
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...
Abstract (from http://www.publish.csiro.au/paper/WF15082.htm): The Monitoring Trends in Burn Severity project is a comprehensive fire atlas for the United States that includes perimeters and severity data for all fires greater than a particular size (~400 ha in the western US, and ~200 ha in the eastern US). Although the database was derived for management purposes, the scientific community has expressed interest in its research capacity. As with any derived data, it is critical to understand inherent limitations to maximise the utility of the dataset without compromising the inferences. The classified severity product in particular is of limited use to research due to a lack of both consistency in developing class...
Abstract (from ScienceDirect): Fire refugia – the unburned areas within fire perimeters – are important to the survival of many taxa through fire events and the revegetation of post-fire landscapes. Previous work has shown that species use and benefit from small-scale fire refugia (1–1000 m2), but our understanding of where and how fire refugia form is largely limited to the scale of remotely sensed data (i.e., 900 m2 Landsat pixels). To examine the causes and consequences of small fire refugia, we field-mapped all unburned patches ≥1 m2 within a contiguous 25.6 ha forest plot that burned at generally low-to-moderate severity in the 2013 Yosemite Rim Fire, California, USA. Within the Yosemite Forest Dynamics Plot...
Abstract (from Biogeosciences): Fire is a dynamic ecological process in forests and impacts the carbon (C) cycle through direct combustion emissions, tree mortality, and by impairing the ability of surviving trees to sequester carbon. While studies on young trees have demonstrated that fire intensity is a determinant of post-fire net primary productivity, wildland fires on landscape to regional scales have largely been assumed to either cause tree mortality, or conversely, cause no physiological impact, ignoring the impacted but surviving trees. Our objective was to understand how fire intensity affects post-fire net primary productivity in conifer-dominated forested ecosystems on the spatial scale of large wildland...
map background search result map search result map Composite Burn Index (CBI) Plot Data from 2015 field campaign Unburned areas within fire perimeters across the Inland Northwestern USA from 1984 to 2014 Composite Burn Index (CBI) Plot Data from 2015 field campaign Unburned areas within fire perimeters across the Inland Northwestern USA from 1984 to 2014