a class of fuels that might range from approximately 3 to 8 inches (7.6 to 20.3 cm) in diameter; named because it takes fuels of this size roughly 1,000 hours to respond to changes in moisture conditions. (Ch. 5)

a class of fuels that might range from approximately 1 to 3 inches (2.5 to 7.6 cm) in diameter; named because it takes fuels of this size roughly 100 hours to respond to changes in moisture conditions. (Ch. 5)

the actual amount of moisture lost to the atmosphere from plant and soil surfaces. (Ch. 23)

a measure of how much plant-available moisture a soil is capable of holding at a given depth. (Ch. 23)

the distance from projected future climate pixels back to analogous current climate locations; the speed at which a climate or species niche must travel to reach a particular future location. Note that backward velocity reflects the minimum distance, given the projected future conditions at a site, that a climate-adapted organism would have to migrate to colonize the site. (Ch. 2, 18)

the ratio of the lowest average 7-day summer flow to the year-round average daily flow. (Ch. 10)

streamflow that occurs between periods of rainfall or snowmelt. Usually this component of streamflow does not originate from surface runoff and instead originates from groundwater storage or water fluxes from the soil subsurface. (Ch. 10)

a strategy for decision-making with known uncertainties whereby conservation actions are identified that could provide benefits under a range of possible future scenarios such as those associated with climate change. (Ch. 17)

the center of timing of the mass of streamflow for an annual water year calculated using a weighted mean: (flow1*1 + flow2*2 + […] + flow365*365) / (flow1 + flow2 + [...] + flow365) where flowd is the flow volume on each day of the water year. (Ch. 10)

a location with a set of similar (analogous) climate conditions to a given location of interest. A location can have future climate analogs (areas that are projected to have similar climatic conditions in the future), current climate analogs (areas with similar current climatic conditions), and historical climatic analogs (areas that had similar climatic conditions in the past). (Ch. 2, 3, 7, 14)

a "normal" period is typically defined as three decades, e.g., from 1971-2000. The climate or fire variables averaged across such a 30-year span can represent "normal" climate or environmental conditions during that time period. (Ch. 6)

a metric that represents the rate at which temperature isotherms (units of the same temperature) shift in response to climate warming; the direction and rate at which organisms must move to maintain constant climatic conditions through time. For example, in Chapter 9, climate velocity specifically refers to the rate at which August mean stream temperature isotherms shift at sites along a stream. (Ch. 2, 9, 15).

“a metric of potential ground wetness” that “models water flow accumulation as a function of upstream contributing area and slope.” “Smallest CTI values are typically found along ridgelines and largest values in valley bottoms” (Buttrick et al., 2015). (Ch. 21)

links of habitat that connect larger habitat patches and facilitate species movements across the landscape. (Ch. 12)

the moisture content of materials that may be fuel for fire. Although fire occurrence depends on many factors, lower DFM can contribute to greater fire potential. (Ch. 5)

a soil that has chronically low seasonal moisture and thus may be especially vulnerable to drought conditions during climatically dry periods. (Ch. 23)

the portion of a land facet found within an ecoregion. For example, in Chapter 13, 162 land facets were stratified by 11 ecoregions to produce 794 ecofacets. (Ch. 13)

"the capacity of ecosystems to reorganize and regain their fundamental structure, processes, and functioning (i.e., to recover) when altered by stressors like drought and disturbances like inappropriate livestock grazing and altered fire regimes" (Chambers et al. 2017). See also resilience. (Ch. 24)

“a category of land with a distinctive (i.e., mappable) combination of landscape elements, including climate, geology, geomorphology, soils, and potential natural vegetation. Ecological types differ from each other in their ability to produce vegetation and respond to management and natural disturbances” (Chambers et al. 2017). (Ch. 24)

diversity of ecotypes (i.e., locations with unique climatic, landform, lithology, and land cover characteristics, see Sayre et al. (2014)) within a given spatial neighborhood. (Ch. 19)

a concept borrowed from electrical circuitry that treats landscapes and conductive surfaces across which species can travel, analogous to electrical current moving through a network of circuits. (Ch. 14)

climate-change velocity, assuming that organisms travel in straight lines. (Ch. 15)

locations with suitable climate that are geographically removed from a species current distribution; "may vary in proximity to a species’ current distribution, with consequent implications for their overall value" (Stralberg et al. 2018). (Ch. 18)

the outer edge of a wildfire or prescribed fire. (Ch. 8)

"remnants of habitat that maintain ecological function following relatively low-severity fire" (Meddens et al. 2018). (Ch. 8)

a metric of fire frequency representing the average number of years between fires for a given location. (Ch. 7)

the distance from current climate locations to the nearest site with an analogous future climate; note that forward velocity reflects the minimum distance an organism in the current landscape must migrate to maintain constant climate conditions. (Ch. 2)

a type of model that projects future suitable habitat for each study species, based on observed associations between locations where species currently exist, and the climate, land cover, and other environmental features found at those locations. (Ch. 16)

“an approximation of relative, local temperature” (Buttrick et al. 2015) in which southwest-facing slopes have the highest values and northeast-facing slopes have the lowest values. An index based on topography of how much solar warming a site receives by virtue of its latitude, slope, and aspect (i.e., the direction a slope is facing); see McCune and Keon (2002). (Ch. 19, 20, 21)

hydrologic units exist within a nested hierarchy from large regions (2-digit hydrologic units; HUC-2) to small watersheds (12 or higher-digit hydrologic units). In practice, “HUC-6” refers to watersheds of intermediate size. (Ch. 12)

a depiction of streamflow over time, typically by plotting streamflow on the vertical axis and days of the water year on the horizontal axis. (Ch. 10)

"characterized by relatively constant climate conditions that facilitate species persistence or, for individual species, overlap between current and future climatic niches" (Stralberg et al. 2018). (Ch. 18)

unique combinations of geophysical factors that stratify the landscape into discrete classes relevant to the needs of an analysis. (Ch. 13)

a measure of the variety of land facets (i.e., locations with unique landform, HLI, elevation, and soil order characteristics) within a given spatial neighborhood. (Ch. 19)

a classification of the landscape based on topography, namely slope and Topographic Position Index. Physical landscape features such as peaks, ridges, cliffs, slopes, and valleys, differentiated by warm, neutral, and cool heat loads. (Ch. 19, 20)

a remote-sensing image of the Earth's surface produced by the Landsat program for a location at a given time. (Ch. 8)

"the degree to which regional landscapes, encompassing a variety of natural, semi-natural and developed land cover types, will sustain ecological processes and are conducive to the movement of many types of organisms" (Buttrick et al. 2015). The potential for species movement, which may be decreased by human modification of the landscape. (Ch. 13, 14

an approach to identifying potential movement routes that minimize the "cost" associated with travel. "Cost" can be conceptualized and quantified in many ways; in Chapter 15, it represents the exposure of an organism to unsuitable climate conditions (i.e., too warm or too cool compared to the climate conditions the organism is tracking as it migrates). (Ch. 15)

surficial geology that provides parent material for soil formation, including sediment deposits and areas of exposed bedrock. (Ch. 20)

"defined by sustained climatic suitability along broad spatial and temporal gradients"; distinct from microrefugia, which "suggest a decoupling of local climate conditions from the surrounding landscape" (Stralberg et al. 2018). (Ch. 18)

the total exposure to dissimilar climate that an organism experiences as it responds to climate change by migrating to newly favorable climate, assuming the organism follows a path that minimizes exposure to dissimilar climate. (Ch. 15)

the distance along the route followed by an organism migrating in response to climate change, assuming the organism follows a path that minimizes exposure to dissimilar climate. (Ch. 15)

climate-change velocity, assuming that organisms travel so as to minimize their total exposure to dissimilar climate, and not necessarily in straight lines. (Ch. 15)

a representation of the potential for a location to serve as a refugium to multiple species within a taxonomic or functional group (e.g., trees or songbirds). (Ch. 18)

climate velocity calculated using multiple climate variables, as opposed to a single variables such as annual temperature. (Ch. 2)

a regional database for the Pacific Northwest of the United States containing observed stream temperatures and modeled stream temperature estimates for historical and future climate scenarios at 1-km resolution. See (Ch. 9)

a metric of fire severity representing the percentage of fires resulting in at least 75% canopy consumption, which can be inferred as the probability of stand-replacing fire for a given location. (Ch. 7)

a theoretical lower limit of plant-available water, defined as the minimal amount of soil moisture below which a plant will wilt and then fail to recover when supplied with sufficient moisture. (Ch. 23)

landscape patterns that combine landforms and lithology. (Ch. 20)

an estimate of the combined evaporation and transpiration that would theoretically occur if these processes were not limited by soil moisture availability. (Ch. 23)

a statistical technique to reduce a large number of correlated variables to a smaller number of 'principal components' (PCs) that retain most of the information from the original set of variables. (Ch. 1, 2, 3)

a map of the landscape in which higher values represent higher benefit for meeting conservation objectives, such as conserving a particular set of species under climate change. (Ch. 17)

a machine-learning model that uses a set of explanatory (predictor) variables to predict an outcome in terms of a set of known classes (e.g., wet and dry). (Ch. 11)

"regions of relative stability for multiple species under climate change" (Stralberg et al. 2018). These are locations to which components of biodiversity can retreat and in which they can persist despite regional declines in climatic and/or habitat suitability. These locations are projected to be increasingly rare in the future. (Ch. 3, 18, 19)

“a measure of the degree of opportunities provided for species within an area to respond to changes in temperature and moisture (changes in climate). A resilient system is one that allows adaptive responses by species and is less likely to change its species composition” (Buttrick et al. 2015). For example, in Chapter 21, resilience to climate change was calculated by multiplying topoclimate diversity and local permeability, and then the results were attributed to land facets within each ecoregion. See also ecological resilience. (Ch. 21)

“the capacity of ecosystems to limit the establishment and population growth of the invader” (Chambers et al. 2017). (Ch. 24)

lands immediately bordering streams or rivers; these areas act as an interface between streams and the surrounding upland landscape. (Ch. 12)

contribution to streamflow from rainfall or snowmelt. (Ch. 10)

a network of climate and weather stations (SNOTEL sites) administered by the U.S. Department of Agriculture Natural Resources Conservation Service in 11 states in the western U.S. (Ch. 4, 5, 23)

a metric of the average time that a given increment of snowfall lasts. In more colloquial terms, it is the average lifespan of a snowflake. It is calculated in Chapter 4 as the difference between the average timing of snow accumulation and the average timing of snow melt. (Ch. 4)

a commonly used measurement of snowpack at a given point in the year (such as April 1st); it is the equivalent amount of liquid water contained within the snowpack. (Ch. 4, 5)

soils are deemed "sensitive" if they have characteristics that may make them more susceptible to impacts from climate change, fire, or human disturbances. (Ch. 22)

“soil temperature regimes are defined by the mean annual soil temperature at a depth of 20 inches, and seasonal fluctuations from the mean. Soil moisture regimes are defined by the length of time plant-available moisture is present during the growing season” (Chambers et al. 2017). (Ch. 24)

species that have been identified in State Wildlife Action Plans as being most in need of conservation action. (Ch. 17)

a metric that represents the degree to which species are projected to be gained or lost in a given geographic area. (Ch. 16)

a metric of how strongly stream water temperature in August responds to inter-annual variability in August air temperature. This was calculated using observed air and stream temperature data. (Ch. 9)

the predicted (modeled) rate of August mean water temperature increase in streams, calculated from stream sensitivity (which varies among streams) to air temperature and streamflow trends. (Ch. 9)

a quantitative descriptive statistic of the flow regime of a stream, typically calculated based on daily (observed or modeled) streamflow data. (Ch. 10)

the degree to which rivers and streams maintain surface-water flow throughout the year. (Ch. 11)

“local climate conditions as influenced by topography” (Buttrick et al. 2015). (Ch. 21)

the difference in elevation between a focal pixel and the mean elevation of the pixels surrounding it at a given radius; see Jenness (2006). (Ch. 19, 20)

small areas within a larger fire perimeter that did not burn, which make a useful (although non-equivalent) proxy for fire refugia. (Ch. 8)

a macroscale hydrologic model that models the land surface as a grid using meteorological input data to simulate land-atmosphere fluxes and the water and energy balances at the surface (see Liang et al. 1994). (Ch. 5, 10)

the 12-month period October 1, for any given year through September 30, of the following year. (Ch. 10)