Shasta Lake, WA, United States
Shasta Lake, WA, United States

Time filter

Source Type

Litschert S.E.,Earth Systems Institute | Brown T.C.,Rocky Research | Theobald D.M.,Colorado State University
Forest Ecology and Management | Year: 2012

Wildfires play a formative role in the processes that have created the ecosystems of the Southern Rockies Ecoregion (SRE). The extent of wildfires is influenced mainly by precipitation and temperature, which control biomass growth and fuel moisture. Forecasts of climate change in the SRE show an increase in temperatures, bringing warmer springs with earlier runoff and longer fire seasons. Increasing wildfire extent and intensity would affect human safety, livelihoods, and landscapes. Our summary of historical wildfire records from the national forests of the SRE from 1930 to 2006 revealed an order of magnitude increase in the annual number of fires recorded over the full time period and in the number of large fires since 1970. We developed a model of percent burned area in the SRE for the period 1970-2006 using temperature and precipitation variables (R 2=0.51, p=1.7E-05). We applied this model to predict percent burned area using data from two downscaled global circulation models (GCMs), for the Intergovernmental Panel on Climate Change Special Report Emissions Scenarios A2 (projects high increases in temperature) and B1 (projects lower temperature increases), for the time period 2010-2070. The results showed increasing trends in median burned areas for all scenarios and GCM combinations with higher increases for the B1 scenario. The results suggest that precipitation increases could at least partially compensate for the effect of temperature increases on burned area but the strength of this ameliorating effect of precipitation will remain uncertain until the GCMs are further developed. © 2011 Elsevier B.V.

Litschert S.E.,Colorado State University | Litschert S.E.,Earth Systems Institute | Theobald D.M.,Colorado State University | Brown T.C.,Rocky Research
Catena | Year: 2014

Forests in the Southern Rockies Ecoregion surround the headwaters of several major rivers in the western and central US. Future climatic changes will increase the incidence of wildfire in those forests, and will likely lead to changes in downstream water quality, including sediment loads. We estimated soil loss under the historic climate and two IPCC climate change emissions scenarios (A2 and B1); each scenario was modeled using statistically downscaled climate data from global circulation models (GCMs; ECHAM5 and HadCM3) for each of thirteen land cover types. We used the Revised Universal Soil Loss Equation (RUSLE) and developed a way to calculate rainfall erosivity, a key factor in RUSLE, to account for climate change. We also incorporated the effects of climate change on wildfire to create stochastic spatial distributions of wildfires and to inform changes in land cover. Based on 100 simulations of future wildfire applied to RUSLE for each GCM-scenario combination, we found that soil loss will likely increase above historic levels but that considerable uncertainty remains about the amount of increase. Across the GCM-scenario combinations, mean soil loss increased above historic levels by from 3% (HadCM3-A2) to 65% (ECHAM5-B1) for climate change only and the effects of wildfire increased soil loss an additional 3 to 5%. © 2014 Elsevier B.V.

Bidlack A.L.,Ecotrust | Bidlack A.L.,University of Alaska Southeast | Benda L.E.,Earth Systems Institute | Miewald T.,U.S. Fish and Wildlife Service | And 2 more authors.
Transactions of the American Fisheries Society | Year: 2014

Ecosystem management requires information on habitat suitability across broad scales; however, comprehensive environmental surveys in remote areas are often impractical and expensive to carry out. Intrinsic Potential (IP) models provide a means to identify on a broad scale those portions of the landscape that can provide essential habitat for various freshwater fish species. These models are derived from watershed patterns and processes that are persistent and not readily affected by human activities. We developed an IP model for rearing habitat of Chinook Salmon throughout the Copper River watershed (63,000 km2) in southcentral Alaska, utilizing digital elevation models, expert opinion, and field surveys. Our model uses three variables-mean annual flow, gradient, and glacial influence-and adequately predicts where probable habitat for juvenile Chinook Salmon occurs across this large landscape. This model can help resource managers map critical habitat for salmon throughout the Copper River watershed, direct field research to appropriate stream reaches, and assist managers in prioritizing restoration actions, such as culvert replacement. Intrinsic Potential modeling is broadly applicable to other salmonid species and geographies and may inform future work on the ecological impacts of climate change in polar and subpolar river systems. © American Fisheries Society 2014.

Miller D.,Earth Systems Institute
USDA Forest Service - General Technical Report PNW-GTR | Year: 2013

Large woody debris is recognized as an important component of stream geomorphology and stream ecosystem function, and forest-land management is recognized as an important control on the quantity (and size and species distributions) of wood available for recruitment to streams. Much of the wood present in streams comes from adjacent forests, and riparian management practices now reflect our understanding of the role these forests play in modulating and maintaining stream environments. In steep terrain, slope failures also carry wood (and sediment) to streams from upslope source areas. In these environments, periodic inputs of wood and sediment from landslides and debris flows also play an important role in stream geomorphology and ecosystem dynamics. Channel environments are naturally dynamic systems. Depending on where you are in the channel network, discharge can vary from none in the summer to bed-scouring, channel-avulsing floods in the winter. Slope failures also drive variability in this system. Deposition of wood and sediment occur at discrete points in time and space, thereby creating temporal and spatial variability in channel environments. Redistribution and decay of deposited materials over time further add to this variability, and act to hide the original source of these materials, thereby masking the role of landsliding in setting stream environments. Landslide effects thus depend on when and where you look, and can be dif cult to discern if the landslide occurred some time ago. This makes efforts to anticipate the effects of landsliding very challenging. Are we interested in the short term? The long term? Are we interested in a single reach? Or effects over a basin? Observations also suggest that landslide effects depend on a host of factors, including valley geometry, channel geometry, the quantity and size of sediment and wood in the deposit, the amount of wood and sediment already in the channel, and the amount of wood and sediment that enter the channel over the lifespan of the landslide deposit. This sets the stage for considering slope failure as an upslope source of stream wood, particularly if we are to consider in-stream wood in the context of a stream ecosystem. I will brief y review the evidence on which to base conceptual and empirical models for identifying and characterizing upslope landslide source areas, and for placing them into a channel-network context. Then I'll illustrate the data-analysis and modeling approaches that we and our collaborators have been experimenting with to identify upslope source areas for stream wood and for anticipating the in-stream consequences of management decisions in those areas. These methods span a range of complexity. At the most basic, we use digital elevation data coupled with empirical models to identify the source areas and runout tracks for landslides that could potentially carry material to specified portions of the channel network (e.g., fish-bearing streams). To gain insights to effects of management, we couple stand-growth, wood recruitment, and landscape dynamics models to estimate wood abundances over time and space.

Benda L.,Earth Systems Institute | Miller D.,Earth Systems Institute | Barquan J.,University of Cantabria
Hydrology and Earth System Sciences | Year: 2011

One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we used computer tools to examine the spatial patterns of fluvial landscapes that are associated with five domains of hydro-geomorphic processes and landforms. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to hillslope and valley topography, river network structure, and channel elevation profiles. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects. © Author(s) 2011.

Flitcroft R.L.,U.S. Department of Agriculture | Falke J.A.,U.S. Geological Survey | Reeves G.H.,U.S. Department of Agriculture | Hessburg P.F.,U.S. Department of Agriculture | And 2 more authors.
Forest Ecology and Management | Year: 2016

Pacific Northwest salmonids are adapted to natural disturbance regimes that create dynamic habitat patterns over space and through time. However, human land use, particularly long-term fire suppression, has altered the intensity and frequency of wildfire in forested upland and riparian areas. To examine the potential impacts of wildfire on aquatic systems, we developed stream-reach-scale models of freshwater habitat for three life stages (adult, egg/fry, and juvenile) of spring Chinook salmon (Oncorhynchus tshawytscha) in the Wenatchee River subbasin, Washington. We used variables representing pre- and post-fire habitat conditions and employed novel techniques to capture changes in in-stream fine sediment, wood, and water temperature. Watershed-scale comparisons of high-quality habitat for each life stage of spring Chinook salmon habitat suggested that there are smaller quantities of high-quality juvenile overwinter habitat as compared to habitat for other life stages. We found that wildfire has the potential to increase quality of adult and overwintering juvenile habitat through increased delivery of wood, while decreasing the quality of egg and fry habitat due to the introduction of fine sediments. Model results showed the largest effect of fire on habitat quality associated with the juvenile life stage, resulting in increases in high-quality habitat in all watersheds. Due to the limited availability of pre-fire high-quality juvenile habitat, and increased habitat quality for this life stage post-fire, occurrence of characteristic wildfires would likely create a positive effect on spring Chinook salmon habitat in the Wenatchee River subbasin. We also compared pre- and post-fire model results of freshwater habitat for each life stage, and for the geometric mean of habitat quality across all life stages, using current compared to the historic distribution of spring Chinook salmon. We found that spring Chinook salmon are currently distributed in stream channels in which in-stream habitat for most life stages has a consistently positive response to fire. This compares to the historic distribution of spring Chinook, in which in-stream habitat exhibited a variable response to fire, including decreases in habitat quality overall or for specific life stages. This suggests that as the distribution of spring Chinook has decreased, they now occupy those areas with the most positive potential response to fire. Our work shows the potentially positive link between wildfire and aquatic habitat that supports forest managers in setting broader goals for fire management, perhaps leading to less fire suppression in some situations. © 2015.

Fullerton A.H.,National Oceanic and Atmospheric Administration | Burnett K.M.,Oregon State University | Steel E.A.,U.S. Department of Agriculture | Flitcroft R.L.,Oregon State University | And 5 more authors.
Freshwater Biology | Year: 2010

1. In this review, we first summarize how hydrologic connectivity has been studied for riverine fish capable of moving long distances, and then identify research opportunities that have clear conservation significance. Migratory species, such as anadromous salmonids, are good model organisms for understanding ecological connectivity in rivers because the spatial scale over which movements occur among freshwater habitats is large enough to be easily observed with available techniques; they are often economically or culturally valuable with habitats that can be easily fragmented by human activities; and they integrate landscape conditions from multiple surrounding catchment(s) with in-river conditions. Studies have focussed on three themes: (i) relatively stable connections (connections controlled by processes that act over broad spatio-temporal scales >1000 km2 and >100 years); (ii) dynamic connections (connections controlled by processes acting over fine to moderate spatio-temporal scales ~1-1000 km2 and <1-100 years); and (iii) anthropogenic influences on hydrologic connectivity, including actions that disrupt or enhance natural connections experienced by fish.2. We outline eight challenges to understanding the role of connectivity in riverine fish ecology, organized under three foci: (i) addressing the constraints of river structure; (ii) embracing temporal complexity in hydrologic connectivity; and (iii) managing connectivity for riverine fishes. Challenges include the spatial structure of stream networks, the force and direction of flow, scale-dependence of connectivity, shifting boundaries, complexity of behaviour and life histories and quantifying anthropogenic influence on connectivity and aligning management goals. As we discuss each challenge, we summarize relevant approaches in the literature and provide additional suggestions for improving research and management of connectivity for riverine fishes.3. Specifically, we suggest that rapid advances are possible in the following arenas: (i) incorporating network structure and river discharge into analyses; (ii) increasing explicit consideration of temporal complexity and fish behaviour in the scope of analyses; and (iii) parsing degrees of human and natural influences on connectivity and defining acceptable alterations. Multiscale analyses are most likely to identify dominant patterns of connections and disconnections, and the appropriate scale at which to focus conservation activities. Published 2010. This article is a US Government work and is in the public domain in the USA.

McCleary R.J.,University of British Columbia | McCleary R.J.,Foothills Research Institute | Hassan M.A.,University of British Columbia | Miller D.,Earth Systems Institute | Moore R.D.,University of British Columbia
Water Resources Research | Year: 2011

Lithologic transitions and glaciations create complex longitudinal profiles that control contemporary erosion and deposition processes. In areas with these characteristics, traditional morphometric approaches for predicting process domains, such as area-slope plots, can be augmented by considering other predictors measured from high resolution lidar-derived digital elevation models (DEMs). Ordinal logistic regression was used to model the distribution of hillslope, swale, colluvial channel, and fluvial channel domains, as identified during field surveys. The study area was a glaciated region of the Rocky Mountain foothills with a complex lithostructural setting. Relationships between domains and a suite of geographic information system-derived descriptors were explored. Predictors included profile anomalies measured at the reach and basin scale using a normalized stream length-gradient (SL/k) index. Drainage area was the dominant factor controlling domains. A model with area as the only predictor was 82% accurate. Reach slope relations were not consistent. A model that also included lithology and basin-scale SL/k index variation was 87% accurate. Domain transitions had larger area thresholds in basins with resistant conglomerate versus sandstone or shale formations and where SL/k index was more variable along a profile. In a restricted model of hillslope, swale, and colluvial channel domains, profile curvature measured over 100 m was also related to domain occurrence. A model for regional-scale mapping applications with six additional predictors was 95% accurate. The results showed that ordinal logistic regression can be used to predict and map process domains in regions with complex physiography using descriptors measured from high - resolution DEMs.

Fullerton A.H.,National Oceanic and Atmospheric Administration | Jensen D.,National Oceanic and Atmospheric Administration | Steel E.A.,National Oceanic and Atmospheric Administration | Miller D.,Earth Systems Institute | McElhany P.,National Oceanic and Atmospheric Administration
Environmental Modeling and Assessment | Year: 2010

Complex relationships between landscape and aquatic habitat conditions and salmon (Oncorhynchus spp.) populations make science-based management decisions both difficult and essential. Due to a paucity of empirical data, models characterizing these relationships are often used to forecast future conditions. We evaluated uncertainties in a suite of models that predict possible future habitat conditions and fish responses in the Lewis River Basin, Washington, USA. We evaluated sensitivities of predictions to uncertainty in model parameters. Results were sensitive to 60% of model parameters but substantially so (|partial regression coefficients| >0.5) to <10%. We also estimated accuracy of several predictions using field surveys. Observations mostly fell within predicted ranges for riparian shade and fine-sediment deposition, but large woody debris estimates matched only half the time. We provide suggestions to modelers for improving model accountability, and describe how managers can incorporate prediction uncertainty into decision-making, thereby improving the odds of successful salmon habitat recovery. © Springer Science+Business Media B.V. 2008.

Benda L.,Earth Systems Institute | Bigelow P.,Bigelow Watershed Geomorphology
Geomorphology | Year: 2014

Forest management and stream habitat can be improved by clarifying the primary riparian and geomorphic controls on streams. To this end, we evaluated the recruitment, storage, transport, and the function of wood in 95km of streams (most drainage areas<30km2) in northern California, crossing four coastal to inland regions with different histories of forest management (managed, less-managed, unmanaged). The dominant source of variability in stream wood storage and recruitment is driven by local variation in rates of bank erosion, forest mortality, and mass wasting. These processes are controlled by changes in watershed structure, including the location of canyons, floodplains and tributary confluences; types of geology and topography; and forest types and management history. Average wood storage volumes in coastal streams are 5 to 20 times greater than inland sites primarily from higher riparian forest biomass and growth rates (productivity), with some influence by longer residence time of wood in streams and more wood from landsliding and logging sources. Wood recruitment by mortality (windthrow, disease, senescence) was substantial across all sites (mean 50%) followed by bank erosion (43%) and more locally by mass wasting (7%). The distances to sources of stream wood are controlled by recruitment process and tree height. Ninety percent of wood recruitment occurs within 10 to 35m of channels in managed and less-managed forests and upward of 50m in unmanaged Sequoia and coast redwood forests. Local landsliding extends the source distance. The recruitment of large wood pieces that create jams (mean diameter 0.7m) is primarily by bank erosion in managed forests and by mortality in unmanaged forests. Formation of pools by wood is more frequent in streams with low stream power, indicating the further relevance of environmental context and watershed structure. Forest management influences stream wood dynamics, where smaller trees in managed forests often generate shorter distances to sources of stream wood, lower stream wood storage, and smaller diameter stream wood. These findings can be used to improve riparian protection and inform spatially explicit riparian management. © 2013 Elsevier B.V.

Loading Earth Systems Institute collaborators
Loading Earth Systems Institute collaborators