Carbon isotope discrimination and water stress in trembling aspen following variable retention harvesting

Variable retention harvesting (VRH) has been proposed as a silvicultural practice to maintain biodiversity and ecosystem integrity. No previous study has examined tree carbon isotope discrimination to provide insights into water stress that could lead to dieback and mortality of trees following VRH. We measured and compared the carbon isotope ratios (δ13C) in stem wood of trembling aspen (Populus tremuloides Michx.) before and after VRH. Eight trees were sampled from isolated residual, edge and control (interior of unharvested stand) positions from each of seven plots in three regions (Calling Lake and Drayton Valley, Alberta and Lac Duparquet, Qu

A catchment-scale assessment of stream temperature response to contemporary forest harvesting in the Oregon Coast Range

Historical forest harvesting practices were reviewed in the original Alsea Watershed Study where they found increased energy loading to the stream and produced higher stream temperatures. This was an important early research site that led to the development of contemporary forest management practices to protect water quality and fish habitat in Oregon and elsewhere. Here we present an analysis of 6 years (3 years pre-harvest and 3 years post-harvest) of summer stream temperature data from a reference (Flynn Creek) and a harvested catchment (Needle Branch). The collected parameters include air temperature, the mean and max, stream temperature, mean and max, and the diel (daily) temperature fluctuations (max minus the minimum temperature)

Fish and temperature data from Hinkle Creek summer 2021

These data were all collected in summer 2021 at Hinkle Creek watershed, a headwater ecosystem in a managed forest landscape in western Oregon. The data set has two components. The first component of the data set includes information about age 1 and older fish collected from two sections of the South Fork of Hinkle Creek in summer 2021 using multiple pass depletion backback electrofishing methods. Electrofishing in these two reaches were conducted in July 2021 and again in September 2021 – each month has its own csv data file. Information in these two components of the data set include the total length (mm), weight (g) and species of fish (Oncorhynchus clarkii; Oncorhynchus mykiss). We also include data on which pass each fish was captured so depletion-based population estimates can be calculated. The second component of this study is stream temperature from the mainstem of the South Fork Hinkle Creek, and also includes two data files. The first data file includes stream temperature (in Celsius) from summer 2021 collected using a HOBO data logger within 20m of each of the two fish survey locations. The second data file includes maximum daily temperatures from each site in 2021 and from data collected at these sites from 2006 to 2011, before the Archie Creek Fire impacted this site (in Sept. 2020)

Potential bioavailability of representative pyrogenic organic matter compounds in comparison to natural dissolved organic matter pools

Pyrogenic organic matter (PyOM) from wildfires impacts river corridors globally and is widely regarded as resistant to biological degradation. Though recent work suggests PyOM may be more bioavailable than historically perceived, estimating bioavailability across its chemical spectrum remains elusive. To address this knowledge gap, we assessed potential bioavailability of representative PyOM compounds relative to ubiquitous dissolved organic matter (DOM) with a substrate-explicit model. The range of potential bioavailability of PyOM was greater than natural DOM; however, the predicted thermodynamics, metabolic rates, and carbon use efficiencies (CUEs) overlapped significantly between all OM pools. Compound type (e.g., natural versus PyOM) had approximately 6-fold less impact on predicted respiration rates than simulated carbon and oxygen limitations. Within PyOM, the metabolism of specific chemistries differed strongly between unlimited and oxygenlimited conditions – degradations of anhydrosugars, phenols, and polycyclic aromatic hydrocarbons (PAHs) were more favorable under oxygen limitation than other molecules. Notably, amino sugar-like, protein-like, and lignin-like PyOM had lower carbon use efficiencies relative to natural DOM of the same classes, indicating potential impacts in process-based model representations. Overall, our work illustrates how similar PyOM bioavailability may be to that of natural DOM in the river corridor, furthering our understanding of how PyOM may influence riverine biogeochemical cycling

Long-term effects of forest harvesting on summer low flow deficiets in the Coast Range of Oregon

We examined long-term changes in daily streamflow associated with forestry practices with two datasets (this one and the original Alsea Streamflow dataset (1972) over a 60-year period (1959–2017) in the Alsea Watershed Study, Oregon Coast Range, Pacific Northwest, USA. In this contemporary period, 2006 to 2017 (12 water years), data were collected at 10-minute intervals, including three to eight years of pre-harvest data rating curves were developed. Based 40 to 55 stage-discharge data points collected for each watershed. Each watershed has datasets describing the paired stage heights at both pre and post-harvest periods, the corrected stages based on reference and electronic readings, and flows calculated based upon the rating curve and stage heights. All measurements are in feet (ft), meters (m), cubic feet per second (cfs), or cubic meters per second (cms).Keywords: water deficits; forest harvesting; plantations; Alsea watershed study; riparian buffe

A Global Index for Mapping the Exposure of Water Resources to Wildfire

Wildfires are keystone components of natural disturbance regimes that maintain ecosystem structure and functions, such as the hydrological cycle, in many parts of the world. Consequently, critical surface freshwater resources can be exposed to post-fire effects disrupting their quantity, quality and regularity. Although well studied at the local scale, the potential extent of these effects has not been examined at the global scale. We take the first step toward a global assessment of the wildfire water risk (WWR) by presenting a spatially explicit index of exposure. Several variables related to fire activity and water availability were identified and normalized for use as exposure indicators. Additive aggregation of those indicators was then carried out according to their individual weight. The resulting index shows the greatest exposure risk in the tropical wet and dry forests. Intermediate exposure is indicated in mountain ranges and dry shrublands, whereas the lowest index scores are mostly associated with high latitudes. We believe that such an approach can provide important insights for water security by guiding global freshwater resource preservation.Keywords: wildfire hazard, global index, water security, water resources exposure, wildfire water ris

Scientists' warning on extreme wildfire risks to water supply

2020 is the year of wildfire records. California experienced its three largest fires early in its fire season. The Pantanal, the largest wetland on the planet, burned over 20% of its surface. More than 18 million hectares of forest and bushland burned during the 2019–2020 fire season in Australia, killing 33 people, destroying nearly 2500 homes, and endangering many endemic species. The direct cost of damages is being counted in dozens of billion dollars, but the indirect costs on water‐related ecosystem services and benefits could be equally expensive, with impacts lasting for decades. In Australia, the extreme precipitation (“200 mm day −1 in several location”) that interrupted the catastrophic wildfire season triggered a series of watershed effects from headwaters to areas downstream. The increased runoff and erosion from burned areas disrupted water supplies in several locations. These post‐fire watershed hazards via source water contamination, flash floods, and mudslides can represent substantial, systemic long‐term risks to drinking water production, aquatic life, and socio‐economic activity. Scenarios similar to the recent event in Australia are now predicted to unfold in the Western USA. This is a new reality that societies will have to live with as uncharted fire activity, water crises, and widespread human footprint collide all‐around of the world. Therefore, we advocate for a more proactive approach to wildfire‐watershed risk governance in an effort to advance and protect water security. We also argue that there is no easy solution to reducing this risk and that investments in both green (i.e., natural) and grey (i.e., built) infrastructure will be necessary. Further, we propose strategies to combine modern data analytics with existing tools for use by water and land managers worldwide to leverage several decades worth of data and knowledge on post‐fire hydrology

Alsea watershed study revisited: unpublished temperature datasets from pre-harvest 2006 to 2010

These data contain temperature readings from dataloggers launched in Deer Creek, Flynn Creek, and Needle Branch from 2006 to 2010. These loggers were apart of the Alsea Watershed Revisisted Study Revisited articles, but the data was incomplete due to logging gaps, temperature spikes, or other issues. The "Thermistor Functionality" datasets indicate whether dataloggers launched in each stream have complete datasets or not. Despite these data not being complete, they help tell the data collection story for the Alsea Watershed Study Revisited

Data and scripts describing dissolved organic carbon concentrations across a stream network in Oregon following the 2020 Holiday Farm Wildfire

In 2020, the Holiday Farm Wildfire burned ~18 % of the McKenzie sub-basin in Oregon, USA. To investigate the impact of the wildfire on in-stream dissolved organic carbon (DOC) concentrations, we collected water samples from 129 stream sites within the McKenzie sub-basin stream network over four distinct seasonal wetness conditions (wetting, wet, drying, dry) between November 2022 and September 2023. This data was used to create spatial network models to model DOC concentrations across the stream network. This data package consists of (1) a spreadsheet spreadsheet containing DOC concentrations, landscape characteristics, and site information for the stream sites within the McKenzie sub-basin, OR, USA. (2) A spatial stream network (SSN) object developed for the McKenzie sub-basin from the proceeding DOC and landscape data. (3) Scripts written in R used to process, analyze, and report our findings from this data. This data package is associated with the publication "The influence of burn severity on dissolved organic carbon concentrations across a stream network differs based on seasonal wetness conditions post-fire" submitted to Biogeosciences (Wampler et al. 2024)