Pacific Northwest Research Articles

Association mapping with a diverse population of Puccinia graminis f. sp. tritici identified avirulence loci interacting with the barley Rpg1 stem rust resistance gene

BackgroundWheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is an important disease of barley and wheat. A diverse sexual Pgt population from the Pacific Northwest (PNW) region of the US contains a high proportion of individuals with virulence on the barley stem rust resistance (R) gene, Rpg1. However, the evolutionary mechanisms of this virulence on Rpg1 are mysterious considering that Rpg1 had not been deployed in the region and the gene had remained remarkably durable in the Midwestern US and prairie provinces of Canada.Methods and resultsTo identify AvrRpg1 effectors, genome wide association studies (GWAS) were performed using 113 Pgt isolates collected from the PNW (n = 89 isolates) and Midwest (n = 24 isolates) regions of the US. Disease phenotype data were generated on two barley lines Morex and the Golden Promise transgenic (H228.2c) that carry the Rpg1 gene. Genotype data was generated by whole genome sequencing (WGS) of 96 isolates (PNW = 89 isolates and Midwest = 7 isolates) and RNA sequencing (RNAseq) data from 17 Midwestern isolates. Utilizing ~1.2 million SNPs generated from WGS and phenotype data (n = 96 isolates) on the transgenic line H228.2c, 53 marker trait associations (MTAs) were identified. Utilizing ~140 K common SNPs generated from combined analysis of WGS and RNAseq data, two significant MTAs were identified using the cv Morex phenotyping data. The 55 MTAs defined two distinct avirulence loci, on supercontig 2.30 and supercontig 2.11 of the Pgt reference genome of Pgt isolate CRL 75-36-700-3. The major avirulence locus designated AvrRpg1A was identified with the GWAS using both barley lines and was delimited to a 35 kb interval on supercontig 2.30 containing four candidate genes (PGTG_10878, PGTG_10884, PGTG_10885, and PGTG_10886). The minor avirulence locus designated AvrRpg1B identified with cv Morex contained a single candidate gene (PGTG_05433). AvrRpg1A haplotype analysis provided strong evidence that a dominant avirulence gene underlies the locus.ConclusionsThe association analysis identified strong candidate AvrRpg1 genes. Further analysis to validate the AvrRpg1 genes will fill knowledge gaps in our understanding of rust effector biology and the evolution and mechanism/s of Pgt virulence on Rpg1.

First Report of Pseudomonas amygdali pv. morsprunorum causing Bacterial Canker in Sweet Cherry Orchards in Washington State.

In 2023, an outbreak of bacterial canker disease (BCD) in sweet cherry orchards caused significant economic losses to growers and nurseries in the Pacific Northwest, USA (Fig. S1). The cherry industry in Washington State alone is valued at over $800 million (USDA NASS, 2022). BCD poses a recurring threat to the state's sweet cherry [Prunus avium (L.) L.] orchards, especially young and newly planted orchards. Three Pseudomonas species, including P. syringae pv. syringae (Pss), P. amygdali pv. morsprunorum (Pam) (formerly P. syringae pv. morsprunorum Race 1, Psm1), and P. avellanae pv. morsprunorum (formerly P. syringae pv. morsprunorum Race 2, Psm2), have been reported to be associated with BCD in sweet cherries (Hulin et al. 2019). While Pss is widely prevalent in the United States, Pam has only been reported in Michigan (Renick et al., 2008) as well as in Europe, Central America, South Africa and Australia (Hulin et al. 2019) . In 2023, we surveyed more than 60 cherry orchards and collected hundreds of canker samples from newly planted up to 8-year-old trees. BCD prevalence ranged from 40-100% in cherry orchards, leading to the removal of hundreds of thousands of trees. Affected cherry trees exhibited characteristic bacterial canker symptoms, including dead bud, canker, and gummosis (Fig. S1). Bacteria were isolated from canker tissues or ooze on King's B (KB) agar plates (King et al., 1954) and more than 300 fluorescent Pseudomonas isolates were obtained from 12 symptomatic sweet cherry cultivars. PCR results using Pss- and Pam- specific primers (SyrB and Psm1, Table S1) (Sorensen et al., 1998; Kałużna et al., 2016) revealed that 91.9% and 8% isolates were tested positive for SyrB and Psm1, indicating that these isolates potentially belong to Pss and Pam, respectively. Pathogenicity tests using immature cherries cv. Sentina showed that all isolates caused typical necrotic lesions and could be re-isolated and re-identified as Pss and Pam, thus completing Koch's postulates. The identity of three Pam representative isolates (S79, S158, S202) was further confirmed by comparing gyrD and rpoD housekeeping genes as well as 16S rRNA gene sequence with other Pam strains in GenBank (Parkinson et al., 2010; Gomila et al., 2017). Blast searches against GenBank using gyrB (GenBank accession numbers PP357444-PP357446), rpoD (PP357447-PP357449) and 16S rRNA (GenBank accession numbers PP421223-PP421225) gene sequences, ranging from 520 to 859bp, matched those of the Pam isolates (GenBank accession numbers CP026558 or PP218075) with 100% homology and 100% query coverage, further indicating that these isolates are indeed Pam. This represents the first documented record of Pam causing BCD in the Pacific Northwest, USA, suggesting the complexity of the disease, which underscores the need for effective management strategies for cherry growers in the region.

ω-3 PUFA for Secondary Prevention of White Matter Lesions and Neuronal Integrity Breakdown in Older Adults

Older adults with lower intake and tissue levels of long-chain ω-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6) have more brain white matter lesions (WMLs), an association suggesting that small-vessel ischemic disease, a major contributor to the development of dementia, including Alzheimer disease, may be preventable through ω-3 treatment. To determine whether ω-3 treatment reduces WML accumulation in older adults without dementia harboring WMLs and with suboptimal ω-3 status. This quadruple-blinded, placebo-controlled, randomized clinical trial with treatment stratification by apolipoprotein E ε4 allele (APOE*E4) carrier status used linear mixed-effects models to estimate mean annual change between groups. The study was conducted at Oregon Health & Science University, a major academic medical center in the Pacific Northwest, from May 2014 to final participant visit in September 2019. Data analysis concluded in July 2022. Participants were adults without dementia aged 75 years and older with WMLs greater than or equal to 5 cm3 and plasma ω-3 PUFA less than 5.5 weight percentage of total. Three-year treatment with 1.65 g of ω-3 PUFA (975 mg of EPA and 650 mg of DHA) vs a soybean oil placebo matched for taste, smell, and appearance. The primary outcome was annual WML progression measured using magnetic resonance imaging. Secondary outcomes included diffusion tensor imaging of fractional anisotropy (DTI-FA), representing neuronal integrity breakdown. A total of 102 participants (62 women [60.8%]; mean age, 81 years [range, 75-96 years]) were equally randomized, 51 per treatment group. Although the ω-3 group had less annual WML accumulation than the placebo group, the difference was not statistically significant (1.19 cm3 [95% CI, 0.64-1.74 cm3] vs 1.34 cm3 [95% CI, 0.80-1.88 cm3]; P = .30). Similarly, the ω-3 group had less annual DTI-FA decline than the placebo group, but the difference was not statistically significant (-0.0014 mm2/s [95% CI, -0.0027 to 0.0002 mm2/s] vs -0.0027 mm2/s [95% CI, -0.0041 to -0.0014 mm2/s]; P = .07). Among APOE*E4 carriers, the annual DTI-FA decline was significantly lower in the group treated with ω-3 than the placebo group (-0.0016 mm2/s [95% CI, -0.0032 to 0.0020 mm2/s] vs -0.0047 mm2/s [95% CI, -0.0067 to -0.0025 mm2/s]; P = .04). Adverse events were similar between treatment groups. In this 3-year randomized clinical trial, ω-3 treatment was safe and well-tolerated but failed to reach significant reductions in WML accumulation or neuronal integrity breakdown among all participants, which may be attributable to sample size limitations. However, neuronal integrity breakdown was reduced by ω-3 treatment in APOE*E4 carriers, suggesting that this treatment may be beneficial for this specific group. ClinicalTrials.gov Identifier: NCT01953705.

Western spotted skunk spatial ecology in the temperate rainforests of the Pacific Northwest

AbstractA major threat to small mammalian carnivore populations is human‐induced land use change, but conservation and management are inhibited by limited knowledge about their ecology and natural history. To fill a key knowledge gap of the western spotted skunk (Spilogale gracilis), we investigated their spatial ecology at the landscape and home range scale in the temperate rainforests of the Oregon Cascades during 2017–2019. For the landscape scale analysis, we used detections of western spotted skunks at 112 baited camera traps and fitted a dynamic occupancy model to investigate spatial distribution and drivers of inter‐seasonal and inter‐annual changes in occupancy. Concurrently, we radio‐collared 25 spotted skunks (9 female, 16 male) and collected 1583 relocations. Using continuous‐time movement models, we estimated large home range sizes for both male and female spotted skunks, relative to their body mass, and highly overlapping home ranges that indicated a lack of territoriality. Using these home ranges, we fitted a resource selection function using environmental covariates that we assigned to various hypotheses such as resources, predator avoidance, thermal tolerance, and disturbance. Overall, western spotted skunks were widely distributed across our study area (seasonal occupancy up to 63.7 ± 5.3%) and highly detectable (weekly detection probability = 41.2%). At both spatial scales, spotted skunks selected wetter areas and local valleys, which we attributed to areas with more food resources. At the home range scale, spotted skunks selected locations with lower predation risk and areas surrounded by more previously logged forests. In this montane environment, inter‐seasonal contractions in the spatial distributions of spotted skunks were strongly driven by their response to cold temperature and accumulated snow. This was especially evident when seasonal occupancy declined significantly following a severe heavy snow event in February 2019. Given that there is little information available on the natural history of the western spotted skunk, these results provide essential information about their ecology to focus future monitoring efforts and may help identify potential threats (e.g., forest management, severe snow events, or wildfires) to this species.

First Record of Breeding Behavior by the Chestnut-sided Warbler in Washington

The Chestnut-sided Warbler (Setophaga pensylvanica) typically breeds in early successional deciduous forests of the northeastern United States and southeastern Canada. In recent decades, however, the species has become increasingly regular as a vagrant in the western U.S. and Canada. Over several weeks in June and July 2023, near Gig Harbor, Pierce County, we observed the first documented breeding behavior of the Chestnut-sided Warbler in Washington State, including territorial singing by the male and nest-building by the female. The increase in early successional vegetation following logging or wildfires could favor the Chestnut-sided Warbler becoming a regular breeding species in the Pacific Northwest.

Braiding frameworks for collaborative stewardship scholarship

Human-environment relationships are most frequently viewed from evolutionary perspectives, despite the vast body of literature which highlights how many Indigenous peoples engage with and understand place, plants, and animals as kinship relations. My goals in this essay are twofold: first, to suggest we adopt the phrase stewardship to recognize and uphold notions of respect, reciprocity, and relationships that are common within many Indigenous worldviews, and secondly, to advocate for the use of pluralistic approaches to our collaborative scholarship. I offer examples from my own experiences in reconstructing stewardship histories across people, plants, and places in the Pacific Northwest.

Pan-omics-based characterization and prediction of highly multidrug-adapted strains from an outbreak fungal species complex

Strains from the Cryptococcus gattii species complex (CGSC) have caused the Pacific Northwest cryptococcosis outbreak, the largest cluster of life-threatening fungal infections in otherwise healthy human hosts known to date. In this study, we utilized a pan-phenome-based method to assess the fitness outcomes of CGSC strains under 31 stress conditions, providing a comprehensive overview of 2,821 phenotype-strain associations within this pathogenic clade. Phenotypic clustering analysis revealed a strong correlation between distinct types of stress phenotypes in a subset of CGSC strains, suggesting that shared determinants coordinate their adaptations to various stresses. Notably, a specific group of strains, including the outbreak isolates, exhibited a remarkable ability to adapt to all three of the most commonly used antifungal drugs for treating cryptococcosis (amphotericin B, 5-fluorocytosine, and fluconazole). By integrating pan-genomic and pan-transcriptomic analyses, we identified previously unrecognized genes that play crucial roles in conferring multidrug resistance in an outbreak strain with high multidrug adaptation. From these genes, we identified biomarkers that enable the accurate prediction of highly multidrug-adapted CGSC strains, achieving maximum accuracy and area under the curve (AUC) of 0.79 and 0.86, respectively, using machine learning algorithms. Overall, we developed a pan-omic approach to identify cryptococcal multidrug resistance determinants and predict highly multidrug-adapted CGSC strains that may pose significant clinical concern.

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest.

The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference headwater streams across the northwestern U.S. to evaluate the effects of wildfire occurrence and severity on total Hg (THg) and methylmercury (MeHg) transport and bioaccumulation. Suspended particulate THg and MeHg concentrations were 89 and 178% greater in burned watersheds compared to unburned watersheds and increased with burn severity, likely associated with increased soil erosion. Concentrations of filter-passing THg were similar in burned and unburned watersheds, but filter-passing MeHg was 51% greater in burned watersheds, and suspended particles in burned watersheds were enriched in MeHg but not THg, suggesting higher MeHg production in burned watersheds. Among invertebrates, MeHg in grazers, filter-feeders, and collectors was 33, 48, and 251% greater in burned watersheds, respectively, but did not differ in shredders or predators. Thus, increasing wildfire frequency and severity may yield increased MeHg production, mobilization, and bioaccumulation in headwaters and increased transport of particulate THg and MeHg to downstream environments.

Integrated Pest Management: Success Stories and Key Takeaways

Integrated Pest Management (IPM) has revolutionized pest control in various agricultural settings, including orchards. By blending cultural, biological, and chemical methods, IPM aims to minimize pest damage while reducing environmental and health impacts. One of the most successful strategies within IPM is mating disruption, which uses synthetic pheromones to confuse male insects and prevent them from finding mates. This technique has been particularly effective against pests like the codling moth in apple and pear orchards, significantly reducing insecticide use by up to 90% in some regions.The implementation of IPM in orchards has numerous long-term advantages. Lower manufacturing costs, less environmental contamination, and increased worker safety have all resulted from reduced pesticide use. Furthermore, a healthier ecological balance has been promoted by the rise in natural predators and parasitoids brought about by the decrease in chemical treatments. Many growers have reported greater fruit quality due to more targeted pest control and healthier trees, despite worries that reduced use of pesticides would harm fruit quality. Important pests have also been suppressed regionally as a result of IPM's efficacy, such as the codling moth in the Pacific Northwest, whose populations have dropped to the point where little intervention is needed. Economic assessments highlight IPM's financial sustainability by demonstrating considerable long-term cost savings. According to one study, IPM adopters in apple orchards in Nova Scotia had 25% reduced pest management expenses over a ten-year period than those using conventional approaches. These results demonstrate how integrated pest management (IPM) has the ability to provide long-term, efficient pest control that is advantageous to growers, the environment, and consumers alike. IPM's widespread use attests to its effectiveness and sustainability. Integrative pest management (IPM) ensures the long-term health and production of agricultural systems by combining various pest control techniques into a balanced solution that satisfies both ecological and financial requirements.

The economics of home energy usage: Insights from urban economy

Recent regional investigations in the United States have revealed a thought-provoking perspective: household electricity consumption may act as an inferior commodity, displaying a negative correlation with wealth. This finding challenges the outcomes of various other econometric analyses and underscores the importance of scrutinizing power consumption patterns across different regional service areas. While it is commonly believed that home electricity usage decreases as income rises, this may not always hold true universally. This study focuses on power usage in Seattle, Washington households, a prominent urban economy in the Pacific Northwest. Employing dynamic error correction modeling techniques, the research demonstrates statistically significant fluctuations in domestic power usage attributed to variations in actual value, actual revenue, and cold weather. In the immediate future, energy for homes in this urban economy resembles any other commodity. However, investing in electricity for homes in Seattle may not be advisable in the long run. Home power usage in Seattle declines with each percentage point increase in actual per capita income over 1.2 %. This finding highlights the need for careful consideration and strategic planning in energy management policies for urban economies like Seattle.

Host Jump of an Exotic Fish Rhabdovirus into a New Class of Animals Poses a Disease Threat to Amphibians.

Spring viremia of carp virus (SVCV) is a rhabdovirus that primarily infects cyprinid finfishes and causes a disease notifiable to the World Organization for Animal Health. Amphibians, which are sympatric with cyprinids in freshwater ecosystems, are considered non-permissive hosts of rhabdoviruses. The potential host range expansion of SVCV in an atypical host species was evaluated by testing the susceptibility of amphibians native to the Pacific Northwest. Larval long-toed salamanders Ambystoma macrodactylum and Pacific tree frog Pseudacris regilla tadpoles were exposed to SVCV strains from genotypes Ia, Ib, Ic, or Id by either intraperitoneal injection, immersion, or cohabitation with virus-infected koi Cyprinus rubrofuscus. Cumulative mortality was 100% for salamanders injected with SVCV, 98-100% for tadpoles exposed to virus via immersion, and 0-100% for tadpoles cohabited with SVCV-infected koi. Many of the animals that died exhibited clinical signs of disease and SVCV RNA was found by in situ hybridization in tissue sections of immersion-exposed tadpoles, particularly in the cells of the gastrointestinal tract and liver. SVCV was also detected by plaque assay and RT-qPCR testing in both amphibian species regardless of the virus exposure method, and viable virus was detected up to 28 days after initial exposure. Recovery of infectious virus from naïve tadpoles cohabited with SVCV-infected koi further demonstrated that SVCV transmission can occur between classes of ectothermic vertebrates. Collectively, these results indicated that SVCV, a fish rhabdovirus, can be transmitted to and cause lethal disease in two amphibian species. Therefore, members of all five of the major vertebrate groups (mammals, birds, reptiles, fish, and amphibians) appear to be vulnerable to rhabdovirus infections. Future research studying potential spillover and spillback infections of aquatic rhabdoviruses between foreign and domestic amphibian and fish species will provide insights into the stressors driving novel interclass virus transmission events.

Process Your Cryo-EM Data Using Computing Resources at Pacific Northwest Center for Cryo-EM (PNCC)

Process Your Cryo-EM Data Using Computing Resources at Pacific Northwest Center for Cryo-EM (PNCC)

Modular Training Methods at the Pacific Northwest Center for Cryo-EM Using Varied Learning Delivery Mechanisms

Modular Training Methods at the Pacific Northwest Center for Cryo-EM Using Varied Learning Delivery Mechanisms

Transformative justice to support truth and reconciliation within nurse-midwifery education.

Nursing education holds a history framed in white supremacy and whiteness. Efforts to employ antiracist strategies have been hindered, largely due to an inability for faculty to acknowledge and hold accountability for racialized harms that occur within nursing educational structures. A nurse-midwifery program in the Pacific Northwest United States uncovered harm that impacted students and identified a need to respond and hold accountability. Guided by the framework of Transformative Justice, a truth and reconciliation process was implemented as a first step to better address racism within nursing and nurse-midwifery education. This paper describes the process to support other institutions in their work to address harms within nursing education.

Recent Expansion of the Cascades Volcano Observatory Geophysical Network at Mount Rainier for Improved Volcano and Lahar Monitoring

Abstract The U.S. Geological Survey Cascades Volcano Observatory (CVO) recently expanded its continuous geophysical monitoring at Mount Rainier, an active stratovolcano in Washington state. CVO monitors volcanoes in Oregon, Washington, and Idaho to characterize volcanic systems and detect unrest. Mount Rainier has a history of large lahar occurrences in the Holocene, including at least one that may not have been associated with volcanic activity. Pierce County, Washington, is one of the areas most at risk from large lahars. In the 1990s, CVO collaborated with Pierce County to install the Rainier lahar detection system (RLDS), an automated system designed to detect large lahars in high-risk drainages and mitigate hazards to heavily populated areas. The system was designed to detect lahars within 5–10 min of their occurrence and alert authorities of the need to evacuate populated low-lying areas before lahar arrival. In addition, CVO and the Pacific Northwest Seismic Network (PNSN) maintained and expanded a network of seismic and geodetic monitoring stations on and near the edifice to provide adequate volcano monitoring capabilities. Since 2016, CVO has worked to upgrade the existing RLDS and to expand its capabilities into other drainages around Mount Rainier. This expansion includes installation of 25 new broadband seismic stations with many including infrasound along high-risk drainages, as well as support for equipment upgrades at existing PNSN and CVO volcano monitoring sites. All stations transmit continuous, near-real-time data with dramatically improved spatial coverage for volcano monitoring and lahar hazard mitigation compared to the previous system.

Carbon‐Water Tradeoffs in Old‐Growth and Young Forests of the Pacific Northwest

AbstractDespite much interest in relationships among carbon and water in forests, few studies assess how carbon accumulation scales with water use in forested watersheds with varied histories. This study quantified tree growth, water use efficiency, and carbon‐water tradeoffs of young versus mature/old‐growth forest in three small (13–22 ha) watersheds in the H.J. Andrews Experimental Forest, Oregon, USA. To quantify and scale carbon‐water tradeoffs from trees to watersheds, tree‐ring records and greenness and wetness indices from remote sensing were combined with long‐term vegetation, climate, and streamflow data from young forest watersheds (trees ∼45 years of age) and from a mature/old‐growth forest watershed (trees 150–500 years of age). Biomass production was closely related to water use; water use efficiency (basal area increment per unit of evapotranspiration) was lower; and carbon‐water tradeoffs were steeper in young forest plantations compared with old‐growth forest for which the tree growth record begins in the 1850s. Greenness and wetness indices from Landsat imagery were not significant predictors of streamflow or tree growth over the period 1984 to 2017, and soil C and N did not differ significantly among watersheds. Multiple lines of evidence show that mature and old‐growth forest watersheds store and accumulate more carbon, are more drought resistant, and better sustain water availability compared to young forests. These results provide a basis for reconstructions and predictions that are potentially broadly applicable, because first‐order watersheds occupy 80%–90% of large river basins and study watersheds are representative of forest history in the Pacific Northwest region.

Island area and diet predict diversity and distribution of bats in a Pacific Northwest archipelago

Abstract The island biogeography theory predicts that species richness in islands and island-like systems is the ultimate result of island isolation and area. Species with high dispersal capabilities are predicted to be less affected by these factors because of their capacity to move more efficiently between islands or habitats, and here we test this idea in bats, the only mammals capable of flight. We conducted mist net and acoustic surveys across 21 islands in the San Juan Archipelago (Washington State, United States) and adjacent northwest mainland to: (i) investigate the effects of island area, distance from mainland, and habitat on bat diversity; and (ii) evaluate whether differences in morphological (body mass, forearm length, wing loading) and ecological (dietary niche breadth, foraging guild) traits among species influence their prevalence across islands. We found that island size strongly influenced patterns of species richness, with larger islands having a greater number of bat species. However, neither island distance from mainland nor any measure of habitat availability was a significant predictor of species richness at the scale of this study. Additionally, we found that dietary niche breadth, as opposed to any morphological trait, best predicted the prevalence of species across the islands. Our results suggest that species with more specialized diets may be more vulnerable to habitat fragmentation, and provide insight into how geographic and ecological factors affect the diversity of insular bat communities, adding to growing knowledge about the role of species traits as mediators of their responses to large-scale landscape structure.

Stigma Reduction Theory in Digital Abortion Communication: A Content Analysis of Planned Parenthood’s #GoodbyeStigma Webpages

This study examines how Planned Parenthood of the Pacific Southwest’s #GoodbyeStigma webpages aligns with stigma reduction theory via qualitative content analysis. Data showed stigma reduction theory is a useful framework for evaluating and designing digital abortion stigma reduction communication. Recommendations for further research and how to implement stigma reduction theory in digital abortion stigma reduction communication are included.

Effects of log booms on physical habitat, water quality, and benthic invertebrates in the lower Fraser River and estuary

To facilitate the movement and processing of timber in some regions of the Pacific Northwest, logs are tied together to form large rectangular rafts (often called “booms”) which are transported and stored in aquatic environments. In the lower Fraser River, British Columbia, some reaches have >50% of shoreline with adjacent log booms, yet our understanding of the effects of log booms on habitats and biota is very limited. We compared sites that have never had log booms to nearby ones with active boom storage occurring to examine differences in environmental characteristics. In contrast to reference sites, nearly all active sites had compacted sediments and little vegetation coverage, likely caused by logs “grounding” onto benthic environments due to tidally influenced water level changes. Total benthic invertebrate abundance was higher at reference sites which had relatively more Amphipoda and Trichoperta, but fewer Haplotaxida, compared to active sites whose compacted and more detrital-laden sediments should favour haplotaxids. Water quality variables generally did not differ between reference and active sites. Grounding of log booms and contact with the below substrate is in contradiction of best management practices and has clear effects on the physical habitat and biota of the area underneath booming sites.

Quantifying the Variability of “Fixed-Width” Buffers on Harvested Lands in Western Oregon and Washington

Abstract In contemporary forest management, buffers of unharvested trees are left along streams to protect riparian and aquatic ecosystems. Buffer regulations often focus on specific minimum width requirements, which aid in straightforward regulation and application, but minimum widths also suggest buffered edges are uniform and contain little variability. Conceptual papers suggest that alternative buffer configurations may offer greater flexibility in landscape-level protection, increase forest complexity, and enhance aquatic and riparian biodiversity. However, before considering alternatives to fixed-width buffers, it is necessary to quantify the inherent variability in current buffer practices present on the landscape. In this study, we used aerial imagery to quantify variability of buffer widths in two hundred randomly selected recently harvested units on managed land in Oregon and Washington with both fish-bearing and non-fish-bearing sections of stream. Wider buffers on larger streams had a greater magnitude of variability, but when normalized by stream size, variation was greater in smaller streams, and overall, variation ranged from 25% to 50% of the mean width. Despite local variability, buffer widths rarely fell below 9.14 m (30 ft). The variation quantified here provides an initial measure of variability to inform future management, given emerging interest in variable retention buffers. Study Implications: In contemporary forest management, riparian and aquatic habitat protection usually relies on minimum buffer width regulations. Minimum requirements create the perception that buffered edges are uniform distances from streams containing little variability, so conceptual papers have suggested alternative buffer configurations with variable retention edges to enhance ecological benefits. However, there are several reasons why, in practice, buffer widths may vary substantially from minimum sizes within and across harvest units under current forest management, but this potential variation has not been quantified. Before considering alternative riparian management options, it is necessary to quantify and understand the inherent variability in current practices. By utilizing high-resolution aerial imagery and digital elevation models, we quantified buffer width variation. Using a set of two hundred recently harvested units, we demonstrate notable buffer width variation across managed Pacific Northwest forests. We attribute the variation in buffer widths to the presence of road crossings, tributary junctions, underlying valley slope and slope variation, and flexibility in regulations that may be overlooked in broad evaluations of strict minimum widths. Understanding fundamental information about buffer width variability provides information about current practices and provides a standard against which proposed increases in variability may be compared.