Northwest Science 95(3-4)
Genetic Differentiation of English Sole in the Northeast Pacific Ocean and Salish Sea – Gary A. Winans, Jon Baker, Lyndal Johnson, Ingrid B. Spies, James E. West
The English sole (Parophrys vetulus, family Pleuronectidae) is an abundant ground fish used as a sentinel of marine pollution in the inland marine waters of Washington and Oregon. We use 15 microsatellite loci to evaluate patterns of genetic variability within and among 17 collections of sole from coastal sites and within the southern Salish Sea. Over 470 alleles were identified in 15 loci, and high levels of genetic richness, as estimated by expected heterozygosity (HE) and allele richness (AR), were detected. Fish sampled from coastal areas at the northern end of our study area had the lowest values of genetic richness, in contrast to collections at the southern end. The level of differentiation among all collections was low: mean FST value was 0.0006. Nineteen comparisons had statistically significant FST values (meanFST of 0.0029) and involved comparisons involving three locations associated with urban areas (Port Gardner [Everett, WA], Sinclair Inlet [Bremerton, WA] and Commencement Bay [Tacoma, WA]). A statistically significant, but weak, isolation by distance pattern (IBD) was seen in the five coastal collections over 1100 km of coastline. In contrast, in the Salish Sea collections, the pattern of differentiation was patchy and marked by several distinctive collections in close proximity to urban areas. The pattern of differentiation in the Salish Sea parallels differences seen in ecotoxicological characteristics of the English sole that inhabit separate urban embayments differing in pollution characteristics. Future work can focus on evaluating the stability and meaningfulness of this subtle variability in a time of local and global environmental changes.
Population Characteristics of Brook Trout in Idaho Streams and Alpine Lakes – Curtis J. Roth, Patrick A. Kennedy, Kevin A. Meyer
In western North America, nonnative brook trout (Salvelinus fontinalis) frequently threaten native salmonids via competition and hybridization, so fisheries managers often implement eradication programs for conservation purposes. In conjunction with such programs, managers often construct population models to evaluate the effects of different management strategies designed to control the undesirable population, but such models require demographic data (e.g., age, growth, sex ratios, and survival), which are lacking for western brook trout populations. Brook trout were sampled from 12 alpine lakes and two streams in Idaho, with total length varying from 80 to 380 mm and age varying from 1 to 11 yrs. Across all waters, the von Bertalanffy growth parameters varied from 231 to 490 mm (mean = 345 mm) and Kvaried from 0.15 to 0.76 (mean = 0.37). Survival estimates, constructed from age-length keys, were corrected for streams with mark-recapture data; for alpine lakes, corrections were made via gill net selectivity data. Survival varied from 0.30 to 0.56 (mean = 0.45), and except for one waterbody, estimates were minimally affected by correcting for capture efficiency. The proportion of the population that was male varied from 0.34 to 0.75 (mean = 0.53). Our results indicate that brook trout population vital rates in Idaho were similar to those observed in their native range.
Effects of Post-fire Timber Harvest and Mastication on Shrub Regrowth in the Sierra Nevada Mountains: A Lake Tahoe Case Study – Susan D. Kocher, Daylin Wade
Increasingly large high-severity wildfires in dry forests of the western United States have led to concern about how best to regenerate new forests after wildfires. Harvesting fire-killed trees, burning woody debris, and tree planting are commonly used reforestation strategies. This study evaluated the effects of a novel forest restoration approach that involved masticating un-merchantable dead trees and spreading the woody debris generated across the site to prevent erosion from the 2007 Angora Fire in Lake Tahoe, California. Woody material covered 82% of the site after treatment, with an average depth of 6.6 cm, and volume of 190 tonnes per hectare. We found that this treatment reduced shrub regrowth, compared to an untreated area nearby, and that shrub regrowth was inversely related to fuel depth. Seven years after the fire, shrub cover averaged only 50% on treated plots compared to 92% on untreated plots. The tallest shrubs averaged 69 cm in height on the treated site compared to 114 cm on nearby untreated sites. Tree seedlings planted on the treated site averaged 141 cm in height, well above the height of the shrubs. Advantages of this approach include controlling erosion while reducing drought stress, the potential for weed introduction, and the need for herbicide to control shrub competition. Although leaving a layer of woody material where new trees have been planted does constitute a fire hazard, so too does a vigorous shrub layer. Managers should consider and weigh these factors when deciding on a post-fire reforestation strategy.
Status of Three Large Populations of Western Pearlshell (Bivalvia: Margaritiferidae: Margaritifera falcata) in the Willamette River Basin, Oregon – Travis Williams, Celeste A. Searles Mazzacano
Freshwater mussels in the western U.S. are under-studied compared to their eastern cousins, and no western species receive federal protection. Mussel distribution throughout Oregon’s rivers and streams is poorly documented, and there are limited historical records to inform assessments of whether, and by how much, current populations may have declined. We launched a long-term project to characterize freshwater mussel populations throughout the Willamette River basin. Surveys were conducted in the mainstem Willamette River and a major tributary, the Middle Fork Willamette, during three years. A two-stage sampling process was used; transects were surveyed qualitatively, and then 0.25 m2 quadrats were placed randomly in transects for quantitative surveys. Mussels visible at the substrate surface were counted using viewing scopes and snorkeling, and scuba diving in deeper water. To facilitate detection of juveniles (< 3.50 cm long) and calculation of the burial factor, some quadrats were double sampled; mussels visible at the surface were counted, then the substrate was excavated to a depth of 10 to 20 cm, and all mussels (surface and buried) were counted and their shell length measured. Dense western pearlshell (Margaritifera falcata) populations were found at all locations, but they differed greatly in length class structure, density, and presence of juveniles. Some sites also contained small numbers of floaters (Anodonta spp.) and notably, a single western ridgemussel (Gonidea angulata) was found in a highly urbanized reach. These surveys provide baseline data on the current status of several freshwater mussel populations in the Willamette River basin.
Distribution, Relative Abundance, and Body Size of Sculpins in the Elwha River Watershed Following the Removal of Two Hydroelectric Dams – Roger A. Tabor, Jeffery R. Johnson, Roger J. Peters, Rebecca Paradis, Michael L. McHenry, Samuel J. Brenkman, George R. Pess, Todd R. Bennett, Martin C. Liermann
Dam removal often shows positive effects for many fish species, especially migratory species. In contrast, information regarding the effects on less migratory species is lacking. The Elwha River, Washington had two hydroelectric dams removed from 2011 to 2014, which resulted in the loss of two reservoirs. Because of glacial history, the Elwha River system has a depauperate freshwater fish fauna, including just two sculpin species (coastrange sculpin [Cottus aleuticus] and prickly sculpin [C. asper]). Both species exhibit a similar migratory life history strategy, which includes a planktonic larval stage that drifts downstream to a nursery area (e.g., lake, large river, or estuary), followed by an upriver movement pattern. Due to these characteristics, Elwha River dam removal and loss of the reservoirs may have had important effects on these two sculpin species. We sampled sculpins with longitudinal electrofishing surveys in 2018 and 2019 to evaluate their current distribution, relative abundance, and body size. These metrics were generally similar to other river systems in the Pacific Northwest, with fewer and larger migratory sculpins upstream. Additionally, we compared our findings to pre-dam surveys. After dam removal, sculpins in upstream reaches were less abundant and had a smaller range of sizes. This suggests the population characteristics of sculpins in the Elwha River has changed, but it is unclear how indirect effects, such as anadromous salmonid (Salmonidae) increases, may influence their overall abundance. This study also provides a baseline to monitor sculpin population changes in the future.
Spatiotemporal Responses of Wintering Bald Eagles to Changes in Salmon Carcass Availability in the Pacific Northwest – Ethan S. Duvall
Each winter, thousands of bald eagles (Haliaeetus leucocephalus) from across western North America migrate to Pacific Northwest rivers to feed on the carcasses of post-spawning chum salmon (Oncorhynchus keta). However, declining salmon populations and impacts of climate change are reducing the availability of salmon carcasses as a wintering food source for eagles. The ability of eagles to adjust to these impacts is crucial to their survival, and their responses are currently unknown. I hypothesized that eagles are responding by redistributing to non-river habitat in search of alternative food sources. Specifically, I examined the redistribution of over-wintering eagles from river habitat to nearby agricultural areas in response to seasonal declines in carcass availability. Over two consecutive winters, I conducted weekly eagle surveys on a 30-km stretch of the Nooksack River and a 22.5-km stretch of farmland northwest of the river. I examined the association between salmon carcass distribution and eagle abundance on the Nooksack River, and evaluated the temporal relationship between eagle abundance on the Nooksack River versus neighboring farmland. I found a strong negative association between eagle abundance on the river versus adjacent farmland, and observed eagles primarily concentrated near dairy farms and waterfowl rafts. My results suggest that eagles are responding to declining carcass availability by redistributing to non-river habitat in search of alternative food sources, and that a substantial fraction may migrate to agricultural areas.
Pollinators Prefer Yellow Flowers over Red in Scotch Broom (Cytisus scoparius L. Link), but Not Enough to Affect Plant Fitness – Robert F. Bode, Maria Breznau, Kaylen Furuta
In well-established flowering plant invasions, floral phenotypes that do not attract pollinators are predicted to be eliminated through natural selection. We explored this hypothesis in the invasive plant species Scotch broom (Cytisus scoparius), which has yellow flowers frequented by a diverse community of bee species, as well as red-tinged flowers that are predicted to be pollinated at a significantly lower rate. We predicted that plants with the red-flower phenotype will have fewer flowers visited, produce fewer seed pods per flower, and produce fewer seeds per pod than the yellow-flowered type. To investigate this, we measured the proportion of flowers pollinated for red- and yellow-flowered phenotypes, observed the number of seed pods produced per flower, and counted seeds per pod. Although we found lower pollination in the red-flowered phenotype, we did not see differences in female fitness. Scotch broom is an invader predicted to be limited in fecundity by the rate of pollinator visits and would be expected to lose phenotypes that attract fewer pollinators. We found the persistence of a less-attractive phenotype, likely because the reduction in male fitness is not paired with a reduction in female fitness.
Cellobiase Activity as an Indicator of Fungal Decay in the Wood of Woodpecker Nest Cavities in the Pacific Northwest – Jeffrey M. Kozma, Teresa J. Lorenz, Jerred Seveyka
Woodpeckers require trees and snags with decayed wood in order to excavate nest and roost cavities, and interior wood hardness is considered an important factor determining where a woodpecker can create a cavity. In most ecosystems, saprophytic fungi are responsible for the decay and softening of wood, and are thought to be important in providing soft wood for woodpecker cavity excavation. We conducted a study of cellulose-degrading enzymes in the wood surrounding woodpecker nest cavities. We measured wood hardness, percent wood density loss (PWDL), and cellobiase activity, an extracellular fungal cellulase that degrades cellulose within wood surrounding the nest cavities of the northern flicker (Colaptes auratus), black-backed woodpecker (Picoides arcticus), white-headed woodpecker (Dryobates albolarvatus), and hairy woodpecker (D. villosus) in Oregon and Washington. We found that mean wood hardness was significantly lower, and cellobiase and PWDL were significantly higher, at nest cavities than controls for each woodpecker species. Wood hardness was higher and cellobiase lower at nests of black-backed woodpecker than northern flicker, but did not differ among the other woodpecker species. Our results suggest that increased amounts of cellobiase result in softer wood due to the increased decay caused by higher fungal enzyme activity and that measuring cellobiase can be used to estimate wood decay without directly measuring wood hardness. All four woodpecker species selected nest substrates with softer wood and higher fungal enzyme activity than controls. This supports findings from previous studies of the importance of saprophytic fungi for woodpecker cavity excavation.
How Long Can Dead Fish Tell Tales? Effects of Time, Tissue, Preservation, and Handling on Genotyping Success – David A. Venditti, Craig A. Steele, Brian S. Ayers,
Joshua L. McCormick
Genetic analyses have become increasingly powerful, more readily available to biologists, and have made ever more degraded DNA potentially useful. Single nucleotide polymorphisms (SNP) are a relatively new “class” of markers that show promise for use with degraded or archived samples. We sequenced a panel of 298 SNPs from Chinook salmon (Oncorhynchus tshawytscha) tissue in three comparative studies to determine the effect of DNA quality at sampling, time in archive, and tissue type and preservation method on SNP genotyping success using logistic regression. The first study evaluated pristine DNA from live adults sampled at three hatcheries and archived up to 6 years. The second study compared samples from carcasses with varying levels degradation (i.e., condition) and archived up to 15 years. The third study compared heart and fin samples preserved either in ethanol or on paper from carcasses with varying levels of degradation and processed within 6 months. Genotyping success for fresh tissue did not decline over the 6-year archive period at two of the three hatcheries, suggesting sample handling techniques may be more influential than time in archive. Genotyping success of archived carcass samples depended more on carcass condition than time in archive. Heart tissue genotyped consistently more often than fin samples from all but poor condition carcasses. Based on these results, we make tissue-sampling recommendations for different intended purposes. We also provide simple, post-collection sample handling procedures that can increase genotyping success regardless of tissue or preservation method.
Case Report of Traumatic Rib Fracture in Mammoth from Frenchman Hills – Tonnemaker Mammoth Site, Washington – George V. Last, Katherine Newhall-Perry, Rosalie L. Faubion, Neil L. Mara, Bax R. Barton
A deformed rib from a Columbian mammoth (Mammuthus columbi) was found among more than 100 mammoth bones excavated from an alfalfa field at the Tonnemaker Hill Farm in the Frenchman Hills north of Royal City, Grant County, Washington. The mammoth remains were deposited within fine-grained Missoula flood sediments sometime after 16 ka. We performed a detailed examination of the rib, including computerized tomography imaging, and investigated the possible etiology of the deformity. The deformity consists of hypertrophic bone formation localized toward the distal (sternal) end of the rib. The circumference of the lesion is nearly twice that of the medial circumference of the rib diaphysis. This lesion is consistent with an incompletely healed fracture or a fracture nonunion with pseudarthrosis (false joint) formation. Gross examination and computerized tomography scan images of the proximal aspect of the rib, as well as cursory inspection of the other skeletal remains, have yet to reveal definitive evidence of other bony abnormalities. We surmise, therefore, that this fracture was the consequence of blunt force trauma in a healthy animal. To our knowledge, this is the first report of a rib fracture with incomplete healing or false joint formation in a M. columbi individual in the Pacific Northwest. We suspect the incidence of rib fractures among M. columbi was greater than the Pacific Northwest literature suggests and encourage examination of existing collections for evidence of similar findings. The incidence and frequency of such injuries may provide insight into M. columbi behavior.
Northwest Science 96: Accepted papers
Postglacial Fire and Vegetation History from Doheney Lake in the Sinlahekin Wildlife Area, Okanogan County, Washington (USA) – Megan K. Walsh, Kevin C. Haydon, Dale Swedberg
In recent decades, dry Pinus ponderosa-dominated forests of the eastern Cascades have experienced a dramatic increase in large, high-severity wildfires resulting in significant damage to natural resources. However, relatively little is known about long-term trends in postglacial fire activity in these forests. The purpose of this study was to reconstruct the fire and vegetation history of the Doheney Lake watershed, located in north-central Washington, using macroscopic charcoal and pollen analysis of a ca. 12,330 year-long lake sediment record. The results illustrate that regional climatic change, as well as climatically-controlled vegetation shifts, were the primary drivers of fire activity during much of the postglacial period. In particular, the establishment of the modern forest between ca. 7500-6000 cal yr BP due to cooler and moister conditions led to greater amounts of burnable biomass and generally higher levels of fire activity. The study results also suggest that greater interannual climate variability linked to drought may have played a role in the highly variable fire activity during much of the past ~6000 years. Additionally, it is likely that Indigenous cultural burning contributed to the fire activity at the site prior to Euro-American settlement, in particular during the past ~4000 years. Since ca. 125 cal yr BP (1825 CE), an almost complete absence of fire has allowed for the encroachment of shade-tolerant trees and has resulted in the potential for catastrophic wildfire, like that experienced at the site in 2015.
Influences of Succession and Biogeoclimate on Forage Resources for Elk in Northern Idaho – Deborah S. Monzingo, John G. Cook, Rachel C. Cook, Jon S. Horne, Lisa A. Shipley
Natural disturbance shaped forest communities for millennia, but fire suppression and timber harvest declines have altered forest structure across the western U.S., reducing the abundance of forage for ungulates. We evaluated quality and quantity of forage resources for lactating elk (Cervus canadensis) and their calves in relation to season, succession, and biogeoclimate, the latter indexed by potential vegetation (PV) zones, across 36,500 km2 in Idaho’s Clearwater and St. Joe River Basins. In 0.2-ha macroplots (n = 359), we measured characteristics of forest overstory, biomass of current annual growth of undergrowth vegetation (kg/ha), and nutritional content of these plants. Using biomass, digestible energy (kJ/g), digestible protein (DP, g/100 g forage), and prior knowledge of elk diet selection and nutritional constraints, we developed eight forage resource metrics. The greatest abundance of undergrowth vegetation (500–1,000 kg/ha) occurred during the first 20 years after stand-replacing disturbance and declined as the overstory closed in wetter PV zones. Digestible energy decreased whereas DP increased as stands aged. Evidence of nutritional limitations for lactating elk increased markedly after mid-summer—early seral, high elevation spruce-fir forests on productive soils provided the best opportunity for lactating elk to satisfy their requirements in late summer. Our findings demonstrate the importance of disturbance regimes that maintain early seral communities in mosaics with mid- and late seral stages and suggest that implementing stand replacing disturbance in relatively moist forest zones at mid- and high elevations provides the greatest improvement in forage resources for lactating elk and their calves in summer.
Drivers of Forested Riparian Microclimate on the Olympic Peninsula of Washington State – Katrina R. Keleher, Richard E. Bigley, Warren D. Devine
Riparian zones have unique microclimates that support distinct assemblages of aquatic and terrestrial species, which has resulted in a regulatory emphasis in recent decades on riparian protections. However, an understanding of the drivers of riparian microclimate in these protected riparian areas is still lacking. This study examined drivers of variability in summer air temperature and humidity in the riparian zones of ten drainage basins (31-789 ha) on the western Olympic Peninsula, Washington. Model selection analysis was used to explore hypotheses about the influences of three types of drivers on microclimate: regional climate gradients, proximity to stream, and solar radiation. Proximity to stream had the strongest influence on microclimate: the air became warmer and drier with increasing distance from the stream and with increasing steepness of the stream valley slope. Basins at higher elevations (28-362 m) had warmer, drier microclimates, a pattern attributed to greater coastal marine climate influence at lower elevations. Variation in microclimate also was associated with variation in solar exposure modeled as a function of topography. Testing of canopy closure influence on microclimate was hindered by the fact that canopy closure was uniformly high across the study area (87-98%) as a result of unmanaged, primarily second-growth stream buffers. Each of the microclimate drivers identified in this study was a function of topography, across a range of scales. By understanding these relationships between topographic variation and riparian microclimate, managers and researchers will be able to more accurately and efficiently delineate the extent of riparian microclimate influence.
Overwinter Mass Loss of Townsend’s Big-eared Bats in Five Caves – Jericho C. Whiting, Martha C. Wackenhut, Bill Doering
Quantifying overwinter mass loss in bats is important for understanding hibernation energetics, habitat conservation, and the ability of bats to persist with novel pathogens. Townsend’s big-eared bat (Corynorhinus townsendii) is a species of conservation concern. Little is known about overwinter mass loss of this bat in western North America. We conducted a retrospective analysis to quantify overwinter mass loss of 362 females and males during 1987 and 1988 in five caves in an important area for the conservation of this bat in western North America. Although body mass of 13 females in cave C62 averaged 1.1 g heavier than 12 females in cave C54 when captured in October, all those females recaptured in March lost similar percentages of body mass ( = 22.7%) over winter. In cave C27, body mass of six females averaged 2.6 g heavier than eight males when captured in October. Those recaptured females and males in March lost similar percentages of body mass ( = 19.5%) over winter. In caves C27 and C54, mass of 96 male bats decreased by a mean of 21% between October and March. In five caves, mass of 227 female bats decreased by a mean of 23.4% between October and March. Our results indicate that females are heavier than males when entering hibernation, and that females generally lose more mass than males during hibernation. Moreover, female bats entering hibernation in our study area weighed more than female bats of this species in other studies when entering hibernation. Our data provide researchers in western North America with mass loss estimates for female and male Townsend’s big-eared bats.
Influence of Above-Ground Pipeline and Associated Factors on Movement of Winter Active Boreal Mammals in the Alberta In-Situ Oil Sands – Michael L. Charlebois, Hans G. Skatter, Sondre Skatter, John L. Kansas
Above-ground pipelines (AGP) associated with in-situ oil sands may restrict mammal movement potentially increasing extinction probability and decreased reproductive success. Our 12-year study used winter track count techniques to assess the response of winter-active mammals to AGP in northern Alberta, Canada. The primary questions were: Which species were most prone to movement obstruction by AGP, facilities or natural factor(s) and which factor exerted the strongest influence on crossing likelihood.
A total of 2,068 trails of 12 different species were observed. All species crossed more than half of the time. Focal species crossed on average eighty percent of the time. Crossing likelihood of white-tailed deer (Odocoileus virginianus), ermine (Mustela erminea), coyote (Canis latrans), lynx (Lynx canadensis), and fisher (Martes pennanti) were significantly influenced by predictors including pipeline height, pipeline corridor width, infrastructure age, vegetation type, and proximity to infrastructure. Deer and lynx crossing likelihood was positively affected by pipe height. Deer, coyote and ermine crossing likelihood was positively affected by age of pipe. Fisher and deer crossing likelihood was negatively affected by pipeline corridor widths. Our investigations show that most species cross AGP with high crossing frequencies of pipe heights ranging from 130 cm to 160 cm.
These findings are important for impact mitigation because: the scarcity of published studies of wildlife movement responses to AGP, our inclusion of small and mid-sized carnivores, and, our investigation of multiple factors.
We highlight mitigation/design improvements, effects of pipeline corridor widths, and challenges posed by coupling infrastructure with pipelines, serving to reduce movement barriers/fragmentation.
Cascadia Clues to a 1700 Earthquake as Documented in the 1800s – Brian F. Atwater, David K. Yamaguchi, Jessie K. Pearl
Northwest newcomers of the nineteenth century recorded ecological anomalies later ascribed to a Cascadia earthquake. The most salient were subfossil trees in brackish tidelands. James Graham Cooper, as a naturalist attached to the Smithsonian Institution in the 1850s, called attention to western redcedar standing dead in tidal marshes of Shoalwater Bay (modern Willapa Bay). Two such redcedar served as bearing trees for John J. Lowell, then subdividing a Shoalwater Bay township under contract with the General Land Office. Cleveland Rockwell, mapping tidal shores west of Astoria for the United States Coast Survey in 1868, fringed them with radiating symbols that evoke sprawling spruce stumps. Today, redcedar trunks and spruce stumps in these and other tidelands serve as evidence for lowering of coastal land during a Cascadia earthquake in 1700. Since that earthquake, sedimentation and gradual uplift have enabled post-earthquake succession from tidal flat through tidal marsh to new tidal forest. This post-1700 succession had reached an intermediate stage in 1805 at a Columbia River tidal marsh that Meriwether Lewis called a “marsey prairie.” Post-1700 succession in nearby freshwater tidal forests may have influenced Lewis’s division of Sitka spruce into massive upland old growth and smaller tideland trees. These assorted field observations make sense today by analogy with forest death and renewal near Anchorage that the 1964 Alaska earthquake occasioned.
Comparative Phylogeography of Microsnails from the Pacific Northwest – Megan L. Smith, Connor Lang, David Sneddon, Jessica Wallace, Anahí Espíndola, Jack Sullivan, Bryan C. Carstens
Leaf-litter dwelling invertebrates serve an important role in ecosystem function by breaking down nutrients and potentially acting as indicators of habitat quality. However, this community is understudied due to difficulties related to sampling and taxonomic identification. To explore this community, we sampled leaf litter from the Coastal and Cascades ranges of the Pacific Northwest of North America (PNW) and searched > 200 samples for micro-invertebrates. We removed and photographed more than 400 invertebrate specimens, sequenced a portion of the mitochondrial gene cytochrome oxidase I (COI) for 60 samples, and used COI and the BLASTn database to identify invertebrates. Using these sequences and environmental data from the collection localities, we investigated the phylogeographic history of the two best-sampled species of microsnails, Columella edentula (toothless column snail) and Punctum randolphii (conical spot snail). Results suggest that populations of these species from the Coastal and Cascades ranges may have survived in a single refugium during the Pleistocene glacial cycles and recolonized the Coastal and Cascades ranges during the Holocene. Our results add to the knowledge of species responses to the Pleistocene glacial cycles in the PNW and suggest that future studies should aim to increase representation of micro-invertebrates, perhaps using metabarcoding techniques.
Implications of Metrics and Methodology for Juvenile Salmonid Monitoring in Western Oregon Streams – Ronald J. Constable Jr., Erik Suring
We attempted to determine whether electrofishing removal estimates or single pass snorkeling was a more reliable method for Oregon Department of Fish and Wildlife (ODFW) monitoring of juvenile coho salmon (Oncorhynchus kisutch) and steelhead (O. mykiss) abundance and occupancy trends. Based on 1997–2000 data we assumed abundance estimates from the method that tracked more closely with parental abundance would better approximate true juvenile abundance. Parental abundance from spawning ground surveys and juvenile abundance metrics unique to each method were estimated from 2000–2004 and 2007–2008. Parental abundance did not explain the variation in juvenile abundance from either method (r2 < 0.22), invalidating our assumption, but results had relevance for snorkel surveys used in ODFW monitoring. For both species, correlations between density (fish/m²) and abundance (quantity, based on fish/km) estimates from snorkeling were weak (r < 0.379) but correlations between abundance estimates from both methods were strong (r > 0.846); implying abundance was more appropriate than density for ODFW monitoring. Neither method could sample all habitats, and annually variable proportions of coho salmon (15–47%) and steelhead (0–24%) abundance estimates obtained by electrofishing were in pools too shallow to meet the ODFW depth criterion for snorkeling. This resulted in lowering the criterion to ≥ 20 cm in 2010. The lower criterion, relative to original, has not shown differences in trends but 30% more pools have been sampled, resulting in 23% higher abundance estimates with 10% proportionately smaller confidence intervals. These changes improved ODFW monitoring and related management decisions.
Three-year Effects of Crown Removal by Clipping or Burning on Beargrass (Xerophyllum tenax) Size and Biomass – David H. Peter, Timothy B. Harrington
Beargrass (Xerophyllum tenax [Pursh] Nutt.), an evergreen perennial herb of the northern Rocky Mountains, Pacific Northwest and northern California, is used in Native American basketry and commercial floral greens. We studied beargrass size and biomass responses to crown removal by clipping or burning over three years in a coast Douglas-fir (Pseudotsuga menziesii var. menziesii) woodland having variable shrub cover in the southeastern Olympic Peninsula of Washington State. Clipping forested plants resulted in 28% mortality, mostly from smaller plants growing under 26% more total cover than the surviving plants; however, only 3% of completely crown scorched open grown plants died. Three years after treatment, crown width of surviving plants was only 61% of the pre-treatment size for clipped plants compared to 88% for completely crown scorched plants. Regression analyses indicated that the percentage of crown scorch accounted for only 16% and 27% of crown width and foliar height variation, respectively, one year post-burn, decreasing to 10% and 19% at three years post-burn. During the three years after burning, percentage flowering increased linearly to 64% of plants. Three years post-burn foliar browse was higher on crown scorched than on non-crown scorched plants. Although shade tolerant, long-term survival of lowland beargrass is likely limited by combined competition from shrubs and trees. Stand density management is needed to maintain healthy, reproducing populations in the lowlands of western Washington.