Oregon Streams Research Articles

Cattle Grazing Effects on Macroinvertebrates in an Oregon Mountain Stream

Cattle grazing effects on aquatic macroinvertebrates were assessed in a 4-year experiment of a mountain stream in northeastern Oregon. From 1996 through 1999, 10 cow–calf pairs were introduced into 6 experimental units along the stream for 42 days between July and September, and effects on aquatic macroinvertebrates were compared with 3 units in which no grazing occurred. Streambank and geomorphological variables were also measured to provide context for interpretation of effects on aquatic macroinvertebrates. Macroinvertebrate response to grazing was subtle, indicated by significantly lower abundance in grazed units. We measured more profound effects on streambanks: grazing caused an average decrease of 18% in bank length of the highest stability/cover class and caused an average increase of 8% in the lowest condition class over the course of each summer. By June of each following year, banks had recovered to their previous June condition, but grazing each summer caused a progressively larger decline in bank condition by September. Streambank effects were accompanied by an increase in cobble embeddedness over time in grazed units and were correlated with grazing-associated stream widening. Treatment effects were overwhelmed, however, by a profound decline in the abundance of most macroinvertebrates over the study period, with a drop in September 1999 to 14% of the initial September abundance of 1997. While the drop was more precipitous in grazed units, declines were common to all study units, suggesting that something more widespread affected the system during this time. Logging on lands just upstream of the study area in 1998 and 1999, in which trucks drove through the study stream without the benefit of a culvert, sent sediment plumes into the study area each of those 2 years and could have caused the precipitous decline in aquatic macroinvertebrates.

Habitat selection models to account for seasonal persistence in radio telemetry data

Models for the analysis of habitat selection data incorporate covariates in an independent multinomial selections model (McCracken et al. 1998) Ramsey and Usner 2003 and an extension of that model to include a persistence parameter (2003). In both cases, all parameters are assumed to be fixed through time. Radio telemetry data collected for habitat selection studies typically consist of animal relocations through time, suggesting the need for an extension to these models. We use a Bayesian approach that allows for the habitat selection probabilities, persistence parameter, or both, to change with season. These extensions are particularly important when movement patterns are expected to differ seasonally and/or when availabilities of habitats change throughout the study period due to weather or migration. We implement and compare the models using radio telemetry data for westslope cutthroat trout in two streams in eastern Oregon.

Use of Felled Junipers to Protect Streamside Willows From Browsing

Willow (Salix) communities are important components of riparian ecosystems. However, browsing by livestock and wildlife species can negatively impact willow size and abundance, and make restoration efforts difficult. A common solution has been fencing of affected willows to exclude ungulates, but fencing is expensive and may not complement desirable land management strategies. An alternative to fencing is the use of structures that limit access to streamside willows, without excluding ungulate access to the entire riparian zone. We examined the use of felled western juniper trees (Juniperus occidentalis Hook) placed over streamside willow shrubs. Four replicates of felled western juniper treatments (covered) and noncovered treatments were applied to a 1.2-km length of stream in southeastern Oregon. Willows (< 2 m) within treatment areas were censused, tagged, examined for evidence of browse-use, and measured for maximum height during August 2002, before treatment. Posttreatment measurements were made in August and October 2003. Results indicate that by August 2003 (posttreatment) the average growth of willows in covered treatments was 25 cm (480%) greater than in noncovered treatments. By October 2003 (posttreatment), more shrubs were browsed in noncovered (84%) than covered (39%) treatments. Our data suggest that covering small willow shrubs (< 2 m tall) with felled western juniper is an effective deterrent to browsing.

Diatom assemblages as indicators of timber harvest effects in coastal Oregon streams

Spatially patchy and temporally varied cycles of timber harvest across a landscape may have subtle effects on stream conditions that are difficult, but important, to assess. The objective of our study was to examine the relationship between benthic diatom composition and timber harvest in coastal Oregon watersheds. Physical habitat conditions, water chemistry, and periphyton composition were characterized for 46 sites from 2 subbasins with different timber harvest intensities (0.3 km 2/y vs 3 km2/y, between 1972-1998). Landscape variables including geology, vegetative cover types, and harvest intensity, were quantified for the watershed up- stream of each sample point. Nonmetric Multidimensional Scaling analysis of periphyton com- position showed that the 1st axis was primarily driven by Achnanthidium minutissimum (r 52 0.91) whereas the 2nd axis was driven by Nitzschia inconspicua (r 5 0.77). The 1st axis was positively correlated with % of upstream area harvested between 1972 and 1998 (r 5 0.54) and water- quality variables such as total P (TP) (e.g., rTP 5 0.74). A subset comparison (n 5 12) between harvested (30% harvested 1972-1998, n 5 6) and unharvested (0% harvested 1972-1998, n 5 6) watersheds with similar geology (.80% basalts), broadleaf vegetative cover (8-35% broadleaf), and other reach-scale characteristics revealed higher total N, TP, turbidity, and conductivity in the harvested than the unharvested watersheds (p , 0.05). Shannon diversity and species rich- ness also were higher in the harvested group (p , 0.05). Our data suggest that diatom assem- blages may be useful in assessing the long-term impact of timber harvest within coastal Oregon watersheds.

Estimating the Size of Historical Oregon Salmon Runs

Increasing the abundance of salmon in Oregon's rivers and streams is a high-priority, public policy objective. Salmon runs have been reduced from predevelopment conditions (typically defined as prior to 1850), but it is unclear by how much. Considerable public and private resources have been devoted to restoring salmon runs, but it is uncertain what the current recovery potential is because much of the freshwater and estuarine habitat for salmon has been altered and there is no expectation that it will be returned to a predevelopment condition. The goals of all salmon recovery efforts are based on assumptions about the size of the runs prior to significant habitat alteration, coupled with an estimate of the amount and quality of freshwater and estuarine habitat currently available. We estimated the historical aggregate salmon run size in rivers along the Oregon coast (excluding the Columbia River) using two methods: (1) converting estimated aboriginal population levels into numbers of salmon; (2) extrapolating cannery pack into numbers of salmon. Annual aboriginal harvest of all salmon species is estimated to have been approximately 10 million pounds per year (4,500,000 kg) or 1.75–5.36 million salmon, a harvest level similar to that occurring during the height of commercial fishing on Oregon's coastal rivers in the late 1800s and early 1900s. Extrapolating cannery pack data, the estimated size of the late 1800s aggregate runs of coho salmon (Oncorhynchus kisutch) was 1.5–2.5 million. The estimated size of aggregate runs of chinook salmon (Oncorhynchus tshawytscha) runs was 290,000–517,000. Compared to our estimates of mid-1800s coho salmon levels, early 2000 runs (during favorable ocean conditions), were 11–19% of the historical level. During poor ocean conditions (1990s), current coho salmon runs were 3–6% of the historical size.

Patterns and sources of thermal heterogeneity in small mountain streams within a forested setting

Spatial thermal patterns and the sources of those patterns were examined in four mountain streams in northeast Oregon and Idaho during hot summer days in 2001. Summer baseflow ranged from <0.007 to 0.22 m 3/s. Maximum and minimum temperatures increased in the downstream direction, with the diurnal range decreasing with increasing stream size. Each stream was thermally diverse spatially, diurnally, and seasonally, with unique landform and geologic influences on the daily temperature maxima. Insolation was the most important predictor for maximum temperature at each stream. Minimum daily temperatures were less variable than maxima and followed a seasonal and elevation gradient, with minimum air temperature a more important predictor than either the insolation from the previous day or channel features. Models for each stream using insolation and physical habitat characteristics explain 32 to 67% of maximum temperature and 17 to 51% of minimum temperature variability. Groundwater inputs moderated thermal conditions, particularly local maxima, but did not subsume the predominant temperature range controls of insolation and air temperature.

Use of Felled Junipers to Protect Streamside Willows From Browsing

Willow (Salix) communities are important components of riparian ecosystems. However, browsing by livestock and wildlife species can negatively impact willow size and abundance, and make restoration efforts difficult. A common solution has been fencing of affected willows to exclude ungulates, but fencing is expensive and may not complement desirable land management strategies. An alternative to fencing is the use of structures that limit access to streamside willows, without excluding ungulate access to the entire riparian zone. We examined the use of felled western juniper trees (Juniperus occidentalis Hook) placed over streamside willow shrubs. Four replicates of felled western juniper treatments (covered) and noncovered treatments were applied to a 1.2-km length of stream in southeastern Oregon. Willows (&lt; 2 m) within treatment areas were censused, tagged, examined for evidence of browse-use, and measured for maximum height during August 2002, before treatment. Posttreatment measurements were made in August and October 2003. Results indicate that by August 2003 (posttreatment) the average growth of willows in covered treatments was 25 cm (480%) greater than in noncovered treatments. By October 2003 (posttreatment), more shrubs were browsed in noncovered (84%) than covered (39%) treatments. Our data suggest that covering small willow shrubs (&lt; 2 m tall) with felled western juniper is an effective deterrent to browsing.

Diatom assemblages as indicators of timber harvest effects in coastal Oregon streams

Diatom assemblages as indicators of timber harvest effects in coastal Oregon streams

Watershed-Based Survey Designs

Watershed-based sampling design and assessment tools help serve the multiple goals for water quality monitoring required under the Clean Water Act, including assessment of regional conditions to meet Section 305(b), identification of impaired water bodies or watersheds to meet Section 303(d), and development of empirical relationships between causes or sources of impairment and biological responses. Creation of GIS databases for hydrography, hydrologically corrected digital elevation models, and hydrologic derivatives such as watershed boundaries and upstream-downstream topology of subcatchments would provide a consistent seamless nationwide framework for these designs. The elements of a watershed-based sample framework can be represented either as a continuous infinite set defined by points along a linear stream network, or as a discrete set of watershed polygons. Watershed-based designs can be developed with existing probabilistic survey methods, including the use of unequal probability weighting, stratification, and two-stage frames for sampling. Case studies for monitoring of Atlantic Coastal Plain streams, West Virginia wadeable streams, and coastal Oregon streams illustrate three different approaches for selecting sites for watershed-based survey designs.

Use of Natural Temperature Patterns to Identify Achievable Stream Temperature Criteria for Forest Streams

Abstract Almost 90% of the streams listed on the EPA's nationwide database as water-quality impaired for temperature are in the Northwest. Historic records, monitoring of streams in federal wilderness areas in Oregon, and available data for least-impaired streams in Oregon, Washington, and Idaho show that many of these streams cannot achieve state temperature criteria. Forest management often is cited as a cause for increased stream temperature above state standards. The expectation that all forested streams should be below state targets has led to unnecessary listing of streams as impaired, wasting limited watershed protection resources. State water-quality programs should base water temperature criteria on natural patterns of stream temperature and on factors that have biological relevance to beneficial uses. West. J. Appl. For. 19(4):252–259.

VARIATION IN THE RELATIONSHIP BETWEEN SNOWMELT RUNOFF IN OREGON AND ENSO AND PDO1

ABSTRACT: The value of using climate indices such as ENSO or PDO in water resources predictions is dependent on understanding the local relationship between these indices and streamflow over time. This study identifies long term seasonal and spatial variations in the strength of El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) correlations with timing and magnitude of discharge in snowmelt streams in Oregon. ENSO is best correlated with variability in annual discharge, and PDO is best correlated with spring snowmelt timing and magnitude and timing of annual floods. Streams in the Cascades and Wallowa mountains show the strongest correlations, while the southernmost stream is not correlated with ENSO or PDO. ENSO correlations are weaker from 1920 to 1950 and vary significantly depending on whether Southern Oscillation Index (SOI) or Niño 3.4 is used. PDO correlations are strong from 1920 to 1950 and weak or insignificant other years. Although there are not consistent increasing or decreasing trends in annual discharge or spring snowmelt timing, there are significant increases in fractional winter runoff that are independent of precipitation, PDO, or ENSO and may indicate monotonic winter warming.

A STABLE ISOTOPE TRACER STUDY OF NITROGEN UPTAKE AND TRANSFORMATION IN AN OLD-GROWTH FOREST STREAM

The understanding of nitrogen dynamics in streams of temperate forest biomes historically has been constrained by a combination of anthropogenic disturbances and technical limitations. We report here on a study in an undisturbed stream in Oregon, USA, using a stable isotopic tracer to quantify uptake, transformation, and retention of nitrogen. We added 15NH4Cl for six weeks to Mack Creek, a third-order stream in a 500-year-old-growth coniferous forest and monitored 15N in dissolved, aquatic, and terrestrial riparian food web components. Data collected before, during, and for four weeks after the tracer addition allowed us to derive uptake rates of inorganic N and to trace its fates. Short uptake lengths (35–55 m) and residence times (8–12 min) of ammonium indicated strong demand. Despite nitrate concentrations of 55–68 μg/L, nitrification rates were also high, with 40– 50% of the 15NH4+ converted to nitrate over the 220-m study reach. Aquatic bryophytes and biofilm on large wood (“epixylon”) showed the highest biomass-adjusted uptake rates. All aquatic consumers sampled, both vertebrate and invertebrate, showed incorporation of tracer 15N by the end of the experiment; small invertebrate grazers were more strongly labeled than their food sources. Increased 15N label in 15 of the 17 riparian plant species sampled suggested transfer of aquatic N to the terrestrial ecosystem. At the end of the release, 81% of the added tracer was accounted for, with 49% exported (primarily as 15NO3−) and 32% retained within the stream and riparian biota (primarily by bryophytes, epixylon, and fine benthic organic material). Our results suggest that, in streams within undisturbed primary forests, uptake and retention of nitrogen may be highly efficient and that there may be strong connections between terrestrial and aquatic ecosystems.

Thermal heterogeneity, stream channel morphology, and salmonid abundance in northeastern Oregon streams

Heterogeneity in stream water temperatures created by local influx of cooler subsurface waters into geomorphically complex stream channels was associated with increased abundance of rainbow trout (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) in northeastern Oregon. The addition of cold water patch frequency and area as explanatory variables in salmonid habitat models indicated that doubling of cold water patch frequency was associated with increases in rainbow trout and chinook salmon abundances of 31% and 59%, respectively. Doubling of cold water patch area was associated with changes of 10% in rainbow trout abundance but was not associated with chinook abundance after accounting for other habitat factors. The physiognomy, distribution, and connectivity of cold water patches, important attributes determining the effectiveness of these habitats as thermal refuges for stream fishes, were associated with channel bedform and riparian features. Monitoring of thermal heterogeneity and salmonid populations in response to ongoing habitat restoration efforts will provide additional insights into causal relationships among these factors.

Macroinvertebrate Assemblage Change in a Small Eastern Oregon Stream Following Disturbance by Grazing Cattle

ABSTRACT Badger Creek (Ochoco National Forest, Oregon) was sampled before and after cattle arrived and on July 31 in a reach of stream where cattle were present and a reach where they were not. Index values and ordination of these samples indicates that seasonality and local conditions are important drivers in macroinvertebrate community composition. In both a three month survey and the single date sampling, disturbance by grazing cattle was correlated with more Chironomidae larvae and fewer mayflies, indicating that cattle create an environment conducive to the macroinvertebrate assemblage compositions found in low oxygen, organically enriched systems.

Electrofishing Effort Requirements for Assessing Species Richness and Biotic Integrity in Western Oregon Streams

Abstract We examined the sampling effort required in wadeable western Oregon streams at base flow to estimate fish species richness, percent abundance, and biotic integrity when employing three persons and one backpack electrofisher. Reaches were oversampled longitudinally and data were recorded separately for each habitat unit, allowing us to treat each habitat unit separately during data analyses. The median values of species richness from Monte Carlo simulations of the data indicated that a stream reach 40 times its mean wetted width was adequate to estimate 90% of species richness (i.e., all common species) in western Oregon fish assemblages. A reach length of 40 wetted channel widths was also adequate to precisely score an index of biotic integrity developed for western Oregon. However, where 40 channel widths are less than 150 m, we recommend a minimum distance of 150 m to ensure that sufficient numbers of individuals are captured, rare habitats are encountered, and riparian conditions do not fully ...

Controls on Patterns of Coarse Organic Particle Retention in Headwater Streams

Organic matter retention is an integral ecosystem process affecting C and nutrient dynamics and biota in streams. Influences of discharge (Q), reach-scale channel form, and riparian vegetation on coarse particulate organic matter (CPOM) retention were analyzed in 2 headwater streams in northeastern Oregon. Ginkgo biloba leaves were released in coniferous forest reaches and downstream floodplain meadow reaches during spring high flow and summer baseflow. Transitional reaches were also analyzed during summer baseflow. Paper strips, simulating sedge blade retention, were released in meadow reaches during high flow. Mean transport distances (S_P) were calculated as the inverse of the longitudinal loss rate (k) of leaves in transport. The metrics S_P, width-specific discharge (Q_W = Q/stream width), and the mass transfer coefficient (v_dep=Q_W/S_P) were used to investigate retention. Values of S_P (0.9-97 m) were 2 to 11 times longer during high flow than baseflow. Mean S_P in forest reaches (29.3 m) was significantly shorter than in meadow reaches (68.9 m) during high flow but not during baseflow. Standardizing k for the scaling effects of Q by analyzing the relationship between Q_W and S_P, in which the slope equaled the inverse of mean v_dep of all Ginkgo releases, indicated times when v_dep was higher or lower than predicted by Q. Values of S_P were driven largely by Q, yet most experiments in which values of v_dep exceeded those predicted by Q_W occurred during high flow. Values of v_dep (0.3-32 mm/s) across experiments were generally inversely related to S_P but did not differ between forest and meadow reaches during high flow. Unlike meadow reaches, mean v_dep in forest reaches was higher during high flow (5.2 mm/s) than baseflow (1.1 mm/s). Values of v_dep were positively related to large wood volume and negatively related to the extent of floodplain inundation during high flow. Yet, in the meadow reach that had lower relative channel constraint, paper strips were transported farther onto the floodplain as Q rose, resulting in long-term (∼1.5 mo) retention. Despite downstream increases in Q, there were no differences in mean baseflow S_P or v_dep among reaches in either stream, indicating some longitudinal compensation in retention. Alternating associations between retention metrics and structural elements of the stream channels between flow periods suggests dynamic reach-scale hydrologic-retention thresholds in response to changes in Q. Analysis of v_dep across experiments indicated that channel morphology, stream wood, and riparian vegetation are major controls on CPOM retention.

Influence of large woody debris on the morphology of six central European streams

The impact of large fallen trees on channel form is described for six short stream sections in central Europe influenced by large woody debris (LWD sections), five of which are compared to nearby reference sections free of LWD (reference sections). Three-dimensional models of streambed topography were generated by surveying cross-sections with a spacing of 1 per 1/15 channel width. Parameters derived from digital terrain models and cross-sections compared between LWD sections and reference sections include the extent of pools, bars, and cutbanks, streambed and bank complexity, cross-sectional area, width, depth, and cross-section complexity as described by Andrle's [Math. Geol. 26 (1994) 83] ‘angle-measurement-technique’ (AMT analysis), a measure of the deviation of a cross-section line from a straight line. Structural diversity is greater in LWD sections at almost all spatial scales, particularly in terms of pool volume (Mann–Whitney U-test, p<0.01) and cross-section complexity described by median angle of AMT analysis (Mann–Whitney U-test, p<0.05). Large pools are clearly associated with large fallen trees and attain volumes up to 36 m 3. With the exception of the ratio of one LWD section where the fallen tree is oriented parallel to flow, the ratio of pool volume to bed planimetric area ranges from 424 to 693 m 3/ha, which is in the upper range reported for small, high-gradient streams in Oregon, NW America (229–755 m 3/ha) [Can. J. Fish. Aquat. Sci. 47 (1990) 1103]. Pool volume of LWD sections is strongly correlated to the blockage ratio (Spearman rank order correlation, r s=0.93, p<0.01). Differences in channel morphology between the LWD sections and reference sections indicate a strong morphologic control of large woody debris in these central European stream sections.

Incorporating prior knowledge in environmental sampling: ranked set sampling and other double sampling procedures

AbstractEnvironmental sampling can be difficult and expensive to carry out. Those taking the samples would like to integrate their knowledge of the system of study or their judgment about the system into the sample selection process to decrease the number of necessary samples. However, mere convenience or non‐random sampling can severely limit statistical inference. Methods do exist that integrate prior knowledge into a random sampling procedure that allows for valid statistical inference. Double sampling methods use this extra information to select samples for measurement, thus reducing the number of necessary samples (in order to achieve a desired objective) and thereby reducing sampling costs. The level of prior information required can range from a linear relationship with a known auxiliary variable to simple ranking based on auxiliary information. We examine three types of double sampling methods (ranked set sampling, weighted double sampling and double sampling with ratio estimation), with accompanying examples from Oregon stream habitat data. All three methods can provide increased precision and/or lower sampling costs over simple random sampling. The appropriate double sampling method for the data and research situation depends upon the type of prior information available. The categories of prior information are summarized in a table and illustrated using the example data. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Relationships of channel characteristics, land ownership, and land use patterns to large woody debris in western Oregon streams

Regression tree analysis was used to test the relationship of channel and aquatic habitat characteristics from 3793 stream reaches in western Oregon State to the abundance of large woody debris (LWD). Stream reaches were drawn from diverse ownerships and land uses – land cover types over a broad geographic extent. When all land uses – land covers were considered, ownership and land use patterns were related to LWD abundance. When nonforested land uses were excluded, however, these factors became less important. In forested streams, LWD abundance was predicted primarily by stream gradient and bankfull channel width, with the volume, frequency, and size of LWD pieces decreasing as channel size increased. Within forested lands, stand age and forest distribution were related to LWD size but had small correlations with LWD volume and abundance. The strong relationship of stream gradient and bankfull channel width with LWD suggests that in forested areas, the most significant factor related to LWD counts is the geomorphology of stream reaches and their surrounding areas. Land managers in western Oregon who want to improve aquatic habitat quality may want to direct their efforts to increasing LWD in larger streams, which typically include smaller quantities of LWD.

Physical Aquatic Habitat I. Errors Associated with Measurement and Estimation of Residual Pool Volumes

Residual pools have been used as a measure of physical aquatic habitat, but measurement techniques usually entail estimates or unquantified errors. In order for residual pools to be a useful metric of stream channels, it is important for the errors associated with their measurement to be quantified. We used precise, digital terrain models of a third-order mountain stream in Oregon to identify the sensitivity of measurements to error and the consequences of those errors in calculating the volumes of residual pools. Precise quantification of the elevations of the crests of riffles is critical for precise measurement of the volume of individual residual pools because they serve as control points for the water surface elevations of residual pools. Reach-level estimates of the total volume of residual pools, however, are relatively insensitive to errors incurred in measuring individual pools. This insensitivity indicates that reach-level measurements of residual pool volume may be more appropriate than measurements of individual pools as metrics in monitoring schemes that use low-precision measurement techniques.