Graduation date: 1992

Deuterium ratios (δD) of hydrated volcanic glass have been used to reconstruct paleoenvironments, although the reliability and proper sample preparation protocol have been debated. In this study, hydrated volcanic ash samples from the lee of the Cascades were prepared using two separate methods. Method 1 involves sonicating and rinsing samples with hydrochloric acid (HCl) followed by hand-selection of glass shards (125-212µm). Method 2 requires hydrochloric acid (HCl) and hydrofluoric acid (HF) abrasion as well as heavy liquid separation of shards (70-150µm). Method 2 produced more consistent results with decreased intra-replicate variability in both water content (-0.92 wt. %) and deuterium values (-2.5‰ δD). Method 2 δD values of ≥99% isotropic glass were also 2.5-10 % more negative relative to Method 1 values, with an increasing discrepancy with age (3.68-32.66 Ma). Method 2 results suggest volcanic glass did not re-equilibrate with modern water, based on 1) < 2‰ discrepancies between samples of the same ash flow taken from unique sample localities and 2) a ~20‰ difference between samples of different ages (~8 Ma apart) from the same locality. These results support the specified use of HF abrasion and heavy liquid separation on 70-150 µm glass shards to minimize the impact of contaminants on reconstructed paleowater δD values.

The Van Dyke's salamander (Plethodon vandyke,) is a rare species endemic to Washington State. It has been found in cool moist microhabitats along streams, splash zones of waterfalls, and headwater seeps. We explored the association of the Van Dyke's salamander with hydrologic condition, geomorphology, disturbance characteristics, and vegetation structure in first- and second-order streams, and headwater seeps in the Cascade Range of Washington. We conducted salamander surveys and measured habitat characteristics at 50 streams and 40 seeps May-October 2000-2002. We described Van Dyke's salamander occurrence in stream and seep sites at three spatial scales: between sites, within sites, and between microhabitat sites. Using presence and absence as the response, we fit logistic regression models predicting Van Dyke's salamander occurrence. To identify the model that best fit the data, we ranked a priori models using Bayesian Information Criterion (BIC). Results were consistent for both stream and seep sites, at all three spatial scales. Best approximating models indicated that Van Dyke's salamander occurrence at sites was related to geological and hydrological habitat characteristics that provided hydnc and thermal stability. The probability of Van Dyke's salamander occurrence along streams was associated with habitat characteristics that protected salamanders from exposure, provided a source cover, and stream habitat types providing splash zone areas. Between streams, Van Dyke's salamander occurrence was positively associated with the proportion of valley walls with canopy cover <5%, the proportion of the stream channel dominated by bedrock, boulder, or soil substrates, and additional stream channels entering the main channel. Within streams, the probability of Van Dyke's salamander occurrence increased with the presence of non-forested areas, the presence of bedrock dominated stream habitat types, and the presence of vertical or V-shaped valley wall morphology. Between microhabitat sites, the probability of Van Dyke's salamander occurrence increased with an absence of trees, the presence of seeps, and the presence of small cobble sized substrates. The probability of Van Dyke's salamander occurrence in seeps was associated with habitat characteristics that protected salamanders within the larger landscape, provided a moisture gradient from dry to saturated, and the presence of cover objects. Between seeps, Van Dyke's salamander occurrence was positively associated with seep faces having a dry and sheeting hydrology, and with seep faces >5 m high. Within seeps, the probability of Van Dyke's salamander occurrence was negatively associated with seeps that had proportionately more point measures of total overhead cover that were >25%. Between microhabitat sites, the probability of Van Dyke's salamander occurrence was positively associated with an increase in the percent cover of small cobble, small gravel, and bedrock substrates. We conducted mark-recapture surveys of the Van Dyke's salamander at two high-gradient stream sites located within the Cascade Range of Washington State, June-November 2002. Sites known to support populations of the Van Dyke's salamander were chosen, and were ecologically different. One site, lacking significant overstory and located within the blast zone created by the 1980 eruption of Mount St. Helens, was surveyed 10 times. The other site, located in an old-growth coniferous stand, was surveyed 11 times. Abundance of salamanders at the blast zone site was estimated to be 458 (95% Cl: 306-739). Abundance of salamanders at the old-growth site was estimated to be 100 individuals (95% Cl: 61-209). Capture probabilities were extremely low (5 = <0.10) for all trapping occasions at both sites, with an average capture probability for the two sites of 0.038 (range = 0.02-0.09). Analysis of movement patterns suggested that most individual salamanders had home ranges <2 m, at least when moving on or near the surface. Individuals were recaptured under the same cover object as initial capture 36% of the time, and 89% of the recaptured individuals moved <2 m. Our results indicated that populations of the Van Dyke's salamander were rare on the landscape, even within the species documented range. Van Dyke's salamander occurrence was associated with geological and hydrological habitat characteristics that created microhabitats favorable for a species that is especially sensitive to heat and drying due to physiological constraints. Animals were difficult to detect due to fossorial habits and low capture probabilities, and it is likely that the Van Dyke's salamander was not detected even at sites where it existed. Life history characteristics, such as lunglessness and fossorial habits, low capture probabilities, and low abundances make it difficult to manage for and protect the Van Dyke's salamander. However, habitat associations may be used to identify and protect habitats suitable for Van Dyke's salamander occurrence. / Graduation date: 2004

Graduation date: 1991

University, Diss., 2004--Kiel.

University, Diss., 2004--Kiel.

The Breitenbush Hot Springs area lies on the boundary of folded middle to late Tertiary Western Cascade rocks and younger High Cascade rocks. Within the mapped area the Western Cascade rocks are represented by four formations. The Detroit Beds, a sequence of interstratified tuffaceous sandstone, mudflow breccia, and tuff, is overlain unconformably by the Breitenbush Tuff. The Breitenbush Tuff consists of three units of welded pumice-rich crystal-vitric ash-flow tuffs interbedded with tuffaceous sedimentary rocks. The Outerson Formation unconformably overlies the Breitenbush Tuff and consists primarily of basaltic lava and breccia. The Outerson Formation includes three localized members: a basal, glassy, aphanitic basalt, the Lake Leone Sediments, and the Outerson Tuff. The Outerson Formation is cut by a number of feeder dikes and plugs and is unconformably overlain by the Cheat Creek Sediments, composed of volcanic sedimentary rocks and a distinctive basaltic tuff. The Western Cascade formations total more than 1660 m {5500 ft) of strata and range from Oligocene to Pliocene in age. The High Cascade rocks are represented by two formations: the Triangulation Peak Volcanics of basalt and andesite lava and breccia, lying unconformably atop the Cheat Creek Sediments; and unconformably beneath the Collowash Volcanics, a series of thin basaltic lava flows and breccias. The Western and High Cascade rocks are covered extensively by surficial deposits, primarily glacial drift. The High Cascade formations are at least 840 m (2800 ft) thick, ranging in age from Pliocene to Pliestocene. The Western Cascade rocks have been folded and faulted in the Breitenbush Hot Springs area, and form the eastern limb of the north-trending Breitenbush Anticline. The folded rocks and the erosional unconformities between the rock units probably represent two local episodes of orogeny: one in early to middle Miocene and another in late Pliocene to Pleistocene time. The Outerson Formation represents a depositional sequence between the periods of uplift and deformation. Faulting accompanied the orogenic sequences. The primary volcanic landforms in the area have been destroyed by erosion but skeletal remains of High Cascade volcanoes are recognized. Stream erosion and glaciation are responsible for the present landforms. Breitenbush Hot Springs occurs, in part, along basaltic dikes which channel the water through impermeable Breitenbush Tuff. The dikes are believed to be associated with the Outerson basalts. The Hot Springs discharge upwards at 3400 l/min. (900 gpm) of water at temperatures up to 92°C (198°F).

Monitoring wildlife habitats has become important to forest ecosystem management because it provides valuable information about the response of forests and their species to harvest practices, impacts from recreational use, conservation efforts, and natural and human-caused disturbances. Monitoring is a complex task that requires a variety of abiotic and biotic measurements and decisions about what should be measured, and when and where measurements should be taken. Riparian habitats contain unusually high diversity and are important to land managers. Wildlife assessments of riparian areas have focused on vertebrate species such as amphibians, birds, and mammals, but have largely ignored the arthropod components of the habitats. Arthropods constitute over 85% of all species and posses characteristics that make them valuable for tracking environmental changes. The purpose of this study was to gather site-specific data about epigaeic, riparian beetle community composition of the H.J. Andrews Experimental Forest (HJA). The patterns of beetle distribution, abundance, and diversity were analyzed and the results were used to characterize and compare the riparian and adjacent upslope beetle communities. Almost 8,000 beetle specimens representing about 250 species were collected from 141 pitfall traps placed along 10 transects in 3 different channel morphologies along Lookout Creek in the HJA. Traps were opened during six 30-day sampling periods over 2 years. Riparian and adjacent upslope beetle communities had high diversity measurements. The average difference of the calculated Simpson's Diversity Index between the two communities was 0.0116 and represented about 1% of the average riparian diversity. Analysis of species-curves indicated that the riparian habitats contained a higher total number of species. Multivariate Principal Coordinate Analysis indicated that the two habitats had distinctly different beetle communities. Multigroup Discriminant Analysis correctly classified 89.7% of the sampling units as the habitat group into which they were assigned a priori. Detailed recommendations for monitoring riparian habitats were discussed. / Graduation date: 2000

This study describes the composition of forest landscapes surrounding northern spotted owl (Strix occidentalis caurina) nests in the central Cascade Mountains of Oregon. I compared forest composition around 126 owl nests in 70 pair territories with forest composition around 119 points drawn randomly from all terrestrial cover-types, and around 104 points drawn randomly from the old-forest (closed canopy, > 80 yrs) cover type. All nest sites and random points were drawn from U.S. Forest Service lands and were not drawn from privately owned lands or Wilderness Areas. Forest cover was classified on a Landsat Thematic Mapper image. I quantified the percentage of old-forest within 200 concentric circular plots (0.04-5.0-km radii), centered on each analyzed point, using a geographic information system. I used logistic regression to make spatially-explicit inferences. Owl nests were surrounded by more old-forest when compared to points drawn randomly from all terrestrial cover types: there was significantly (P<0.05) more old-forest around the owl nests in plots as large as 1.79 km in radius. When compared to points drawn randomly from the old-forest cover type, owl nests were surrounded by significantly (P<0.05) more old-forest in plots with 0.17-0.80-km radii. Exploratory analyses suggest that the landscape scales most pertinent to northern spotted owl nest site positioning in this study area appear to be (in descending order): the surrounding 10-15 ha (~200-m radius), the surrounding 25-30 ha (~300-m radius), the surrounding 200 ha (800-m radius), and possibly the surrounding 700 ha (1,500-m radius). This study supports the assertion that northern spotted owls are strongly associated with older forests. The results also indicate that owl nests are most associated with higher proportions of old-forest near the nest implying that the arrangement of habitat is important for nest-site selection/positioning Since spotted owls in the central Cascade Mountains of Oregon are known to have home-ranges that average 1,769 ha, it is important to recognize that these results apply to nest-site selection/positioning on the landscape and not to the amount of habitat necessary for pair persistence or successful reproduction. / Graduation date: 1998

xvi, 182 p. : col. ill. / Volatile components (H 2 O, CO 2 , S, Cl) dissolved in magmas influence all aspects of volcanic activity from magma formation to eruption explosivity. Understanding the behavior of volatiles is critical for both mitigating volcanic hazards and attaining a deeper understanding of large-scale geodynamic processes. This work relates the dissolved volatile contents in olivine-hosted melt inclusions from young volcanics in the Central Oregon and Northern California Cascades to inferred magmatic processes at depth and subsequent eruptive activity at the surface. Cinder cone eruptions are the dominant form of Holocene volcanism in the Central Oregon segment of the High Cascades. Detailed field study of deposits from three cinder cones in Central Oregon reveals physical and compositional similarities to explosive historic eruptions characterized as violent strombolian. This work has important implications for future hazard assessments in the region. Based on melt inclusion data, pre-eruptive volatile contents for seven calc-alkaline cinder cones vary from 1.7-3.6 wt.% H 2 O, 1200-2100 ppm S, and 500-1200 ppm Cl. Subarc mantle temperatures inferred from H 2 O and trace elements are similar to or slightly warmer than temperatures in other arcs, consistent with a young and hot incoming plate. High-magnesium andesites (HMA) are relatively rare but potentially important in the formation of continental crust. Melt inclusions from a well-studied example of HMA from near Mt. Shasta, CA were examined because petrographic evidence for magma mixing has stimulated a recent debate over the origin of HMA magmas. High volatile contents (3.5-5.6 wt.% H 2 O, 830-2900 ppm S, 1590-2580 ppm Cl), primitive host crystals, and compositional similarities with experiments suggest that these inclusions represent mantle-derived magmas. The Cascades arc is the global end member, warm-slab subduction zone. Primitive magma compositions from the Cascades are compared to data for arcs spanning the global range in slab thermal state to examine systematic differences in slab-derived components added to the mantle wedge. H 2 O/Ce, Cl/Nb, and Ba/La ratios negatively correlate with inferred slab surface temperatures predicted by geodynamic models. Slab components become increasingly solute-rich as slab surface temperatures increase from ∼550 to 950°C at 120 km depth. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Dr. Paul J. Wallace, Chair and Advisor; Dr. Katharine Cashman, Member; Dr. Ilya Bindeman, Member; Dr. Richard Taylor, Outside Member