Population and behavioral responses of small mammals to silviculture and downed wood treatments in the Oregon Coast Range

Forest managers are challenged to provide timber revenues and other resources for society while protecting and enhancing components of biodiversity that are often associated with older forests or older forest structure, such as dead wood. We examined small mammal response to timber harvest in stands 8-10 years following group-selection, two-story, and clearcut harvest, how provision of new downed wood influenced small mammals in group-selection and clearcut stands, and use of downed wood by Townsend's chipmunks (Tamias townsendii) in group-selection stands. Densities of adult and reproductive female deer mice (Peromyscus maniculatus) were greatest in harvested stands, whereas other measures for deer mice and Townsend's chipmunks (e.g., densities of male deer mice and male chipmunks), and densities of Oregon voles (Microtus oregoni) and Pacific shrews (Sorex pacificus) were similar among all stand conditions. Density of vagrant shrews (Sorex vagrans) was greatest in clearcut stands and decreased with decreasing harvest intensity. Although limited data precluded statistical analysis, abundances of northern flying squirrels (Glaucomys sabrinus) and western red-backed voles (Clethrionomys californicus) were similar between unharvested control stands and group-selection stands. Within two years following augmentation of downed wood, we did not detect any response of small mammal populations to the downed wood. Our results suggest that small mammal populations can benefit from alternative silvicultural treatments that retain overstory trees and that stands with areas of closed-canopy forest can provide habitat for species that are more abundant in intact and mature forest conditions (e.g., northern flying squirrels). In our study of use of wood by Townsend's chipmunks, the model indicating disproportionate use of paths with downed wood by Townsend's chipmunk was 22.6 times more likely than the null model, and a chipmunk was 3.0 times more likely to select locations with downed wood at average wood densities (paths with 26% wood). Chipmunks selected wood that was 1.2 times larger in diameter than randomly available wood and there was no evidence that chipmunks disproportionately used wood that was elevated. Our findings document that downed wood is an important habitat component for Townsend's chipmunks and suggest that downed wood influences movements of chipmunks

Characteristics and spatial relationships of day-roosts and activity areas of female long-eared myotis (Myotis evotis) in western Oregon

Management of habitat for bats requires sound information on their habitat requirements. I used radio telemetry to identify 80 roosts for 24 long-eared myotis (Myotis evotis); 74 roosts were identified for 21 females and 6 roosts for 3 males. Females primarily used dead and defective conifer trees (n=22) and conifer stumps (n=41) though they also used 3 live conifer trees, 1 live and 5 dead hardwood trees, and 2 conifer logs. Males used one each of the following structures: dead conifer, dead hardwood, conifer log, conifer stump, slash pile, and rock crevice. Female long-eared myotis primarily roosted in conifer stumps in landscapes dominated by younger forests and used dead or defective conifer trees and stumps in landscapes characterized by older forests. Roosts generally were located in upland habitats. Odds of a dead or defective conifer being used as a roosts was associated with decay class, presence of snags, and distance to the edge of the stand. Odds of a conifer stump being used was associated with amount of species of stump, height of the stump on the downhill side, access, woody debris within 1 m, and slope (%). Twelve female long-eared myotis were tracked on 23 nights to determine activity areas. Individuals had a mean nightly activity area of 39.5 ha which was centered 0.550 km from the day-roost and 0.16 km from available water; the maximum distance a bat was detected from a day-roost was 2.4 km. Odds of an area being used as an activity area was associated with distance to available water and percent of older forest conditions. Individual bats used the same general foraging area on different nights, suggesting that there are landscape features that function as centers of bat activity. Management of habitats for bats should consider spatial relationships of day-roosts and activity areas. Maintenance of large dead and defective conifers within 1 km of available water should provide roosting and foraging habitat for long-eared myotis and other species of bats. Leaving tall stumps also may provide structures for roosting

Eonycteris major, Greater Dawn Bat

Eonycteris major is assessed as Near Threatened under criterion A2cd as the species global population is suspected to have declined by a rate of 25–29% over the past 12.9 years (three generations; GL = 4.3 years; Pacifici et al. 2013). Although data are limited as the species is rarely captured, the species decline is thought to result from the extent of disturbance at their cave roosts, loss of karst habitats, and the overall extensive forest loss and degradation on Borneo

Shear development and overprinting in a back-arc basin, Klamath Falls, Oregon

Three key tectonic domains of western North America, the Walker Lane Fault Zone (WLFZ), northwestern Basin and Range (NWBR), and Cascade arc, intersect in south-central Oregon. Bounded by Cascade arc volcanoes in the west, the Klamath Graben is traditionally regarded as the western-most extent of the Basin and Range extensional province at the latitude of the California-Oregon border. Northwest-directed dextral shear across the Modoc Plateau domain of the WLFZ organizes into north and northwest-trending faults that end in the Klamath Graben. New geologic mapping with airborne LiDAR data reveals the nature of previously unrecognized interactions between faults within the Klamath Graben. North and northwest-trending faults define the Klamath Graben. Slip partitioning between north-trending normal faults and northwest-trending right-oblique faults suggest that the graben evolved due to transfer of northwest-directed shear into north-trending normal faults. Aftershock focal mechanisms from the 1993 Klamath Falls earthquake sequence show that active faulting involves both northwest-trending dextral faults and north-trending normal faults within the graben. North and northwest-trending basin-bounding faults are dominantly normal. Inside the graben, northwest-striking fault strands show ~3:1 strike-slip to normal offset across drainages within an alluvial fan. South of the alluvial fan, two faults change to northeast-strike and create a pull-apart basin, resulting in northwest-directed extension. Geodetic velocities of ~5 mm∙yr-1 towards ~N45°W, relative to stable North America, coincide with average fault strike along the graben-central strand, but are probably faster than geologic rates. Strata tilted ~5-40° are offset by northwest-striking dextral faults in the graben center and suggest that northwest-directed dextral shear overprints previous basin extension. Cumulative right-slip for the whole graben is probably <1 km and is restricted to the southern half of the graben. Cessation of strike-slip faulting prior to intersecting the Cascade arc suggests that the arc acts as a thermal boundary and limits westward growth of the WLFZ

Repeated lithospheric-scale reactivation of an inherited plate boundary in the eastern Alaska Range, Alaska, USA

Accretionary orogens, such as the North American Cordillera, form by repeated collisions of allochthonous oceanic and continental fragments (terranes). Due to the closure of ocean basins that is required for far-traveled terranes to become part of the orogen, fault systems at the boundaries of allochthonous terranes commonly form as plate boundaries and experience multiple phases of reactivation after collision. The repeated phases of reactivation along the terrane-boundary fault systems often mask the earlier deformation events and lead to uncertainty regarding the location of the main lithospheric-scale geologic boundary between terranes. In this dissertation, I present the geologic evolution of the master reactivated plate boundary structure in the Alaska Range suture zone of southern Alaska. In the first chapter, I use detailed geologic mapping, structural analysis, U-Pb and 40Ar/39Ar geochronology, geochemistry of spinel-group minerals, and receiver function seismology to parse metamorphic rocks in the suture zone. With these methods, I show that the main suturing structure is located along the boundary between amphibolite grade schists and gneisses associated with North America in the north and greenschist grade metagreywacke and slate associated with allochthonous oceanic terranes in the south. The main suturing structure was reactivated after ca. 32 Ma and nucleated an imbricate thrust system that progressed southward. I argue that reactivation along the boundary between the metasedimentary belts is the third phase of activity on this structure, owing to the penetration of that boundary through the lithosphere. In the second chapter, I use regional geologic mapping, U-Pb and 40Ar/39Ar geochronology, Hf isotope analysis, and statistical tests to confirm the correlation between Alaska Range suture zone metamorphic rocks in the Alaska Range and hypothesized correlative metasedimentary and plutonic belts in southwestern Yukon Territory. After confirming the correlation, I use the correlative rock packages to create a sequential restoration of slip on the Denali fault system. The outcome of this work shows that terrane accretion that metamorphosed the Alaska Range suture zone rocks took place at ca. 90 Ma along east-dipping shear zones, and subsequently those suture zone rocks have been dissected by ~480 km of dextral slip on the Denali fault since ca. 50 Ma. In the third chapter, I use modern river detrital apatite fission-track thermochronology and 40Ar/39Ar geochronology to highlight southern Alaska as a type-example of long-lived oblique flat slab subduction. With the datasets, I show that the most recent and rapid bedrock exhumation in southern Alaska is spatially associated with strike-slip fault systems that were active at the time of slab flattening. Moreover, I argue that transpressional deformation and flat slab-associated magmatism were localized on the strike-slip structures due to their role as active lithospheric-scale shear zones. This analysis challenges models of diffuse upper-plate deformation in flat slab subduction environments and instead argues that strike-slip fault systems that penetrate the upper plate are essential for localizing deformation associated with obliquely convergent plate motion. In my view, the overall impact of this dissertation is to show that by coupling detailed field and analytical work, each phase of reactivation for major orogenic structures can be resolved and coupled to regional tectonic/geodynamic scenarios at the time of formation and reactivation. Similarly, an overarching theme of the conclusions drawn herein is that the active strain distribution in strike-slip dominated orogens is strongly influenced by the locations of inherited structures that penetrate the lithosphere

Activity areas of female long-eared myotis in coniferous forests in Western Oregon

We used radiotelemetry to investigate the temporal patterns of activity, characteristics of activity areas, and the spatial relationships among activity areas, day roosts, and water for female long-eared myotis (Myotis evotis). We tracked 12 adult female long-eared myotis for 23 nights from June to August, 1996 and 1997, on the western slope of the Cascade Mountains in Oregon, USA. The activity areas of nine bats (n=11 nights) averaged 38.3 ha and were centred an average of 518 m from the day roost (SE=60 m) and 73 m from water (SE=10 m); centres of activity were significantly closer to water than random points (P<0.001). Odds of an area being used decreased with distance to available water (P=0.0001). Activity areas typically encompassed water but did not include the day roost. Activity areas did not significantly differ in forest composition as determined from randomly selected circular plots. Bodies of open water appear to function as important centres of activity for long-eared myotis. We contend that management of habitats for bats should consider spatial relationships among activity areas, day roosts and water

Use of conifer stumps in clearcuts by bats and other vertebrates

Although conifer stumps can constitute a large proportion of the volume of wood remaining in clearcuts, the amount and pattern of use of conifer stumps by bats and other vertebrates is poorly known. We made 18 168 observations of conifer stumps in four clearcuts to examine use of bark crevices on conifer stumps in clearcuts in western Oregon, USA. Use of bark crevices by vertebrates did not exceed 1.5% of the stumps searched during any survey with upper 95% confidence intervals not exceeding 5%. Ten species of vertebrates were observed using bark crevices, with the western fence lizard (Sceloporus occidentalis) most often detected. Use of stumps by bats was primarily limited to long-eared myotis (Myotis evotis). Most stumps used by vertebrates were relatively large Douglas-fir (Pseudotsuga menziesii) stumps located in open areas. Although bark crevices on conifer stumps in clearcuts provide habitat for some species of vertebrates they do not provide the breadth or long-term value as habitat for bats and other vertebrates as snags. Management of roost structures for bats, including the long-eared myotis, should focus on maintaining present and future availability of snags in an area

CUE_2013.pptx

Three key tectonic domains of western North America, the Walker Lane Fault Zone (WLFZ), northwestern Basin and Range (NWBR), and Cascade arc, intersect in south-central Oregon. Bounded by Cascade arc volcanoes in the west, the Klamath Graben is traditionally regarded as the western-most extent of the Basin and Range extensional province at the latitude of the California-Oregon border. Northwest-directed dextral shear across the Modoc Plateau domain of the WLFZ organizes into north and northwest-trending faults that end in the Klamath Graben. New geologic mapping with airborne LiDAR data reveals the nature of previously unrecognized interactions between faults within the Klamath Graben. North and northwest-trending faults define the Klamath Graben. Slip partitioning between north-trending normal faults and northwest-trending right-oblique faults suggest that the graben evolved due to transfer of northwest-directed shear into north-trending normal faults. Aftershock focal mechanisms from the 1993 Klamath Falls earthquake sequence show that active faulting involves both northwest-trending dextral faults and north-trending normal faults within the graben. North and northwest-trending basin-bounding faults are dominantly normal. Inside the graben, northwest-striking fault strands show ~3:1 strike-slip to normal offset across drainages within an alluvial fan. South of the alluvial fan, two faults change to northeast-strike and create a pull-apart basin, resulting in northwest-directed extension. Geodetic velocities of ~5 mm∙yr-1 towards ~N45°W, relative to stable North America, coincide with average fault strike along the graben-central strand, but are probably faster than geologic rates. Strata tilted ~5-40° are offset by northwest-striking dextral faults in the graben center and suggest that northwest-directed dextral shear overprints previous basin extension. Cumulative right-slip for the whole graben is probably <1 km and is restricted to the southern half of the graben. Cessation of strike-slip faulting prior to intersecting the Cascade arc suggests that the arc acts as a thermal boundary and limits westward growth of the WLFZ.Keywords: Fault, Shear, Klamath, Walker Lane, Overprinting, Basin and Range, Geolog

Photographic estimation of roosting density of Geoffroys Rousette Fruit Bat <i>Rousettus amplexicaudatus</i> (Chiroptera: Pteropodidae) at Monfort Bat Cave, Philippines

Conservation and management of bats requires reliable and repeatable data regarding the size and patterns of variation in size of bat colonies. Counts and densities calculated via photography have proven more accurate and repeatable than visual counts and ocular estimates. Unfortunately, the potential of photography to investigate the size of a bat colony and roost density has rarely been explored. In the summer of 2006, a colony of Geoffroys Rousette Fruit Bat, Rousettus amplexicaudatus, was photo-documented in the Monfort Bat Cave, in the Island Garden City of Samal, Davao del Norte, Mindanao, Philippines. We selected 39 images to develop roost density estimates. Mean (+or-SE) roosting density was 403+or-167.1 bats/m2 and 452.3+or-168.8 bats/m2 on the walls and ceiling of the cave, respectively; densities were not significantly different from each other (P=0.38). Based on these standardized data, we estimate that the initial 100m of the cave contained 883,526 bats. Ultimately, this photographic technique can be used to develop a statistical approach which involves repeatable estimates of colony size for Geoffroys Rousette Fruit Bats at Monfort Cave and will enhance ongoing monitoring activities throughout this species range