Publications
Filter Total Items: 1999
Density, ages, and growth rates in old-growth and young-growth forests in coastal Oregon
We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) old-growth stands on 10 sites and compared them with young-growth stands (50-70 years old, regenerated after timber harvest) in the Coast Range of western Oregon. The diameters and diameter growth rates for the first 100 years of trees
in the old-growth stands were significantly grea
Authors
J. C. Tappeiner, D. Huffman, T. Spies, John D. Bailey
Clonal expansion and seedling recruitment of Oregon grape (Berberis nervosa) in Douglas-fir (Pseudotsuga menziesii) forests: Comparisons with salal (Gaultheria shallon)
Seedling regeneration and morphology of Oregon grape (Berberis nervosa Pursh) and salal (Gaultheria shallon Pursh) were studied in thinned and unthinned Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in the central Coast Range, Oregon. Above- and below-ground growth of both species were significantly and negatively correlated with stand density. Oregon grape appears to have less potenti
Authors
David W. Huffman, John C. Tappeiner
Growth responses of young Douglas-fir and tanoak 11 years after various levels of hardwood removal and understory suppression in southwestern Oregon, USA
At two sites in southwestern Oregon, height, diameter, and crown width of young Douglas-fir (Pseudotsuga menziesii) and sprout-origin tanoak (Lithocarpus densiflorus) were measured 1–11 years after reducing the density of a 2-year-old tanoak stand to 0%, 25%, 50%, and 100% of its initial cover. Some plots also included suppression of understory vegetation. Tanoak cover developed linearly with time
Authors
T.B. Harrington, John C. Tappeiner
Intestinal helminths of river otters (Lutra canadensis) from the Pacific Northwest
The intestinal helminth fauna of river otters, Lutra canadensis, from the Pacific Northwest was characterized by low species richness and intensity of infection. River otters from the lower Columbia River (n = 23) were infected with 9 species of helminths (83% prevalence); those from a relatively undisturbed reference area near the headwaters of the Trask and Wilson rivers on the Oregon coast (n =
Authors
Eric P. Hoberg, Charles J. Henny, O.R. Hedstrom, Robert A. Grove
Productivity of golden eagles wearing backpack radiotransmitters
We examined the association between the presence of backpack radiotransmitters and Golden Eagle (Aquila chrysaetos) reproduction (percentage of occupied territories producing young, and number of nestlings produced) over three years. The association between radio-tagging and nesting success and the number of nestlings produced varied significantly among years. A negative association with tagging w
Authors
J.M. Marzluff, M.S. Vekasy, Michael N. Kochert, Karen Steenhof
An energy-circuit population model for great egrets (Ardea alba) at Lake Okeechobee, Florida, U.S.A
I simulated the annual population cycles of Great Egrets (Ardea alba) at Lake Okeechobee, Florida, to provide a framework for evaluating the local population dynamics of nesting and foraging wading birds. The external forcing functions were solar energy, minimum air temperature, water depth, surface-water drying rate, and season. Solar input controlled the production of prey at moderate to high la
Authors
Jeff P. Smith
Nesting season food habits of 4 species of herons and egrets at Lake Okeechobee, Florida
Based on the composition of nestling regurgitations collected during 3 breeding seasons, fish were the most important prey group for Great Egrets (Ardea alba: N = 200 nest-day samples; aggregate percent biomass [APB] = 73.4%), Snowy Egrets (Egretta thula: N = 115; APB = 91.4%), and Tricolored Herons (E. tricolor: N = 68; APB = 97.3%). For Little Blue Herons (E. caerulea: N = 57), grass shrimp (Pal
Authors
Jeff P. Smith
Status and breeding ecology of the southwestern willow flycatcher in the Grand Canyon
Ernpidonax trailIll extirnus is one of several recognized subspecies of the Willow Flycatcher (Unitt 1987, Browning 1993), a neotropical migrant that breeds across much of North America. This southwestern race is a riparian obligate, nesting in dense patches of willow (Salix sp.), willow-cottonwood (Populus sp.), or other similarly structured habitats. In some areas of the Southwest, it nests in d
Authors
Mark K. Sogge, Timothy J. Tibbitts, Jim R. Petterson
Primary song by a juvenile willow flycatcher
The timing of song development in suboscines, in which song appears not to be
learned from other adults is poorly known. The Willow Flycatcher (Empidonax traillii) is a
suboscine with a primary song typically referred to as fitz-bew. I report here an instance of
very early singing by a 6-8-wk-old Willow Flycatcher, which sang in an aggressive context in
response to a recording of adult flycatc
Authors
M. K. Sogge
Holocene vegetation and historic grazing impacts at Capitol Reef National Park reconstructed using packrat middens
Mid- to late-Holocene vegetation change from a remote high-desert site was reconstructed using plant macrofossils and pollen from 9 packrat middens ranging from 0 to 5400 yr in age. Presettlement middens consistently contained abundant macrofossils of plant species palatable to large herbivores that are now absent or reduced, such as winterfat (Ceratoides lanatd) and ricegrass (Stipa hymenoides).
Authors
K.L. Cole, N. Henderson, D.S. Shafer
Shorebird diet and size selection of nereid polychaetes in South Carolina coastal diked wetlands
Coastal wetlands that are diked and managed may supplement declining natural habitat for migrating shorebirds (Charadriiformes). However, data on shorebird diet in these diked wetlands are scarce. We examined shorebird diet and prey size selection in brackish diked wetlands at the Yawkey Center on South Island, South Carolina, USA. Gut contents of seven Lesser Yellowlegs (Tringa flavipes) and seve
Authors
Louise M. Weber, Susan M. Haig
Factors controlling threshold friction velocity in semiarid and arid areas of the United States
A physical model was developed to explain threshold friction velocities u*t for particles of the size 60a??120 I?m lying on a rough surface in loose soils for semiarid and arid parts of the United States. The model corrected for the effect of momentum absorption by the nonerodible roughness. For loose or disturbed soils the most important parameter that controls u*t is the aerodynamic roughness he
Authors
Beatrice Marticorena, G. Bergametti, Jayne Belnap