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376 - 400 of 1229 Items << < 11 12 13 14 15 16 17 18 19 20 > >>
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The Mount Jefferson Primitive Area is one of three High Cascade wilderness areas in Oregon. It is second in size among these, covers approximately 136 square miles, and with the addition of a large roadless area in Warm Springs Indian Reservation...
1963-05-10 (iso8601)
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Phacelia capitata Rruckeberg is a member of the
Phacelia magellanica polyploid complex (species group
Magellanicae), a group of wide-ranging, polymorphic
perennials in western North America related to the South
American P. secunda (= P....
1985-04-11 (iso8601)
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Temperate nearshore reefs along the Pacific coast of North America are highly valuable to commercial and recreational fisheries yet comprise a small fraction of the seabed. Monitoring fisheries resources in this region is difficult; high-relief...
2015 (iso8601)
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Since settlement of the Intermountain West, sage grouse abundance and
productivity has declined and their range has decreased. The decline of sage grouse
populations is primarily due to permanent loss and degradation of sagebrush-grassland...
2000-02-29 (iso8601)
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The genus Lichnanthe Burmeister contains eight extant and one
fossil species which are strictly nearctic in distribution. The
subfamily Glaphyrinae, however, is distributed nearly world-wide.
Five species were previously described and three are...
1976-08-10 (iso8601)
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Habitat selection behavior was investigated as a proximate mechanism influencing spatial distributions of three species of anuran larvae. Rana cascadae, Hyla regilla, and Bufo boreas overlap in distribution in lakes and ponds of the Cascade Mts....
1981-03-19 (iso8601)
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A severe wildfire burned 454 hectares of a second-growth Douglas-fir forest
in 1977 on a north-facing slope in Pattee Canyon, near Missoula, Montana. The
slope was aerially seeded with a grass mixture, from which Dactylis glomerata
established...
1991-10-10 (iso8601)
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The Warner Creek Fire collection consists of documents related to the Warner Creek Fire in Willamette National Forest, Oregon in October 1991, and its aftermath. The majority of the collection is the Administrative Record presented by the U.S.F.S....
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Lichen sensitivity to air quality has been recognized in Europe
for over 125 years: recently Federal agencies in this country have
begun using lichens as air quality bioindicators. This study presents
the results of three different approaches to...
1994-12-09 (iso8601)
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A simplified autoradiographic method for estimating species-specific
phytoplankton production rates in mixed natural communities
was evaluated in the laboratory and employed in the field. Laboratory
experiments were designed to test the...
1976-09-21 (iso8601)
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Several dolphin species have global distributions. The extent of their radiation and limits to gene flow are presumably a product of oceanographic features both recent and historical, behavioral specializations and social organization....
2014-12-08 (iso8601)
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DNA markers that detect polymorphisms within and between two biological species of the coniferous laminated-root-rot fungus Phellinus weirii were developed and used to
measure the amount and distribution of genetic variation. In a preliminary...
1992-04-24 (iso8601)
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1. Overlapping river and road networks provide a framework for studying the complex interactions between natural and human systems, with river-road intersections as focal areas of study. Roads can alter the morphology of stream channels, pose...
2010-01-01
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The hypothesis is explored that lodgepole pine at the seedling emergence period is more resistant to low temperatures than ponderosa pine. Differential tolerance between species to low temperatures is then related to the prevalence of lodgepole...
1967-01-19 (iso8601)
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A biosystematic study was made on the species of Hackelia of
northwest America and adjacent Canada. During the course of the
study 140 populations, representing all species and varieties, were
transplanted to the greenhouse for study under...
1973-07-30 (iso8601)
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Craneflies of the genus Lipsothrix inhabit decomposing wood in
streams. The life cycles and ecological relationships of L. nigrilinea
(Doane) and L. fenderi Alexander were investigated to determine how they
exploit and respond to the wood habitat...
1982-09-28 (iso8601)
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The influence of fire and climate events on age structure of different species was examined in
old-growth mixed conifer in the southern Sierra Nevada. Within a 48-ha stem-mapped sample area, after a
mechanical thinning, all stumps were examined...
2005 (iso8601)
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The response of three hardwoods from Ghana and a hardwood and
three softwoods from the United States to liquid and gas-phase impregnation
was investigated. Impregnation with liquids included a sink-float
test in a water-glycerine solution and...
1976-04-02 (iso8601)
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The effect of scale is an important concern in mapping of biodiversity. Scale issues include the grid cell size used for analysis and the effect of the extent and internal boundaries. Because biodiversity analysis involves combinatorial processes,...
1997-10-25 (iso8601)
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Vegetation provides food for many insects, and many insects serve as food for bats. We investigated the linkages among these three trophic levels in riparian areas throughout the Oregon Coast Range by examining the influence of vegetation cover,...
2007-01-08T18:57:45Z (iso8601)
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Quantitative assessments of many West coast rockfish stocks of both major and
minor importance to commercial fisheries have shown varying declines in abundances. The population sizes of less-abundant, co-occurring unassessed species may also be...
2003-08-05 (iso8601)
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This thesis includes four separate studies. The first two studies assessed edge effects in a
700-year-old forest. After 20 years of exposure, epiphyte assemblages on the clearcut edge
were similar to those of the forest interior, but there were...
1995-11-22 (iso8601)
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The relation of nutria (Myocastor coypus) feeding to total abundance, species composition, and seasonal use of the marsh flora on
the William L. Finley National Wildlife Refuge was studied during
1969 and 1970. Nutria numbers were estimated by...
1971-05-06 (iso8601)
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Introgressive hybridization between two invasive species has the potential to contribute to their invasion success and provide genetic resiliency to rapidly adapt to new environments. Additionally, differences in the behaviour of hybrids may lead...
2019-10-07
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