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626 - 650 of 1229 Items << < 21 22 23 24 25 26 27 28 29 30 > >>
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Active habitat management plays a key role in the preservation of native ecosystems
and rare species, especially in the Willamette Valley of Oregon, where natural
succession to woodlands threatens the few wetland prairies remaining after 150...
2000-03-13 (iso8601)
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The relationship between ground vegetation and light intensity under a 60 to 65-year-old Douglas-fir forest was investigated. Biomass and height of ground vegetation were measured and cover was estimated on small sample units (30 centimeters in...
1977-11-18 (iso8601)
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Water resources are managed for a variety of human needs, including agriculture, industrial and municipal consumption, hydropower generation, and recreation. There has been a recent push to incorporate habitat needs of aquatic wildlife into water...
2023-08-01
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The copepod population in Oregon coastal waters was examined from 116 oblique plankton tows taken during 1962. Quantitative Clarke-
Bumpus samplers were used and stations ranged from 5-105 miles from shore along four hydrographic lines. Forty-six...
1964-05-15 (iso8601)
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Climate change may cause significant changes in the distribution, abundance, and species mix of commercial fishery resources. In any given area stocks of some species may decline; stocks of other species may increase; and new species may appear in...
2008 (iso8601)
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The objectives of this dissertation were to describe the complex oceanographic conditions around the Galápagos Archipelago (eastern equatorial Pacific), their seasonal variability, and their effects on patterns of cetacean occurrence. The...
2003-04-29 (iso8601)
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Like other species interactions in ecological systems, host-pathogen interactions are influenced by environmental factors, landscape characteristics and the broader community context. My thesis explores the potential influences of food-web...
2010-08-24T19:52:45Z (iso8601)
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Disturbance has both direct and indirect ramifications that can influence species abundance, distribution, and ultimately the diversity found within a community. As a result, we might expect disturbance to play a particularly important role in the...
2013-06-11 (iso8601)
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Two native shrub species (Piliostigma reticulatum and Guiera senegalensis) are prominent vegetation components in farmers’ fields in Senegal. However, their role in nutrient cycling and ecosystem function has largely been overlooked. A study...
2007-01-18T17:08:57Z (iso8601)
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The food habits and ecology were studied for 31 species of mayfly nymphs from the St. Maries River in Idaho, during 1967 and 1968. The nymphs were basically herbivores, feeding on variable amounts of detritus, diatoms and filamentous algae;...
1969-06-01
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Twenty-one thousand fish representing 9 orders, 14 families and 56 species were collected from various habitats of the Navasota River drainage. Some species such as Notropis lutrensis, Gambusia affinis and Lepomis macrocllirlls were taken...
2011-06-30
2011-06-30 1972-08-01 |
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Tropical island ecosystems have proven to be inordinately vulnerable to
invasions by exotic plants and animals. Today these islands only contain small
remnant populations of the original flora and fauna, and these populations are facing
increasing...
1992-05-29 (iso8601)
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The canyon grasslands of the Hells Canyon National Recreation Area (HCNRA) are a unique ecosystem within the Pacific Northwest Bunchgrass Region (PNWBR) with a long history of natural and anthropogenic disturbances including fire, invasive species...
2015-06-09 (iso8601)
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The Brassicaceae, Mustard Family, is a well marked natural
family, whose tetramerous flowers, tetradynamous stamens, and
distinctive bi- carpellary fruits, clearly distinguish it from related
families. It is a large family of some 3, 000...
1977-04-19 (iso8601)
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Field studies were conducted from 1996 to 1998 in three villages in a Highland watershed in Mae Hong Son Province, northern Thailand. The objectives of the study were to classify and define the fruit-based agroforestry cropping system and...
2000-08-25 (iso8601)
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Determining age in crustaceans is inherently imprecise because they molt
periodically and do not retain hard structures throughout their lifespan. Morphological
measurements, such as carapace length, are often used to estimate age because
methods...
2009-02-02T18:10:22Z (iso8601)
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Ecological traits of the endemic Bear Lake whitefish Prosoopium abyssicola and the Bonneville whitefish prosopium silonotus were investigated. Spatial distributions indicated distinctive differences in depth contour preference. Catch per unit...
2003-05-01
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Despite the importance of habitat in determining species distribution and persistence, habitat dynamics are rarely modeled in studies of metapopulations. We used an integrated habitat-occupancy model to simultaneously quantify habitat change, site...
2012-04 (iso8601)
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Between 1970 and 1974, data were collected on the distribution and biology of the spotted owl (Strix occidentalis) in Oregon. One-hundred and sixteen pairs and seven single birds were located. Spotted owls occurred throughout the mountains of...
1975-10-22 (iso8601)
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The food habits and ecology were studied for 31 species of mayfly nymphs from the St. Maries River in Idaho, during 1967 and 1968. Mayfly nymphs were basically herbivores, feeding on variable amounts of detritus, diatoms and filamentous algae;...
1969-06-01
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We combine large observed data sets and dynamically downscaled climate data to explore historic and future (2050-2069) stream temperature changes over the topographically diverse Greater Yellowstone Ecosystem (elevation range=824-4017m). We link...
2013-10 (iso8601)
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Two separate studies on the distribution of gammarid amphipods
in the bathyal and abyssal benthic environments demonstrated that
different assemblages could be found at a single depth over distances on
the order of 100 kilometers. These studies...
1976-06-07 (iso8601)
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Douglas-fir and western hemlock growth and stocking were examined on two neighboring clear-cut watersheds in the Western Cascades of Oregon and related to the intensity of burning and logging disturbance, habitat type, soil type, aspect and the...
1985-05-08 (iso8601)
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A study of the population dynamics and ecology of the fleas
associated with the gray-tailed vole, Microtus canicaudus Miller, was
conducted on three sites surrounding the city of Corvallis, Oregon.
Over a period of 12 months, 22,641 adult and...
1975-05-22 (iso8601)
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