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891.
The early fall diet of Oregon blue grouse ( Dendragapus obscurus pallidus ) from Wallowa County, Oregon, was determined from 145 crops obtained during 1981 and 1982. Of more than 50 plant and animal foods in the diet, short-horned grasshoppers ( Acrididae ), prickly lettuce ( Lactuca serriola ), yellow salsify ( Tragopogon dubius ), wild buck-wheat ( Eriogonum spp.), and snowberry ( Symphoricarpos albus ) occurred in 30% or more of the crops and collectively amounted to 68% of the diet by weight. Seven of the 12 most common foods were consumed differentially by the four sex and age classes of birds. Results indicated that blue grouse foraged in forest and grassland habitats. 相似文献
892.
893.
F. Sherwood Taylor Ph.D. M.A. B.Sc. 《Annals of science》2013,70(3):185-202
894.
Fish hatchery systems in both Utah and Nevada are now an integral part of the fishery management scheme. Historic development of hatcheries, including the early stocking of exotics, is presented. Disease control and dry pelleted feed are discussed in historical perspective and present status. 相似文献
895.
F.W. Gibbs M.Sc. Ph.D. 《Annals of science》2013,70(2):122-151
896.
Western juniper ( Juniperus occidentalis spp. occidentalis ) has rapidly expanded into shrub steppe communities in the intermountain Northwest during the past 120 yr. Cutting juniper is a management tool used to restore shrub steppe communities. Response of the understory after cutting is strongly influenced by plant species composition existing prior to treatment. This study assessed distribution patterns of understory plants over 2 growing seasons after tree cutting in a western juniper woodland. Cover, density, and diversity of understory species were compared among 3 locations: interspaces, duff zones (previously under tree canopies), and debris zones (beneath cut trees). Plant cover density increased in all zones following tree cutting. Understory vegetation in cut woodlands exhibited strong zonal distribution. Cover and density of Poa sandbergii and Sitanion hystrix and canopy cover of annual forbs were greatest in duff zones ( P P < 0.05). Debris zones tended to have the lowest overall understory cover and plant density values. Under juniper debris many species common to interspaces were reduced in density, although plants that survived or established beneath debris grew larger than their counterparts in interspaces. Species increased in density and cover under debris were plants characteristic of duff zones and whose seeds are typically wind dispersed. 相似文献
897.
898.
To assess the potential hazard from radioactive wastes, a plant with known radiosensitivity, Tradescantia clone 02, was grown in radioactive soil obtained from uranium mill tailings. The levels of radiation on these tailings varied from 0.03mR/hr (background) to a maximum of 3.00 mR/hr. Tradescantia grown in soil with a radiation level greater than 0.10 mR/hr evidenced significantly reduced reproductive integrity and fecundity, as measured by the number of stunted hairs per stamen, pollen viability, and numbers of somatic mutations. Based on these data, the radioactivity from uranium mill tailings has the potential to alter normal plant succession due to its detrimental effect on any species that is relatively radiosensitive. 相似文献
899.
900.
Aerodynamics. Insects can halve wind-turbine power. 总被引:1,自引:0,他引:1