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Interaction between introduced trout and larval salamanders (Ambystoma macrodactylum) in high-elevation lakes Interaction between introduced trout and larval salamanders (Ambystoma macrodactylum) in high-elevation lakes

The larval stage of the long-toed salamander (Ambystoma macrodactylum) is the top vertebrate predator in high-elevation fishless lakes in the North Cascades National Park Service Complex, Washington (U.S.A.). Although most of these high-elevation lakes were naturally fishless, trout have been stocked in many of them. We sought to determine the effects of physicochemical factors and...
Authors
T. Tyler, W.J. Liss, L. Ganio, Gary L. Larson, Robert L. Hoffman, E. Deimling, G.A. Lomnicky

Phytoplankton assemblages in high-elevation lakes in the northern Cascade Mountains, Washington State, USA Phytoplankton assemblages in high-elevation lakes in the northern Cascade Mountains, Washington State, USA

Phytoplankton assemblages in high-elevation lakes of North Cascades National Park Service Complex were studied during the open-water period in 1989. Collectively, 93 taxa were identified in 55 samples from 51 lakes. Based on cell densities, cyanobacteria had the highest relative abundance (36.7 %), followed by chlorophytes (29.8 %), and chrysophytes (19.6 %). Aphanocapsa delicatissima...
Authors
Gary L. Larson, C. D. McIntire, R.E. Truitt, W.J. Liss, Robert L. Hoffman, E. Deimling, G.A. Lomnicky

Effects of pesticides on Canada Geese Effects of pesticides on Canada Geese

This paper summarizes published and unpublished sources relating to exposure of Canada geese (Branta canadensis) to pesticides, emphasizing documented episodes of poisoning by organochlorine (OC), organophosphorus (OP), and carbamate compounds. Canada geese accumulate the lipid-soluble OC compounds, although they have a lower potential for biomagnification of these pesticides than...
Authors
L. J. Blus

Diet and morphology of extant and recently extinct northern bears Diet and morphology of extant and recently extinct northern bears

I examined the relationship of diets to skull morphology of extant northern bears and used this information to speculate on diets of the recently extinct cave (Ursus spelaeus) and short-faced (Arctodus simus) bears. Analyses relied upon published skull measurements and food habits of Asiatic (U. thibetanus) and American (U. americanus) black bears, polar bears (U. maritimus), various...
Authors
David J. Mattson

Stenocybe fragmenta, a new species of Mycocaliciaceae with fragmenting spores Stenocybe fragmenta, a new species of Mycocaliciaceae with fragmenting spores

The new species Stenocybe fragmenta (Ascomycota, Mycocaliciaceae) is described from western North America. The species was collected from twigs of Cercocarpus montanus and Rhamnus purshiana. Stenocybe fragmenta is characterized by 5–7 septate, 18–30 μm long ascospores that fragment at maturity. This is the first report of spore fragmentation among the Mycocaliciaceae.
Authors
E.B. Peterson, Jouko Rikkinen

Vulnerability of desert biological soil crusts to wind erosion: The influences of crust development, soil texture, and disturbance Vulnerability of desert biological soil crusts to wind erosion: The influences of crust development, soil texture, and disturbance

Biological soil crusts, consisting of cyanobacteria, green algae, lichens, and mosses, are important in stabilizing soils in semi-arid and arid lands. Integrity of these crusts is compromised by compressional disturbances such as foot, vehicle, or livestock traffic. Using a portable wind tunnel, we found threshold friction velocities (TFVs) of undisturbed crusts well above wind forces...
Authors
Jayne Belnap, Dale A. Gillette

Demographic and growth responses of a guerrilla and a phalanx perennial grass in competitive mixtures Demographic and growth responses of a guerrilla and a phalanx perennial grass in competitive mixtures

The advantages of guerrilla and phalanx growth for the guerrilla Elymus lanceolatus ssp. lanceolatus and phalanx E. l. ssp. wawawaiensis were evaluated over 2 years in two taxon mixtures with a range of densities of each subspecies and under two levels of watering. Ramet numbers and biomass of the guerrilla subspecies were higher than those of the phalanx grass in the first year but in...
Authors
L. David Humphrey, David A. Pyke

Impact of alternative regeneration methods on genetic diversity in coastal Douglas-fir Impact of alternative regeneration methods on genetic diversity in coastal Douglas-fir

Genetic implications of natural and artificial regeneration following three regeneration methods (group selection, shelterwood, and clearcut) were investigated in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) using genetic markers (17 allozyme loci). In general, harvesting followed by either natural or artificial regeneration resulted in offspring populations...
Authors
W.T. Adams, J. Zuo, J.Y. Shimizu, J. C. Tappeiner
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