An Arctic ecosystem : the coastal tundra at Barrow, Alaska

From the Foreward: This book is one of a series of volumes reporting results of research by U. S. scientists participating in the International Biological Program (IBP). As one of the 58 nations taking part in the IBP during the period July 1967 to June 1974 , the United States organized a number of large, multidisciplinary studies pertinent to the central IBP theme of "the biological basis of productivity and human welfare."Direct financial support of the Biome-wide program was derived from three major sources: the National Science Foundation, the State of Alaska and the petroleum industry through the University of Alaska. The NSF funding was under the joint sponsorship of the U. S. Arctic Research Program (Division of Polar Programs) and the U. S. International Biological Program (Ecosystem Analysis). The Army Research Office and the Department of Energy (previously AEC and ERDA) both contributed funded projects to the Program. Industry support was provided through unrestricted grants from: Atlantic Richfield Company, Alyeska Pipeline Service Company, BP Alaska, Inc. Cities Service Company, Exxon Company, USA (Humble Oil and Refining Company), Gulf Oil Corporation , Marathon Oil Company, Mobil Oil Company, Prudhoe Bay Environmental Subcommittee of the Alaska Oil and Gas Association, Shell Oil Company, Standard Oil Company of California, Standard Oil (Indiana) Foundation Inc., and Sun Oil Company

Preliminary observations on movements of tailed frog tadpoles (Ascaphus truei) in streams through harvested and natural forests

The tailed frog (Ascaphus truei) is designated a species 'at risk' or 'of special concern' in California, Oregon, Washington (USA), and British Columbia (Canada). Forest practices often have negative impacts on Ascaphus adults and larvae, including absence from some clear felled areas. Recolonization of logged sites may be critical to sustaining productive amphibian populations. Given the uncommonly long larval stage of Ascaphus, movements by larvae may be particularly important in the recolonization of managed forests. We investigated movement rates of Ascaphus larvae and the influence of stream parameters in four stream basins (Ashlu, Elaho, Squamish and Mamquam) transecting recently harvested and unmanaged forests in southwestern British Columbia (1995, 1996 and 1999). Larvae in streams flowing through unmanaged forests moved about 7.4 times as far as those flowing through clear felled reaches. Streams with high levels of logjams showed low larval movement rates. Recently harvested sites may produce unfavourable conditions impeding recolonization by Ascaphus larvae. High gradient streams also showed low larval movement rates. The role of stream-dwelling larvae in dispersal of Ascaphus is unknown, but this disperal mechanism would be energy-efficient because it can be passive with the stream current

Effects of stand age, size, and juxtaposition on abundance of western redback salamanders (Plethodon vehiculum) in Coastal British Columbia

Terrestrial-breeding amphibians live at high densities, show strong site fidelity, and have relatively stable populations, long life spans, and high vulnerability to dehydration. These traits make them potentially useful indicators of effects of canopy removal during logging. We compared the relative abundance of western redback salamanders (Plethodon vehiculum) in old-growth and managed second-growth stands on Vancouver Island, and found significantly more individuals in old-growth stands. Salamanders were more abundant in larger stands of old growth, but showed no relationship with stand or patch size among mature second-growth stands. Managed stands contained more salamanders when old growth was adjacent. Juvenile:adult ratios within managed stands were significantly higher in stands not adjacent to old growth, suggesting poor survivorship to adulthood in younger stand

Determinants of the tailed frog's range in British Columbia, Canada

The tailed frog is the only stream-breeding frog in Canada. Due to its highly specialized habitat requirements and its vulnerability to habitat degradation, it is of concern through much of its range in the Pacific Northwest. The purpose of this study was to determine the range of the tailed frog in British Columbia, and to generate hypotheses for its current distribution. The tailed frog is resident of steep mountain streams. Along the coast, other than its absence from Vancouver Island and Haida Gwaii, the tailed frog's distribution coincides closely with the Coastal Western Hemlock (CWH) biogeoclimatic zone. In the interior, an area with a continental climate, its distribution is allied with the Engelmann Spruce/Subalpine Fir (ESSF) biogeoclimatic zone. However, streams in the ESSF are likely only suitable to tadpoles if a thick blanket of snow buffers them from winter freezing. Thus, drier subzones of the ESSF are less likely to support tailed frogs. This close association with moist biogeoclimatic zones may reflect the species preference for a humid temperate climate regime. The tailed frog's distribution may also be associated with geology: in contrast to streams underlain by competent plutonic rocks (e.g., granite), which typically have coarse gravel beds with locked boulder steps, areas with highly fractured or weak rock types (e.g. shale) have a finer and more mobile stream bedload, leading to unstable channel conditions. These streams provide less favorable habitat for tadpoles. Along the coast, the presently documented northern distribution lies at the Nass River, and the factors limiting northward dispersal are not apparent. In the interior of British Columbia, northward advancement appears to be limited in part both to underlying rock type and climat

Effects of stand age, size, and juxtaposition on abundance of western redback salamanders (Plethodon vehiculum) in Coastal British Columbia

Terrestrial-breeding amphibians live at high densities, show strong site fidelity, and have relatively stable populations, long life spans, and high vulnerability to dehydration. These traits make them potentially useful indicators of effects of canopy removal during logging. We compared the relative abundance of western redback salamanders (Plethodon vehiculum) in old-growth and managed second-growth stands on Vancouver Island, and found significantly more individuals in old-growth stands. Salamanders were more abundant in larger stands of old growth, but showed no relationship with stand or patch size among mature second-growth stands. Managed stands contained more salamanders when old growth was adjacent. Juvenile:adult ratios within managed stands were significantly higher in stands not adjacent to old growth, suggesting poor survivorship to adulthood in younger standsDupuis and Bunnell "Effects of stand age, size, and juxtaposition on abundance of western redback salamanders (Plethodon vehiculum) in Coastal British Columbia." Northwest Science. 1999; 73(1): 27-3

Alchemy and Uncertainty: What Good Are Models?

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