Treesearch

Sympatric coastrange sculpin, Cottus aleuticus, and prickly sculpin, C. asper, occupied distinct habitats in the mainstem Smith River, northwestern California. For example, 90% of coastrange sculpin (n = 294) used habitat with water velocity > 5 cm s-1, whereas 89% of prickly sculpin (n = 981) used habitat with water velocity ≤ 5 cm s-1. Sixty-five percent of coastrange sculpin were found at depths < 1 m, whereas 37% of prickly sculpin occupied depths > 7 m. The strong spatial separation of coastrange and prickly sculpin in the mainstem Smith River contrasts with the overlap in their use...

A ground-based canopy model that estimates the volume of occupied space in forest canopies was tested using the Wind River Canopy Crane. A total of 126 trees in a 0.25 ha area were measured from the ground and directly from a gondola suspended from the crane. The trees were located in a low elevation, old-growth forest in the southern Washington Cascades. The ground-based model was based on six measurements and assumptions about the individual crown shape (e.g., conic, parabolic). the crane-based measurements required up to 377 measurements per tree. The two models were then compared, both...

These proceedings summarize the results of a symposium designed to address current issues of agencies with wildland fire protection responsibility at the Federal and State levels. The topics discussed at the symposium include fire economics, planning, and policy on wildfire and prescribed fire. Representatives from several international organizations presented the experiences in their countries on the same issues. Forty-five invited papers and 12 posters were presented at the symposium that described the issues and presented state-of-the-art techniques to address technical issues on fire...

The fine-scale genetic structure of a subalpine conifer, whitebark pine (Pinus albicaulis Engelm.), was studied at nested geographic levels from watershed to adjacent stems in the eastern Sierra Nevada Range of California. A combination of several characteristics contributed to unpredicted genetic structure in this species. This includes being one of only 20 pine species worldwide with wingless, bird-dispersed seeds; having the reputed capacity to reproduce vegetatively; and forming distinct growth morphologies at different elevations in this part of its natural range. Genetic differentiati...

The prospect of human-induced global warning has received centerstage attention from ecologists concerned about future ecosystems. While such effects deserve critical analysis, they are best understood in the context of natural climate change. Anthropogenic atmospheric effects are often discussed as if background climates were stable (Mahlman 1997). Even in the recent past, however, climates have changed at similar rates and magnitudes to predicted anthropogenic changes, catalyzing significant natural changes in terrestrial ecosystems. With or without the complication of human effects,...

Significant climate anomalies have characterized the last 1000 yr in the Sierra Nevada, California, USA. Two warm, dry periods of 150- and 200-yr duration occurred during AD 900-1350, which were followed by anomalously cold climates, known as the Little Ice Age, that lasted from AD 1400 to 1900. Climate in the last century has been significantly warmer. Regional biotic and physical response to these climatic periods occurred. Climate variability presents challenges when interpreting historical variability, including the need to accommodate climate effects when comparing current ecosystems...