Treesearch

The concept of historic range of variability (HRV) is briefly evaluated within the context of its application in ecosystem management over the past two decades. Despite caveats to the contrary, an implicit assumption continues to emerge of climatic stationarity, and, by corollary, that presettlement centuries provide an appropriate reference period. This is examined from the perspective of historic climate change and ecosystem response. As a means of developing reference prescriptions and management targets, HRV is generally inappropriate, although if historic periods are used for reconstru...

Thermal regimes of eight periglacial talus slopes, at contrasting elevations, aspects, and substrates, in the Sierra Nevada, California, had complex microclimatic patterns partially decoupled from external conditions. Over three years, warm seasons showed mean talus matrix temperatures and daily variances lower than surfaces and cooler than free-air; talus surface and matrix positions low in the taluses were colder than higher positions, yielding highly positive altitudinal temperature differentials; ground surface temperatures had greater daily extremes than talus positions; and talus...

The American pika (Ochotona princeps) has become a species of concern for its sensitivity to warm temperatures and potential vulnerability to global warming. We explored the value of radiocarbon dating of fecal pellets to address questions of population persistence and timing of site extirpation. Carbon was extracted from pellets collected at 43 locations in the western Great Basin, USA, including three known occupied sites and 40 sites of uncertain status at range margins or where previous studies indicated the species is vulnerable. We resolved calibrated dates with high precision...

Climate change poses challenges for the Southwest, where an already parched region is expected to get hotter and, in its southern half, significantly drier (Garfin et al. 2013). Increased heat and sustained drought will stress water sources and redefine urban landscapes. As landscapes gradually evolve from lush to xeric, tolerance of trees to water-related stress resulting from excess irrigation today and deficit irrigation tomorrow will become increasingly important. This article describes a 14-year evaluation of seven drought tolerant species that were obtained from a nursery in the arid...

We revisit the common standards recommended by Ralph et al. (1993, 1995a) for conducting point-count surveys to assess the relative abundance of landbirds breeding in North America. The standards originated from discussions among ornithologists in 1991 and were developed so that point-count survey data could be broadly compared and jointly analyzed by national data centers with the goals of monitoring populations and managing habitat. Twenty years later, we revisit these standards because (1) they have not been universally followed and (2) new methods allow estimation of absolute abundance...

In this investigation, we adapted identity theory to reassess a conceptualization of place attachment—conceived herein as an attitudinal construct used by environmental psychologists to describe people's bonding to the physical landscape. Past work has conceptualized the construct in terms of three components: cognitive, affective, and conative elements. Based on the tenets of identity theory, we hypothesized that the cognitive component—reflected in the dimension place identity—is an antecedent of these other affective and conative facets. We empirically tested this reconceptualization...

Miconia calvescens de Candolle (Melastomataceae) is an invasive tree considered the most serious threat to natural ecosystems of Hawaii and other Pacific islands. The success of M. calvescens as an invasive species is greatly owing to its shade tolerance and the shaded habitat it creates, where many native plant species that are light-demanding cannot survive. Salbia lotanalis Druce (Lepidoptera: Crambidae), a neotropical leaf roller attacking M. calvescens, was evaluated for two mechanisms by which it reduces leaf area of its host plant: feeding (defoliation), which removes leaf tissue,...

A principal challenge of federal forest management has been maintaining and improving habitat for sensitive species in forests adapted to frequent, low- to moderate-intensity fire regimes that have become increasingly vulnerable to uncharacteristically severe wildfires. To enhance forest resilience, a coordinated landscape fuel network was installed in the northern Sierra Nevada, which reduced the potential for hazardous fire, despite constraints for wildlife protection that limited the extent and intensity of treatments. Small mammal and songbird communities were largely unaffected by...