Treesearch

Statistics of central tendency and dispersion may not capture relevant or desired characteristics of the distribution of continuous phenomena and, thus, they may not adequately describe temporal patterns of change. Here, we present two methodological approaches that can help to identify temporal changes in environmental regimes. First, we use higher-order statistical moments (skewness and kurtosis) to examine potential changes of empirical distributions at decadal extents. Second, we adapt a statistical procedure combining a non-metric multidimensional scaling technique and higher density...

Mountain meadow habitats are valued for their ecological importance. They attenuate floods, improve water quality, and support high biodiversity. Many meadow habitats in the western US are degraded, and efforts are increasing to restore these montane meadow ecosystems. Rewatering projects such as pond-and-plug quickly raise the water table by blocking the existing incised stream channel and can result in the rapid recovery of wet meadow habitats. Based on the existing literature, however, it is difficult to determine realistic expectations for outcomes of restoration projects across a...

PREMISE OF THE STUDY: Females often outnumber males in Salix populations, although the mechanisms behind female bias are not well understood and could be caused by both genetic and ecological factors. We investigated several ecological factors that could bias secondary sex ratios of Salix sitchensis colonizing Mount St. Helens after the 1980 eruption. M ETHODS: We determined whether S. sitchensis secondary sex ratios varied across disturbance zones created by the eruption and across mesic and hydric habitats within each zone. For one population, we tracked adult mortality, whole-plant...

Population declines of several successional-scrub bird species are partly associated with deceased habitat availability as abandoned farmlands return to forest and recently harvested forests regrow. Restoration of mixed-oak (Quercus spp.) forest is also a concern because of widespread oak regeneration failure, especially on moist, productive sites where competition from faster-growing tree species is fierce following stand-replacing disturbances. Several silvicultural methods are proposed to promote oak regeneration but many are not experimentally tested, especially on productive sites. We...

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We documented a dramatic decline in juvenile frogs in a Bd-infected population of Cascades frogs (Rana cascadae) in the mountains of northern California and used a laboratory experiment to show that Bd isolated in the midst of this decline induced...

The search for natural enemies of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), in northeastern Asia, its native range, was initiated within a year of its discovery in the United States (Bauer et al., 2005, 2014). Although the official response to EAB’s invasion in both the United States and Canada was to regulate and attempt to eradicate EAB, the size and complexity of the outbreak prompted scientists and policy makers to support exploration for natural enemies as a potential tool for management of EAB. In 2008, when populations of EAB were already...

Context Functional connectivity—the facilitation of individual movements among habitat patches—is essential for species’ persistence in fragmented landscapes. Evaluating functional connectivity is critical for predicting range shifts, developing conservation plans, and anticipating effects of disturbance, especially for species affected by climate change. Objectives We examined whether simplifying forest structure influenced animal movements and whether an experimental approach to quantifying functional connectivity reflects normal behavior, which is often assumed but remains untested....

The importance of multiple processes and instream factors to aquatic biota has been explored extensively, but questions remain about how local spatiotemporal variability of aquatic biota is tied to environmental regimes and the geophysical template of streams. We used an individual-based trout model to explore the relative role of the geophysical template versus environmental regimes on biomass of trout (Oncorhynchus clarkii clarkia). We parameterized the model with observed data from each of the four headwater streams (their local geophysical template and environmental regime) and then...

Convective instability can influence the behaviour of large wildfires. Because wildfires modify the temperature and moisture of air in their plumes, instability calculations using ambient conditions may not accurately represent convective potential for some fire plumes. This study used the North American Regional Reanalysis to develop a climatology of the convective environment specifically tied to large fire events. The climatology is based on the period 1979–2009 and includes ambient convective available potential energy (CAPE) as well as values when surface air is warmed by 0.5, 1.0 or...

The Northern Forest Futures database (NFFDB) supports the reporting of both current and projected future forest conditions for the 20 states that make up the U.S. North, an area bounded by Maine, Maryland, Missouri, and Minnesota. The NFFDB database and attendant reporting tools are available to the public as a Microsoft AccessTM database. The NFF_CurrentReports tool generates customized reports for a variety of forest statistics for the 2008 inventory year. The NFF_ProjectionReports program supports the reporting of projected forest statistics by decade through the year 2060 for any of 14...