Treesearch

The walnut twig beetle, Pityophthorus juglandis Blackman, and its fungal associate Geosmithia morbida Kolařík et al., produce thousand cankers disease, which has devastated black walnut (Juglans nigra L.) in several states of the western U.S.A. To better understand beetle flight dynamics and life history, flight times were documented in the urban corridor along the Colorado Front Range during 2 years - in 2008 with yellow sticky card traps and in 2012 with baited multiple funnel traps. Walnut twig beetles were determined to be active throughout the trapping season from March through...

Deadwood in forests influences fire intensity, stores carbon and nutrients, and provides wildlife habitat. We used a 54-year-old density management experiment in Larix occidentalis Nutt. forests to evaluate density dependence of woody detritus accumulation. Based on self-thinning theory, we expected woody detritus produced by the current stand to increase with stand density. Density-dependent woody detritus accumulation was apparent for fine woody debris and snags and for all woody detritus pools combined. Clear size-density relationships were apparent for coarse woody debris (CWD) and...

Basal area (BA) is a good predictor of timber stand volume and forest growth. This study developed predictive models using field and airborne LiDAR (Light Detection and Ranging) data for estimation of basal area in Pinus taeda plantation in south Brazil. In the field, BA was collected from conventional forest inventory plots. Multiple linear regression models for predicting BA from LiDAR-derived metrics were developed and evaluated for predictive power and parsimony. The best model to predict BA from a family of six models was selected based on corrected Akaike Information Criterion (AICc)...

The spatial patterns resulting from large fires include refugial habitats that support surviving legacies and promote ecosystem recovery. To better understand the diverse ecological functions of refugia on burn mosaics, we used remotely sensed data to quantify neighborhood patterns of areas relatively unchanged following the 2011 Las Conchas fire. Spatial patterns of refugia measured within 10-ha moving windows varied across a gradient from areas of high density, clustered in space, to sparsely populated neighborhoods that occurred in the background matrix. The scaling of these patterns...

Organizational hierarchy is an inescapable aspect of many exemplary high reliability organizations (HROs). As organizations begin to adopt HRO theorizing to improve practice, it is increasingly important to explain how HRO principles - which assume the hallmarks of a flat hierarchy - can be understood and enacted in rigidly stratified organizations. We propose a preliminary theoretical model suggesting how various supervisor - subordinate and work group communication patterns and practices enable members to navigate hierarchy to achieve high reliability. We test the model using structural...

We are in the midst of a wave of 50th anniversaries. Specifically, the wave consists of 50th anniversaries for legislative milestones in the United States. That’s because the 1960s were a time of profound social and environmental change. The Civil Rights Act, the Wilderness Act, and the Land and Water Conservation Fund Act were all enacted in 1964. The Voting Rights Act was passed in 1965. The National Historic Preservation Act was in 1966, and the Wild and Scenic Rivers Act of 1968 was signed into law on the same day as the National Trails System Act. Other groundbreaking legislation will...

Some federal public lands have been legally protected as “wilderness areas” since 1964 in the US. A federal science program evolved first in response to a novel public lands management concept, and subsequently in response to new issues that emerged both as society changed and more knowledge about social and ecological values of wilderness accumulated. Wilderness science needs have largely been defined by government and cooperating academic scientists through identification of researchable questions which, historically, have centered on science disciplines, wilderness attributes, or...

Dormancy strategies, including diapause and quiescence, enable insects to evade adverse conditions and ensure seasonally appropriate life stages. A mechanistic understanding of a species’ dormancy is necessary to predict population response in a changing climate. Climate change is influencing distribution patterns and population success of many species, including Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), the most important mortality agent of pines in western North America. Diapause is considered absent in D. ponderosae, and quiescence in the final larval...

Genome evolution is predicted to be rapid following the establishment of new (neo) sex chromosomes, but it is not known if neo-sex chromosome evolution plays an important role in speciation. Here we combine extensive crossing experiments with population and functional genomic data to examine neo-XY chromosome evolution and incipient speciation in the mountain pine beetle. We find a broad continuum of intrinsic incompatibilities in hybrid males that increase in strength with geographic distance between reproductively isolated populations. This striking progression of reproductive isolation...

Chromosomal rearrangement can be an important mechanism driving population differentiation and incipient speciation. In the mountain pine beetle (MPB, Dendroctonus ponderosae), deletions on the Y chromosome that are polymorphic among populations are associated with reproductive incompatibility. Here, we used RAD sequencing across the entire MPB range in western North America to reveal the extent of the phylogeographic differences between Y haplotypes compared to autosomal and X-linked loci. Clustering and geneflow analyses revealed three distinct Y haplogroups geographically positioned...