Treesearch

Droughts in the western United States are expected to intensify with climate change. Thus, an adequate representation of ecosystem response to water stress in land models is critical for predicting carbon dynamics. The goal of this study was to evaluate the performance of the Community Land Model (CLM) version 4.5 against observations at an old-growth coniferous forest site in the Pacific Northwest region of the United States (Wind River AmeriFlux site), characterized by a Mediterranean climate that subjects trees to water stress each summer. CLM was driven by site-observed meteorology and...

This report gives early results, 18 years after treatment and 30 years after planting, from a trial of early thinning and gap creation intended to increase biodiversity in a very uniform extensive Douglas-fir plantation. Gap creation has introduced canopy irregularity and a substantial hemlock component into what was originally a very uniform pure Douglas-fir plantation, produced some natural regeneration of Douglas-fir, and considerably changed diameter distributions. Long-term effects will depend on whether additional stand density manipulation is carried out in coming years.

Many hectares of intensively managed Douglas-fir (Pseudotsuga menziesii Mirb. Franco) stands in western North America are fertilized with nitrogen (N) to increase growth rates, but only about ⅔ of all stands respond. Understanding the mechanisms of response facilitates prioritization of stands for treatment. The primary objective of this study was to test the hypothesis that the short-term basal area growth response to a single application of 224 kg N ha
-1 as urea was associated with reduced stable carbon isotope discrimination (Δ13C) and increased intrinsic water use efficiency (iWUE) in...

Recent phylogenetic, phylogeographic, and morphometric studies have established the genetic affinities of the American marten (Martes americana), Pacific marten (M. caurina), European pine marten (M. martes), stone (beech, house) marten (M. foina), Japanese marten (M. melampus), yellow-throated marten (M. flavigula), Nilgiri marten (M, gwatkinsil), sable (M. zibellina), fisher (Pekania pennanti), wolverine (Gulo gulo), and tayra (Eira barbara). In this chapter, we evaluate the extent to which species in the Martes Complex share ecological adaptations and biological traits, and how such...

Variation in host responses to pathogens can have cascading effects on populations and communities when some individuals or groups of individuals display disproportionate vulnerability to infection or differ in their competence to transmit infection. The fungal pathogen, Batrachochytrium dendrobatidis (Bd) has been detected in almost 700 different amphibian species and is implicated in numerous global amphibian population declines. Identifying key hosts in the amphibian-Bd system—those who are at greatest risk or who pose the greatest risk for others—is challenging due in part to many...

Our research seeks to expand the concept of urban environmental stewardship to include the everyday stewardship practices of urban nontimber forest products foragers. Ethnographic data from 58 urban foragers and 18 land stewards in the city of Seattle (USA) revealed that foragers reported using a variety of practices to enhance and minimize negative desirable species and their habitats. Many of these practices were identical to those practiced by restoration volunteers in formal programs and align with Seattle Parks Department management objectives. Foragers actively sought to learn more...

Virus–plant interactions range from parasitism to mutualism. Viruses have been shown to increase fecundity of infected plants in comparison with uninfected plants under certain environmental conditions. Increased fecundity of infected plants may benefit both the plant and the virus as seed transmission is one of the main virus transmission pathways, in addition to vector transmission. Trade-offs between vertical (seed) and horizontal (vector) transmission pathways may involve virulence, defined here as decreased fecundity in infected plants. To better understand plant–virus symbiosis...

This report describes and documents the OpCost forest operations cost model, a key component of the BioSum analysis framework. OpCost is available in two editions: as a callable module for use with BioSum, and in a stand-alone edition that can be run directly from R. OpCost model logic and assumptions for this open-source tool are explained, references to the literature used in all of the submodels included in OpCost are provided, and guidance is offered on how to change the default hourly machine rates associated with overall logging cost calculations. OpCost enhancements such as cost...

We developed a process to address terrestrial wildlife species for which management for ecosystem diversity may be inadequate for providing ecological conditions capable of sustaining viable populations. The process includes (1) identifying species of conservation concern, (2) describing source habitats, and other important ecological factors, (3) organizing species into groups, (4) selecting surrogate species for each group, (5) developing surrogate species assessment models; (6) applying surrogate species assessment models to evaluate current and historical conditions, (7) developing...

The economic linkages between national forests and surrounding areas are one of the important ways public lands contribute to the well-being of private individuals and communities. One way national forests contribute to the economies of surrounding communities is by attracting recreation visitors who, as part of their trip, spend money in communities on the peripheries of national forests. We use survey data collected from visitors to all forest and grasslands in the National Forest System to estimate the average spending per trip of national forest recreation visitors engaged in various...