Treesearch

Tree populations usually show adaptations to their local environments as a result of natural selection. As climates change, populations can become locally maladapted and decline in fitness. Evaluating the expected degree of genetic maladaptation due to climate change will allow forest managers to assess forest vulnerability, and develop strategies to preserve forest health and productivity. We studied potential genetic maladaptation to future climates in three major European tree species, Norway spruce (Picea abies), silver fir (Abies alba), and European beech (Fagus sylvatica). A common...

Aim: To explore the recent (past ~1,000 year) migration history of yellow-cedar (Callitropsis nootkatensis), a climate-threatened tree, which appears to lag behind its potential climatic niche at a leading northern range edge, and infer its continued migration potential under changing climate. Location: Southeast Alaska, USA. Methods: We located 11 leading range edge yellow-cedar stands near Juneau, Alaska, determined their proportional occupancy of modelled habitat and estimated stand ages to determine approximate time of establishment. We used future climate projections to determine the...

Commentary on featured paper in an issue of Tree Physiology.

The terrestrial condition assessment (TCA) evaluates effects of uncharacteristic stressors and disturbance agents on land-type associations (LTAs) to identify restoration opportunities on national forest system (NFS) lands in the United States. A team of agency scientists and managers, representing a broad array of natural resource disciplines, developed a logic structure for the TCA to identify appropriate data sources to support analyses. Primary national data sources included observed insectand pathogen-induced mortality, key critical loads for soil and the atmosphere, long term...

Daily flight activity patterns of forest insects are influenced by temporal and meteorological conditions. Temperature and time of day are frequently cited as key drivers of activity; however, complex interactions between multiple contributing factors have also been proposed. Here, we report individual Bayesian network models to assess the probability of flight activity of three exotic insects, Hylurgus ligniperda, Hylastes ater, and Arhopalus ferus in a managed plantation forest context. Models were built from 7,144 individual hours of insect sampling, temperature, wind speed, relative...

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...