Treesearch

In the course of routine examinations of powdery mildews collected in Idaho and Oregon, USA, some of the identified species proved to be new to North America, in some cases on new host plants. Leveillula papilionacearum and L. picridis are first records from the USA. Astragalus filipes, Dalea ornata and D. searlsiae are new hosts for Leveillula papilionacearum. Enceliopsis, Heliomeris and Machaeranthera are new host genera for L. picridis. Additional records refer to powdery mildew species which have been rarely reported from North America or first records on certain hosts.

Bark beetle outbreaks have killed large numbers of trees across North America in recent years. Lidar remote sensing can be used to effectively estimate forest biomass, but prediction of both live and dead standing biomass in beetle-affected forests using lidar alone has not been demonstrated. We developed Random Forest (RF) models predicting total, live, dead, and percent dead basal area (BA) from lidar metrics in five different beetle-affected coniferous forests across western North America. Study areas included the Kenai Peninsula of Alaska, southeastern Arizona, north-central Colorado,...

The science associated with the use of airborne and satellite Light Detection and Ranging (LiDAR) to remotely sense forest structure has rapidly progressed over the past decade. LiDAR has evolved from being a poorly understood, potentially useful tool to an operational technology in a little over a decade, and these instruments have become a major success story in terms of their application to the measurement, mapping, or monitoring of forests worldwide. Invented in 1960, the laser and, a short time later, LiDAR, were found in research and military laboratories. Since the early 2000s,...

As the climate changes and invasive species continue to spread, proactive management may be needed to conserve native plant populations. Selecting appropriate plant material for restoration or other actions that will sustain populations is an integral part of any such plan and must take into account genetic differentiation to limit maladaptation. Common garden studies are used to determine the genetic basis of trait variation among populations from different geographic sources. However, maternal effects, the effect of environment during offspring development, can also affect performance,...

High-elevation, five-needle white pines are among the most picturesque trees in many national parks as well as other federal, state, and private lands in western North America. These trees often live to a great age; the trees' gnarled trunks give testimony to fierce winds that buffet them on exposed rocky sites. Ancient limber pines (Pinus flexilis) in Rocky Mountain National Park occupy the edge of Trail Ridge Road, and a remarkable old giant stands sentinel on the shore of Lake Haiyaha. Limber pines accompany Rocky Mountain bristlecone pines (P. aristata) on the exposed ridges around...

This report from the Washington State Academy of Sciences (WSAS) is in response to a request from the Washington State Department of Natural Resources (DNR) to "identify approaches and opportunities ripe for research on understanding and managing root diseases of Douglas-fir." Similar to the process used by the National Research Council, the WSAS upon agreeing to undertake a project such as requested by the DNR assembles a committee of state, regional, national, and/or international experts, as needed; develops a statement of task to guide the study; conducts the study; and makes recommenda...

Reliable predictions of regional-scale population connectivity are needed to prioritize conservation actions. However, there have been few examples of regional connectivity models that are empirically derived and validated. The central goals of this paper were to (1) evaluate the effectiveness of factorial least cost path corridor mapping on an empirical resistance surface in reflecting the frequency of highway crossings by American black bear, (2) predict the location and predicted intensity of use of movement corridors for American black bear, and (3) identify where these corridors cross...

Estimating the economic benefits of reduced health damages due to improvements in environmental quality continues to challenge economists. We review welfare measures associated with reduced wildfire smoke exposure, and a unique dataset from California's Station Fire of 2009 allows for a comparison of cost of illness (COI) estimates with willingness to pay (WTP) measures. The WTP for one less symptom day is estimated to be $87 and $95, using the defensive behavior and contingent valuation methods, respectively. These WTP estimates are not statistically different but do differ from a $3...

Losses of the soil resources from otherwise productive and well functioning watersheds is often a recurring problem confronting hydrologists and watershed managers. These losses of soil have both on-site and off-site effects on the watershed impacted. In addition to the loss of inherent soil resources through erosion processes, on-site effects can include the breakdown of soil structure, a decline in organic matter and nutrients in the soil, and a reduction in available soil moisture (Morgan 1995, Gregersen et al. 2007, Brooks et al. 2013). The net impact of these on-site effects can be a...

Designing woody fuel sampling methods that quickly, accurately and efficiently assess biomass at relevant spatial scales requires extensive knowledge of each sampling method's strengths, weaknesses and tradeoffs. In this study, we compared various modifications of three common sampling methods (planar intercept, fixed-area microplot and photoload) for estimating fine woody surface fuel components (1-, 10-, 100-h fuels) using artificial fuelbeds of known fuel loadings as reference. Two modifications of the sampling methods were used: (1) measuring diameters only and both diameters and...