Understanding how pollinators respond to anthropogenic land use is key to conservation of biodiversity and ecosystem services, but few studies have addressed this topic in coniferous forests, particularly those managed intensively for wood production. This study reports on voucher material generated as part of Zitomer et al. (2023), that assessed changes in wild bee communities with time since harvest in 60 intensively managed Douglas-fir (Pseudotsuga menziesii) stands in the Oregon Coast Range across a gradient in stand age spanning a typical harvest rotation (0-37 years post-harvest). We additionally assessed relationships of bee diversity and community composition to relevant habitat features, including availability of floral resources and nest sites, understory vegetation characteristics, and composition of the surrounding landscape. Specimens were collected using a combination of passive sampling methods-blue vane traps and white, blue, and yellow bowl traps- and hand-netting and were identified to the lowest possible taxonomic level by A.R. Moldenke and L.R. Best. Four hundred and ten taxonomic voucher specimens were deposited into the Oregon State Arthropod Collection (Accession# OSAC_AC_2023_01_09-001-01) to serve as a reference for future research.

Despite widespread concerns about the anthropogenic drivers of global pollinator declines, little information is available about the impacts of land management practices on wild bees outside of agricultural systems, including in forests managed intensively for wood production. We assessed changes in wild bee communities with time since harvest in 60 intensively managed Douglas-fir (Pseudotsuga menziesii) stands across a gradient in stand ages spanning a typical harvest rotation. We measured bee abundance, species richness, and alpha and beta diversity, as well as habitat characteristics (i.e., floral resources, nesting substrates, understory vegetation, and early seral forest in the surrounding landscape) during the spring and summer of 2018 and 2019. We found that bee abundance and species richness declined rapidly with stand age, decreasing by 61% and 48%, respectively, for every 5 years since timber harvest. Asymptotic estimates of Shannon and Simpson diversity were highest in stands 6-10 years post-harvest and lowest after the forest canopy had closed, ~11 years post-harvest. Bee communities in older stands were nested subsets of bee communities found in younger stands, indicating that changes were due to species loss rather than turnover as the stands aged. Bee abundance-but not species richness-was positively associated with floral resource density, and neither metric was associated with floral richness. The amount of early seral forest in the surrounding landscape seemed to enhance bee species richness in older, closed-canopy stands, but otherwise had little effect. Changes in the relative abundance of bee species did not relate to bee functional characteristics such as sociality, diet breadth, or nesting substrate. Our study demonstrates that Douglas-fir plantations develop diverse communities of wild bees shortly after harvest, but those communities erode rapidly over time as forest canopies close. Therefore, stand-scale management activities that prolong the precanopy closure period and enhance floral resources during the initial stage of stand regeneration will provide the greatest opportunity to enhance bee diversity in landscapes dominated by intensively managed conifer forests.

Western pine beetle (Dendroctonus brevicomis LeConte) is a major cause of ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) mortality in western North America. Twenty-first century epidemics are among the largest in history and have affected hundreds of thousands of hectares. We synthesize literature on the chemical ecology of western pine beetle and on efforts to exploit our understanding of the western pine beetle-ponderosa pine system to reduce host tree losses. This literature dates back to the early 20th century and focuses on populations in California and Oregon, U.S., where western pine beetle exerts its largest impacts. Research in the 1960s–1970s yielded an effective semiochemical attractant (exo-brevicomin, frontalin, and myrcene) that helped inform understanding of the biology, ecology, and management of this species. Later, research focused on isolation and identification of semiochemical repellents. To date, Verbenone Plus (acetophenone, (E)-2-hexen-1-ol + (Z)-2-hexen-1-ol, and verbenone) is the only semiochemical repellent demonstrated effective for protecting ponderosa pines from mortality attributed to western pine beetle in multiple studies in Canada and the U.S.

Rising global temperatures driven by anthropogenic carbon emissions are creating new challenges for food crop agriculture and forest management around the world. Droughts and other severe weather events are becoming more common and more extreme, causing both chronic stress and acute damage in cultivated and natural plant life, whereas warmer temperatures favor outbreaks of plant diseases and insect pests in many situations. At the same time, growing awareness of the health and environmental risks associated with broad-spectrum chemical pesticides has led crop growers and forest managers to seek out more selective, sustainable alternative techniques to mitigate the impact of harmful arthropods. Arthropod repellents have proven an efficacious strategy to reduce these impacts in the field of public health, where they are a key tactic in the suppression of diseases transmitted by hematophagous arthropods, but repellents are comparatively rarely employed to manage pests of agriculture and forestry. This chapter describes several cases in which repellents using beetle semiochemicals antiaggregation pheromones have been developed and evaluated in the field by the authors, successfully reducing tree mortality and/or crop damage induced by coffee berry borer (Hypothenemus hampei Ferrari) in Arabica coffee (Coffea arabica L.); by aggressive Dendroctonus bark beetles in single trees and small stands of North American forest species; and by ambrosia beetles on apple and avocado crops, as well as southeastern forest species.

Whitebark pine, Pinus albicaulis Engelm., is a subalpine tree endemic to western North America. This species provides multiple ecosystem services and is suffering widespread mortality from mountain pine beetle, Dendroctonus ponderosae Hopkins. Verbenone is a pheromone produced as D. ponderosae feed, and high air concentrations of verbenone deter D. ponderosae from colonizing trees. Synthetic verbenone has been formulated into products used to prevent D. ponderosae from colonizing trees. We compared the ability of verbenone pouches and SPLAT Verb to protect individuals and small stands of P. albicaulis. With individual trees in Montana, all treated trees survived regardless of verbenone formulation and rate, whereas untreated trees suffered 70 and 90% mortality in 2015 and 2016. In plot experiments in California from 2015 to 2017, and Oregon from 2015 to 2018, verbenone was applied to trees spaced similar to 10 m apart, and survival of small (12.7-23 cm DBH = diameter at 1.37 m height), medium (23.1-33 cm DBH) and large (>33 cm DBH) trees was compared. In California, where >80% of untreated trees survived, pouches increased survival similar to 2 to 3% and SPLAT Verb increased survival similar to 4 to 7% regardless of tree size. In Oregon, verbenone pouches and SPLAT Verb performed similarly on medium and small trees, but large trees had greater survival when treated with SPLAT Verb (similar to 93%) than pouches (similar to 82%). Compared to verbenone pouches, SPLAT Verb appears to better protect P. albicaulis from D. ponderosae.

AbstractLong-term management strategies are invoked once an invasive species has become established and spread beyond feasible limits for eradication or containment. Although an invasive species may be well-established in small to large geographical areas, prevention of its spread to non-affected areas (e.g., sites, regions, and cross-continent) through early detection and monitoring is an important management activity. The level for management of established invasive species in the United States has increasingly shifted to larger geographical scales in the past several decades. Management of an invasive fish may occur at the watershed level in the western States, with watershed levels defined by their hydrologic unit codes (HUC) ranging from 2 digits at the coarsest level to 8 digits at the finest level (USGS 2018). Invasive plant management within national forests, grasslands, and rangelands can be implemented at the landscape level (e.g., Chambers et al. 2014), although management can still occur at the stand or base level. Landscapes in this chapter refer to areas of land bounded by large-scale physiographic features integrated with natural or man-made features that govern weather and disturbance patterns and limit frequencies of species movement (Urban et al. 1987). These are often at a large physical scale, such as the Great Basin.

Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowledge gaps that could be addressed in future research.

Several formulations of the antiaggregation pheromone verbenone (4,6,6-trimethylbicyclo [3.1.1]hept-3-en-2-one) are registered to protect pine trees and forest stands from mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), but failures in efficacy are not uncommon. In 2011-2013, a novel formulation of (-)-verbenone was developed (SPLAT (R) Verb, 10.0% (-)-verbenone by weight, EPA Reg. No. 80286-20, ISCA Technologies Inc., Riverside, CA, USA) for protecting individual lodgepole pine, Pinus contorta Dougl. ex Loud., and small stands of P. contorta from mortality attributed to D. ponderosae. We evaluated the efficacy of lower doses of SPLAT (R) Verb than previously considered for tree protection on the Beaverhead-Deerlodge National Forest, Montana, USA, 2014-2015. In an individual tree study, D. ponderosae pressure was not sufficient to adequately challenge the treatments as only 56.7% of the untreated controls died. However, if one additional tree in the untreated control had died, all verbenone treatments (30 g, 50 g, and 70 g of SPLAT (R) Verb/tree, and one 7-g verbenone pouch/tree) would have been considered efficacious. In a small-scale stand study, fewer P. contorta were colonized by D. ponderosae on 0.41-ha experimental plots treated with 2.5 kg and 3.5 kg of SPLAT (R) Verb [250 g and 350 g of (-)-verbenone, respectively] and the 7-g verbenone pouch [50 pouches/plot, 350.0 g of (-)-verbenone/plot] compared to the untreated control. No significant difference was observed between 1.5 kg of SPLAT (R) Verb [150 g of (-)-verbenone] and the untreated control. Fewer P. contorta were killed by D. ponderosae on experimental plots treated with 1.5 kg, 2.5 kg and 3.5 kg of SPLAT (R) Verb and the verbenone pouch compared to the untreated control. No other significant differences were observed among treatments. Collectively, these data suggest that lower doses of SPLAT (R) Verb can be used for tree protection than previously considered, and at a substantial cost savings that could make this strategy economically viable for area-wide management of D. ponderosae.

We summarize the status of semiochemical-based management of the major bark beetle species in western North America. The conifer forests of this region have a long history of profound impacts by phloem-feeding bark beetles, and species such as the mountain pine beetle (Dendroctonus ponderosae) and the spruce beetle (D. rufipennis) have recently undergone epic outbreaks linked to changing climate. At the same time, great strides are being made in the application of semiochemicals to the integrated pest management of bark beetles. In this review, we synthesize and interpret these recent advances in applied chemical ecology of bark beetles for scientists and land managers.

Fire suppression and other factors have resulted in high wildfire risk in the western US, and prescribed burning can be an effective tool for thinning forests and reducing fuels to lessen wildfire risks. However, prescribed burning sometimes fails to substantially reduce fuels and sometimes damages and kills valuable, large trees. This study compared fuel reductions between spring and fall prescribed burns and tested whether removing (i.e., raking) fuels within 1 m of boles reduced fire damage to ponderosa pine ( Pinus ponderosa Douglas ex Lawson & C. Lawson). In 2007 and 2008, raking was applied to alternating trees along 18 transects in central Oregon, USA. Fuels surrounding 292 trees were burned in fall 2010, and fuels surrounding 216 trees were burned in spring 2012. Both seasons of burn affected most fuel size classes similarly, with one exception being duff, which was more fully consumed in fall than in spring. Where fall burning occurred, raking reduced the percentage of dead cambium samples from 24.3 ±4.9 % to 6.4 ±3.0 % (point estimates ±95 % confidence intervals), in addition to reducing bole scorch. Conversely, where spring burning occurred, injury of not-raked trees was milder, so raking did not have the potential to greatly reduce damage. Redistributing fuels away from boles would be more beneficial under relatively dry conditions when duff is prone to extensive smoldering. Our study and most other studies suggest that duff is, on average, drier in fall than in spring, so raking would tend to afford more protection from fall burns than from spring burns. The little tree mortality that occurred was split nearly evenly between raked trees (25) and not-raked trees (30), so raking did not appreciably increase survival in this study. However, the finding that raking reduced injury suggests that it may reduce mortality from more intense burns.

Wild and prescribed fire-induced injury to forest trees can produce immediate or delayed tree mortality but fire-injured trees can also survive. Land managers use logistic regression models that incorporate tree-injury variables to discriminate between fatally injured trees and those that will survive. We used data from 4024 ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and 3804 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees from 23 fires across Oregon and Washington to assess the discriminatory ability of 21 existing logistic regression models and a polychotomous key (Scott guidelines). We used insights from the validation exercise to build new models for each tree species and to identify fire-injury variables which consistently produce accurate mortality predictions. Only 8% of Ponderosa pine and 14% of Douglas-fir died within 3 years after fire. The amount of crown volume consumed, the number of bole quadrants with dead cambium and the presence of beetles were variables that classified most accurately, but surviving trees in our sample displayed a wide range of fire injury making the accurate classification of dead trees difficult. For ponderosa pine, our new model correctly classified 99% of live trees and 12% of dead trees while the Malheur model (Thies et al., 2006) correctly classified 95% of live trees and 24% of dead trees. The Scott guidelines accurately predicted at least 98% of live ponderosa pine trees but less than 2% of dead ponderosa pine. For Douglas-fir the Scott guidelines accurately predicted at least 80% of live trees and generally less than 10% of dead trees. Misclassification rates can be controlled by the choice of decision criteria used in the models and managers are encouraged to consider costs of the two types of misclassifications when choosing decision criteria for specific land management decisions. (C) 2017 Elsevier B.V. All rights reserved.

Fire is a driving force in the North American landscape and predicting post-fire tree mortality is vital to land management. Post-fire tree mortality can have substantial economic and social impacts, and natural resource managers need reliable predictive methods to anticipate potential mortality following fire events. Current fire mortality models are limited to a few species and regions, notably Pinus ponderosa and Pseudotsuga menziesii in the western United States. The efficacy of existing mortality models to predict fire-induced tree mortality is central to effective forest management. This study validated 54 logistic regression mortality models from seven published articles and two sets of mortality guidelines from two sources. Survival and a suite of fire injury metrics were monitored for 3654 trees representing 14 species that burned in fires between 2002 and 2009 in the Pacific Northwest, USA. Tree species included Abies amabilis, A. concolor, A. grandis, A. lasiocarpa, Calocedrus decurrens, Chamaecyparis lawsoniana, C. nootkatensis, Thuja plicata, Pinus contorta, P. lambertiana, P. monticola, Picea engelmannii, Larix occidentalis, and Tsuga heterophylla. Existing logistic models adequately described post-fire mortality of A. concolor, A. lasiocarpa, C. decurrens, C. lawsoniana, L. occidentalis, P. engelmannii, P. contorta, and P. lambertiana. We also evaluated predictive accuracy of two published mortality guidelines that apply to species in the Pacific Northwest. In addition to validating existing models, we also developed new logistic regression models and simplified mortality guidelines, or thresholds. We created new logistic regression models for species with adequate sample size and which had no existing species-specific model (A. amabilis, A. grandis, P. monticola, and T. heterophylla). Most recommended models contained a crown scorch term and either a cambium injury term or a bark beetle infestation term. New post fire mortality thresholds were developed for A. amabilis, A. concolor, A. grandis, P. contorta, P. lambertiana, P. monticola, P. engelmannii, L. occidentalis, and T. heterophylla. We were not able to validate or develop acceptable logistic mortality models or thresholds for C. nootkatensis or T. plicata. Injury to cambium and crown were both significant predictors in all but one set of new thresholds. The validation of existing models and guidelines allows managers to determine which models will likely perform best and identifies knowledge gaps where no adequate models exist to predict post-fire tree mortality. The new logistic regression models and threshold guidelines provide improved accuracy, with simpler application for fire and forest management. Published by Elsevier B.V.

We evaluated the efficacy of a newly registered formulation of (-)-verbenone for protecting individual lodgepole pines, Pinus contorta Dougl. ex Loud., ponderosa pines, P . ponderosa Dougl. ex Laws., and sugar pines, P . lambertiana Dougl., from mortality attributed to mounatin pine beetle, Dendroctonus ponderosae Hopkins.

The balsam woolly adelgid (Adelges piceae (Ratzeburg) (Homoptera: Adelgidae)) (BWA) is a nonnative, invasive insect that threatens Abies species throughout North America. It is well established in the Pacific Northwest, but continues to move eastward through Idaho and into Montana and potentially threatens subalpine fir to the south in the central and southern Rocky Mountains. We developed a climatic risk model and map that predicts BWA impacts to subalpine fir using a two-step process. Using 30-year monthly climate normals from sites with quantitatively derived BWA damage severity index values, we built a regression model that significantly explained insect damage. The sites were grouped into two distinct damage categories (high damage and mortality versus little or no mortality and low damage) and the model estimates for each group were used to designate distinct value ranges for four climatic risk categories: minimal, low, moderate, and high. We then calculated model estimates for each cell of a 4-kilometer resolution climate raster and mapped the risk categories over the entire range of subalpine fir in the western United States. The spatial variation of risk classes indicates a gradient of climatic susceptibility generally decreasing from the Olympic Peninsula in Washington and the Cascade Range in Oregon and Washington moving eastward, with the exception of some high risk areas in northern Idaho and western Montana. There is also a pattern of decreasing climatic susceptibility from north to south in the Rocky Mountains. Our study provides an initial step for modeling the relationship between climate and BWA damage severity across the range of subalpine fir. We showed that September minimum temperature and a metric calculated as the maximum May temperature divided by total May precipitation were the best climatic predictors of BWA severity. Although winter cold temperatures and summer heat have been shown to influence BWA impacts in other locations, these variables were not as predictive as spring and fall conditions in the Pacific Northwest.

Severity rating systems are fundamental to understanding the impacts of disturbance agents in forest stands. The balsam woolly adelgid (BWA), Adelges piceae (Ratzeburg) (Hemiptera: Adelgidae), is an invasive forest pest in North America that infests and causes mortality in true fir, Abies spp. There is currently no single system for evaluating damage caused by BWA in the western United States. Because range expansion through favored habitat is inevitable, it is imperative to begin long-term monitoring using a unified approach to evaluate changing conditions and hasten management opportunities. We developed a new rating system for two western host species: grand fir and subalpine fir. Unlike other severity scales, our index describes stand-level damage rather than impacts on individual host trees alone. We sampled 57 sites across the current range of BWA in the western United States and compiled severity indices using 10 metrics of overstory and understory damage. We used analyses of variance to identify five discrete severity classes and translated the results into a descriptive table of damage characteristics for each class. This index is proposed as an improvement over existing rating systems for western North America because of its broader scope, demonstrated ability to distinguish between classes, and identification of the predominant indicators that will improve the efficiency and efficacy of field assessments. The adoption of this system will facilitate long-term monitoring through site resurveys that will be directly comparable over time, also allowing future studies to conduct risk assessments and target stands that face the greatest threat to forest health.

A non-native invasive sawfly, the amber-marked birch leaf miner Profenusa thomsoni (Konow), was first detected in south-central Alaska in 1996 and is now widely distributed throughout urban and wild birch trees in Alaska. Impacts have been considered primarily aesthetic because leaf miners cause leaves of birch trees (Betula spp.) to senesce prematurely, but the leaf miners likely also reduce birch vigour and thereby increase susceptibility to diseases and other insects. We tested the ability of commercially available biological control agents to control P. thomsoni. The entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuillemin GHA strain and the entomopathogenic nematode Steinernema carpocapsae (Weiser) were applied in aqueous suspension to the soil/litter surface beneath infested birch trees in Alaska at one site in 2007 and 2008 and two sites in 2010. There was no evidence the fungus or nematode controlled P. thomsoni. Instead, there was evidence the fungus increased the density of this pest insect at two sites, likely by reducing its predators. As tested, B. bassiana and S. carpocapsae do not appear effective as biological controls of P. thomsoni.