The association between environmental factors and Engelmann spruce mortality in western Colorado was investigated using Bayesian hierarchical zero-and-one inflated beta regressive model. The results indicated that the probability of mortality occurrence rate was positively associated with moderate to warm temperature zones, moderate precipitation, and single canopy stands with the smaller size class of spruce within stands. The probability of full mortality rate was positively associated with warm and humid climate zones with spruce as subdominant species in the vertically complex stands. On the other hand, higher mortality rate was more associated with local stand characteristics than climate factors that low mortality rate associated with stands dominated by spruce of a large size classes. The correlation model offers an approach to create predicted risk map for probability and rate of spruce mortality that could help manager in precedent planning for the upcoming outbreak events. Recommendations for Resource Managers This study aims to investigate the environmental association of spruce bark beetle caused mortality in landscape context with binomial-beta hierarchical framework. Both regional-scale climate and stand-level characteristics should be considered to assess the risk and severity of outbreak caused mortality at a large spatial scale. The mortality risk is higher and more severe in warmer zones, especially the stands with spruce as subdominant tree species should be more concerned. Predicted map could improve the ability to spatially assess the risk of spruce mortality assisting managers to be better prepared for the future outbreaks, particularly in the risky area.
The case studies presented in this special section illustrate some of the diverse and wide-ranging effects that bark beetles can have on the ecosystem goods and services. They capture the impacts of only a few of the recent bark beetle outbreaks in wildland, periurban, and urban forests of the West, but show some of the complex ways insects can change forests, with results of these changes radiating in many directions.
Bark beetles are primary disturbance agents in western US forests. Outbreaks affect goods and services associated with forest ecosystems including timber, water, fish and wildlife habitats and populations, recreation opportunities, and many others. They can also affect wildfire behavior and its intensity. Assessments and evaluations of such impacts are important information to land managers, policy makers, and forest stakeholders, as well as to the broader public. Arriving at a complete and accurate assessment and evaluation is a complex process that necessarily considers effects and impacts on a variety of resources affecting diverse stakeholders over time and space. Within that complex process are interactions and feedbacks between ecological factors and socioeconomic factors. We argue that ecosystem goods and services are an operative bridge between those ecological factors and socioeconomic factors. Hence, they provide a context in which to systematically identify effects and affected resources and consider interactions and feedbacks among them which lead to further impacts. Such a context enhances one's ability to reveal, assess, and evaluate the full range and scope of impacts.
Unprecedented outbreaks of defoliating insects severely damaged blueberry crops near Port Graham on the Kenai Peninsula in Alaska from 2008-2012. The Native people in this region rely heavily on gathered blueberries and other foods for sustenance and nourishment. Influences of topography and stand structure on blueberry abundance and fruiting were examined and used to develop spatial models to predict abundance and productivity of blueberry plants. Fruiting was associated with decreased canopy density, a low basal area and southwesterly aspects. Stands with relatively high site indices have greater abundance of blueberry plants, while the opposite trend was observed with productivity. Results demonstrate the feasibility of modeling the abundance and productivity of blueberry plants using easily obtained satellite imagery in conjunction with a well-organized field data collection system.
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.
Subalpine fir decline(SFD) has killed more trees in Colorado’s high elevation forests than any other insect or disease problem.The widespread nature of this disorder suggests that the cause involves climatic factors.We examined the influence of varying combinations of average annual temperature and precipitation on the incidence and distribution of SFD.Climatic transition matrices generated in this study indicate that most healthy trees are found in climatic zones with moderate to low temperatures and high precipitation;whereas,SFD occurs mostly in zones of moderate temperatures and moderate precipitation.The contrasting distributions define an environmental mismatch.Forests matched with favorable climatic conditions thrive;those that are mismatched can become vulnerable to decline disease.
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.
The magnitude and urgency of current mountain pine beetle outbreaks in the western United States and Canada have resulted in numerous studies of the dynamics and impacts of these insects in forested ecosystems. This paper reviews some of the aspects of the spatial dynamics and landscape ecology of this bark beetle. Landscape heterogeneity influences dispersal patterns in many ways, but little is known about these influences that can be used in management efforts, and the natural range of variability of this insect remains undefined. Short range spread is often determined by the active responses of the beetle to chemical and physical cues. Long-range spread is often facilitated by winds above the canopy, which can move insects hundreds of kilometers. New concepts and tools are emerging that have been adapted from landscape ecology and spatial statistics. Categorical map analysis has been widely used to quantify infested landscapes. Spatial statistical analysis and point process models are acquiring more recent favor. Landscape entomology is an active area of forestry research.
Bark beetles (Coleoptera: Curculionidae: Scolytinae) are mortality agents to multiple tree species throughout North America. Understanding spatiotemporal dynamics of these insects can assist management, prediction of outbreaks, and development of “real time” assessments of forest susceptibility incorporating insect population data. Here, dispersal of Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.) is estimated over four regions within Colorado and Wyoming from 1994 to 2010. Infestations mapped from aerial insect surveys are utilized as a proxy variable for Douglas-fir beetle (DFB) activity and analyzed via a novel GIS technique that co-locates infestations from adjacent years quantifying distances between them. Dispersal distances of DFB infestations were modeled with a cumulative Gaussian function and expressed as a standard dispersal distance (SDD), the distance at which 68% of infestations dispersed in a given flight season. Average values of SDD ranged from under 1 kilometer for the region of northwestern Colorado to over 2.5 kilometers for infestations in Wyoming. A statistically significant relationship was detected between SDD and infestation area in the parent year, suggesting that host depletion and density-dependent factors may influence dispersal. Findings can potentially provide insight for managers—namely, likelihood of DFB infestation increase for locations within two to five kilometers of an existing infestation.
Insects are ectotherms that cannot regulate their own temperature, and thus rely on and are at the disposal of the surrounding environment. In this study, long-term climatic data are used to stratify forested regions of Alaska into climatic zones based on temperature and precipitation. Temperature and precipitation are shown to be important ecological drivers in determining the distribution of aspen leaf minor (Phyllocnistis populiella Chambers) and the aspen (Populus tremuloides Michx.) host in the state of Alaska. Climatic regions based on temperatures and precipitation accounted for 83 to 97% of the variability in the probability of observing aspen and the aspen leaf minor (ALM). The frequency of observing aspen was highest throughout the central region of the state, which represents a climate with low to moderate levels of precipitation and cold to mild temperatures. The highest probability of observing aspen was in the mild-very cold region of the state. The probability of observing ALM in a given climate zone followed a pattern similar to aspen. Differences were in the colder and drier climate zones where the probability of observing ALM decreased to near zero. The derived climatic models could be used to provide a basis for the analysis of climatic impacts on the distribution of forest insects throughout the state.
The objective of this study was to model the influence of temperature and precipitation on the distribution and abundance of the ambrosia beetles in the genus Trypodendron. Although these beetles do not attack and kill healthy trees, their gallery holes and accompanying black and gray stain associated with symbiotic ambrosial fungi can cause significant economic losses to commercial logs and wood products. Beetles were collected along a 1,100-km latitudinal transect 4 times at 2-week intervals at 43 sites beginning early July using Lindgren-funnel traps baited with ethanol, alpha-pinene, and lineatin. Average annual temperature and precipitation were used to partition the state into 25 climatic zones. Large-scale patterns of beetle distribution were correlated with elevation and the temperature and precipitation zones. Results indicate that reasonably accurate predictions of beetle abundance can be generated using models based on trap data collected across several climate zones. Predictions derived from this latitudinal transect can be extrapolated to more remote areas using species– environment relationships based on temperature and precipitation combinations. Partitioning large geographic areas using climatic zones offers a logical approach for predicting insect activity in remote areas, and if implemented on a long-term basis would be able to provide estimates of yearly and seasonal trends in the infestation. Such information would allow forest managers to evaluate the impact on forest ecosystem services and improve future assessments that predict the influence of a changing climate on insect pest migrations and their intensification during outbreaks.
A blind analysis searching for the decay B-s(0) -> mu(+)mu(-) has been performed using proton-proton collisions at a centre-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. With an integrated luminosity of 2.4 fb(-1) no excess of events over the background expectation is found and an upper limit is set on the branching fraction BR(B-s(0) -> mu(+)mu(-)) <2.2(1.9) x 10(-8) at 95% (90%) confidence level. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
The amber-marked birch leafminer (Profenusa thomsoni [Konow]) (Hymenoptera: Tenthredinidae) has caused severe infestations of birch species in Anchorage, AK, since 2002. Its spatial distribution has been monitored since 2006 and summarized using interpolated surfaces based on simple kriging. Results indicate that this insect pest is unevenly distributed, occurring in multi-neighborhood sized patches that migrate from year to year. Patches showing heavy infestation one year are followed by light infestations the following year. In this study, we developed methods of assessing and describing spatial distributions of P. thomsoni as they vary from year to year, and speculate on potential causes of these trends in landscape patterns.
We developed a method of mapping fuel-generating disturbances based on spatial fuel models which were in turn developed using a combination of satellite imagery, topographic data, and field data. This is a potentially significant product for fuel management, pest management, forest planners, and others. With these maps, the spatial distribution, extent, and abundance of different fuel-generating disturbances can be estimated, and spatial prescriptions developed. The procedures are demonstrated by modeling the spatial distribution of various small-scale disturbances that cause fuels in the Black Hills National Forest, South Dakota and the Lincoln National Forest, New Mexico.
An important objective of forest health research is that it is applicable to and used by end users. A survey, interviews, and two case studies determined how to best transfer research to US Forest Service end users in the Rocky Mountain Region. The survey indicated research information was most often found via the Internet, peer-to-peer interactions, publications, specialist visits, and field days. However, the most preferred methods were site visits by specialists, field days, and peers. Interviewees indicated that increased workloads and decreased budgets restricted them from staying current with research findings. Case studies found transferring findings directly from a researcher can be inefficient while using boundary spanners reduces researchers' efforts on technology transfer. To be better disseminated to end users, research findings should use face-to-face media, be easy to interpret and quick to use, and build on or establish trust between researchers, boundary spanners, and end users.
Introduction Trees do not just die; there is always a primary cause, and often contributing factors. Trees need adequate quantities of water, heat, light, nutrients, carbon dioxide, oxygen, and other abiotic resources to sustain life, growth, and reproduction. When these factors are deficient or excessive, they cause mortality. According to the concept of baseline mortality (Chapters 1, 2, and 3), a certain number of trees must die as a forest ages to maintain a healthy condition. Abiotic factors kill trees in different ways, e.g., starvation, desiccation, uprooting, or stem breakage. The patterns of mortality and how the forest responds determine how changing stand structures impact sustainability and productivity. Here, we discuss abiotic factors, and how they influence diameter and age class distributions. We conclude this chapter by suggesting general principles about the impacts of abiotic disturbances on stand structures within forest ecosystems. Weather events Weather is the set of all phenomena occurring in a given atmosphere at a given time. Weather phenomena include wind, clouds, rain, snow, fog, dust storms, ice storms, hurricanes, tornadoes, and others. Some weather events can reset forest succession directly by killing trees. Weather events also can influence the rate and direction of forest succession indirectly by increasing fuels to enhance fire risk or by predisposing trees to other stresses.
Invasive pathogens have caused immeasurable ecological and economic damage to forest ecosystems. Damage will undoubtedly increase over time due to increased introductions and evolution of invasive pathogens in concert with complex environmental disturbances, such as climate change. Forest Service Research and Development must fulfill critical roles and responsibilities to address issues related to invasive forest pathogens. This paper identifies critical, long-term research needs in four key areas: (1) prediction and prevention, (2) early detection and rapid response, (3) management and mitigation, and (4) restoration and rehabilitation. The paper also addresses issues related to national and international collaboration, scientific applications, and communication.
Climate change will likely have dramatic impacts on forest health because many forest trees could become maladapted to climate. Furthermore, climate change will have additional impacts on forest health through changes in the distribution and severity of forest disease. Methods are needed to predict the influence of climate change on forest disease so that appropriate forest management practices can be implemented to minimize disease impacts. Initial approaches for predicting the future distribution of pathogens are dependent on reliable data sets that document the current, precise location of accurately identified pathogens and hosts. Precise distribution information can be used in conjunction with available climate surfaces to determine which climatic factors and interactions influence species distribution. This information can be used to develop bioclimatic models to predict the probability of suitable climate space for host and pathogen species across the landscape. A similar approach using climate surfaces under predicted future climate scenarios can be used to project suitable climate space for hosts and pathogens in the future. Currently such predictions are well developed for many forest host species, but predictive capacity is extremely limited for forest pathogens because of lacking distribution data. Continued surveys and research are needed to further refine bioclimatic models to predict influences of climate and climate change on forest disease.