Mountain Pine Beetle Infestation Research Articles

The effects of cumulative forest disturbance on streamflow in a large watershed in the central interior of British Columbia, Canada

Abstract. The Baker Creek watershed (1570 km2), situated in the central interior of British Columbia, Canada, has been severely disturbed by both logging and natural disturbance, particularly by a recent large-scale mountain pine beetle (MPB) infestation (up to 2009, 70.2% of the watershed area had been attacked by MPB) and subsequent salvage logging. The concept of equivalent clear-cut area (ECA) was used to indicate the magnitude of forest disturbance, with consideration of hydrological recovery following various types of disturbance (wildfire, logging and MPB infestation), cumulated over space and time in the watershed. The cumulative ECA peaked at 62.2% in 2009. A combined approach of statistical analysis (i.e. time series analysis) and graphic method (modified double mass curve) was employed to evaluate the impacts of forest disturbance on hydrology. Our results showed that severe forest disturbance significantly increased annual mean flow. The average increment in annual mean flow caused by forest disturbance was 48.4 mm yr−1, while the average decrease in annual mean flow caused by climatic variability during the same disturbance period was 35.5 mm yr−1. The opposite changes in directions and magnitudes clearly suggest an offsetting effect between forest disturbance and climatic variability, with the absolute influential strength of forest disturbance (57.7%) overriding that from climate variability (42.3%). Forest disturbance also produced significant positive effects on low flow and dry season (fall and winter) mean flow. Implications of our findings for future forest and water resources management are discussed in the context of long-term watershed sustainability.

Ecohydrology of an outbreak: mountain pine beetle impacts trees in drier landscape positions first

ABSTRACTVegetation pattern and landscape structure intersect to exert strong control over ecohydrological dynamics at the watershed scale. The hydrologic implications of vegetation disturbance (e.g. fire, disease) depend on the spatial pattern and form of environmental change. Here, we investigate this intersection at Tenderfoot Creek Experimental Forest (TCEF), Montana, with a focus on the mountain pine beetle (Dendroctonus ponderosae) epidemic currently affecting the Rocky Mountains. We calibrated QuickBird remote sensing imagery with a leaf‐level spectral library of local vegetation. We used this spectral library to determine diagnostic vegetation indices for differentiating stages of beetle infestation within the 37 km2 TCEF watershed. These indices formed the basis of a three‐component mixing model to establish the extent and magnitude of beetle infestation across the TCEF watershed. We compared disturbance patterns with spatially distributed topography and vegetation variables derived from a light detection and ranging‐based digital elevation model of TCEF. We determined that certain landscape characteristics (low vegetation density, south‐facing slopes, steep slopes, locations with small contributing areas and locations with lower values of the topographic wetness index) were significantly more likely to exhibit the effects of beetle infestation. Our efforts to monitor vegetation mortality across space and time provide a context for assessing landscape susceptibility to initial mountain pine beetle infestation and how outbreak (i.e. landscape scale infestation) patterns may affect watershed ecohydrology via altered water and biogeochemical cycles. Copyright © 2012 John Wiley & Sons, Ltd.

Effect of Bark Beetle Infestation on Secondary Organic Aerosol Precursor Emissions

Bark beetles are a potentially destructive force in forest ecosystems; however, it is not known how insect attacks affect the atmosphere. The emissions of volatile organic compounds (VOCs) were sampled i.) from bark beetle infested and healthy lodgepole pine (Pinus contorta var. latifolia) trees and ii.) from sites with and without active mountain pine beetle infestation. The emissions from the trunk and the canopy were collected via sorbent traps. After collection, the sorbent traps were extracted with hexane, and the extracts were separated and detected using gas chromatography/mass spectroscopy. Canister samples were also collected and analyzed by a multicolumn gas chromatographic system. The samples from bark beetle infested lodgepole pine trees suggest a 5- to 20-fold enhancement in total VOCs emissions. Furthermore, increases in the β-phellandrene emissions correlated with bark beetle infestation. A shift in the type and the quantity of VOC emissions can be used to identify bark beetle infestation but, more importantly, can lead to increases in secondary organic aerosol from these forests as potent SOA precursors are produced.

A Bayesian space–time model for discrete spread processes on a lattice

In this article we present a Bayesian Markov model for investigating environmental spread processes. We formulate a model where the spread of a disease over a heterogeneous landscape through time is represented as a probabilistic function of two processes: local diffusion and random-jump dispersal. This formulation represents two mechanisms of spread which result in highly peaked and long-tailed distributions of dispersal distances (i.e., local and long-distance spread), commonly observed in the spread of infectious diseases and biological invasions. We demonstrate the properties of this model using a simulation experiment and an empirical case study – the spread of mountain pine beetle in western Canada. Posterior predictive checking was used to validate the number of newly inhabited regions in each time period. The model performed well in the simulation study in which a goodness-of-fit statistic measuring the number of newly inhabited regions in each time interval fell within the 95% posterior predictive credible interval in over 97% of simulations. The case study of a mountain pine beetle infestation in western Canada (1999–2009) extended the base model in two ways. First, spatial covariates thought to impact the local diffusion parameters, elevation and forest cover, were included in the model. Second, a refined definition for translocation or jump-dispersal based on mountain pine beetle ecology was incorporated improving the fit of the model. Posterior predictive checks on the mountain pine beetle model found that the observed goodness-of-fit test statistic fell within the 95% posterior predictive credible interval for 8 out of 10years. The simulation study and case study provide evidence that the model presented here is both robust and flexible; and is therefore appropriate for a wide range of spread processes in epidemiology and ecology.

Forest mortality in high-elevation whitebark pine (Pinus albicaulis) forests of eastern California, USA; influence of environmental context, bark beetles, climatic water deficit, and warming

Whitebark pine ( Pinus albicaulis Engelm.) in subalpine zones of eastern California experienced significant mortality from 2007 to 2010. Dying stands were dense (mean basal area 47.5 m2/ha), young (mean 176 years), and even-age; mean stand mortality was 70%. Stands were at low elevations (mean 2993 m), on northerly aspects, and experienced warmer, drier climates relative to the regional species distribution. White pine blister rust was not observed; mountain pine beetle infestations were extensive. Ring widths were negatively correlated with climatic water deficit and positively correlated with water-year precipitation. Although trees that survived had greater growth during the 20th century than trees that died, in the 19th century trees that eventually died grew better than trees that survived, suggesting selection for genetic adaptation to current climates as a result of differential tree mortality. Air surveys (2006–2010) in the Sierra Nevada, Mt. Shasta, and Warner Mountains showed similar trends to the intensive studies. Observed mortality from air surveys was highest in the Warner Mountains (38%) and lowest in the Sierra Nevada (5%); northern aspects at lower elevations within each mountain region had the highest probabilities of mortality and dying stands had higher climatic water deficit. Scenarios for the future of whitebark pine in California are discussed.

Climate Change and Ecosystem Disruption: The Health Impacts of the North American Rocky Mountain Pine Beetle Infestation

In the United States and Canada, pine forest ecosystems are being dramatically affected by an unprecedented pine beetle infestation attributed to climate change. Both decreased frequency of extremely cold days and warmer winter temperature averages have led to an enphytotic devastating millions of acres of pine forest. The associated ecosystem disruption has the potential to cause significant health impacts from a range of exposures, including increased runoff and water turbidity, forest fires, and loss of ecosystem services. We review direct and indirect health impacts and possible prevention strategies. The pine beetle infestation highlights the need for public health to adopt an ecological, systems-oriented view to anticipate the full range of potential health impacts from climate change and facilitate effective planned adaptation.

Refining spatial neighbourhoods to capture terrain effects

Spatially explicit ecological research has increased substantially in the past 20 years. Most spatial approaches require the definition of a spatial neighbourhood or the region over which spatial relationships are modelled or assessed. Spatial neighbourhood definitions impact analysis results, and there are benefits in considering neighbourhood definitions that better capture ecological processes. The goal of this research is to present a simple and flexible approach in constraining ecological spatial neighbourhoods using terrain data. Using watershed boundaries, we can restrict spatial neighbourhoods from combining populations or processes that should be separated by terrain effects. We demonstrate the need for ecological constraints by way of a simulation study and highlight our approach with a case study examining mountain pine beetle (Dendroctonus ponderosae, Coleoptera; Hopkins) infestation hot spots. Our results demonstrate how failure to constrain neighbourhoods can lead to errors when the spatial signals from unrelated populations are mixed. Also, unconstrained spatial neighbourhoods can unintentionally detect spatial relationships across many scales. There will be benefits to studies that develop new, ecology-based approaches in defining spatial neighbourhoods that better illuminate ecological function of phenomena under study.

Verbenone Plus Reduces Levels of Tree Mortality Attributed to Mountain Pine Beetle Infestations in Whitebark Pine, a Tree Species of Concern

In western North America, recent outbreaks of the mountain pine beetle, Dendroctonus ponderosae Hopkins, have been severe, long-lasting and well-documented. We review previous research that led to the identification of Verbenone Plus, a novel four-component semiochemical blend [acetophenone, (E)-2-hexen-1-ol + (Z)-2-hexen-1- ol, and (–)-verbenone] that has been demonstrated to inhibit the response of a closely-related bark beetle species, western pine beetle, D. brevicomis LeConte, to attractant-baited traps and trees. In this study, we evaluate the efficacy of Verbenone Plus for protecting stands of whitebark pine, Pinus albicaulis Engelm., a species of concern being considered for listing as a threatened and endangered species, from mortality attributed to D. ponderosae infestations in the central Sierra Nevada, California, USA. The experimental design was completely randomized with two treatments (untreated control, Verbenone Plus) and four replicates (0.4-ha square plots) per treatment. A total of 450 trees were killed by D. ponderosae, 377 were P. albicaulis and 73 were lodgepole pine, P. contorta Dougl. ex Laws. Significantly, fewer pines (P. albicaulis and P. contorta) and P. albicaulis (only) were killed by D. ponderosae on Verbenone Plus-treated plots compared to the untreated control. On average, there was ~78% reduction in tree mortality attributed to Verbenone Plus. We discuss the implications of these and other results to the development of Verbenone Plus as a semiochemical-based tool for tree protection.

Mountain pine beetle infestation impacts: modeling water and energy budgets at the hill‐slope scale

ABSTRACTThe mountain pine beetle (MPB) epidemic in western North America is generating growing concern associated with aesthetics, ecology, and forest and water resources. Given the substantial acreage of prematurely dying forests within Colorado and Wyoming (~two million acres in 2008), MPB infestations have the potential to significantly alter forest canopy, impacting several aspects of the local water and land‐energy cycle. Hydrologic processes that may be influenced include canopy interception of precipitation and radiation, snow accumulation, melt and sublimation, soil infiltration and evapotranspiration. To investigate the changing hydrologic and energy regimes associated with MPB infestations, we used an integrated hydrologic model coupled with a land surface model to incorporate physical processes related to energy at the land surface. This platform was used to model hillslope‐scale hydrology and land‐energy changes throughout the phases of MPB infestation through modification of the physical parameterisation that accounts for alteration of stomatal resistance and leaf area indices. Our results demonstrate that MPB infested watersheds will experience a decrease in evapotranspiration, an increase in snow accumulation accompanied by earlier and faster snowmelt and associated increases in runoff volume and timing. Impacts are similar to those projected under climate change, yet with a systematically higher snowpack. These results have implications for water resource management because of higher tendencies for flooding in the spring and drought in the summer. Copyright © 2011 John Wiley & Sons, Ltd.

Future Water Supply and Demand in the Okanagan Basin, British Columbia: A Scenario-Based Analysis of Multiple, Interacting Stressors

Surface water is critical for meeting water needs in British Columbia’s Okanagan Basin, but the timing and magnitude of its availability is being altered through climate and land use changes and growing water demand. Greater attention needs to be given to the multiple, interacting factors occurring and projected to occur in this region if water is going to be sustainably provisioned to human users and available for ecosystem needs. This study contributes to that goal by integrating information on physical, biological and social processes in order to project a range of possible changes to surface water availability resulting from land-use, climatic and demographic change, as well as from Mountain Pine Beetle infestation. An integrated water management model (Water Evaluation and Planning system, WEAP) was used to consider future scenarios for water supply and demand in both unregulated and reservoir-supported streams that supply the District of Peachland. Results demonstrate that anticipated future climate conditions will critically reduce streamflow relative to projected uses (societal demand and ecological flow requirements). The surficial storage systems currently in place were found unable to meet municipal and instream flow needs during “normal” precipitation years by the 2050s. Improvements may be found through demand reduction, especially in the near term. Beyond the implications for the District of Peachland, this work demonstrates a method of using an accessible modeling tool for integrating knowledge from the fields of climate science, forest hydrology, water systems management and stream ecology to aid in water and land management decision-making.

Silviculture Options for Use in Ranges Designated for the Conservation of Northern Caribou in British Columbia

This review and synthesis of silviculture strategies was conducted to clarify options for managing forest stands in areas designated for conservation of habitat for the northern ecotype of woodland caribou in British Columbia. Information about the ecology, distribution, population status, and legal management measures for herds of northern caribou provided the background for assessing risk to forestry operations. A review of current scientific research and operational trials was used to reveal potential impacts of forestry on caribou life requisites. Specific attention was paid to the implications of the recent mountain pine beetle infestation. General guidelines (desired conditions) are provided for operating in areas designated for the conservation of caribou.

Regeneration and Growth Following Mountain Pine Beetle Attack: A Synthesis of Knowledge

The mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) infestation has altered forests of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) to an unprecedented extent in British Columbia. After an MPB outbreak, advance regeneration significantly contributed to form a new canopy and stand; however, the time needed to form a new stand depends on site-specific conditions. Assessment of regeneration and the growth of residual trees in stands after MPB attack are critical for three purposes: (1) forecasting long-term development (yield) of attacked stands; (2) selecting stands for growth-improving silvicultural treatments; and (3) forecasting impacts to ecological attributes such as hydrology, habitat, and vegetation types. This article reviews and synthesizes recent research concerning lodgepole pine stand performance after MPB attack in British Columbia. Species composition, abundance, spatial distribution, and overall stand health are described. This information is important for forest managers or practitioners who make decisions regarding management of MPB-attacked stands. Moreover, a number of key gaps exist in our knowledge about factors affecting advance regeneration and the residual trees of MPB-attacked stands. This article presents a list of knowledge gaps for management information and further research initiatives.

Evaluating the Use of Humidification Systems During Heat Treatment of MPB Lumber

Lumber produced from lodgepole pine logs attacked by the mountain pine beetle (MPB) infestation in British Columbia, Canada, exhibits very low initial moisture content (MC). Depending on the time elapsed since attack, the initial MC can be significantly lower than the fiber saturation point (FSP ∼30%). Lumber exhibiting 19% MC or less is considered ready for the dimension lumber market and does not necessarily need to be kiln dried. However, phytosanitary regulations require that lumber products be heat treated before delivery to customers. For lumber already quite dry, the Canadian Food Inspection Agency (CFIA) kiln drying/heat treatment schedules may be too long and can result in overdrying. For the significant volume of MPB lumber with an initial MC below 19%, the use of low-pressure steam or cold water spray could allow this lumber to be heat treated without causing further drying. This approach should result in improved lumber quality because overdrying would certainly be minimized and probably eliminated. In this study, two sorts (dry and wet sort) of MPB lumber were dried in a pilot laboratory kiln humidified with low-pressure steam or cold water spray. Twelve drying runs were carried out. The experimental results indicated that the times to reach the temperature of 56°C in the core of the lumber were shortened and warp for the dry-sort lumber group was reduced when the low-pressure steam or cold water spray system was used. Thus, for MPB lumber with a low initial MC, the utilization of lower pressure steam or cold water spray during heat treatment represents an attractive alternative to reduce kiln residence time, minimize or eliminate overdrying, and improve lumber quality.

Mountain pine beetle dispersal: spatiotemporal patterns and role in the spread and expansion of the present outbreak

Dispersal has been least understood in mountain pine beetle ecology. We developed a novel regional dynamic conceptual model of mountain pine beetle infestation using the tree mortality estimated from the British Columbia annual aerial overview survey to quantitatively determine short-distance dispersal (SDD) and long-distance dispersal (LDD) at local (forest district) and regional (provincial) scales. The dispersal patterns were characterized based on distances between a sink patch to its nearest source patch. At the regional scale, SDD accounted for 85.3% of mountain pine beetle dispersal to non-infested areas and 96.8% of beetle dispersal to infested areas. Although SDD was a dominant dispersal mode, LDD played a more important role in the early stage of the current mountain pine beetle outbreak. At the local scale, three patterns of dispersal to non-infested areas were identified. First, LDD dominated in the forest districts where only sparse infestations occurred. Second, LDD was a dominant or important factor in the early stages of the infestations in some districts. Third, SDD dominated throughout the infestations in more severely infested forest districts. However, for dispersal to infested areas, SDD was a dominant mode in most of the forest districts. We conclude from the spatiotemporal patterns of dispersal observed at local and regional scales that LDD is a key factor in the initiation and early stage of the infestations in new remote areas, and SDD dominate in the spread and expansion of the outbreak as the infestations intensify and reach epidemic levels. However, it should be conscious that there is uncertainty that LDD might have been over emphasized in the dispersal before local dynamics is fully taken into account.

Standardized Occupancy Maps for Selected Wildlife in Central British Columbia

Habitat occupancy models were developed for 10 vertebrate species that we expected would demonstrate a gradient of response to extensive losses of lodgepole pine (Pinus contorta) and other linked habitat alterations resulting from the mountain pine beetle (Dendroctonus ponderosae) infestation and gradual changes in regional climate. A process-based Bayesian Belief Network approach was used to develop interlinked species models focussed at two levels of land management: (1) the forest stand level including changes in forest overstorey and understorey species composition, within-stand structures, canopy closure, and amounts of standing and fallen deadwood; and (2) the landscape level including changes in size of habitat patches, seral stage composition, and proximity to roads. We also considered indirect influences of broad ecological changes including alteration of some key species interactions (e.g., displacementfrom preferred habitat and [or] increased risk of mortality). We used results of this modelling to provide preliminary predictions of species occupancy in a large area of British Columbia designated by the Nature Conservancy of Canada as their Central Interior ecoregion. This work demonstrates an approach to building species occupancy models capable of representing the effects of large-scale disturbances on habitat supply at both the stand and landscape levels of habitat management. The resultant occupancy maps are also useful when integrated into various strategic planning initiatives including species recovery, silvicultural investments, and long-term conservation planning.

Aboriginal Business Capacity Building Programs in the Central Interior of British Columbia: A Collaborative Project Between the University and Communities

Aboriginal communities in Canada are typically marginalized, have very low employment participation rates, and have limited economic infrastructure. The downturn in global economies further marginalized these communities. The University of Northern British Columbia’s (UNBC) Continuing Studies department piloted an Aboriginal and Small Business Leadership Certificate program in the central interior of British Columbia (BC) between November 2008 and May 2009. The aim of the program was to address some of the issues faced by Aboriginal communities affected by the mountain pine beetle infestation in central BC. The success of the pilot project led UNBC Continuing Studies to collaborate with some communities in the central interior of BC to access funds through the federal government’s Community Adjustment Funds initiative in order to develop and deliver a business capacity building project. The project consisted of a certificate program with enhanced Aboriginal content and an internship program to provide workplace experience for students. This paper reports on the practice of community engagement and learning as a result of this project.

Developing Indicators for Regional Water Quality Assessment: An Example from British Columbia Community Watersheds

An increased understanding of regional surface water quality and the key factors which differentiate regional from local differences is necessary for monitoring impacts such as mountain pine beetle infestation and related land management practices. This study develops a framework to identify water quality indicators which differentiate parameters influenced by rock type, by relatively short term anthropogenic activities, and those resulting from longer term climatic variability. Rock type was an overriding factor related to stream water chemistry in this British Columbia case study; with differences between watersheds differentiated by Ca, EC, Al and Fe. Grouping watersheds by their dominant rock type permitted the investigation of water quality with other watershed characteristics. The % forest cover, % pine cover, and dominant runoff processes demonstrated significant relationships with soluble cations, metals, turbidity and total organic carbon. Turbidity levels showed low variability, and relationships with mountain pine beetle were not strong; suggesting the need for more detailed data sets, selective monitoring of storm events, and longer term monitoring to improve predictive capacity.

Combining land surface temperature and shortwave infrared reflectance for early detection of mountain pine beetle infestations in western Canada

The current mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreak, whichbeganin1999,continuestobetheleadingcauseofpinetreemortalityinBritishColumbia. Information regarding the location and spatial extent of the current attack is required for mit- igating practices and forest inventory updates. This information is available from spaceborne observations. Unfortunately, the monitoring of the mountain pine beetle outbreak using remote sensing is usually limited to the visible stage at which the expansion of the attack beyond its initial hosts is unpreventable. The disruption of the sap flow caused by a blue-staining fungi carried by the beetles leads to: 1. a decrease in the amount of liquid water stored in the canopy, 2. anincrease incanopy temperature, and 3. anincrease inshortwave infraredreflectance shortly after the infestation. As such, the potential for early beetle detection utilizing thermal remote sensing is possible. Here we present a first attempt to detect a mountain pine beetle attack at its earliest stage (green attack stage when the foliage remains visibly green after the attack) using the temperature condition index (TCI) derived from Landsat ETM+ imagery over an affected area in British Columbia. The lack of detailed ground survey data of actual green attack areas limits the accuracy of this research. Regardless, our results show that TCI has the ability to differentiate between affected and unaffected areas in the green attack stage, and thus it provides information on the possible epicenters of the attack and on the spatial extent of the outbreak at later stages (red attack and gray attack). Furthermore, we also developed a moisture condition index (MCI) using both shortwave infrared and thermal infrared measurements. The MCI index is shown to be more effective than TCI in detecting the green attack stage and provides a more accurate picture of beetle spread patterns. C 2011 Society of Photo-Optical Instrumentation Engineers

Post-harvest seedling recruitment following mountain pine beetle infestation of Colorado lodgepole pine stands: a comparison using historic survey records

The extent and severity of overstory lodgepole pine ( Pinus contorta var. latifolia Engelm. ex Wats.) mortality from mountain pine beetle ( Dendroctonus ponderosae Hopkins) has created management concerns associated with forest regeneration, wildfire risk, human safety, and scenic, wildlife, and watershed resources in western North America. Owing to the unprecedented nature of the outbreak and associated management in the southern Rocky Mountains, it is unknown if the forests that regenerate after this current period of extensive change will differ from those that regenerated in the past. Here, we compare the density and species composition of post-harvest seedling recruits in pre-outbreak (1980–1996) and outbreak stands (2002–2007). Lodgepole pine accounted for more than 95% of post-harvest seedling recruitment and the density of seedlings colonizing clearcuts was equal during both the pre-outbreak and outbreak periods. Compared with harvested areas, the density of tree regeneration was 75% lower in uncut forests and was more evenly distributed among subalpine fir ( Abies lasiocarpa (Hook.) Nutt.) and lodgepole pine. This comparison provides evidence that the density of seedling recruitment will be at least as high after extensive pine beetle caused mortality as under healthy, pre-outbreak conditions and that the species composition of stands regenerating after this outbreak will differ between treated and untreated areas.

Differences in the constitutive terpene profile of lodgepole pine across a geographical range in British Columbia, and correlation with historical attack by mountain pine beetle

AbstractThe mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), is a destructive insect pest in western Nearctic conifer forests. Currently, British Columbia, Canada, is experiencing the largest recorded outbreak of this insect, including areas that historically have had low climatic suitability for it. We analyzed 26 constitutive resin terpenes in phloem samples from British Columbia lodgepole pine (Pinus contorta) populations to test for differential resistance to mountain pine beetle attack, based upon the likelihood of previous exposure to mountain pine beetle. We assessed sampled trees for number of mountain pine beetle attacks, number of pupal chambers, and tree survival the following spring. Significant differences were found when levels of certain terpenes in lodgepole pine populations that had likely experienced substantial mountain pine beetle infestations in the past were compared with those in populations that likely had not experienced large outbreaks of mountain pine beetle. Although we expected southern pine populations to contain more total terpenes than northern populations, owing to higher historical exposure to the beetle, the converse was found. Northern populations generally had higher levels of constitutive terpenes and beetle attack than southern populations. Because several terpenes are kairomones to the mountain pine beetle and also serve as precursors for the synthesis of pheromones, the lower levels of terpenes expressed by lodgepole pines from the historical range of the mountain pine beetle may render them less chemically perceptible to foraging beetles.