Publications

a molecular identification protocol for roots of boreal forest tree species.		2014	25383267
sapling leaf trait responses to light, tree height and soil nutrients for three conifer species of contrasting shade tolerance.	we developed models to describe the responses of four commonly examined leaf traits (mass per area, weight, area and nitrogen (n) concentration) to gradients of light, soil nutrients and tree height in three conifer species of contrasting shade tolerance. our observational dataset from the sub-boreal spruce forests of british columbia included subalpine fir (abies lasioscarpa [hook.] nutt; high shade tolerance), interior spruce (picea glauca × picea engelmannii [moench] voss; intermediate shade ...	2014	25422385
rapid increases in forest understory diversity and productivity following a mountain pine beetle (dendroctonus ponderosae) outbreak in pine forests.	the current unprecedented outbreak of mountain pine beetle (dendroctonus ponderosae) in lodgepole pine (pinus contorta) forests of western canada has resulted in a landscape consisting of a mosaic of forest stands at different stages of mortality. within forest stands, understory communities are the reservoir of the majority of plant species diversity and influence the composition of future forests in response to disturbance. although changes to stand composition following beetle outbreaks are w ...	2015	25859663
a model for mountain pine beetle outbreaks in an age-structured forest: predicting severity and outbreak-recovery cycle period.	the mountain pine beetle (mpb, dendroctonus ponderosae), a tree-killing bark beetle, has historically been part of the normal disturbance regime in lodgepole pine (pinus contorta) forests. in recent years, warm winters and summers have allowed mpb populations to achieve synchronous emergence and successful attacks, resulting in widespread population outbreaks and resultant tree mortality across western north america. we develop an age-structured forest demographic model that incorporates tempera ...	2015	25976694
ectomycorrhizal fungi mediate indirect effects of a bark beetle outbreak on secondary chemistry and establishment of pine seedlings.	dendroctonus ponderosae has killed millions of pinus contorta in western north america with subsequent effects on stand conditions, including changes in light intensity, needle deposition, and the composition of fungal community mutualists, namely ectomycorrhizal fungi. it is unknown whether these changes in stand conditions will have cascading consequences for the next generation of pine seedlings. to test for transgenerational cascades on pine seedlings, we tested the effects of fungal inoculu ...	2015	26033270
bacteria influence mountain pine beetle brood development through interactions with symbiotic and antagonistic fungi: implications for climate-driven host range expansion.	bark beetles are associated with diverse communities of symbionts. although fungi have received significant attention, we know little about how bacteria, and in particular their interactions with fungi, affect bark beetle reproduction. we tested how interactions between four bacterial associates, two symbiotic fungi, and two opportunistic fungi affect performance of mountain pine beetles (dendroctonus ponderosae) in host tissue. we compared beetle performance in phloem of its historical host, lo ...	2015	26037523
differences in defence responses of pinus contorta and pinus banksiana to the mountain pine beetle fungal associate grosmannia clavigera are affected by water deficit.	we tested the hypotheses that responses to the mountain pine beetle fungal associate grosmannia clavigera will differ between the evolutionarily co-evolved host lodgepole pine (pinus contorta var. latifolia) and the naïve host jack pine (pinus banksiana) and that these responses will be influenced by water availability. g. clavigera inoculation resulted in more rapid stem lesion development in lodgepole than in jack pine; water deficit delayed lesion development in both species. decreased hydrau ...	2016	26205849
nonstructural carbohydrate dynamics of lodgepole pine dying from mountain pine beetle attack.	bark beetle outbreaks are an important cause of tree death, but the process by which trees die remains poorly understood. the effect of beetle attack on whole-tree nonstructural carbohydrate (nsc) dynamics is particularly unclear, despite the potential role of carbohydrates in plant defense and survival. we monitored nsc dynamics of all organs in attacked and protected lodgepole pines (pinus contorta) during a mountain pine beetle (dendroctonus ponderosae) outbreak in british columbia, starting ...	2016	26256444
a novel semiochemical tool for protecting pinus contorta from mortality attributed to dendroctonus ponderosae (coleoptera: curculionidae).	verbenone (4,6,6-trimethylbicyclo[3.1.1]hept-3-en-2-one) is an antiaggregant of the mountain pine beetle, dendroctonus ponderosae hopkins (coleoptera: curculionidae), a notable forest insect capable of causing extensive levels of tree mortality in western north america. several formulations of verbenone are registered for tree protection, but failures in efficacy are not uncommon, particularly when applied during large infestations. a formulation of (-)-verbenone was developed (specialized phero ...	2015	26470118
mountain pine beetle host selection between lodgepole and ponderosa pines in the southern rocky mountains.	recent evidence of range expansion and host transition by mountain pine beetle (dendroctonus ponderosae hopkins; mpb) has suggested that mpb may not primarily breed in their natal host, but will switch hosts to an alternate tree species. as mpb populations expanded in lodgepole pine forests in the southern rocky mountains, we investigated the potential for movement into adjacent ponderosa pine forests. we conducted field and laboratory experiments to evaluate four aspects of mpb population dynam ...	2016	26546596
carbon isotopic composition of forest soil respiration in the decade following bark beetle and stem girdling disturbances in the rocky mountains.	bark beetle outbreaks are widespread in western north american forests, reducing primary productivity and transpiration, leading to forest mortality across large areas and altering ecosystem carbon cycling. here the carbon isotope composition (δ(13) c) of soil respiration (δj ) was monitored in the decade after disturbance for forests affected naturally by mountain pine beetle infestation and artificially by stem girdling. the seasonal mean δj changed along both chronosequences. we found (a) enr ...	2016	26824577
transcriptome and secretome analyses of the wood decay fungus wolfiporia cocos support alternative mechanisms of lignocellulose conversion.	certain wood decay basidiomycetes, collectively referred to as brown rot fungi, rapidly depolymerize cellulose while leaving behind the bulk of cell wall lignin as a modified residue. the mechanism(s) employed is unclear, but considerable evidence implicates the involvement of diffusible oxidants generated via fenton-like chemistry. toward a better understanding of this process, we have examined the transcriptome and secretome of wolfiporia cocos when cultivated on media containing glucose, puri ...	2016	27107121
volatile and within-needle terpene changes to douglas-fir trees associated with douglas-fir beetle (coleoptera: curculionidae) attack.	mass attack by tree-killing bark beetles (curculionidae: scolytinae) brings about large chemical changes in host trees that can have important ecological consequences. for example, mountain pine beetle (dendroctonus ponderosae hopkins) attack increases emission of terpenes by lodgepole pine (pinus contorta dougl. ex loud.), affecting foliage flammability with consequences for wildfires. in this study, we measured chemical changes to douglas-fir (pseudotsuga menziesii var. glauca (mirb.) franco) ...	2016	27231258
fire severity unaffected by spruce beetle outbreak in spruce-fir forests in southwestern colorado.	recent large and severe outbreaks of native bark beetles have raised concern among the general public and land managers about potential for amplified fire activity in western north america. to date, the majority of studies examining bark beetle outbreaks and subsequent fire severity in the u.s. rocky mountains have focused on outbreaks of mountain pine beetle (mpb; dendroctonus ponderosae) in lodgepole pine (pinus contorta) forests, but few studies, particularly field studies, have addressed the ...	2016	27411244
change in soil fungal community structure driven by a decline in ectomycorrhizal fungi following a mountain pine beetle (dendroctonus ponderosae) outbreak.	western north american landscapes are rapidly being transformed by forest die-off caused by mountain pine beetle (dendroctonus ponderosae), with implications for plant and soil communities. the mechanisms that drive changes in soil community structure, particularly for the highly prevalent ectomycorrhizal fungi in pine forests, are complex and intertwined. critical to enhancing understanding will be disentangling the relative importance of host tree mortality from changes in soil chemistry follo ...	2017	27659418
mountain pine beetle dynamics and reproductive success in post-fire lodgepole and ponderosa pine forests in northeastern utah.	fire injury can increase tree susceptibility to some bark beetles (curculionidae, scolytinae), but whether wildfires can trigger outbreaks of species such as mountain pine beetle (dendroctonus ponderosae hopkins) is not well understood. we monitored 1173 lodgepole (pinus contorta var. latifolia doug.) and 599 ponderosa (pinus ponderosa doug. ex law) pines for three years post-wildfire in the uinta mountains of northeastern utah in an area with locally endemic mountain pine beetle. we examined ho ...	2016	27783632
relative importance of climate and mountain pine beetle outbreaks on the occurrence of large wildfires in the western usa.	extensive outbreaks of bark beetles have killed trees across millions of hectares of forests and woodlands in western north america. these outbreaks have led to spirited scientific, public, and policy debates about consequential increases in fire risk, especially in the wildland-urban interface (wui), where homes and communities are at particular risk from wildfires. at the same time, large wildfires have become more frequent across this region. widespread expectations that outbreaks increase ex ...	2016	27787956
water-deficit and fungal infection can differentially affect the production of different classes of defense compounds in two host pines of mountain pine beetle.	bark beetles are important agents of tree mortality in conifer forests and their interaction with trees is influenced by host defense chemicals, such as monoterpenes and phenolics. since mountain pine beetle (dendroctonus ponderosae hopkins) has expanded its host range from lodgepole pine (pinus contorta doug. ex loud. (var. latifolia engelm.))-dominated forests to the novel jack pine (pinus banksiana lamb.) forests in western canada, studies investigating the jack pine suitability as a host for ...	2016	27881799
climate influences on whitebark pine mortality from mountain pine beetle in the greater yellowstone ecosystem.	extensive mortality of whitebark pine, beginning in the early to mid-2000s, occurred in the greater yellowstone ecosystem (gye) of the western usa, primarily from mountain pine beetle but also from other threats such as white pine blister rust. the climatic drivers of this recent mortality and the potential for future whitebark pine mortality from mountain pine beetle are not well understood, yet are important considerations in whether to list whitebark pine as a threatened or endangered species ...	2016	27907251
sapwood stored resources decline in whitebark and lodgepole pines attacked by mountain pine beetles (coleoptera: curculionidae).	recent outbreaks of forest insects have been directly linked to climate change-induced warming and drought, but effects of tree stored resources on insects have received less attention. we asked whether tree stored resources changed following mountain pine beetle (dendroctonus ponderosae hopkins) attack and whether they affected beetle development. we compared initial concentrations of stored resources in the sapwood of whitebark pine (pinus albicaulis engelmann) and lodgepole pine (pinus contor ...	2016	28028093
multiscale habitat relationships of snowshoe hares (lepus americanus) in the mixed conifer landscape of the northern rockies, usa: cross-scale effects of horizontal cover with implications for forest management.	snowshoe hares (lepus americanus) are an ecologically important herbivore because they modify vegetation through browsing and serve as a prey resource for multiple predators. we implemented a multiscale approach to characterize habitat relationships for snowshoe hares across the mixed conifer landscape of the northern rocky mountains, usa. our objectives were to (1) assess the relationship between horizontal cover and snowshoe hares, (2) estimate how forest metrics vary across the gradient of sn ...	2017	28070281
influence of stand structure on carbon-13 of vegetation, soils, and canopy air within deciduous and evergreen forests in utah, united states.	carbon isotope ratios (δ(13)c) were studied in evergreen and deciduous forest ecosystems in semi-arid utah (pinus contorta, populus tremuloides, acer negundo and acer grandidentatum). measurements were taken in four to five stands of each forest ecosystem differing in overstory leaf area index (lai) during two consecutive growing seasons. the δ(13)cleaf (and carbon isotope discrimination) of understory vegetation in the evergreen stands (lai 1.5-2.2) did not differ among canopies with increasing ...	1997	28307459
altitude trends in conifer leaf morphology and stable carbon isotope composition.	the natural ratio of stable carbon isotopes (δ(13)c) was compared to leaf structural and chemical characteristics in evergreen conifers in the north-central rockies, united states. we sought a general model that would explain variation in δ(13)c across altitudinal gradients. because variation in δ(13)c is attributed to the shifts between supply and demand for carbon dioxide within the leaf, we measured structural and chemical variables related to supply and demand. we measured stomatal density, ...	2000	28308741
autumn stomatal closure in six conifer species of the central rocky mountains.	environmental and water relations parameters during fall were monitored for six conifer tree species common to the central rocky mountains growing naturally at the same location (pinus contorta, pinus ponderosa, pinus flexilus, pseudotsuga menziesii, abies lasiocarpa, picea engelmannii). subsequent to what appeared to be the beginning of seasonal stomatal closure, leaf conductance to water vapor declined sharply following the onset of freezing air temperatures at night. a coincident rapid declin ...	1984	28311019