Publications

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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 ...201728070281
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 ...201727659418
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) ...201627231258
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 ...201626546596
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 ...201628028093
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 ...201627907251
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 ...201627787956
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 ...201627783632
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 ...201627411244
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 ...201626824577
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 ...201627881799
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 ...201626205849
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 ...201627107121
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 ...201626256444
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 ...201526033270
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 ...201525976694
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 ...201525859663
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 ...201526037523
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 ...201526470118
effects of dwarf mistletoe on stand structure of lodgepole pine forests 21-28 years post-mountain pine beetle epidemic in central oregon.lodgepole pine (pinus contorta) forests are widely distributed throughout north america and are subject to mountain pine beetle (dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. dwarf mistletoe (arceuthobium americanum) also influences stand structure and occurs frequently in post-mountain pine beetle epidemic ...201425221963
a molecular identification protocol for roots of boreal forest tree species. 201425383267
comparative genomics of the pine pathogens and beetle symbionts in the genus grosmannia.studies on beetle/tree fungal symbionts typically characterize the ecological and geographic distributions of the fungal populations. there is limited understanding of the genome-wide evolutionary processes that act within and between species as such fungi adapt to different environments, leading to physiological differences and reproductive isolation. here, we assess genomic evidence for such evolutionary processes by extending our recent work on grosmannia clavigera, which is vectored by the m ...201424627033
influence of water deficit on the molecular responses of pinus contorta × pinus banksiana mature trees to infection by the mountain pine beetle fungal associate, grosmannia clavigera.conifers exhibit a number of constitutive and induced mechanisms to defend against attack by pests and pathogens such as mountain pine beetle (dendroctonus ponderosae hopkins) and their fungal associates. ecological studies have demonstrated that stressed trees are more susceptible to attack by mountain pine beetle than their healthy counterparts. in this study, we tested the hypothesis that water deficit affects constitutive and induced responses of mature lodgepole pine × jack pine hybrids (pi ...201424319029
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 ...201425422385
cloning and characterization of chitinases from interior spruce and lodgepole pine.chitinases have been implicated in the defence of conifers against insects and pathogens. cdna for six chitinases were cloned from interior spruce (picea glauca x engelmannii) and four from lodgepole pine (pinus contorta). the cloned interior spruce chitinases were annotated class i pgechia1-1 and pgechia1-2, class ii pgechia2-1, class iv pgechia4-1, and class vii pgechia7-1 and pgechia7-2; lodgepole pine chitinases were annotated class i pcchia1-1, class iv pcchia4-1, and class vii pcchia7-1 an ...201424564978
belowground legacies of pinus contorta invasion and removal result in multiple mechanisms of invasional meltdown.plant invasions can change soil biota and nutrients in ways that drive subsequent plant communities, particularly when co-invading with belowground mutualists such as ectomycorrhizal fungi. these effects can persist following removal of the invasive plant and, combined with effects of removal per se, influence subsequent plant communities and ecosystem functioning. we used field observations and a soil bioassay with multiple plant species to determine the belowground effects and post-removal leg ...201425228312
proteomics indicators of the rapidly shifting physiology from whole mountain pine beetle, dendroctonus ponderosae (coleoptera: curculionidae), adults during early host colonization.we developed proteome profiles for host colonizing mountain pine beetle adults, dendroctonus ponderosae hopkins (coleoptera: curculionidae). adult insects were fed in pairs on fresh host lodgepole pine, pinus contorta dougl. ex loud, phloem tissue. the proteomes of fed individuals were monitored using itraq and compared to those of starved beetles, revealing 757 and 739 expressed proteins in females and males, respectively, for which quantitative information was obtained. overall functional cate ...201425360753
recent mountain pine beetle outbreaks, wildfire severity, and postfire tree regeneration in the us northern rockies.widespread tree mortality caused by outbreaks of native bark beetles (circulionidae: scolytinae) in recent decades has raised concern among scientists and forest managers about whether beetle outbreaks fuel more ecologically severe forest fires and impair postfire resilience. to investigate this question, we collected extensive field data following multiple fires that burned subalpine forests in 2011 throughout the northern rocky mountains across a spectrum of prefire beetle outbreak severity, p ...201425267633
mountain pine beetle infestation of lodgepole pine in areas of water diversion.the rocky mountains have experienced extensive infestations from the mountain pine beetle (dendroctonus ponderosae hopkins), affecting numerous pine tree species including lodgepole pine (pinus contorta dougl. var. latifolia). water diversions throughout the rocky mountains transport large volumes of water out of the basins of origin, resulting in hydrologic modifications to downstream areas. this study examines the hypothesis that lodgepole pine located below water diversions exhibit an increas ...201424681362
chemical similarity between historical and novel host plants promotes range and host expansion of the mountain pine beetle in a naïve host ecosystem.host plant secondary chemistry can have cascading impacts on host and range expansion of herbivorous insect populations. we investigated the role of host secondary compounds on pheromone production by the mountain pine beetle (dendroctonus ponderosae) (mpb) and beetle attraction in response to a historical (lodgepole pine, pinus contorta var. latifolia) and a novel (jack pine, pinus banksiana) hosts, as pheromones regulate the host colonization process. beetles emit the same pheromones from both ...201424400902
evaluations of emamectin benzoate and propiconazole for protecting individual pinus contorta from mortality attributed to colonization by dendroctonus ponderosae and associated fungi.protection of conifers from bark beetle colonization typically involves applications of liquid formulations of contact insecticides to the tree bole. an evaluation was made of the efficacy of bole injections of emamectin benzoate alone and combined with the fungicide propiconazole for protecting individual lodgepole pine, pinus contorta dougl. ex loud., from mortality attributed to colonization by mountain pine beetle, dendroctonus ponderosae hopkins, and progression of associated blue stain fun ...201423868360
mountain pine beetles colonizing historical and naive host trees are associated with a bacterial community highly enriched in genes contributing to terpene metabolism.the mountain pine beetle, dendroctonus ponderosae, is a subcortical herbivore native to western north america that can kill healthy conifers by overcoming host tree defenses, which consist largely of high terpene concentrations. the mechanisms by which these beetles contend with toxic compounds are not well understood. here, we explore a component of the hypothesis that beetle-associated bacterial symbionts contribute to the ability of d. ponderosae to overcome tree defenses by assisting with te ...201323542624
population densities and tree diameter effects associated with verbenone treatments to reduce mountain pine beetle-caused mortality of lodgepole pine.mountain pine beetle, dendroctonus ponderosae hopkins (coleoptera: curculionidae: scolytinae), is among the primary causes of mature lodgepole pine, pinus contorta variety latifolia mortality. verbenone is the only antiaggregant semiochemical commercially available for reducing mountain pine beetle infestation of lodgepole pine. the success of verbenone treatments has varied greatly in previous studies because of differences in study duration, beetle population size, tree size, or other factors. ...201323448035
transcriptome resources and functional characterization of monoterpene synthases for two host species of the mountain pine beetle, lodgepole pine (pinus contorta) and jack pine (pinus banksiana).the mountain pine beetle (mpb, dendroctonus ponderosae) epidemic has affected lodgepole pine (pinus contorta) across an area of more than 18 million hectares of pine forests in western canada, and is a threat to the boreal jack pine (pinus banksiana) forest. defence of pines against mpb and associated fungal pathogens, as well as other pests, involves oleoresin monoterpenes, which are biosynthesized by families of terpene synthases (tpss). volatile monoterpenes also serve as host recognition cue ...201323679205
the cytochromes p450 of grosmannia clavigera: genome organization, phylogeny, and expression in response to pine host chemicals.grosmannia clavigera is a fungal associate of the mountain pine beetle (dendroctonus ponderosae) and a pathogen of lodgepole pine (pinus contorta) that must overcome terpenoid oleoresin and phenolic defenses of host trees. g. clavigera responds to monoterpene influx with complementary mechanisms that include export and the use of these compounds as a carbon source. cytochromes p450 (cyps) may also be involved in the metabolism of host defense compounds. we have identified and phylogenetically cl ...201323111002
n2-fixation and seedling growth promotion of lodgepole pine by endophytic paenibacillus polymyxa.we inoculated lodgepole pine (pinus contorta var. latifolia (dougl.) engelm.) with paenibacillus polymyxa p2b-2r, a diazotrophic bacterium previously isolated from internal stem tissue of a naturally regenerating pine seedling to evaluate biological nitrogen fixation and seedling growth promotion by this microorganism. seedlings generated from pine seed inoculated with strain p2b-2r were grown for up to 13 months in a n-limited soil mix containing 0.7 mm available n labeled as ca((15)no3)2 to fa ...201323420205
grassland restoration with and without fire: evidence from a tree-removal experiment.forest encroachment threatens the biological diversity of grasslands globally. positive feedbacks can reinforce the process, affecting soils and ground vegetation, ultimately leading to replacement of grassland by forest species. we tested whether restoration treatments (tree removal, with or without fire) reversed effects of nearly two centuries of encroachment by abies grandis and pinus contorta into dry, montane meadows in the cascade range, oregon, usa. in nine, 1-ha plots containing a patch ...201222611845
the impact of phloem nutrients on overwintering mountain pine beetles and their fungal symbionts.in the low nutrient environment of conifer bark, subcortical beetles often carry symbiotic fungi that concentrate nutrients in host tissues. although bark beetles are known to benefit from these symbioses, whether this is because they survive better in nutrient-rich phloem is unknown. after manipulating phloem nutrition by fertilizing lodgepole pine trees (pinus contorta douglas var. latifolia), we found bolts from fertilized trees to contain more living individuals, and especially more pupae an ...201222732605
post-fire spatial patterns of soil nitrogen mineralization and microbial abundance.stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. however, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. the objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial ...201223226324
evolution of conifer diterpene synthases: diterpene resin acid biosynthesis in lodgepole pine and jack pine involves monofunctional and bifunctional diterpene synthases.diterpene resin acids (dras) are major components of pine (pinus spp.) oleoresin. they play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. the core structures of dras are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (ggpp) by diterpene synthases (ditpss). previously described gymnosperm ditpss of dra biosynthesis are bifunctional enzymes that catalyze the initial bic ...201223370714
characterizing the physical and genetic structure of the lodgepole pine × jack pine hybrid zone: mosaic structure and differential introgression.understanding the physical and genetic structure of hybrid zones can illuminate factors affecting their formation and stability. in north-central alberta, lodgepole pine (pinus contorta dougl. ex loud. var. latifolia) and jack pine (pinus banksiana lamb) form a complex and poorly defined hybrid zone. better knowledge of this zone is relevant, given the recent host expansion of mountain pine beetle into jack pine. we characterized the zone by genotyping 1998 lodgepole, jack pine, and hybrids from ...201223346232
the push-pull tactic for mitigation of mountain pine beetle (coleoptera: curculionidae) damage in lodgepole and whitebark pines.in an attempt to improve semiochemical-based treatments for protecting forest stands from bark beetle attack, we compared push-pull versus push-only tactics for protecting lodgepole pine (pinus contorta douglas ex loudon) and whitebark pine (pinus albicaulis engelm.) stands from attack by mountain pine beetle (dendroctonus ponderosae hopkins) in two studies. the first was conducted on replicated 4.04-ha plots in lodgepole pine stands (california, 2008) and the second on 0.81-ha plots in whitebar ...201223321106
consistency and variation in phenotypic selection exerted by a community of seed predators.phenotypic selection that is sustained over time underlies both anagenesis and cladogenesis, but the conditions that lead to such selection and what causes variation in selection are not well known. we measured the selection exerted by three species of predispersal seed predators of lodgepole pine (pinus contorta latifolia) in the south hills, idaho, and found that net selection on different cone and seed traits exerted by red crossbills (loxia curvirostra) and cone borer moths (eucosma recissor ...201223289569
spatiotemporal patterns of mountain pine beetle activity in the southern rocky mountains.the current mountain pine beetle (mpb; dendroctonus ponderosae) outbreak in the southern rocky mountains has impacted approximately 750 000 ha of forest. weather and habitat heterogeneity influence forest insect population dynamics at multiple spatial and temporal scales. comparison of forest insect population dynamics in two principal host species may elucidate the relative contribution of weather and landscape factors in initiating and driving extensive outbreaks. to investigate potential driv ...201223185879
dispersal of warren root collar weevils (coleoptera: curculionidae) in three types of habitat.warren root collar weevil, hylobius warreni wood, is a native, flightless insect distributed throughout the boreal forest of north america. it is an emerging problem in young plantings of lodgepole pine, pinus contorta variety latifolia, in western canada, where larval feeding can kill young trees by girdling the root collar. susceptible plantings are becoming more abundant following salvage harvesting and replanting activities in the wake of an ongoing epidemic of mountain pine beetle, dendroct ...201222732616
the legacy of attack: implications of high phloem resin monoterpene levels in lodgepole pines following mass attack by mountain pine beetle, dendroctonus ponderosae hopkins.the mountain pine beetle (dendroctonus ponderosae hopkins) is the most serious pest of pines (pinus) in western north america. host pines protect themselves from attack by producing a complex mixture of terpenes in their resin. we sampled lodgepole pine (pinus contorta variety latifolia) phloem resin at four widely separated locations in the interior of british columbia, canada, both just before (beginning of july) and substantially after (end of august) the mountain pine beetle dispersal period ...201222507014
comparing the impacts of mitigation and non-mitigation on mountain pine beetle populations.mountain pine beetles, dendroctonus ponderosae (hopkins) attack and can ultimately kill individuals and groups of pine trees, specifically lodgepole pine (pinus contorta dougl. ex. loud var. latifolia engl.). in british columbia, beetle attack has increased from 164 000 ha in 1999 to over 13 million ha in 2008. mitigation efforts can play a key role in addressing the impact beetle infestations can have on the forested landscape. in this research, the impact of mitigation on a mountain pine beetl ...201120855146
diversity and decay ability of basidiomycetes isolated from lodgepole pines killed by the mountain pine beetle.when lodgepole pines (pinus contorta douglas ex louden var. latifolia engelm. ex s. watson) that are killed by the mountain pine beetle (dendroctonus ponderosae) and its fungal associates are not harvested, fungal decay can affect wood and fibre properties. ophiostomatoids stain sapwood but do not affect the structural properties of wood. in contrast, white or brown decay basidiomycetes degrade wood. we isolated both staining and decay fungi from 300 lodgepole pine trees killed by mountain pine ...201121217795
growth, aboveground biomass, and nutrient concentration of young scots pine and lodgepole pine in oil shale post-mining landscapes in estonia.the investigation was carried out in 8-year-old scots pine (pinus sylvestris l.) and lodgepole pine (pinus contorta var. latifolia engelm.) plantations on post-mining area, northeast estonia. the aim of the study was to assess the suitability of lodgepole pine for restoration of degraded lands by comparing the growth, biomass, and nutrient concentration of studied species. the height growth of trees was greater in the scots pine stand, but the tree aboveground biomass was slightly larger in the ...201121374054
seed release in serotinous lodgepole pine forests after mountain pine beetle outbreak.there are concerns that large-scale stand mortality due to mountain pine beetle (mpb) could greatly reduce natural regeneration of serotinous rocky mountain (rm) lodgepole pine (pinus contorta var. latifolia) because the closed cones are held in place without the fire cue for cone opening. we selected 20 stands (five stands each of live [control], 3 years since mpb [3-yr-mpb], 6 years since mpb [6-yr-mpb], and 9 years since mpb [9-yr-mpb] mortality) in north central british columbia, canada. the ...201121516894
ecosystem, location, and climate effects on foliar secondary metabolites of lodgepole pine populations from central british columbia.lodgepole pines, pinus contorta douglas ex louden var. latifolia engelm. ex s. watson, are encountering increased abiotic stress and pest activity due to recent increases in temperature and changes in precipitation throughout their range. this tree species counters these threats by producing secondary metabolites, including phenolics and terpenoids. we examined foliar levels of lignin, soluble phenolics, monoterpenoids, sesquiterpenoids, and diterpenoids in 12 stands in british columbia, canada. ...201121537900
viability of forest floor and canopy seed banks in pinus contorta var. latifolia (pinaceae) forests after a mountain pine beetle outbreak.• premise of the study: seed banks are important for the natural regeneration of many forest species. most of the seed bank of serotinous lodgepole pine is found in the canopy, but after an outbreak of mountain pine beetle (mpb), a considerable forest-floor seed bank develops through the falling of canopy cones. after large-scale mortality of pine stands from mpb, however, the viability of seeds in both the canopy and the forest-floor cone bank is uncertain. • methods: we sampled cones in five s ...201121613163
low levels of population genetic structure in pinus contorta (pinaceae) across a geographic mosaic of co-evolution.• premise of the study: population genetic analyses provide information on the population context in which evolutionary processes operate and are important for understanding the evolution of geographically variable traits. earlier studies showed that cone structure of lodgepole pine in the rocky mountains diverged among populations because of geographic variation in coevolutionary interactions involving mammalian and avian seed predators. analyses of population genetic variation are needed to de ...201121613166
modeling lodgepole pine radial growth relative to climate and genetics using universal growth-trend response functions.forests strongly affect earth's carbon cycles, making our ability to forecast forest-productivity changes associated with rising temperatures and changes in precipitation increasingly critical. in this study, we model the influence of climate on annual radial growth using lodgepole pine (pinus contorta) trees grown for 34 years in a large provenance experiment in western canada. we use a random-coefficient modeling approach to build universal growth-trend response functions that simultaneously i ...201121639044
genetic variation of lodgepole pine, pinus contorta var. latifolia, chemical and physical defenses that affect mountain pine beetle, dendroctonus ponderosae, attack and tree mortality.plant secondary chemistry is determined by both genetic and environmental factors, and while large intraspecific variation in secondary chemistry has been reported frequently, the levels of genetic variation of many secondary metabolites in forest trees in the context of potential resistance against pests have been rarely investigated. we examined the effect of tree genotype and environment/site on the variation in defensive secondary chemistry of lodgepole pine, pinus contorta var. latifolia, a ...201121845434
survival and population size of a resident bird species are declining as temperature increases.1. a large number of migratory bird species appear to be declining as the result of climate change, but whether resident bird species have or will be adversely affected by climate change is less clear. we focus on the south hills crossbill (loxia curvirostra complex), which is endemic to about 70 km(2) of rocky mountain lodgepole pine (pinus contorta latifolia) forest in southern idaho, usa. 2. our results indicate that the south hills crossbill has declined by over 60% between 2003 and 2008, a ...201122010811
Cross-species transferability of SSR loci developed from transciptome sequencing in lodgepole pine.With the advent of next generation sequencing technologies, transcriptome level sequence collections are arising as prominent resources for the discovery of gene-based molecular markers. In a previous study more than 15 000 simple sequence repeats (SSRs) in expressed sequence tag (EST) sequences resulting from 454 pyrosequencing of Pinus contorta cDNA were identified. From these we developed PCR primers for approximately 4000 candidate SSRs. Here, we tested 184 of these SSRs for successful ampli ...201122171820
Effect of water stress and fungal inoculation on monoterpene emission from an historical and a new pine host of the mountain pine beetle.The mountain pine beetle (Dendroctonus ponderosae, MPB) has killed millions of lodgepole pine (Pinus contorta) trees in Western Canada, and recent range expansion has resulted in attack of jack pine (Pinus banksiana) in Alberta. Establishment of MPB in the Boreal forest will require use of jack pine under a suite of environmental conditions different from those it typically encounters in its native range. Lodgepole and jack pine seedlings were grown under controlled environment conditions and su ...201121874397
lodgepole pine: the first evidence of seed-based somatic embryogenesis and the expression of embryogenesis marker genes in shoot bud cultures of adult trees.of the various alternatives for cloning elite conifers, somatic embryogenesis (se) appears to be the best option. in recent years, significant areas of lodgepole pine (pinus contorta) forest have been devastated by the mountain pine beetle (mpb) in western canada. in an attempt to establish an se propagation system for mpb-resistant lodgepole pine, several families displaying varying levels of resistance were selected for experimentation involving shoot bud and immature seed explants. in bud cul ...201020935320
integrating environmental and genetic effects to predict responses of tree populations to climate.climate is a major environmental factor affecting the phenotype of trees and is also a critical agent of natural selection that has molded among-population genetic variation. population response functions describe the environmental effect of planting site climates on the performance of a single population, whereas transfer functions describe among-population genetic variation molded by natural selection for climate. although these approaches are widely used to predict the responses of trees to c ...201020349837
suitability of live and fire-killed small-diameter ponderosa and lodgepole pine trees for manufacturing a new structural wood composite.finding alternative uses for raw material from small-diameter trees is a critical problem throughout the united states. in western states, a lack of markets for small-diameter ponderosa pine (pinus ponderosa) and lodgepole pine (pinus contorta) can contribute to problems associated with overstocking. to test the feasibility of producing structural composite lumber (scl) beams from these two western species, we used a new technology called steam-pressed scrim lumber (spsl) based on scrimming tech ...201020378344
co-invasion by pinus and its mycorrhizal fungi.summary: *the absence of co-evolved mutualists of plants invading a novel habitat is the logical corollary of the more widely recognized 'enemy escape'. to avoid or overcome the loss of mutualists, plants may co-invade with nonnative mutualists, form novel associations with native mutualists or form associations with native cosmopolitan mutualists, which are native but not novel to the invading plant. *we tested these hypotheses by contrasting the ectomycorrhizal fungal communities associated wi ...201020456067
nitrogen concentration in mountain pine beetle larvae reflects nitrogen status of the tree host and two fungal associates.individual lodgepole pines (pinus contorta) were fertilized with urea at nitrogen (n) inputs equivalent to 0, 315, or 630 kg/ha. four months after application of the fertilizer, inner bark tissue n concentrations were significantly higher in the trees that had received the low dose (315 kg/ha) fertilization treatment than in the control trees; trees that had received the high-dose treatment (630 kg/ha) were intermediate and not significantly different from either of the other treatments. there w ...201020550794
seeing the forest through the trees: differential dispersal of hylobius warreni within modified forest habitats.hylobius warreni wood, also known as the warren root collar weevil, is a flightless insect that feeds on conifers throughout the boreal forests of canada. mature trees typically can withstand feeding, but larval feeding around the root collar may cause mortality to young trees. recently, a large outbreak of mountain pine beetle (dendroctonus ponderosae hopkins) has killed a high proportion of mature lodgepole pine (pinus contorta douglas variety latifolia) across british columbia, canada. this r ...201020550804
regulation of energy partitioning and alternative electron transport pathways during cold acclimation of lodgepole pine is oxygen dependent.second year needles of lodgepole pine (pinus contorta l.) were exposed for 6 weeks to either simulated control summer ['summer'; 25 °c/250 photon flux denisty (pfd)], autumn ('autumn'; 15°c/250 pfd) or winter conditions ('winter'; 5 °c/250 pfd). we report that the proportion of linear electron transport utilized in carbon assimilation (etr(co2)) was 40% lower in both 'autumn' and 'winter' pine when compared with the 'summer' pine. in contrast, the proportion of excess photosynthetic linear elect ...201020630988
antibodies raised against tobacco aquaporins of the pip2 class label viscin tissue of the explosive dwarf mistletoe fruit.dwarf mistletoes, genus arceuthobium, are parasitic flowering plants and forest pests. in western north america, arceuthobium americanum (lodgepole pine dwarf mistletoe) is principally found on pinus contorta var. latifolia (lodgepole pine). dwarf mistletoes disperse their seeds by an explosive process that involves the buildup of hydrostatic pressure within a mucilaginous fruit tissue called the 'viscin'. living viscin tissue envelops the discharged seeds. this study examined the possibility th ...201020653906
the effect of varying organosolv pretreatment chemicals on the physicochemical properties and cellulolytic hydrolysis of mountain pine beetle-killed lodgepole pine.mountain pine beetle-killed lodgepole pine (pinus contorta) chips were pretreated using the organosolv process, and their ease of subsequent enzymatic hydrolysis was assessed. the effect of varying pretreatment chemicals and solvents on the substrate's physicochemical characteristics was also investigated. the chemicals employed were mgcl2, h2so4, so2, and naoh, and the solvents were ethanol and butanol. it was apparent that the different pretreatments resulted in variations in both the chemical ...201019820908
weather and climate controls over the seasonal carbon isotope dynamics of sugars from subalpine forest trees.we examined the environmental variables that influence the delta(13)c value of needle and phloem sugars in trees in a subalpine forest. we collected sugars from pinus contorta, picea engelmannii and abies lasiocarpa from 2006 to 2008. phloem and needle sugars were enriched in (13)c during the autumn, winter and early spring, but depleted during the growing season. we hypothesized that the late-winter and early-spring (13)c enrichment was due to the mobilization of carbon assimilated the previous ...201019843259
ph affects ammonium, nitrate and proton fluxes in the apical region of conifer and soybean roots.the effect of ph on nitrate and ammonium uptake in the high-affinity transport system and low-affinity transport system ranges was compared in two conifers and one crop species. many conifers grow on acidic soils, thus their preference for ammonium vs nitrate uptake can differ from that of crop plants, and the effect of ph on nitrogen (n) uptake may differ. proton, ammonium and nitrate net fluxes were measured at seedling root tips and 5, 10, 20 and 30 mm from the tips using a non-invasive micro ...201019947965
hydraulic acclimation to shading in boreal conifers of varying shade tolerance.the purpose of this study was to determine how shading affects the hydraulic and wood-anatomical characteristics of four boreal conifers (pinus banksiana, pinus contorta, picea glauca and picea mariana) that differ in shade tolerance. plants were grown in an open field and under a deciduous-dominated overstory for 6 years. sapwood- and leaf-area specific conductivity, vulnerability curves, and anatomical measurements (light and scanning electron microscopy) were made on leading shoots from six t ...201019968826
freeze-thaw-induced embolism in pinus contorta: centrifuge experiments validate the 'thaw-expansion hypothesis' but conflict with ultrasonic emission data.*the 'thaw-expansion hypothesis' postulates that xylem embolism is caused by the formation of gas bubbles on freezing and their expansion on thawing. we evaluated the hypothesis using centrifuge experiments and ultrasonic emission monitoring in pinus contorta. *stem samples were exposed to freeze-thaw cycles at varying xylem pressure (p) in a centrifuge before the percentage loss of hydraulic conductivity (plc) was measured. ultrasonic acoustic emissions were registered on samples exposed to fre ...201020028475
growth-climate relationships vary with height along the stem in lodgepole pine.this study tests the hypothesis that ring growth in the upper stem portion of trees is affected by climatic conditions differently than rings formed at breast height (1.3 m). a total of 389 trees from a network of 65 lodgepole pine (pinus contorta dougl. ex loud. var. latifolia engelm.) sites in alberta were examined using detailed stem analysis in order to examine interannual patterns of basal area increment and volume increment at different positions along the stem. growth at lower sections of ...201020067911
take me to your leader: does early successional nonhost vegetation spatially inhibit pissodes strobi (coleoptera: curculionidae)?the spatial influences of host and nonhost trees and shrubs on the colonization patterns of white pine weevil pissodes strobi (peck) were studied within a stand of planted interior hybrid spruce [picea glauca (moench) voss x picea engelmannii (parry) ex engelm.]. planted spruce accounted for one third of all trees within the stand, whereas the remaining two thirds were comprised of early-successional nonhost vegetation, such as alder (alnus spp.), paper birch (betula papyrifera marsh.), black co ...200919689899
within-population genetic variability in mycorrhizal interactions.the geographic mosaic theory of coevolution hypothesizes that natural selection on species interactions varies among ecosystems, partly because the genes involved in species interactions differ in their fitness effects among environments. this selection mosaic may be expressed, at the extreme, as ecological outcomes ranging from mutualism to parasitism among environments. in a recent laboratory experiment on the interaction between a plant, bishop pine (pinus muricata), and a root-symbiotic ecto ...200919704904
environmental change controls postglacial forest dynamics through interspecific differences in life-history traits.a key goal of functional ecology is identifying relationships between species traits and environmental conditions. here, the nature and significance of these relationships to community composition on long ecological timescales is investigated using paleoecological and paleoenvironmental data from coastal british columbia, canada. rlq and fourth-corner analyses, two three-table statistical techniques, are used to link traits of the region's dominant woody plants to environmental conditions over t ...200919739377
a comparison of ammonium, nitrate and proton net fluxes along seedling roots of douglas-fir and lodgepole pine grown and measured with different inorganic nitrogen sources.significant spatial variability in nh4+, no3- and h+ net fluxes was measured in roots of young seedlings of douglas-fir (pseudotsuga menziesii) and lodgepole pine (pinus contorta) with ion-selective microelectrodes. seedlings were grown with nh4+, no3-, nh4no3 or no nitrogen (n), and were measured in solutions containing one or both n ions, or no n in a full factorial design. net no3- and nh4+ uptake and h+ efflux were greater in douglas-fir than lodgepole pine and in roots not exposed to n in p ...200818034773
the co-occurrence of ectomycorrhizal, arbuscular mycorrhizal, and dark septate fungi in seedlings of four members of the pinaceae.although roots of species in the pinaceae are usually colonized by ectomycorrhizal (em) fungi, there are increasing reports of the presence of arbuscular mycorrhizal (am) and dark septate endophytic (dse) fungi in these species. the objective of this study was to determine the colonization patterns in seedlings of three pinus (pine) species (pinus banksiana, pinus strobus, pinus contorta) and picea glauca x picea engelmannii (hybrid spruce) grown in soil collected from a disturbed forest site. s ...200818157555
use of temporal patterns in vapor pressure deficit to explain spatial autocorrelation dynamics in tree transpiration.to quantify the relationship between temporal and spatial variation in tree transpiration, we measured sap flow in 129 trees with constant-heat sap flow sensors in a subalpine forest in southern wyoming, usa. the forest stand was located along a soil water gradient from a stream side to near the top of a ridge. the stand was dominated by pinus contorta dougl. ex loud. with picea engelmannii parry ex engelm and abies lasiocarpa (hook.) nutt. present near the stream and scattered individuals of po ...200818244950
structure-activity relationships of phenylpropanoids as antifeedants for the pine weevil hylobius abietis.ethyl cinnamate has been isolated from the bark of pinus contorta in the search for antifeedants for the pine weevil, hylobius abietis. based on this lead compound, a number of structurally related compounds were synthesized and tested. the usability of the topliss scheme, a flow diagram previously used in numerous structure-activity relationship (sar) studies, was evaluated in an attempt to find the most potent antifeedants. the scheme was initially followed stepwise; subsequently, all compound ...200818311506
comparative analysis of the small rna transcriptomes of pinus contorta and oryza sativa.the diversity of micrornas and small-interfering rnas has been extensively explored within angiosperms by focusing on a few key organisms such as oryza sativa and arabidopsis thaliana. a deeper division of the plants is defined by the radiation of the angiosperms and gymnosperms, with the latter comprising the commercially important conifers. the conifers are expected to provide important information regarding the evolution of highly conserved small regulatory rnas. deep sequencing provides the ...200818323537
the bioconversion of mountain pine beetle-killed lodgepole pine to fuel ethanol using the organosolv process.lodgepole pine (pinus contorta) killed by mountain pine beetle (dendroctonus ponderosae) (blp) was compared with healthy lodgepole pine (hlp) for bioconversion to ethanol and high-value co-products. the blp and hlp chips were pretreated using an ethanol organosolv process at a variety of severities. it was shown that the blp was easier to pretreat and delignify than were the hlp chips. the resulting pretreated blp substrate had a lower residual lignin, lower degree of polymerization of cellulose ...200818421796
glacial vicariance in the pacific northwest: evidence from a lodgepole pine mitochondrial dna minisatellite for multiple genetically distinct and widely separated refugia.the canadian side of the pacific northwest was almost entirely covered by ice during the last glacial maximum, which has induced vicariance and genetic population structure for several plant and animal taxa. lodgepole pine (pinus contorta dougl. ex. loud.) has a wide latitudinal and longitudinal distribution in the pacific northwest. our main objective was to identify relictual signatures of glacial vicariance in the population structure of the species and search for evidence of distinct glacial ...200818430147
spray deposition from ground-based applications of carbaryl to protect individual trees from bark beetle attack.bark beetles (coleoptera: curculionidae, scolytinae) are recognized as the most important tree mortality agent in western coniferous forests. a common method of protecting trees from bark beetle attack is to saturate the tree bole with carbaryl (1-naphthyl methylcarbamate) using a hydraulic sprayer. in this study, we evaluate the amount of carbaryl drift (ground deposition) occurring at four distances from the tree bole (7.6, 15.2, 22.9, and 38.1 m) during conventional spray applications for pro ...200818453436
tracking monolignols during wood development in lodgepole pine.secondary xylem (wood) formation in gymnosperms requires that the tracheid protoplasts first build an elaborate secondary cell wall from an array of polysaccharides and then reinforce it with lignin, an amorphous, three-dimensional product of the random radical coupling of monolignols. the objective of this study was to track the spatial distribution of monolignols during development as they move from symplasm to apoplasm. this was done by feeding [(3)h]phenylalanine ([(3)h]phe) to dissected cam ...200818550683
conifers have a unique small rna silencing signature.plants produce small rnas to negatively regulate genes, viral nucleic acids, and repetitive elements at either the transcriptional or post-transcriptional level in a process that is referred to as rna silencing. while rna silencing has been extensively studied across the different phyla of the animal kingdom (e.g., mouse, fly, worm), similar studies in the plant kingdom have focused primarily on angiosperms, thus limiting evolutionary studies of rna silencing in plants. here we report on an unex ...200818566193
defoliation effects on enzyme activities of the ectomycorrhizal fungus suillus granulatus in a pinus contorta (lodgepole pine) stand in yellowstone national park.ectomycorrhizal (em) basidiomycete fungi are obligate mutualists of pines and hardwoods that receive fixed c from the host tree. though they often share most recent common ancestors with wood-rotting fungi, it is unclear to what extent em fungi retain the ability to express enzymes that break down woody substrates. in this study, we tested the hypothesis that the dominant em fungus in a pure pine system retains the ability to produce enzymes that break down woody substrates in a natural setting, ...200818679722
on the relative contributions of wind vs. animals to seed dispersal of four sierra nevada pines.selective pressures that influence the form of seed dispersal syndromes are poorly understood. morphology of plant propagules is often used to infer the means of dispersal, but morphology can be misleading. several species of pines, for example, have winged seeds adapted for wind dispersal but owe much of their establishment to scatter-hoarding animals. here the relative importance of wind vs. animal dispersal is assessed for four species of pines of the eastern sierra nevada that have winged se ...200818705371
synergistic blends of monoterpenes for aggregation pheromones of the mountain pine beetle (coleoptera: curculionidae).the superiority of the host monoterpene myrcene as a synergist for trans-verbenol and exo-brevicomin, aggregation pheromone components of the mountain pine beetle, dendroctonus ponderosae hopkins (coleoptera: curculionidae), suggests that the ancestral host of the mountain pine beetle is a pine rich in myrcene. a field trapping experiment in british columbia testing reconstituted bole oleoresin of whitebark pine, pinus albicaulis engelmann, composed of mainly myrcene (20.7%), terpinolene (6.8%), ...200818767736
influences of secondary disturbances on lodgepole pine stand development in rocky mountain national park.although high-severity fire is the primary type of disturbance shaping the structure of lodgepole pine (pinus contorta) stands in the southern rocky mountains, many post-fire stands are also affected by blowdown, low-severity surface fires, and/or outbreaks of mountain pine beetle (mpb; dendroctonus ponderosae). the ecological effects of these secondary disturbances are poorly understood but are potentially important in the context of managing for ecological restoration and fire hazard mitigatio ...200717913129
a coevolutionary arms race causes ecological speciation in crossbills.we examined three ecological factors potentially causing premating reproductive isolation to determine whether divergent selection as a result of coevolution between south hills crossbills (loxia curvirostra complex) and rocky mountain lodgepole pine (pinus contorta latifolia) promotes ecological speciation. one factor was habitat isolation arising because of enhanced seed defenses of lodgepole pine in the south hills. this caused the crossbill call types (morphologically and vocally differentia ...200717273981
generation and annotation of lodgepole pine and oleoresin-induced expressed sequences from the blue-stain fungus ophiostoma clavigerum, a mountain pine beetle-associated pathogen.ophiostoma clavigerum is a destructive pathogen of lodgepole pine (pinus contorta) forests in western north america. it is therefore a relevant system for a genomics analysis of fungi vectored by bark beetles. to begin characterizing molecular interactions between the pathogen and its conifer host, we created an expressed sequence tag (est) collection for o. clavigerum. lodgepole pine sawdust and oleoresin media were selected to stimulate gene expression that would be specific to this host inter ...200717328114
nitrogen fixation associated with suillus tomentosus tuberculate ectomycorrhizae on pinus contorta var. latifolia.tuberculate ectomycorrhizae are a unique form of ectomycorrhiza where densely packed clusters of mycorrhizal root tips are enveloped by a thick hyphal sheath to form a tubercle. the functional significance of such a unique structure has not previously been established. the purpose of the present study was to investigate and measure the potential nitrogenase activity associated with suillus tomentosus/pinus contorta tuberculate ectomycorrhizae in two stand ages, young and old, and across a range ...200717468111
controls of growth phenology vary in seedlings of three, co-occurring ecologically distinct northern conifers.the objective of this study was to investigate the effects of temperature and seed-source elevation on height-growth phenology of three co-occurring and ecologically distinct northern conifers (pinus contorta dougl. ex loud. var. latifolia (lodgepole pine), picea glauca (moench) voss x picea engelmannii parry ex engelm. (interior spruce) and abies lasiocarpa (hook.) nutt. (subalpine fir)). seed from populations of the three indigenous and co-occurring species was collected across an elevational ...200717472945
reconciling divergent interpretations of quaking aspen decline on the northern colorado front range.ecologists have debated over the past 65 years whether quaking aspen (populus tremuloides michx.) has or has not declined in abundance, vigor, or regeneration in western north america. many studies have provided divergent interpretations of the condition of aspen forests, leading to difficulty in translating this ecological information into management recommendations. to reconcile these contrasting conclusions and to test the hypothesis that multiple types of aspen decline and persistence occur ...200717708209
regional heterogeneity and gene flow maintain variance in a quantitative trait within populations of lodgepole pine.genetic variation is of fundamental importance to biological evolution, yet we still know very little about how it is maintained in nature. because many species inhabit heterogeneous environments and have pronounced local adaptations, gene flow between differently adapted populations may be a persistent source of genetic variation within populations. if this migration-selection balance is biologically important then there should be strong correlations between genetic variance within populations ...200616769628
arabidopsis thaliana beta-glucosidases bglu45 and bglu46 hydrolyse monolignol glucosides.in higher plants, beta-glucosidases belonging to glycoside hydrolase (gh) family 1 have been implicated in several fundamental processes including lignification. phylogenetic analysis of arabidopsis thaliana gh family 1 has revealed that at1g61810 (bglu45), at1g61820 (bglu46), and at4g21760 (bglu47) cluster with pinus contorta coniferin beta-glucosidase, leading to the hypothesis that their respective gene products may be involved in lignification by hydrolysing monolignol glucosides. to test th ...200616814332
reducing stem bending increases the height growth of tall pines.the hypothesis was tested that upper limits to height growth in trees are the result of the increasing bending moment of trees as they grow in height. the increasing bending moment of tall trees demands increased radial growth at the expense of height growth to maintain mechanical stability. in this study, the bending moment of large lodgepole pine (pinus contorta dougl. ex loud. var. latifolia engelm.) was reduced by tethering trees at 10 m height to counter the wind load. average bending momen ...200616908504
replicated population divergence caused by localized coevolution? a test of three hypotheses in the red crossbill-lodgepole pine system.several lines of evidence support the hypothesis that local populations of red crossbills (loxia curvirostra complex) enter into a predator-prey arms race with lodgepole pine (pinus contorta latifolia) in the absence of competing pine squirrels (tamiasciurus hudsonicus). nevertheless, the alternative hypotheses that neutral evolution or factors other than squirrels have caused crossbill population differentiation have not been thoroughly tested. we compared crossbill and pine cone morphology bet ...200616910994
effectiveness of bifenthrin (onyx) and carbaryl (sevin sl) for protecting individual, high-value conifers from bark beetle attack (coleoptera: curculionidae: scolytinae) in the western united states.high-value trees, such as those located in residential, recreational, or administrative sites, are particularly susceptible to bark beetle (coleoptera: curculionidae: scolytinae) attack as a result of increased amounts of stress associated with drought, soil compaction, mechanical injury, or vandalism. tree losses in these unique environments generally have a substantial impact. the value of these individual trees, cost of removal, and loss of esthetics may justify protection until the main thru ...200617066800
analysis of freeze-thaw embolism in conifers. the interaction between cavitation pressure and tracheid size.ice formation in the xylem sap produces air bubbles that under negative xylem pressures may expand and cause embolism in the xylem conduits. we used the centrifuge method to evaluate the relationship between freeze-thaw embolism and conduit diameter across a range of xylem pressures (px) in the conifers pinus contorta and juniperus scopulorum. vulnerability curves showing loss of conductivity (embolism) with px down to -8 mpa were generated with versus without superimposing a freeze-thaw treatme ...200616377751
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