Search Results (82)

Lodgepole pine (Pinus contorta Dougl.) exhibits pronounced morphological variation across its range, historically attributed to allopatric differentiation during the Wisconsin glaciation. However, whether genetic divergence aligns with morphological differentiation—a fundamental prediction of allopatric speciation theory—remains untested. We conducted a comprehensive phylogeographic analysis of chloroplast DNA (trnL intron and trnL/trnF spacer) and mitochondrial DNA (nad1 b/c intron) across 31 populations representing all four recognized subspecies to test hypotheses of refugial isolation and to evaluate the genetic basis of current taxonomic classification. Contrary to predictions of allopatric divergence, both organellar genomes showed striking genetic uniformity (π = 0.000178–0.000186; intersubspecific genetic distances: 1.06 × 10⁻⁴ to 3.96 × 10⁻⁴) with no phylogenetic structure corresponding to morphological boundaries. Significant negative neutrality test values (Tajima’s D = −2.26, p < 0.02; Fu and Li’s D* = −4.52, p < 0.02) suggest recent demographic expansion rather than equilibrium divergence. A distinctive 5 bp indel in coastal populations provides molecular evidence for a northern Pacific refugium, and its occurrence in interior populations is consistent with post-glacial pollen-mediated gene flow, though this directionality remains inferential pending nuclear genomic confirmation. These findings suggest that morphological divergence reflects rapid adaptive evolution in heterogeneous environments rather than deep phylogenetic divisions. This pattern exemplifies gene flow-selection balance, in which divergent selection maintains local adaptation despite extensive gene flow—supporting an ecotypic rather than a phylogenetic interpretation of intraspecific diversity. The persistence of morphological variation despite genetic homogeneity indicates strong selection on ecologically important traits, likely driven by variation in fire regimes, differential seed predation, and climate gradients. These results have critical implications for understanding adaptive evolution rates in widespread conifers and for developing conservation strategies that emphasize adaptive processes over taxonomic categories. Full article

The diversity of foliar fungal endophyte communities was examined in three economically and ecologically important pine species in Scotland: Scots pine, Corsican pine and lodgepole pine. Two plantation sites comprising all three species were selected in climatically contrasting parts of Scotland and were sampled in late spring by collecting healthy needles from two age classes. Surface sterilisation was carried out before obtaining cultures of fungal isolates, and representatives of common sterile morphotypes were sequenced to determine taxonomic placement. Overall relative proportions of the dominant taxa across sites, tree species and needle age classes were as follows: Anthostomella spp. (52%), Lophodermium seditiosum (17%) and Desmazierella acicola (7%). Many other less frequent taxa were recovered. The results agreed with previous endophyte studies in that the combined effects of site and tree species produced unique endophytic fungal assemblages. Phylogenetic analyses revealed potential sub-species variation associated with site in Anthostomella pinea. Our findings point to the potential naturalisation of European fungal endophytic species (e.g., Anthostomella spp.) in Scottish pine plantations, particularly in association with Corsican pine. Full article

Research Highlights: We report a 45-year time-line of forest restoration after harvesting and responses of red-backed voles (Myodes gapperi), an indicator species of closed-canopy forests. Background and Objectives: We have a unique long-term window to test four hypotheses that evaluated the relationship of M. gapperi with old forest structural attributes. Materials and Methods: The study began in old-growth lodgepole pine (Pinus contorta var. latifolia) through clearcutting, regeneration, stand thinning, fertilization, and growth to mature forest (1979 to 2024) in southern BC, Canada. Populations of red-backed voles were monitored in all phases of forest restoration. Results: Clearcutting resulted in the extirpation of M. gapperi followed by small (≤2 voles/ha) populations in young (13–23 years) thinned and fertilized stands. At age 33, the mean annual abundance of M. gapperi (6.5 to 8.7/ha) was highest in the heavily thinned and old-growth stands. At age 43, mean numbers of M. gapperi ranged from 2.7 to 4.2/ha in these same stands. Heavily thinned stands had large trees, multi-layered canopies of conifers, and understory patchiness. Conclusions: This is the first report of long-term responses of M. gapperi to the restoration of mature forest. M. gapperi is a suitable species for monitoring the recovery of some old forest structural features. Full article

Subcortical beetle communities interact with a wide range of semiochemicals released from different sources, including trees, fungi, and bark beetle pheromones. While the attraction of bark beetles, their insect predators, and competitors to bark beetle pheromones is commonly studied, the attraction of these beetle communities to other sources of semiochemicals remains poorly understood. We tested the attraction of bark and wood-boring beetles and their predators to host stress volatiles, fungal volatiles, and a mountain pine beetle lure in the field. Host stress volatiles were derived from lodgepole pine trees stressed by three fungal symbionts of mountain pine beetle and two common phytopathogens. Our results showed that bark beetles, particularly mountain pine beetles, show a preference for a combination of fungal volatiles, particularly 2-methyl-1-butanol and its lures. Without the addition of lures, 2-methyl-1-butanol was also identified as a key fungal volatile in the attraction of mountain pine beetle competitors from the Cerambycidae and Buprestidae families. Predators in the Elateridae and Staphylinidae families showed attraction to host stress volatiles and the healthy tree volatile profiles. These findings suggest that these semiochemicals warrant further field testing for potential use in monitoring and management of subcortical beetle populations. Full article

This study quantifies the transpiration of encroached lodgepole pine (Pinus contorta var. murryana (Grev. & Balf.) Engelm.) in a montane meadow using pre-restoration sap-flow measurements. Lodgepole pine transpiration and its response to environmental variables were examined in Rock Creek Meadow (RCM), Southern Cascade Range, CA, USA. Sap-flow data from lodgepole pines were scaled to the meadow using tree survey data and then validated with MODIS evapotranspiration estimates for the 2019 and 2020 growing seasons. A modified Jarvis–Stewart model calibrated to 2020 sap-flow data analyzed lodgepole pine transpiration’s correlation with solar radiation, air temperature, vapor pressure deficit, and soil volumetric water content. Model validation utilized 2021 growing season sap-flow data. Calibration and validation employed a Markov Chain Monte Carlo (MCMC) approach through the DREAM_(ZS) algorithm with a generalized likelihood (GL) function, enabling parameter and total uncertainty assessment. The model’s scaling was compared with simple scaling estimates. Average lodgepole pine transpiration at RCM ranged between 220.6 ± 25.3 and 393.4 ± 45.7 mm for the campaign (mid-July 2019 to mid-August 2020) and 100.2 ± 11.5 to 178.8 ± 20.7 mm for the 2020 partial growing season (April to mid-August), akin to MODIS ET. The model aligned well with observed normalized sap-velocity during the 2020 growing season (RMSE = 0.087). However, sap-velocity, on average, was underpredicted by the model (PBIAS = −6.579%). Model validation mirrored calibration in performance metrics (RMSE = 0.1233; PBIAS = −2.873%). The 95% total predictive uncertainty confidence intervals generated by GL-DREAM_(ZS) enveloped close to the theoretically expected 95% of total observations for the calibration (94.5%) and validation (81.8%) periods. The performance of the GL-DREAM_(ZS) approach and uncertainty assessment in this study shows promise for future MJS model applications, and the model-derived 2020 transpiration estimates highlight the MJS model utility for scaling sap-flow measurements from individual trees to stands of trees. Full article

The recent mountain pine beetle outbreaks have caused widespread mortality among lodgepole pine trees in western North America, resulting in a reduced population of surviving trees. While previous studies have focused on the cascading impacts of these outbreaks on the physiology and growth of the surviving trees, there remains a need for a comprehensive study into the interactions among various physiological traits and the growth in post-outbreak stands. Specifically, the relationship between chemical (primarily terpenes) and anatomical (mainly resin ducts) defences, as well as the allocation of non-structural carbohydrates (NSCs) to support these defence modalities, is poorly understood. To address these gaps, we conducted a field survey of surviving lodgepole pine trees in post-mountain pine beetle outbreak stands in western Canada. Our retrospective analysis aimed at determining correlations between the post-outbreak concentrations of monoterpenes, diterpenes, and NSCs in the phloem and the historical resin duct characteristics and growth traits before and after the outbreak. We detected strong correlations between the post-outbreak concentrations of monoterpenes and historical resin duct characteristics, suggesting a possible link between these two defence modalities. Additionally, we found a positive relationship between the NSCs and the total concentrations of monoterpenes and diterpenes, suggesting that NSCs likely influence the production of these terpenes in lodgepole pine. Furthermore, historical tree growth patterns showed strong positive correlations with many individual monoterpenes and diterpenes. Interestingly, while surviving trees had enhanced anatomical defences after the outbreak, their growth patterns did not vary before and after the outbreak conditions. The complexity of these relationships emphasizes the dynamics of post-outbreak stand dynamics and resource allocations in lodgepole pine forests, highlighting the need for further research. These findings contribute to a broader understanding of conifer defences and their coordinated responses to forest insect outbreaks, with implications for forest management and conservation strategies. Full article

Scots pine (Pinus sylvestris L.) represents one of the most important commercial coniferous tree species, providing valuable timber. Due to climate change, it is experiencing serious problems in some areas, therefore, finding a suitable substitute for its wood is currently a challenge. In this study, we compared the wood quality of three different non-native pine species and Scots pine growing at the same site to ensure identical growing conditions. Black pine (Pinus nigra J. F. Arnold), a pine species native to Southern Europe, lodgepole pine (Pinus contorta Douglas ex Loudon), and ponderosa pine (Pinus ponderosa Douglas ex C. Lawson) native to North America were compared to Scots pine for selected quantitative (productivity) and qualitative (physical and mechanical) properties. Significant differences between pine species were found in all quantitative dendrometric parameters, except average diameter at breast height. The stand volume ranged from 157 m³ ha⁻¹ for lodgepole pine to 356 m³ ha⁻¹ for Scots pine. For qualitative characteristics, wood density, shrinkage, and compressive strength were used to find differences among species in choosing the best alternative. The highest wood density was obtained for Scots pine (458 kg m⁻³), followed by black pine with 441 kg m⁻³. The density of the remaining pine species was significantly lower. Scots pine also exceeded the tested species in compressive strength (44.2 MPa). Lodgepole pine achieved the second highest value (39.3 MPa) but was statistically similar to black pine (36.5 MPa). The tested pine species exhibited similar values in shrinkage, which were statistically insignificant, ranging from 14.3% for lodgepole pine to 15.1% for Scots pine. Based on applications and preferred characteristics, black pine or lodgepole pine could serve as the Scots pine substitute in some areas. And vice versa, ponderosa pine did not attain the Scots pine wood quality. Full article

Winter storage of seedlings in freezers reduces the amount of heat sum available for growth in the following growing season compared to seedlings stored outdoors. To test the effects of a reduced growing period on the autumn frost hardiness of the six species most used in Icelandic afforestation, seedlings were stored outdoors or in a freezer during winter. In spring, the seedlings were planted on 24 May, 7 June, 21 June, and 5 July, and the frost hardiness of all treatments was tested on 12 and 26 September. In general, the probability of freezing damage increased with a later planting date, with outdoor-stored seedlings having the lowest probability of damage. The timing of frost events was of great importance; the later the freezing date, the less damage was observed. Growth cessation occurred at different times for each species, and they responded differently to the reduced heat sum. Lodgepole pine and birch accumulated the most frost hardiness in September. Sitka spruce had less autumn frost hardiness than Lutz spruce. Hybrid larch accumulated less frost hardiness than Russian larch and was most sensitive to the reduced heat sum. The results can be used to determine which species should be prioritised in frozen storage with regard to Iceland‘s short growing season. Full article

Alberta’s forest industry is predicted to be impacted by a medium-term decline in timber supply. Intensive silviculture tools, such as pre-commercial thinning, have been shown to increase individual tree growth, shorten rotation lengths, and improve stand merchantability in important commercial species such as lodgepole pine. However, lodgepole pine stands are susceptible to western gall rust infections, and thinning at an early stage may increase infection rates. This study collected tree and stand level data from 33 operational harvest origin lodgepole pine stands consisting of 11 stands thinned at age 17–19 years (PCT_18), 11 stands thinned at age 23–25 (PCT_24), and 11 unthinned stands. Approximately 40 years after pre-commercial thinning, merchantable volume is similar in all stands but thinned stands, regardless of timing, had greater individual tree size (~15% higher) compared to unthinned stands. Pre-commercially thinned stands also had a higher potential for commercial thinning since they have lower variability in tree size and longer live crown lengths. In addition, delayed thinning (PCT_24) reduced western gall rust infections and the severity of infections compared to both PCT_18 and unthinned stands. In conclusion, pre-commercial thinning should be considered for lodgepole pine stands in order to address timber supply issues in Alberta. Full article

Globally, in remaining wildlands, tree densities and forested cover have increased in grasslands and open forests since European settlement. In the southern Rocky Mountains of Colorado, United States, we determined tree composition and tree cover from historical (years 1875 to 1896) surveys and compared them to current (2002 to 2011) tree composition and current (year 2016) forested land cover for 500,000 ha of the Routt National Forest. Additionally, we examined whether changes in precipitation occurred. Regarding composition, pine (primarily lodgepole pine; Pinus contorta) decreased from 65% to 32% of all trees, with increased subalpine fir (Abies lasiocarpa) from 0.5% to 23% of all trees, and quaking aspen (Populus tremuloides) from 13% to 30% of all trees. According to 80% of 5175 survey points not in forests, the historical landscape was very open, comprised of grasslands, mountain meadows, and other open ecosystems. In contrast, 75% of the current landscape is covered by forests. Change points in the Palmer Modified Drought Index were within historical limits, indicating that forestation was not related to a change in water availability. Based on historical surveys and accounts, we envisioned a historical landscape that was open but embedded with dense lodgepole pine clusters and spruce stands at high elevations, which has now become a predominantly forested landscape of dense forests, similar to global forestation patterns. Full article

The boreal forest of northwestern North America covers an extensive area, contains vast amounts of carbon in its vegetation and soil, and is characterized by extensive wildfires. Catastrophic crown fires in these forests are fueled predominantly by only two evergreen needle-leaf tree species, black spruce (Picea mariana (Mill.) B.S.P.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.). Identifying where these flammable species grow through time in the landscape is critical for understanding wildfire risk, damages, and human exposure. Because medium resolution landcover data that include species detail are lacking, we developed a compound modeling approach that enabled us to refine the available evergreen forest category into highly flammable species and less flammable species. We then expanded our refined landcover at decadal time steps from 1984 to 2014. With the aid of an existing burn model, FlamMap, and simple succession rules, we were able to predict future landcover at decadal steps until 2054. Our resulting land covers provide important information to communities in our study area on current and future wildfire risk and vegetation changes and could be developed in a similar fashion for other areas. Full article

Burn severity is commonly assessed using Burn Ratios and field measurements to provide land managers with estimates of the degree of burning in an area. However, less commonly studied is the ability of spectral indices and Burn Ratios to estimate field-measured fire effects. Past research has shown low correlations between fire effects and Landsat-derived Burn Ratios, but with the launch of the Sentinel-2 constellation, more spectral bands with finer spatial resolutions have become available. This paper explores the use of several red-edge-based indices and Burn Ratios alongside more ‘traditional’ spectral indices for predicting fire effects, measured from the Maple and Berry fires in Wyoming, USA. The fire effects include ash depth, char depth, post-fire dead lodgepole pine (Pinus contorta; PICO) density/stumps, mean basal diameter, cone density on dead post-fire trees, coarse wood percent cover/volume/mass, percent cover of ghost logs and initial regeneration of post-fire PICO/aspen density. All-possible-models regression was used to determine the best models for estimating each fire effect. Models with satisfactory R² values were constructed for post-fire dead PICO stumps (0.663), coarse wood percent cover (0.691), coarse wood volume (0.833), coarse wood mass (0.838), ash depth (0.636) and percent cover of ghost logs (0.717). Red-edge-based indices were included in all of the satisfactory models, which shows that the red-edge bands may be useful for measuring fire effects. Full article

A significant portion of the harvested land base in western Canada is becoming old enough or entering a phase where thinning is a legitimate forest management option. A comprehensive review of the existing knowledge of commercial thinning (CT) treatments applied to pine and spruce-dominated stands in Alberta was conducted, with particular regard to the intensity, timing of interventions, method, and impacts on crop tree growth responses. Although the geographical focus of this review is Alberta, information on this topic is more complete in other areas of North America and Europe, where there is a long history of density management. In areas of eastern North America, our review revealed that CT from below, with tree removal levels from 27 to 43% of the basal area, could increase total merchantable wood produced from 11 to 60 m³ ha⁻¹ over a rotation, depending on stand age and intensity of thinning. For Alberta conditions, and considering the risks, we conclude that commercial thinning basal area removal should be in the range of 25 to 40%, depending on a variety of factors such as species, wind firmness, and insect or disease incidence and risk. Thinning too aggressively and/or too late will increase the blowdown risk but the literature is fairly consistent in suggesting that live crown ratios should be >40% to maximize the chance of growth response and minimize the blowdown risk. In cases where stands are also threatened by stressors such as drought, wind, and insect or disease outbreaks, CT treatments likely offer the potential at limiting the overall risk, but localized knowledge and experience are critical. It is intended that the information presented may support ongoing and future research trials and growth and yield (G&Y) model development about potential CT treatments to apply and the likely results of practical application to commercial forestry. Full article

In the event of an abrupt sunlight reduction scenario, there is a time window that occurs between when food stores would likely run out for many countries (~6 months or less) and ~1 year when resilient foods are scaled up. A promising temporary resilient food is leaf protein concentrate (LPC). Although it is possible to extract LPC from tree biomass (e.g., leaves and needles), neither the yields nor the toxicity of the protein concentrates for humans from the most common tree species has been widely investigated. To help fill this knowledge gap, this study uses high-resolution mass spectrometry and an open-source toolchain for non-targeted screening of toxins on five common North American coniferous species: Western Cedar, Douglas Fir, Ponderosa Pine, Western Hemlock, and Lodgepole Pine. The yields for LPC extraction from the conifers ranged from 1% to 7.5%. The toxicity screenings confirm that these trees may contain toxins that can be consumed in small amounts, and additional studies including measuring the quantity of each toxin are needed. The results indicate that LPC is a promising candidate to be used as resilient food, but future work is needed before LPCs from conifers can be used as a wide-scale human food. Full article

The positive effect of thinning on individual tree growth is well known, but the subsequent growth dynamics of individual trees over a rotation is relatively unknown, even though this is critical for interpreting actual thinning effects. Therefore, in this study, we aimed to investigate the thinning response of individual tree growth dynamics of lodgepole pine (Pinus contorta var. latifolia) over rotation using an individual tree growth model. We used data from an operational site to use as input to the Mixedwood Growth Model, an individual tree growth model, to simulate tree growth throughout the rotation. Overall, we found that thinning increased the absolute growth of individual trees and reduced the growth heterogeneity throughout the rotation. Combining pre-commercial thinning prior to commercial thinning provided maximum growth and less growth variability in individual trees. The positive effect of thinning was immediate and declined with time since thinning with most of the responses occurred within the first 10–15 years of thinning. Full article