Mountain Pine Research Articles

Drivers of forest aboveground biomass and its increments in the Tatra Mountains after 15 years

The stands and soils of forest ecosystems are one of the most important carbon sinks in the terrestrial environment; thus, proper estimation of forest biomass increment is crucial to understand the rate of atmospheric CO2 sequestration. Here, we propose a biomass and biomass increment estimation methodology using forest inventory data from 1991 to 2006 from the Tatra National Park (TNP), Western Carpathians, Poland. Using machine learning techniques (random forest), we showed, for the first time, that stand age, the proportion of Abies alba, Picea abies, and Pinus mugo, and elevation are the most important predictors of aboveground stand biomass. Stand biomass increment is driven by the proportion of P. mugo, A. alba, and P. abies, stand age, elevation, and valley depth. Our results showed that the primary drivers of forest biomass (stand age and species composition) could be modified by the geomorphic properties of the terrain, indicating their importance in the mitigation of negative climate change trends in forest landscapes. Additionally, we showed that the biomass increment assessment using repeated measurements differed from trends of age-based biomass models, indicating the need to consider site-specific factors (e.g., slope and aspect). The potential applicability of these results improves the accuracy of carbon budget modeling and supports decision-making in nature conservation and forest management.

De novo transcriptome analysis and identification of reproduction control genes from the red palm weevil Rhynchophorus ferrugineus.

Recent attacks by the red palm weevil, Rhynchophorus ferrugineus (Olivier), have become a severe problem for palm species. In present work, fat body transcriptome of adult female red palm weevil was analyzed, focusing on the identification of reproduction control genes. Transcriptome study was completed by means of next-generation sequencing (NGS) using Illumina Hiseq 2000 sequencing system. A total of 105,938,182 raw reads, 102,645,544 clean reads, and 9,238,098,960 clean nucleotides with a guanine–cytosine content of 40.31%, were produced. The processed transcriptome data resulted in 43,789 unique transcripts (with mean lengths of 1,172 bp). It was found that 20% of total unique transcripts shared up to 80%–100% sequence identity with homologous species, mainly the mountain pine beetle Dendroctonus ponderosae (59.9%) and red flour beetle Tribolium castaneum (26.9%). Nearly 25 annotated genes were predicted to be involved in red palm weevil reproduction, including five vitellogenin (Vg) transcripts. Among the five Vg gene transcripts, one was highly expressed compared with the other four (FPKM values of 1.963, 1.471, 1.028, and 1.017, respectively), and the five Vg gene transcripts were designated as RfVg, RfVg-equivalent1, RfVg-equivalent2, RfVg-equivalent3, and RfVg-equivalent4, respectively. The high expression level of RfVg verified by RT-polymerase chain reaction analysis suggested that RfVg is the primary functional Vg gene in red palm weevil. A high similarity of RfVg with other Coleopterans was also reflected in a phylogenetic tree, where RfVg was placed within the clade of the order Coleoptera. Awareness of the major genes that play critical roles in reproduction and proliferation of red palm weevil is valuable to understand their reproduction mechanism at a molecular level. In addition, for future molecular studies, the NGS dataset obtained will be useful and will promote the exploration of biotech-based control strategies against red palm weevil, a primary pest of palm trees.

Environmental factors influencing the distribution of habitat types in the highlands of the Kamnik − Savinja Alps

In this work, we investigated the relationship between habitat types (HTs) and selected environmental factors in the highlands at altitudes of 1800–2558 m in the Kamnik-Savinja (KS) Alps in Slovenia. For 275 sampling sites, we identified seven HTs in their typical form and 11 ecotones, and provided field and modelled data for 14 environmental factors. HTs-environment relationships were analysed using multivariate ordination methods. In addition, binomial generalised linear mixed models were applied to reveal the influence of environmental factors on the occurrence of most frequent HTs in the study area [Outer Alpine Pinus mugo scrub (EUNIS code F2.4/Natura 2000 code 4070*), Southern rusty sedge grasslands (E4.413/6170), Cushion sedge carpets (E4.433/6170) and Fine calcareous screes (H2.43/8120)]. Results showed that certain modelled data (e.g. average annual air temperature) combined with field measurements (e.g. inclination, soil surface and soil moisture) can be effective predictors of most representative HTs in the study area, and thus useful for further refining of monitoring. Our study contributes to the knowledge and understanding of the relationships between environmental conditions and the occurrence of highland HTs in KS Alps, which probably concerns a great part of the Alpine highlands. Such knowledge is essential for assessing credible long-term conservation planning.

Growth, Chemistry, and Genetic Profiles of Whitebark Pine Forests Affected by Climate-Driven Mountain Pine Beetle Outbreaks

Climate change-driven Dendroctonus ponderosae outbreaks in semi-naïve Pinus albicaulis may result in rapid natural selection for trees with genotypes and phenotypes associated with survival. In this study, we investigated whether survivors were genetically and chemically different from a living cohort of trees that escaped predation due to smaller size and estimated genetic diversity. We also examined how growth rate and climate sensitivity varied between beetle-killed and surviving trees. Dendroctonus ponderosae predominantly kills large diameter trees; therefore, we predicted that large surviving trees would have distinctive genetic profiles and, due to bottlenecking and drift, survivors would have lower genetic diversity than the abundant smaller mature trees that escaped predation. We found survivors were indeed genetically divergent from the smaller trees but, contrary to expectations, the smaller trees had lower diversity. This suggests that while beetles may select for trees with particular genotypes, other factors are also driving population genetic sub-structuring. Individual tree terpene profiles were diverse and varied by population but showed no clear relationship to survivorship. Two groups of trees with divergent sensitivities to climate were observed in each population, but neither was a clear indicator of survivorship or susceptibility to beetle attack. Growth rate was the best predictor of survivorship with survivors growing significantly slower than beetle-killed trees over their lifetimes although growth rates converged in years just prior to increased beetle activity. Overall, our results suggest that P. albicaulis forests show considerable divergence among populations and within-population genetic sub-structuring, and that they may contain complex mosaics of adaptive potentials to a variety of stressors including D. ponderosae. To protect the ability of this tree to adapt to increasing pressure from beetles, blister rust, and climate change, a top priority should be the maintenance of standing genetic diversity and adaptive shifts in allele frequencies.

Bayesian Predictions of Bark Beetle Attack and Mortality of Three Conifer Species During Epidemic and Endemic Population Stages

Bark beetles naturally inhabit forests and can cause large-scale tree mortality when they reach epidemic population numbers. A recent epidemic (1990s–2010s), primarily driven by mountain pine beetles (Dendroctonus ponderosae), was a leading mortality agent in western United States forests. Predictive models of beetle populations and their impact on forests largely depend on host related parameters, such as stand age, basal area, and density. We hypothesized that bark beetle attack patterns are also dependent on inferred beetle population densities: large epidemic populations of beetles will preferentially attack large-diameter trees, and successfully kill them with overwhelming numbers. Conversely, small endemic beetle populations will opportunistically attack stressed and small trees. We tested this hypothesis using 12 years of repeated field observations of three dominant forest species (lodgepole pine Pinus contorta, Engelmann spruce Picea engelmannii, and subalpine fir Abies lasiocarpa) in subalpine forests of southeastern Wyoming paired with a Bayesian modeling approach. The models provide probabilistic predictions of beetle attack patterns that are free of assumptions required by frequentist models that are often violated in these data sets. Furthermore, we assessed seedling/sapling regeneration in response to overstory mortality and hypothesized that higher seedling/sapling establishment occurs in areas with highest overstory mortality because resources are freed from competing trees. Our results indicate that large-diameter trees were more likely to be attacked and killed by bark beetles than small-diameter trees during epidemic years for all species, but there was no shift toward preferentially attacking small-diameter trees in post-epidemic years. However, probabilities of bark beetle attack and mortality increased for small diameter lodgepole pine and Engelmann spruce trees in post-epidemic years compared to epidemic years. We also show an increase in overall understory growth (graminoids, forbs, and shrubs) and seedling/sapling establishment in response to beetle-caused overstory mortality, especially in lodgepole pine dominated stands. Our observations provide evidence of the trajectories of attack and mortality as well as early forest regrowth of three common tree species during the transition from epidemic to post-epidemic stages of bark beetle populations in the field.

Forecasting the Cumulative Effects of Multiple Stressors on Breeding Habitat for a Steeply Declining Aerial Insectivorous Songbird, the Olive-sided Flycatcher (Contopus cooperi)

To halt ongoing loss in biodiversity, there is a need for landscape-level management recommendations that address cumulative impacts of anthropogenic and natural disturbances on wildlife habitat. We examined the cumulative effects of logging, roads, land-use change, fire, and bark beetle outbreaks on future habitat for olive-sided flycatcher (Contopus cooperi), a steeply declining aerial insectivorous songbird, in Canada’s western boreal forest. To predict the occurrence of olive-sided flycatcher we developed a suite of habitat suitability models using point count surveys (1997–2011) spatially- and temporally-matched with forest inventory data. Flycatcher occurrence was positively associated with small (∼10 ha) 10- to 20-year-old clearcuts, and with 10–100% tree mortality due to mountain pine beetle (Dendroctonus ponderosae) outbreaks, but we found no association with roads or distance to water. We used the parameter estimates from the best-fit habitat suitability models to inform spatially explicit state-and-transition simulation models to project change in habitat availability from 2020 to 2050 under six alternative scenarios (three management × two fire alternatives). The simulation models projected that the cumulative effects of land use conversion, forest harvesting, and fire will reduce the area of olive-sided flycatcher habitat by 16–18% under Business As Usual management scenarios and by 11–13% under scenarios that include protection of 30% of the land base. Scenarios limiting the size of all clearcuts to ≤10 ha resulted in a median habitat loss of 4–6%, but projections were highly variable. Under all three management alternatives, a 50% increase in fire frequency (expected due to climate change) exacerbated habitat loss. The projected losses of habitat in western boreal forest, even with an increase in protected areas, imply that reversing the ongoing population declines of olive-sided flycatcher and other migratory birds will require attention to forest management beyond protected areas. Further work should examine the effects of multiple stressors on the demographic mechanisms driving change in aerial insectivore populations, including stressors on the wintering grounds in South America, and should aim to adapt the design of protected areas and forest management policies to projected climate-driven increases in the size and frequency of wildfires.

New data on the spread of the invasive species Dothistroma septosporum (Dorogin) M. Morelet in Belarus

Red band needle blight, or Dothistroma needle blight is one of the most common and harmful diseases of pine. The causative agents of the disease are pathogenic micromycetes Dothistroma septosporum (Dorogin) M. Morelet and Dothistroma pini Hulbary. Dothistroma needle blight was firstly detected in Belarus in 2012 year, but till now information about this disease in the republic is fragmentary. The article presents the results of a survey of different pine trees, carried out in the period 2016–2020 years in botanical and dendrological gardens, forest nurseries and mini-arboretums at forestry enterprises, urban stands, nurseries of decorative plants, garden centers, for the presence of Dothistroma needle blight. The species identification of the causative agent of the disease was carried out by mycological and molecular genetic methods. In this study, Dothistroma needle blight was revealed on individual trees of Pinus mugo, P. nigra and P. ponderosa in the stands of the Central Botanical Garden of the NAS of Belarus, the dendrological garden of the Glubokoe experimental forestry enterprise, in the nurseries of decorative plants in the Grodno and Minsk regions. In the collected samples of needles, the invasive species Dothistroma septosporum was identified. The frequency of occurrence of the pathogen was 4.8–7.2 %, the proportion of observation sites in which this disease was detected at 60 %. The detection of Dothistroma needle blight on pine trees, mainly on planting material imported from abroad, indicates a transboundary route of D. septosporum entering the country. Analysis of literature data indicates the potential danger of Dothistroma needle blight for pine stands in the republic, which in turn requires the organization of regular monitoring of the disease and the development of methods to limit the spread of D. septosporum in the republic.

Growth and defense characteristics of whitebark pine (Pinus albicaulis) and lodgepole pine (Pinus contorta var latifolia) in a high-elevation, disturbance-prone mixed-conifer forest in northwestern Montana, USA

Recent, widespread tree mortality in the western U.S. resulting from changes in climate, pathogens, insect activity, and forest management practices has led to concerns for many ecologically and culturally important species. Within conifers, resin-based defenses have long been recognized as a primary defense mechanism against a variety of insects and pathogens. Oleoresin produced by trees contain complex mixtures of terpenoids that have numerous insecticidal and fungicidal properties. Research has also identified links between resin duct characteristics and increased probability of survival during bark beetle outbreaks. Whitebark pine (Pinus albicaulis) is a culturally significant high elevation species that provides numerous ecological services within subalpine and alpine ecosystems. Whitebark pine has co-evolved with a suite of biotic and abiotic disturbances. Individual trees allocate resources towards growth and resin-based defenses, making it a good candidate species to evaluate growth and defense relationships and tradeoffs. In this study we compared constitutive resin chemistry, tree growth and resin duct anatomy between similarly aged whitebark and lodgepole pine (P. contorta var latifolia) growing in proximity within a disturbance-prone, mixed-conifer forest in northwestern Montana. These two host species have varying degrees of historical exposure to mountain pine beetle. Our research yields four important findings. First, we did not find evidence of a tradeoff between tree growth and tree defenses (resin duct morphology and resin chemistry). This suggests that trees growing under favorable field conditions can experience high growth rates and still allocate ample resources towards defense. Second, we found that resin ducts and constitutive mono- and sesqui- terpenes were not correlated in lodgepole pine while duct production and area were positively related to constitutive monoterpenes, and duct size and area were positively related to constitutive sesquiterpenes, in whitebark pine. The lack of distinct, consistent relationships between these defensive features suggests that both whitebark and lodgepole pine trees present beetles with numerous, complex combinations of resin-based defenses. Third, based on constitutive terpene profiles, bark beetles are more likely to enter lodgepole pine but more likely to successfully elicit mass attacks in whitebark pine, which agrees with beetle attack and success patterns observed in the field. Fourth, overstory competition, particularly by Engelmann spruce (Picea engelmannii), can influence tree defenses, specifically by reducing constitutive terpene concentrations in lodgepole and whitebark pine. Competitive tree interactions could lead to altered bark beetle-conifer interactions as host and nonhost species migrate in response to changing climate. Our results suggest that strategies designed to support whitebark pine populations can benefit from better understanding interactions among growth, competition and physical and chemical defenses in response to multiple disturbance.

Changes in the Greenness of Mountain Pine (Pinus mugo Turra) in the Subalpine Zone Related to the Winter Climate

In the current alteration of temperature and snow cover regimes, the impacts of winter climate have received considerably less attention than those of the vegetation period. In this study, we present the results demonstrating the influence of the winter climate conditions on the Mountain pine (Pinus mugo Turra) communities in High Tatra Mts (Western Carpathians). The changes in greenness in 2000–2020 were represented by the inter-annual differences of satellite-derived Normalized Difference Vegetation Index (NDVI). The winter climate conditions were characterized by climate indices calculated from the temperature and snow cover data measured at Skalnaté Pleso Observatory (1778 m a.s.l.) over the period between 1941–2020. Areas with P. mugo were classified into two density classes and five altitudinal zones of occurrence. The partial correlation analyses, which controlled the influence of summer climate, indicated that winter warm spells (WWS) caused a significant decrease in the greenness of the P. mugo thickets growing in the dense class D2 (R = −0.47) and in the altitudinal zones A2 (1600–1700 m a.s.l.) and A3 (1700–1800 m a.s.l.) with R = −0.54 for each zone. The changes in greenness were related to the average snow depth (ASD) as well, particularly in the dense class D2 (R = 0.45) and in the altitudinal zone A2 (R = 0.50). Here, in the summers following winters with the incidence of WWS or low ASD, we found decreased greenness following the injury of P. mugo shrubs, but NDVI after winters with higher ASD indicated more greenness. At lower altitudes, injuries may result in the loss of competition capacity of P. mugo near the timberline, where taller mountain tree species can utilize the conditions of warmer climate for expansion. We also found a significant positive effect of warmer winter seasons in the sparse P. mugo thickets (D1) with R = 0.50 and at higher altitudes (R = 0.49 in A4—1800–1900 m a.s.l.; R = 0.53 in A5—1900–2000 m a.s.l.). The increased temperatures in December correlated significantly with the increase of the greenness in all P. mugo pixels (R = 0.47), with the most pronounced effect in the sparse class D1 (R = 0.57) and in altitudinal zones A4 (R = 0.63) and A5 (R = 0.44), creating advantageous conditions for the thermophilisation of the alpine zone by P. mugo.

The Signature of Endemic Populations in the Spread of Mountain Pine Beetle Outbreaks.

The mountain pine beetle (MPB) is among the most destructive eruptive forest pests in North America. A recent increase in the frequency and severity of outbreaks, combined with an eastward range expansion towards untouched boreal pine forests, has spurred a great interest by government, industry and academia into the population ecology of this tree-killing bark beetle. Modern approaches to studying the spread of the MPB often involve the analysis of large-scale, high-resolution datasets on landscape-level damage to pine forests. This creates a need for new modelling tools to handle the unique challenges associated with large sample sizes and spatial effects. In two companion papers (Koch et al. in Environ Ecol Stat. https://doi.org/10.1007/s10651-020-00456-2 , 2020a; J R Soc Interface 17(170):20200434, 2020b), we explain how the computational challenges of dispersal and spatial autocorrelation can be addressed using separable kernels. In this paper, we use these ideas to capture nonstationary patterns in the dispersal flights of MPB. This facilitates a landscape-level inference of subtle properties of MPB attack behaviour based on aerial surveys of killed pine. Using this model, we estimate the size of the cryptic endemic MPB population, which formerly has been measurable only by means of costly and time-intensive ground surveys.

Foraging and nesting ecology of the Stygian Owl (Asio stygius robustus) in the Mountain Pine Ridge region of Belize

Little is known about the foraging ecology and breeding biology of the Stygian Owl (Asio stygius robustus) across Central America. We located one Stygian Owl roost site in the Mountain Pine Ridge Forest Reserve in the Cayo District of Belize, where we collected pellets over a one-year period (n = 145; Mar 2009–Feb 2010). All identified prey items (n = 194) were passerines (69%), bats (19%), or beetles (12%). We used a proportions test and found seasonal variation in diet, with increased passerine prey consumed in the dry season (Jan–May) and increased beetle prey consumed in the wet season (Jun–Dec). This shift in diet may be influenced by temporal variation of passerine abundance and the emergence of beetles at the start of the wet season. In December 2010, we affixed an adult male Stygian Owl with a VHF transmitter, recorded regular movements using triangulation, and located an occupied nest with a single nestling in sub-montane pine forest habitat. The tagged male had a home range of 36 km2 and was documented regularly flying up to 16 km from the nest site through broad-leaved forest to hunt in agricultural habitat, while roosting and nesting only in sub-montane pine forest. The use of human-created habitats, such as agriculture, could unveil threats not previously of concern for this species (e.g., pesticide use). Our findings further our knowledge on seasonal diet for Stygian Owls and highlight distinct habitat usage for both roosting and foraging, which has important conservation implications for an understudied Neotropical owl.

Cavitation fatigue in conifers: a study on eight European species.

After drought-induced embolism and repair, tree xylem may be weakened against future drought events (cavitation fatigue). As there are few data on cavitation fatigue in conifers available, we quantified vulnerability curves (VCs) after embolism/repair cycles on eight European conifer species. We induced 50% and 100% loss of conductivity (LC) with a cavitron, and analyzed VCs. Embolism repair was obtained by vacuum infiltration. All species demonstrated complete embolism repair and a lack of any cavitation fatigue after 50% LC . After 100% LC, European larch (Larix decidua), stone pine (Pinus cembra), Norway spruce (Picea abies), and silver fir (Abies alba) remained unaffected, while mountain pine (Pinus mugo), yew (Taxus baccata), and common juniper (Juniperus communis) exhibited 0.4-0.9 MPa higher vulnerability to embolism. A small cavitation fatigue observed in Scots pine (Pinus sylvestris) was probably biased by incomplete embolism repair, as indicated by a correlation of vulnerability shifts and conductivity restoration. Our data demonstrate that cavitation fatigue in conifers is species-specific and depends on the intensity of preceding LC. The lack of fatigue effects after moderate LC, and relevant effects in only three species after high LC, indicate that conifers are relatively resistant against cavitation fatigue. This is remarkable considering the complex and delicate conifer pit architecture and may be important considering climate change projections.

Changing Perceptions and Actions in Response to Forest Disturbance by Mountain Pine Beetles in North Central Colorado

AbstractForest disturbances caused by insects, pathogens, and fire continue to increasingly occur within forests across the United States and around the world. Given the dynamic nature of these forest disturbances and the role played by local residents in risk management, it is valuable to explore how the human experience, attitudes, and behaviors associated with these ecological processes may evolve over time. In this paper, we assess temporal changes in local residents’ perceptions and actions in response to the mountain pine beetle outbreak that affected large swaths of forests in north central Colorado. Through analyses of secondary and household survey data from 2007 and 2018, we note significant changes in these aspects and identify factors consistently associated with individual and community activeness. The study contributes to knowledge of dynamic socioecological considerations of forest disturbances and improves understanding of how social sciences can help to identify opportunities and barriers to effective forest ecosystem management.

A participatory method for prioritizing invasive species: Ranking threats to Minnesota's terrestrial ecosystems

Terrestrial invasive species threaten the integrity of diverse and highly-valued ecosystems. The Minnesota Invasive Terrestrial Plants and Pests Center (MITPPC) was established by the state of Minnesota to fund research projects aimed at minimizing harms posed by the most threatening terrestrial invasive species to the state's prairies, wetlands, forests, and agriculture. MITPPC used the Analytic Hierarchy Process (AHP) to identify and prioritize diverse invasive species threats. We describe how MITPPC tailored AHP to establish its research priorities and highlight major outcomes and challenges with our approach. We found that subject matter experts considered factors associated with the severity of impact from invasion, rather than the potential for invasion, to be the greatest contributors in identifying the most threatening species. Specifically, out of the 17 total criteria identified by the experts to rank species, negative environmental impact was the most influential threat criterion. Currently, narrowleaf cattail, mountain pine beetle, and the causative agent of Dutch elm disease are top threats to Minnesota terrestrial ecosystems. AHP does not handle data-poor situations well; however, it allows for easy incorporation of new information over time for a species without undoing the original framework. The MITPPC prioritization has encouraged interdisciplinary, cross-project synergy among its research projects. Such outcomes, coupled with the transparent and evidence-based decision structure, strengthen the credibility of MITPPC activities with many stakeholders.

Molecular Signatures of Reticulate Evolution within the Complex of European Pine Taxa

Speciation mechanisms, including the role of interspecific gene flow and introgression in the emergence of new species, are the major focus of evolutionary studies. Inference of taxonomic relationship between closely related species may be challenged by past hybridization events, but at the same time, it may provide new knowledge about mechanisms responsible for the maintenance of species integrity despite interspecific gene flow. Here, using nucleotide sequence variation and utilizing a coalescent modeling framework, we tested the role of hybridization and introgression in the evolutionary history of closely related pine taxa from the Pinus mugo complex and P. sylvestris. We compared the patterns of polymorphism and divergence between taxa and found a great overlap of neutral variation within the P. mugo complex. Our phylogeny reconstruction indicated multiple instances of reticulation events in the past, suggesting an important role of interspecific gene flow in the species divergence. The best-fitting model revealed P. mugo and P. uncinata as sister species with basal P. uliginosa and asymmetric migration between all investigated species after their divergence. The magnitude of interspecies gene flow differed greatly, and it was consistently stronger from representatives of P. mugo complex to P. sylvestris than in the opposite direction. The results indicate the prominent role of reticulation evolution in those forest trees and provide a genetic framework to study species integrity maintained by selection and local adaptation.

Tree growth is more limited by drought in rear-edge forests most of the times

BackgroundEquatorward, rear-edge tree populations are natural monitors to estimate species vulnerability to climate change. According to biogeographical theory, exposition to drought events increases with increasing aridity towards the equator and the growth of southern tree populations will be more vulnerable to drought than in central populations. However, the ecological and biogeographical margins can mismatch due to the impact of ecological factors (topography, soils) or tree-species acclimation that can blur large-scale geographical imprints in trees responses to drought making northern populations more drought limited.MethodsWe tested these ideas in six tree species, three angiosperms (Fagus sylvatica, Quercus robur, Quercus petraea) and three gymnosperms (Abies alba, Pinus sylvestris and Pinus uncinata) by comparing rear-edge tree populations subjected to different degrees of aridity. We used dendrochronology to compare the radial-growth patterns of these species in northern, intermediate, and southern tree populations at the continental rear edge.Results and conclusionsWe found marked variations in growth variability between species with coherent patterns of stronger drought signals in the tree-ring series of the southern populations of F. sylvatica, P. sylvestris, and A. alba. This was also observed in species from cool-wet sites (P. uncinata and Q. robur), despite their limited responsiveness to drought. However, in the case of Q. petraea the intermediate population showed the strongest relationship to drought. For drought-sensitive species as F. sylvatica and P. sylvestris, southern populations presented more variable growth which was enhanced by cool-wet conditions from late spring to summer. We found a trend of enhanced vulnerability to drought in these two species. The response of tree growth to drought has a marked biogeographical component characterized by increased drought sensitivity in southern populations even within the species distribution rear edge. Nevertheless, the relationship between tree growth and drought varied between species suggesting that biogeographical and ecological limits do not always overlap as in the case of Q. petraea. In widespread species showing enhanced vulnerability to drought, as F. sylvatica and P. sylvestris, increased vulnerability to climate warming in their rear edges is forecasted. Therefore, we encourage the monitoring and conservation of such marginal tree populations.

CHANGES IN THE CONTENT OF BIOAVAILABLE HEAVY METAL COMPOUNDS IN THE SOILS OF THE CRIMEAN MOUNTAIN PLATEAUS AFTER AFFORESTATION

About 3 thousand hectares of forest stands were created on the surface of the Crimean mountain plateaus in the middle of the 20th century as a result of afforestation. Studies on the influence of these stands on the properties of mountain meadow soils (Phaeozems) showed that under the forest vegetation, the consolidation of structural aggregates, a decrease in the humus content, and an increase in acidity compared to the soils under the meadow vegetation, which could also affect other soil properties, including the mobility of some metals, were observed. The work objective of this research is to conduct a comparative analysis of the content of Pb, Mn, Cu, and Zn compounds available for biota (1 M ammonium acetate) in the soil under mountain meadows, natural beech forest, and artificial forest stands. Following the obtained results, the available Pb, Mn, and Cu compounds accumulated in the afforested mountain meadow soils relative to the adjacent mountain meadows areas. Thus, the average Pb content in the soil layer of 0–10 cm under the mountain pine stands in comparison with the soil under meadow vegetation was 1.6 times higher, Mn – 1.2 times, Cu – 1.2 times. The Pb content was 2.5 times higher, Mn – 1.5 times higher, and Cu – 1.2 times higher under the silver birch stands. The Pb content was 2.2 times higher, Mn – 2.4 times higher, and Cu – 1.5 times higher under Siberian larch stands. The Pb content was 1.9 times higher, Mn – 1.1 times higher, Cu – 1.3 times higher under the sycamore maple stands, compared to the meadow. Differences between afforested and meadow soils in the content of these elements in most cases were significant, except for the Zn content, signs of accumulation of which under artificial stands were not revealed. The Pb, Mn, and Cu content in the brown forest lessive soil (Luvisols) under the oriental beech corresponded to their concentration under the larch, and the Zn content was significantly higher compared to the soil under all species. The main reason for the increase in the mobility of some elements under tree stands is their transition from immobile forms under the influence of increased acidity of afforested soils. Wood litter due to the low content of trace elements in its composition cannot be a source of their accumulation in the topsoil.

Candidate Genes for the High-Altitude Adaptations of Two Mountain Pine Taxa.

Mountain plants, challenged by vegetation time contractions and dynamic changes in environmental conditions, developed adaptations that help them to balance their growth, reproduction, survival, and regeneration. However, knowledge regarding the genetic basis of species adaptation to higher altitudes remain scarce for most plant species. Here, we attempted to identify such corresponding genomic regions of high evolutionary importance in two closely related European pines, Pinus mugo and P. uncinata, contrasting them with a reference lowland relative—P. sylvestris. We genotyped 438 samples at thousands of single nucleotide polymorphism (SNP) markers, tested their genetic differentiation and population structure followed by outlier detection and gene ontology annotations. Markers clearly differentiated the species and uncovered patterns of population structure in two of them. In P. uncinata three Pyrenean sites were grouped together, while two outlying populations constituted a separate cluster. In P. sylvestris, Spanish population appeared distinct from the remaining four European sites. Between mountain pines and the reference species, 35 candidate genes for altitude-dependent selection were identified, including such encoding proteins responsible for photosynthesis, photorespiration and cell redox homeostasis, regulation of transcription, and mRNA processing. In comparison between two mountain pines, 75 outlier SNPs were found in proteins involved mainly in the gene expression and metabolism.

How should we sustain future forests under extreme risk?

In this paper, we examine the implications of managing for sustained yield in a world characterized by growing risk and uncertainty. We review the history of sustained yield (SY) forestry in North America, with an emphasis on economic benefits and the persistence of the SY paradigm today, despite a publicized shift towards managing for a wider range of forest values called sustainable forest management (SFM). We show that current forest management goals around sustainability as well as SFM indicators are still predicated on maximizing harvest levels and timber flows. We build a simple model to explore the implications of SY under extreme (fat-tailed) risk assumptions to show that maximizing a level of harvest without adequately accounting for risk leads towards the depletion of the forest stock with a corresponding decline in the forest economy. We discuss these results in relation to real-world events such as the increase in catastrophic fires and pest outbreaks like the mountain pine beetle in Western Canada. We then examine the theoretical and practical implications that flow from this model and analysis.

Rocky Mountain Bristlecone Pine (Pinus aristata) is a Confirmed Host to Mountain Pine Beetle (Dendroctonus ponderosae)

Mountain pine beetle (MPB) (Dendroctonus ponderosae Hopkins) is a native bark beetle that reproduces in pine (Pinus) species across western North America. High population levels can result in widespread host tree mortality. Over the past 2 decades, MPB has been responsible for pine mortality across millions of forested hectares in the western United States. Although a majority of the pine species found in the western United States are considered hosts to MPB, the host status of Rocky Mountain (RM) bristlecone pine (Pinus aristata) is unclear. We surveyed stands across the range of RM bristlecone pine in Colorado, USA, and quantified MPB-caused mortality within the past 10 years in stands where RM bristlecone and at least one other pine species co-occurred. We also evaluated in the field whether successful MPB brood production occurred in RM bristlecone pine. Our results confirm that RM bristlecone pine is susceptible to MPB attack and suitable for MPB reproduction. In mixed-species stands, pine species availability influenced MPB attack occurrence. The proportion of trees experiencing fatal beetle attack within a particular Pinus species was best predicted by the basal area proportion of that species in the stand prior to the most recent 10 years of mortality. These results indicate that RM bristlecone pine is vulnerable to ongoing climate change–induced contact with MPB.