Populus Balsamifera Research Articles

Mapping of drought-induced changes in tissue characteristics across the leaf profile of Populus balsamifera.

Leaf architecture impacts the ease of gases diffusion, biochemical process, and photosynthetic performance. For balsam poplar, a widespread North American species, the influence of water availability on leaf anatomy and subsequent photosynthetic performance remains unknown. To address this shortcoming, we characterized the anatomical changes across the leaf profile in three-dimensional space for saplings subjected to soil drying and rewatering using X-ray microcomputed tomography. Our hypothesis was that higher abundance of bundle sheet extensions (BSE) minimizes drought-induced changes in intercellular airspace volume relative to mesophyll volume (i.e. mesophyll porosity, θIAS) and aids recovery by supporting leaf structural integrity. Leaves of 'Carnduff-9' with less abundant BSEs exhibited greater θIAS, higher spongy mesophyll surface area, reduced palisade mesophyll surface area, and less veins compared with 'Gillam-5'. Under drought conditions, Carnduff-9 showed significant changes in θIAS across leaf profile while that was little for 'Gillam-5'. Under rewatered conditions, drought-induced changes in θIAS were fully reversible in 'Gillam-5' but not in 'Carnduff-9'. Our data suggest that a 'robust' leaf structure with higher abundance of BSEs, reduced θIAS, and relatively large mesophyll surface area provides for improved photosynthetic capacity under drought and supports recovery in leaf architecture after rewatering in balsam poplar.

Comparison of the Ability of Woody Plants of Different Species to Accumulate Heavy Metals in Urban Environment

Soil and aerotechnogenic migration of metals into woody plants (birch (Betula pendula) and balsam poplar (Populus balsamifera)) from technogenic zones of Tyumen was studied. Soil and tree leaves were sampled in the conditionally background area, near the airport, railway station and bus station, as well as in the area of enterprises: engine-building, oil refinery, battery and metallurgical plants. The content of acidsoluble form of metals in soils and leaves was determined by atomic emission spectroscopy. It was revealed that the accumulation of metals in soils from the anthropogenic zones of Tyumen compared to the control decreased in the series Pb>Cd>Cr>Cr>Ni>Zn>Cu>Fe>Co>Mn and reached 20 times. The accumulation of metals by birch leaves was found to decrease in the series Pb>Cr>Fe>Co>Cu>Cu>Ni>Zn>Mn>Cd, and by poplar leaves – Cr>Fe>Pb>Zn>Cd>Cu>Co>Mn>Ni. The accumulation and migration of metals in soils and trees from the urban environment were analyzed, which allowed us to identify Cd, Pb and Cr as metals with the “highest ecological risk”.

Development of medicinal and cosmetic cream based on flavonoids

The article discusses the results of the development of a cream based on Populus balsamifera L. bud flavonoids, which have anti-inflammatory, skin-regenerating effects.A cream's anti-inflammatory and wound-healing activity based on a flavonoid substance has been studied. In an experiment on a model of an incised skin wound, it was determined that a cream based on the sum of flavonoids from balsam poplar buds, containing pinostrobin, pinocembrin, tectochrysin, exhibits anti-inflammatory and wound-healing activities. Considering that the effectiveness of local wound treatment mainly depends on the rational treatment of the first phase of the wound process, we have developed a 1 % flavonoid cream and its production technology.The technology for the production of flavonoid cream includes extraction and isolation of the sum of flavonoids from the raw material of Populus balsamifera L. buds, preparation of flavonoid substance and excipients, preparation of the cream base and cream, packaging and labelling of cream. Based on the results of our experiments, a pilot industrial regulation for the production of a new cream based on the sum of flavonoids of Populus balsamifera L. buds has been developed, and pilot production of an original medicinal and cosmetic cream was organised.

Reviving the balm of Gilead: A contemporary formulation inspired by historical wisdom

Background and aims: The balm of Gilead, steeped in cultural significance, remains enigmatic due to its undefined composition and preparation methods. This study aims to recreate a formulation inspired by this elusive balm, combining historical insights with modern botanical knowledge. Methods: The study employed Populus balsamifera seeds infused with organic olive oil, mirroring historical practices. Essential oils—myrrh, frankincense, and cedar—were selected. Evaluation encompassed appearance, texture, aroma, and pH alignment with historical context and dermatological compatibility. Results: The formulated balm exhibited a smooth texture, earthy aroma, and a pH of 5.5, akin to skin’s natural acidity. These attributes echoed historical practices and holistic approaches. Conclusion: While the formulation mirrors historical attributes, challenges persist due to the genuine balm’s undefined composition. The study highlights the potential of employing Populus balsamifera due to limitations. Future directions include chemical analyses and clinical studies to validate therapeutic potential, bridging historical wisdom with contemporary science.

Twenty-year responses of aspen stands to forest tent caterpillar defoliation and overstory dieback in Northeastern Ontario, Canada

Forest tent caterpillar (Malacosoma disstria Hbn.) is a major forest defoliator in North American boreal forests. This pest periodically affects hardwood trees such as trembling aspen (Populus tremuloides Michx.) and balsam poplar (Populus balsamifera L.) across large areas, causing mortality and altering stand attributes and long-term dynamics. In this study, I quantified the responses of aspen stands to forest tent caterpillar defoliation and overstory dieback, including short-term (5 years after dieback) and long-term (20 years later) dynamics. Results indicate that affected stands fully recovered to pre-dieback density but not basal area. Defoliation caused overstory dieback that stimulated understory growth and regeneration but the hardwood regeneration (mostly aspen) did not adequately replace hardwood trees lost to defoliation, resulting in decreased hardwood composition relative to unaffected stands. The high density in affected stands suggested possible further basal area recovery as regeneration and released understory conifers grew into main canopy, following the general trends of boreal mixedwood succession. The results support earlier projections based on residual stand attributes shortly after dieback and reported boreal species growth and mortality rates that indicate forest tent caterpillar defoliation and subsequent overstory dieback would accelerate aspen stand transition to conifer dominance and delay the availability of stands for harvesting by 40–50 years as stands recover.

Characterization of Secondary Metabolites of Leaf Buds from Some Species and Hybrids of Populus by Gas Chromatography Coupled with Mass Detection and Two-Dimensional High-Performance Thin-Layer Chromatography Methods with Assessment of Their Antioxidant Activity.

Poplars provide medicinal raw plant materials used in pharmacy. Leaf buds are one of the herbal medicinal products collected from poplars, having anti-inflammatory and antiseptic properties, but there are no quality standards for their production and there is a need to determine their botanical sources. Therefore, the chemical compositions of the leaf buds from four species and varieties of poplars, Populus balsamifera, P. × berolinensis, P. × canadensis 'Marilandica', and P. wilsonii were investigated and compared using gas chromatography coupled with mass detection (GC-MS) and two-dimensional high-performance thin-layer chromatography (2D-HPTLC) in order to search for taxa characterized by a high content of biologically active compounds and with a diverse chemical composition that determines their therapeutic effects. The presence of 163 compounds belonging to the groups of flavonoids, phenolic acids derivatives, glycerides, and sesquiterpenes was revealed. Moreover, the conditions for the separation and identification of biologically active compounds occurring in analyzed leaf buds using 2D-HPTLC were optimized and used for metabolomic profiling of the studied poplars, enabling their fast and simple botanical identification. The total phenolic (TPC) and flavonoid (TFC) contents of examined extracts were determined and their antioxidant capacities were estimated by spectrophotometric DPPH, ABTS, and FRAP assays. Based on the analysis of phytochemicals and antioxidant activity, P. × berolinensis buds were selected as the raw plant material for medicinal purposes with the highest content of active compounds and the strongest antioxidant activity.

Screening of Key Biogeochemical Indicators of the Environment of Large Industrial Agglomerations (on the Example of the Moskovsky District of St. Petersburg)

The ecological and biogeochemical indicators of the state of the environment on the territory of a large urban agglomeration on the example of the Moskovsky district of St. Petersburg are considers. In 2009–2015–2021, the pH, chemical composition of soils and bark of Populus balsamifera were studied, biotesting of soils using Daphnia magna and Chlorella vulgaris was carried out. An integral indicator of LTP (Landscape Total Pollution) pollution based on the Harrington desirability function was used. An analysis of changes in the state of the environment over the specified period, depending on the functional use of the territory, was given. The aggravation of long-term pollution of environmental components in conditions of increasing emissions from motor vehicles, which is induced by increasing concentrations of Pb, Cd, Zn, Cu, Ni, Fe, Mn in soils and plants, is noted.

Ontogenetic changes in the mechanical stability of the main species of woody plants in the ecosystems of the city of Donetsk

The paper considers the issues of ontogenetic changes in the mechanical stability of 18 species of woody plants growing in the ecosystems of the industrial city of Donetsk: Acer campestre L., Acer negundo L., Acer platanoides L., Acer pseudoplatanus L., Acer saccharinum L., Aesculus hippocastanum L., Betula pendula Roth, Fraxinus excelsior L., Fraxinus lanceolata Borkh., Gleditsia triacanthos L., Populus simonii Carriere, Populus nigra L., Populus balsamifera L., Populus bolleana Lauche, Quercus robur L., Robinia pseudoacacia L., Tilia cordata Mill., Ulmus laevis Pall. It has been established that at the initial stages of the ontogenesis of woody plants, their biomechanics ensures survival through high flexibility. This is due to the low critical mass and load, which are easily achieved when static and dynamic factors act on the plant. Only a significant increase in linear dimensions makes it possible to maintain its own mass weighing several tons and above, as well as withstand the effects of adverse climatic factors. The studied ontogenetic dependences of the mechanical stability of the main species of woody plants in the ecosystems of the city of Donetsk should be used in landscaping the city.

Application of Poloxamer for In Situ Eye Drop Modeling by Enrichment with Propolis and Balsam Poplar Buds Phenolic Compounds.

In situ poloxamer-based gels are increasingly being explored as ocular drug delivery carriers to extend the release of active substances, thereby enhancing bioavailability. The objective of this study was to develop thermally stable in situ gels incorporating balsam poplar bud extract, propolis extract, and p-coumaric acid solution and to evaluate the physicochemical parameters of these gelified eye drops. This research assessed the compatibility of poloxamer-based eye drops with active components, their physicochemical properties, stability post-sterilization and during storage, and the release profiles of the active compounds. Fifteen eye drop formulations were prepared and categorized into three groups based on active components. One of the active components was propolis extract. As an alternative to propolis, eye drops containing the plant precursor, balsam poplar bud extract, were developed. The third group's active component was p-coumaric acid, a dominant phenolic acid in propolis and balsam poplar bud extracts. The study reported phenolic contents of 76.63 CAE mg/g for propolis and 83.25 CAE mg/g for balsam poplar bud aqueous extracts, with balsam poplar bud extracts showing higher SPF values (14.0) compared to propolis (12.7), while p-coumaric acid solution exhibited the highest SPF values (25.5). All eye drops were transparent, with pH values meeting the requirements for ocular drops. Formulations containing 8-10% poloxamer 407 met the criteria for in situ gels. All formulations remained stable for 90 days. Conclusion: The study results indicate that the formulated gels possess suitable physicochemical properties, are resistant to applied autoclaving conditions, and exhibit an extended release of active compounds with an increase in poloxamer content.

Technology for Isolation Essential Oil from the Buds of Populus balsamifera L.

The article presents the results of the development of technology for isolating essential oil from the buds of Populus balsamifera L. and a medicinal substance based on it. For the first time, a technology has been developed for the quantitative isolation of essential oil from the buds of Populus balsamifera L. by the barothermal method at a temperature of 140 ºC, under a vacuum of 1333‒2000 Pa. The main components of the essential oil of Populus balsamifera L. buds, isolated by the barothermal method, were determined to be α-bisabolol, β-eudesmol, and 2-phenylethyl-2-methylbutanoate. A technological scheme for the production of essential oil substance from Populus balsamifera L. buds has been developed, including 2 stages of the main technological process and 2 stages of auxiliary work, and its pilot industrial regulations. The control points during the isolation and preparative production of the essential oil substance from the Populus balsamifera L. buds are the major components α-bisabolol and β-eudesmol. The main critical points in the production of a substance based on the essential oil of Populus balsamifera L. buds are pressure, temperature, and duration of isolation. The stages of production of the substance are controlled using a standard sample of α-bisabolol (1). A quantitative determination of 108 components of essential oil from Populus balsamifera L. buds was carried out, as well as standardization for organoleptic properties and major components. A comparative analysis of essential oil from Populus balsamifera L. buds collected in the vicinity of Karaganda and the North Kazakhstan region was carried out. A substance based on essential oil from Populus balsamifera L. buds has antimicrobial, wound-healing, and antitumor activities with relatively low toxicity.

Итоги развития насаждений на территории сквера у культурно-развлекательного комплекса арена «Уралец» в г. Екатеринбурге

The article presents the results of a study of the species composition, structure, health condition, and stages of development of the plantings in the garden square near CEC «Uralets», Yekaterinburg – alley of the Palace of Sports in Yekaterinburg. This study shows that more than 56% of woody plants were Acer negundo L. and Populus balsamifera L. There were plantings in lines (20% of the area) consisting of trees of Populus and Malus genus, plantings in arrays (about 25% of the area) of Populus balsamifera L. and Fraxinus pennsylvanica Marsh. Other species were planted in groups (55% of the area). The health condition of the plantings was assessed as 2.9 (very poor). The most durable species Larix sibirica Ledeb., Quercus robur L., and Tilia cordata Mill. had the best average scores. Less durable species Prunus maackii Rupr., Pyrus ussuriensis Maxim., Malus baccata L., and Populus balsamifera L. were dying off. Planting density in mowed areas corresponded to the recommended norms, while this indicator was exceeded by an average of 25% in areas without care due to the invasion of Acer negundo L. Three stages were distinguished in the formation process of the garden square near CEC Uralets: 1) individual plots were created and natural plantations were integrated; 2) performed complete transformation of the landscape in the central part, planted ornamental plants and created a single space of the garden square; 3) decorative plantings were added to the garden square. During the reconstruction of the garden square that combines plantings of various origins and functions, step-by-step reconstruction is the most favorable – starting with less durable dying species and preserving Larix sibirica Ledeb., Quercus robur L., Tilia cordata Mill., and Betula pendula Roth.

Models for simulating the temporal development of black cottonwood (Populus balsamifera L. ssp. trichocarpa (Torr. & Gray ex Hook.) Brayshaw) plantations in Iceland

Black cottonwood (Populus balsamifera ssp. trichocarpa) was initially introduced to Iceland in 1944 from the Kenai Peninsula in Alaska and has been widely planted in shelterbelts and afforestation projects since the 1980s. There is currently much interest in increasing the planting of black cottonwood, especially in carbon sequestration projects, because of its rapid growth at an early age. Growth models simulate the growth of a forest over time and are important tools for forest managers, researchers, and policymakers. This study presents, for the first time, site index, individual-tree diameter increment and tree height models for even-aged black cottonwood stands in Iceland. The data were collected from Icelandic national forest inventory (NFI) plots and from three plots from a network of permanent sample plots (PSP). The NFI data were collected during 2005–2022, and the PSP data were collected between 2009 and 2022. The model of McDill and Amateis was selected for predicting site index and dominant height development, and the model of Schumacher was selected for predicting tree height. For diameter increment modelling, an optimization-based modelling approach was found to be more suitable than non-linear regression analysis. The models developed in this study can be used in forestry practice and in optimization studies for thinned black cottonwood stands. The models produced simulation results that corresponded to measured stand development.

Dynamic changes to the plant cuticle include the production of volatile cuticular wax-derived compounds.

The cuticle is a hydrophobic structure that seals plant aerial surfaces from the surrounding environment. To better understand how cuticular wax composition changes over development, we conducted an untargeted screen of leaf surface lipids from black cottonwood (Populus trichocarpa). We observed major shifts to the lipid profile across development, from a phenolic and terpene-dominated profile in young leaves to an aliphatic wax-dominated profile in mature leaves. Contrary to the general pattern, levels of aliphatic cis-9-alkenes decreased in older leaves following their accumulation. A thorough examination revealed that the decrease in cis-9-alkenes was accompanied by a concomitant increase in aldehydes, one of them being the volatile compound nonanal. By applying exogenous alkenes to P. trichocarpa leaves, we show that unsaturated waxes in the cuticle undergo spontaneous oxidative cleavage to generate aldehydes and that this process occurs similarly in other alkene-accumulating systems such as balsam poplar (Populus balsamifera) leaves and corn (Zea mays) silk. Moreover, we show that the production of cuticular wax-derived compounds can be extended to other wax components. In bread wheat (Triticum aestivum), 9-hydroxy-14,16-hentriacontanedione likely decomposes to generate 2-heptadecanone and 7-octyloxepan-2-one (a caprolactone). These findings highlight an unusual route to the production of plant volatiles that are structurally encoded within cuticular wax precursors. These processes could play a role in modulating ecological interactions and open the possibility for engineering bioactive volatile compounds into plant waxes.

Composition of alcohol extracts from poplar leaves (Populus balsamifera L.)

The group composition of alcohol extracts from balsamic poplar leaves Populus balsamifera L, growing in the Krasnoyarsk Krai, Krasnoyarsk (Russia) were examined in this work. Leaves selected in different phases of the growing season were used: June, July, August – fresh, September – fallen leaves. Poplar leaves contain up to 56% of extractive substances, alcohol-soluble substances account for up to 67% of the extract amount. Alcohol extracts were fractionated using solvents with increasing polarity: petroleum ether (boiling point 40 to 70 °C), diethyl ether, ethyl acetate, butanol. The results showed that the alcohol extracts of poplar leaves are dominated by substances extracted with ethyl acetate (up to 60%). The study of the component composition of volatile compounds of individual fractions of alcohol extracts was performed on an Agilent chromatography-mass spectrometer. The presence of various groups of compounds was established: hydrocarbons, alcohols, acids, ketones, etc., including biologically active substances such as megasterol acetate, ℽ-sitosterol, sitosterol, 3,7,11,15-tetramethyl-2-hexadecene-1-ol, diethyltoluamide, 4-methoxy-3-nitrobiphenyl, and other compounds that it can be used in different applications.

Balsam Poplar Buds Extracts-Loaded Gels and Emulgels: Development, Biopharmaceutical Evaluation, and Biological Activity In Vitro.

Balsam poplar buds have been used for wound healing and treating irritated skin in traditional medicine. Balsam poplar buds extracts exhibit anti-inflammatory, antioxidant, and antimicrobial effects. In recent years, scientific research has begun to validate some of these traditional uses, leading to an increased interest in balsam poplar buds as a potential source of natural remedies in modern medicine. The study aims to simulate semi-solid pharmaceutical forms with balsam poplar buds extract and evaluate their quality through biopharmaceutical research. The active compounds identified in Lithuanian poplar buds were p-coumaric acid, cinnamic acid, caffeic acid, galangin, pinocembrin, pinobanksin, and salicin. In gels, pH values ranged from 5.85 ± 0.05 to 5.95 ± 0.07. The determined pH values of emulgels ranged from 5.13 ± 0.05 to 5.66 ± 0.15. After 6 h, the release of active compounds from gels and emulgels ranged from 47.40 ± 2.41% to 71.17 ± 3.54. p-coumaric acid dominates in the balsam poplar buds extracts. The pH values of the prepared sem-solid pharmaceutical forms are suitable for use on the skin. The viscosity of the formulations depends on the amount of gelling agent. All formulations showed antioxidant activity. It is relevant to conduct a more extensive study on the influence of the chosen carrier on the release of active compounds from semi-solid formulations with an extract of balsam poplar buds.

STUDY OF THE QUALITATIVE COMPOSITION OF THE SUBSTANCE OBTAINED FROM POPLAR BUDS BY EXTRACTION METHOD

Currently, among the most acute problems of the Republic of Kazakhstan, it should be noted the creation and development of its own pharmaceutical base, which would meet all international standards. Therefore, an urgent problem today is the creation of new highly effective domestic drugs based on the country's plant resources. It is also important to master the production of original domestic medicines, the creation of safe and environmentally friendly technologies for their production. In this direction, plants of the genus Populus (poplar) of the Salicaceae family (willow) have an advantage due to large reserves of renewable raw materials (poplar plantations in the North Kazakhstan region have industrial reserves of medicinal raw materials) and the content of various classes of compounds with a wide range of biological activity. The aim of the study was to study the qualitative composition of substances from the buds of poplar balsamic Populus balsamifera obtained by extraction method. The tasks assigned included: to obtain a substance from the buds of poplar balsamic Populus balsamifera by extraction; to establish the qualitative composition of the substances obtained. A method for obtaining a substance from the buds of balsamic poplar, includes the use of freshly harvested buds of balsamic poplar, extraction with solvents with an increasing polarity gradient: hexane; dichloromethane; evaporation until the target product is obtained. Thus, the qualitative composition of hexane extract of substances obtained by extraction method was investigated. It was found that extraction with methylene chloride allows the separation of flavonoids.

Drought-induced fiber water release and xylem embolism susceptibility of intact balsam poplar saplings.

Balsam poplar (Populus balsamifera L.) is a widespread tree species in North America with significant ecological and economic value. However, little is known about the susceptibility of saplings to drought-induced embolism and its link to water release from surrounding xylem fibers. Questions remain regarding localized mechanisms that contribute to the survival of saplings in vivo of this species under drought. Using X-ray micro-computed tomography on intact saplings of genotypes Gillam-5 and Carnduff-9, we found that functional vessels are embedded in a matrix of water-filled fibers under well-watered conditions in both genotypes. However, water-depleted fibers started to appear under moderate drought stress while vessels remained water-filled in both genotypes. Drought-induced xylem embolism susceptibility was comparable between genotypes, and a greater frequency of smallerdiameter vessels in GIL-5 did not increase embolism resistance in this genotype. Despite having smaller vessels and a total vessel number that was comparable to CAR-9, stomatal conductance was generally higher in GIL-5 compared to CAR-9. In conclusion, our in vivo data on intact saplings indicate that differences in embolism susceptibility are negligible between GIL-5 and CAR-9, and that fiber water release should be considered as a mechanism that contributes to the maintenance of vessel functional status in saplings of balsam poplar experiencing their first drought event.

The influence of anthropogenic factors on the morphological features of the leaf apparatus of the balsamic poplar (Populus balsamifera L.)

The use of a promising culture of balsamic poplar in the 1950-1970s post-war years in the landscaping of Siberian cities became widespread in squares, parks, lawns along the road network and in urban forests. At the time of the creation of such landscaping facilities, the conditions of their growth did not have significant differences. To date, with the development of motorization, the use of reagents for the maintenance of the road network and the conduct of acaricide treatments in squares and parks, a significant difference has formed in the growing conditions of balsamic poplar crops. Biomonitoring of the state of the environment was carried out at three fundamentally different sites in Novosibirsk. Evaluation of the fluctuating asymmetry of balsamic poplar leaves showed that ordinary plantings along the road network are characterized by a high deviation from the stability of development. Forest crops of balsamic poplar in urban forests are characterized by the presence of deviations from the stability of development. The best indicators were obtained for balsamic poplar plantings in landscape groups in the park - the presence of a weak deviation from the stability of development. The best indicators were obtained for balsamic poplar plantings in landscape groups in the park - the presence of a violation of the stability of development. To date, 50-70-year-old balsamic poplar crops grown on the territory of the megalopolis are characterized by varying degrees of disturbance or deviation from the stability of development. They can be arranged according to the stability reduction scale in the following order: landscape groups in the park, forest crops in urban forests and ordinary planting on lawns along the road network.

Contribution of topographic features and categorization uncertainty for a tree species classification in the boreal biome of Northern Ontario

ABSTRACT Variations within local topography can effectively impact the location of tree species within naturally forested areas. Furthermore, the uncertainty of prediction for classification can vastly differ amongst topography and the overlying tree species groupings. This study investigated the supplementation of a suite of topographic features corresponding to morphometry and hydrological considerations, in addition to multispectral imagery and other LiDAR-derived features, at fine (2 m) spatial resolution for a pixel-based tree species classification of a forested region of the boreal biome in northern Ontario, Canada. The study area conforms to the Abitibi River Forest (ARF) and consists of the tree species of black spruce (Picea mariana), balsam fir (Abies balsamea), trembling aspen (Populus tremuloides), balsam poplar (Populus balsamifera), tamarack (Larix laricina), white spruce (Picea glauca), and eastern white cedar (Thuja occidentalis). Random forest (RF) and support vector machines (SVMs) were implemented for the classification. Topographic features, specifically those conforming to channel base level, valley depth, and multi-resolution valley bottom flatness (MRVBF), were among the most important features for species predictors. The RF and SVM methods were trained on pixels of pure stands (composed of 70%+ of same tree species) for the tree species groupings, which were split by site level. Modelling accuracies for both the pixel and site level were reported, with the best model attaining an overall site level accuracy and corresponding Cohen’s kappa score of 0.79 and 0.69 for classification, respectively. Entropy maps were generated to characterize the uncertainty of prediction, and substantiate that the regions of lowest uncertainty correspond to wetlands, which are dominated by black spruce (Picea mariana). A modified entropy map was calculated from the normalized top two probabilities of tree species groupings predicted per pixel, so as to better highlight regions of prediction uncertainty. A prediction map for the second most-likely tree species groupings was also computed, which supports the presence of balsam fir (Abies balsamea) as a secondary tree species throughout the ARF region.

Soil amendments impact root‐associated fungal communities of balsam poplar on a phosphogypsum reclamation site

During reclamation organisms like fungi directly interact at the soil–plant interface and can potentially impact plant growth, health, and overall revegetation success. Therefore, a study was conducted to determine how topsoil amendments (mycorrhizae, biochar, compost, manure) influence root‐associated fungal communities and growth of fast growing Populus balsamifera trees on a phosphogypsum (PG) reclamation site in Alberta, Canada. Tree height, diameter, biomass, and diversity of Ascomycota and Basidiomycota were assessed using Illumina MiSeq sequencing targeting the fungal internal transcribed spacer region 1 (ITS1) and ITS2. Topsoil amendments and root location (topsoil vs. PG within a treatment), greatly affected the root fungal community. Basidiomycota preferentially grew in PG, and had a high treatment specific root fungal community with highest diversity of ectomycorrhizal fungi and basidiomycete yeast in biochar PG and compost PG. Populus balsamifera roots were associated with a high diversity of Ascomycota, found equally in roots in topsoil and PG, with a trend towards higher diversity and abundance in PG. The core genus found across all samples was Fusarium, a potential plant pathogen. All topsoil amendments strongly reduced abundance of Fusarium and other Ascomycota in poplar roots. Biochar and compost reduced number and abundance of potential fungal pathogens and increased number of potential plant growth promoting Basidiomycota, indicating favorable growth conditions for P. balsamifera on a phosphygypsum reclamation site by application of these amendments. This study indicates compost and biochar can be effective soil amendments to support P. balsamifera establishment and growth on a PG reclamation site.