Shrub Willow Research Articles

Complete chloroplast genome sequencing of five Salix species and its application in the phylogeny and taxonomy of the genus

In this study, whole chloroplast genomes of five Salix species (S. argyracea, S. dasyclados, S. eriocephala, S. integra ‘Hakuro Nishiki’, and S. suchowensis) were sequenced. These chloroplast genomes were 155 ,605, 155, 763, 155, 552, 155, 538, and 155 ,550 bp in length, harboring 131 genes (77 unigenes), 37 tRNA genes, 8 rRNA genes, and 86 mRNA genes, respectively. The genes ycf1, psaI, ycf2-2, rpoC2, rpl22, atpF, and ndhF were under positive selection among the 21 Salix species. psaI, ycf2-2, atpF, and ycf1-2 were under positive selection between the tree willow and shrub willow, and rpoC2, rpl22, and ycf1-2 were positively selected among the shrub genomes. The gene rps7 was most variable among the genomes. Phylogenetic analysis of 21 Salix species and Chosenia arbutifolia provide evidence that the cp genome data partially support the relationship with traditional taxonomic concepts in the Flora of China. This chloroplast genome elucidates Salix taxonomy and provides evidence for evolutionary research.

Heterosis for Biomass-Related Traits in Interspecific Triploid Hybrids of Willow (Salix spp.)

Species hybridization is key for the improvement of shrub willow (Salix spp.) bioenergy crops because hybrids often display heterosis for yield. The development of high-yielding genotypes requires numerous broad attempts at hybridization followed by field evaluation and selection for stable performance. Selection of improved shrub willow varieties for use as a bioenergy crop involves evaluation of full-sib progeny in family-based selection trials. Improving the accuracy of evaluation through the use of components of yield would greatly improve the efficiency of selection. Heterosis for biomass yield in intra- and interspecific F1 and F2 shrub willow crosses, made between Salix sections and ploidy, was examined by utilizing a suite of morphological, physiological, and chemical composition traits collected over the course of 12 weeks in the greenhouse and over 3 years in the field. Triploid families generated from diploid S. viminalis and tetraploid S. miyabeana displayed the greatest levels of heterosis for harvestable biomass and biomass-related growth traits in the greenhouse and in the field. While intraspecific S. purpurea diploids exhibited low levels of heterosis for these traits, interspecific diploids produced moderate levels of heterosis in greenhouse experiments. Differences between greenhouse and field trial results can largely be explained by pest damage, which negatively impacted interspecific diploids. Heterosis for the traits that form the basis for biomass yield, including stem growth, foliar, and physiological traits, was quantified, and family-level differences are discussed.

Estimation of shrub willow leaf chlorophyll concentration across different growth stages using a hand-held chlorophyll meter to monitor plant health and production

Perennial shrub willow crops can simultaneously address environmental issues and produce biomass for biofuels, bioproducts and bioenergy. Chlorophyll is an essential biochemical property for characterizing plant health and growth and remote sensing techniques have been developed to quantify plant chlorophyll concentration. However, these techniques are highly dependent on the ability to obtain a large number of ground-based observations to train and validate the models. Given the species-specific and growth stage-dependent nature of leaf chlorophyll concentration (LCC), and the limited research about LCC estimation for shrub willow, we proposed a new model for quantifying shrub willow LCC from chlorophyll meter (CM) readings. Results indicated that there were statistically significant interaction effects in CM readings between cultivar and root age across willow growth stages. However, neither the cultivar, root age, nor their interaction were statistically significant predictor variables in a model for LCC, so separate response curves for different cultivars or root ages were not necessary. To consider changes in LCC across the growing season, we included growing degree days (GDD) as an additional predictor for estimating LCC from CM readings. The model including GDD performed better (R2 = 0.92, RMSE = 4.81 μg/cm2) than the model (R2 = 0.90, RMSE = 5.38 μg/cm2) using only CM readings. Compared to previous studies, this model reduced complexity and achieved more accurate predictions of seasonal LCC, thus providing a readily applicable approach for mapping willow LCC using remote sensing technologies.

Sexual differences in root growth and antioxidant characteristics in Salix viminalis exposed to cadmium stress

Salix viminalis is a typical dioecious shrub willow, which has been widely used in the heavy metal polluted soil phytoremediation due to its fast growth rate, deep root system, and metal-resistance trait. It has been reported that dioecious plants present sex-specific characteristics when exposed to biotic and abiotic stress. However, different responses to heavy metal cadmium stress between male and female plants of S. viminalis have not been clarified. In this study, male and female S. viminalis clones were treated by 100 μM cadmium stress for a period of 21 days, and the root morphology, hydrogen peroxide content, malondialdehyde, and free proline content, antioxidant enzyme activities, and glutathione content were investigated after every 7-day interval. The results showed that female plants of S. viminalis developed thicker root diameter and volume and also accumulated more hydrogen peroxide than males at the first 7-day interval. Furthermore, sexual dichotomous indexes showed the most significant on the second 7-day interval. These findings suggest that male plants of S. viminalis have stronger cadmium tolerance than female plants and sexual differences in adaptive responses to cadmium are duration dependent, which adds to present evidence of sex-related responses to environmental stress in dioecious plants. Novelty statement Salix viminalis, a dioecious shrub willow, has been widely used in phytoremediation, yet sexually differences in tolerance to cadmium of which remained unclear. This study focused on different responses to cadmium stress between roots of male and female S. viminalis. Results show that male plants of S. viminalis have stronger cadmium tolerance than female plants, which indicates male S. viminalis should be more considered to be applied for phytoremediation and ecological restoration of cadmium-accumulated soil considering cadmium tolerance characteristics. The findings can provide valuable evidence and insights for researches focused on phytoremediation with dioecious woody plants and sexual dimorphism under abiotic stress.

Life cycle assessment of a shrub willow evapotranspiration cover compared with conventional clay and geosynthetic covers in Upstate New York.

The establishment of landfill covers consumes substantial amounts of fuels and materials that contribute to greenhouse gas emissions and fossil fuel depletion (FFD). This study compared the global warming impact (GWI) and FFD of a shrub willow evapotranspiration (ET), conventional clay, and geosynthetic cover using life cycle assessment (LCA). The willow ET cover is a carbon-negative system with a total GWI of -13,206 kgCO2eq ha-1 over 30 years, while the GWI of clay (194,916 kgCO2eq ha-1) and geosynthetic covers (260,212 kgCO2eq ha-1) were substantial. Willow's ability to store carbon in coarse roots and stools creates the opportunity for negative carbon emissions. The FFD impact of the willow ET cover (75,303 MJ surplus ha-1) is 4.7 times lower than the clay cover and 7.7 times lower than the geosynthetic cover. Sensitivity and uncertainty analyses indicated that the GWI of the willow ET cover was less than zero for all scenarios, and the GWI and FFD of the geosynthetic cover were the highest. Willow ET covers can protect human health and the environment, reduce greenhouse gas emissions by sequestering carbon, and provide a source of wood chips that could be used for renewable energy or other applications.

Variations in cell wall traits impact saccharification potential of Salix famelica and Salix eriocephala

Increasing global populations, finite arable land, and the anthropogenic release of carbon dioxide into the atmosphere are driving the search for bio-based alternatives to the petroleum-derived fuels and chemicals that underpin the global economy. With rapid growth rates, a propensity for coppicing, and a wide geographic range across Canada, native shrub willows (Salix spp.) are an attractive source of low-input, high-volume biomass. To date, most willow research has focused on increasing yields and improving cropping systems, while comparatively little work has been done to assess the intrinsic diversity in cell wall traits and bioenergy potential. In this study, we characterized the cell wall composition and wood ultrastructure of 338 xylem samples from two Canadian willow species, Salix famelica and Salix eriocephala, harvested from a common garden experimental plot. Lignin content ranged from 17.5–25.1% in S. famelica and 18.6–24.3% in S. eriocephala. Following alkali pretreatment with 62.5 mM NaOH at 90 °C for 3 h and a 70-h enzymatic digestion with Accellerase 1000, glucose release ranged from 23.0–38.9 wt% in S. famelica and from 20.5–37.7 wt% in S. eriocephala, while xylose release ranged from 9.4–14.9% in S. famelica and from 9.5–15.2% in S. eriocephala. Partial least squares regression modelling showed that lignin content and composition were important negative regulators of glucose release. Overall, this work highlights the innate variability in cell wall traits of native willows and identifies potential genotypes that should be considered in future breeding and deployment strategies for Canadian bioenergy production.

Willows Used for Phytoremediation Increased Organic Contaminant Concentrations in Soil Surface

The Salix genus includes shrub species that are widely used in phytoremediation and various other phytotechnologies due to their advantageous characteristics, such as a high evapotranspiration (ET) rate, in particular when cultivated in short rotation intensive culture (SRIC). Observations made in past field studies suggest that ET and its impact on soil hydrology can also lead to increases in soil pollutant concentrations near shrubs. To investigate this, sections of a mature willow plantation (seven years old) were cut to eliminate transpiration (Cut treatment). Soil concentrations of polychlorinated biphenyls (PCBs), aliphatic compounds C10–C50, polycyclic aromatic hydrocarbons (PAHs) and five trace elements (Cd, Cr, Cu, Ni and Zn) were compared between the Cut and the uncut plots (Salix miyabeana ‘SX61’). Over 24 months, the results clearly show that removal of the willow shrubs limited the contaminants’ increase in the soil surface, as observed for C10–C50 and of 10 PAHs under the Salix treatment. This finding strongly reinforces a hypothesis that SRIC of willows may facilitate the migration of contaminants towards their roots, thus increasing their concentration in the surrounding soil. Such a “pumping effect” in a high-density willow crop is a prominent characteristic specific to field studies that can lead to counterintuitive results. Although apparent increases of contaminant concentrations contradict the purification benefits usually pursued in phytoremediation, the possibility of active phytoextraction and rhizodegradation is not excluded. Moreover, increases of pollutant concentrations under shrubs following migration suggest that decreases would consequently occur at the source points. Some reflections on interpreting field work results are provided.

Different Hatching Rates of Floodwater Mosquitoes Aedes sticticus, Aedes rossicus and Aedes cinereus from Different Flooded Environments.

Simple SummaryIn the lower Dalälven region, floodwater mosquitoes cause recurring problems during floods. Since 2002, flooded areas have been treated with Bacillus thuringiensis israelensis (Bti) to control the number of hatching floodwater mosquitoes. The area is composed of both open meadows that are grazed or mowed, as well as unmanaged open meadows and forest areas that are regularly flooded. This study compared the number of mosquito larvae that hatched from soil samples collected from these environmental categories to assess whether management of flooded areas affected mosquito abundance. The results show that fewer mosquitoes hatched from mowed meadows than from the other categories. It was further clear that Aedes cinereus were more abundant in open areas with tussocks while Aedes sticticus were dominating in forests and in open unkept areas, shrubs, and bushes. This difference is important for nuisance management since Aedes cinereus generally fly only short distances and mainly stay in the area where they hatched, while Aedes sticticus is capable to fly long distances and can cause nuisance problems in larger areas.In the lower Dalälven region, floodwater mosquitoes cause recurring problems. The main nuisance species is Aedes (Ochlerotatus) sticticus, but large numbers of Aedes (Aedes) rossicus and Aedes (Aedes) cinereus also hatch during flooding events. To increase understanding of which environments in the area give rise to mosquito nuisance, soil samples were taken from 20 locations from four environmental categories: grazed meadows, mowed meadows, unkept open grassland areas and forest areas. In each location 20 soil samples were taken, 10 from random locations and 10 from moisture retaining structures, such as tussocks, shrubs, piles of leaves, logs, and roots. The soil samples were soaked with tap water in the lab, and mosquito larvae were collected and allowed to develop to adult mosquitoes for species identification. Fewer larvae hatched from mowed areas and more larvae hatched from moisture retaining structure samples than random samples. The results showed that Aedes cinereus mostly hatch from grazed and unkept areas and hatched as much from random samples as from structures, whereas Aedes sticticus and Aedes rossicus hatched from open unkept and forest areas and hatch significantly more from structure samples. When the moisture retaining structures in open unkept areas where Aedes sticticus hatched were identified it was clear that they hatched predominantly from willow shrubs that offered shade. The results suggest that Ae. sticticus and Ae. cinereus favor different flooded environments for oviposition.

Comparison of Machine and Deep Learning Methods to Estimate Shrub Willow Biomass from UAS Imagery

Shrub willow is considered an important dedicated energy crop in temperate climates for the production of bioenergy, biofuels, and bio-based products. A methodology to rapidly and accurately estimate above-ground biomass (AGB) is essential for understanding potential biomass supply, identifying potential growth limitations, and making management decisions. The main objective of this study was to investigate different statistical, machine learning, and deep learning models to estimate shrub willow AGB at a site in Camillus, NY using multi-spectral unmanned aerial system (UAS) imagery. The efficiency of the convolutional neural network (CNN) deep learning algorithm was compared to the well-known methods including linear regression, decision tree (DT), random forest (RF), and support vector regression (SVR). The RF model estimated the AGB with the root mean square error (RMSE) of 1.73 Mg/ha and R 2 of 0.95, and outperformed other methods. The next most effective method was CNN with the RMSE of 2.69 Mg/ha and R 2 of 0.89. Feature importance analysis indicated that normalized difference vegetation index (NDVI), ratio vegetation index (RVI), and difference vegetation index (DVI) had the greatest contribution to AGB estimation. This study compared shrub willow AGB estimation models using UAS imagery which will streamline bioenergy/biofuel development compared to the existing methods.

Life cycle greenhouse gas emissions of ethanol produced via fermentation of sugars derived from shrub willow (Salix ssp.) hot water extraction in the Northeast United States

BackgroundThe amount of carbon dioxide in the atmosphere has been on the rise for more than a century. Bioenergy crops are seen by the Intergovernmental Panel on Climate Change as an essential part of the solution to addressing climate change. To understand the potential impact of shrub willow (Salix spp.) crop in the northeast United States, effective and transparent life cycle assessment of these systems needs to occur.ResultsHere we show, ethanol produced from the fermentation of sugars from hot water extract of willow grown on cropland can sequester 0.012 ± 0.003 kg CO2eq MJ−1 for a supply system incorporating summer harvest and storage. Despite decreases in soil organic carbon when willow is instead grown on grassland, the produced fuel still can provide significant climate benefits compared to gasoline.ConclusionsShrub willow converted to ethanol can be a carbon negative source of transportation fuel when the electricity and heat required for the conversion process are generated from renewable biomass. The sequestration of carbon in the belowground portion of the plants is essential for the negative GHG balance for cropland and low GHG emissions in grassland.

Influence of shrub willow buffers strategically integrated in an Illinois corn-soybean field on soil health and microbial community composition

Soil serves many important ecological functions and is an integral part of our existence as a society. However, concerns for soil health are growing globally, in part due to the negative impacts of agricultural management on soil resources. The production of perennial bioenergy crops on marginal land in row-crop production systems is one solution that could improve land-use efficiency and address the sustainability of cropland management. Because the relationship between crop management and the environment is complex, more research is needed to evaluate the potential benefits perennial bioenergy crop production has on soil health, as well as other ecosystem services. In this study, shrub willow buffers were strategically integrated into a corn-soybean cropping system with the main objective of reducing nitrate-N leaching from grain crop production while producing biomass for bioenergy. Two buffer systems (defined by landscape positions) were included for comparison, one on marginal land with exposure to nitrate-N leaching from upslope grain (southern plots) and one on fertile soils with less nitrate-N leaching potential (northern plots). Evaluation of soil (chemistry, bulk density, microbial community) and shrub willow vegetation properties (fine roots, leaf litter decomposition, and nutrient uptake dynamics), showed that landscape position plays an important role in (1) the dynamics of soil chemical properties, (2) shrub willow's influence and productivity, and (3) the provision of additional ecosystem services such as reductions in nitrous oxide emissions and nitrate-N leaching. In addition, the combination of crop type and landscape position (N-grain, N-willow, S-grain, and S-willow) influenced the species composition of the soil microbial community, resulting in unique and identifiable communities. These results highlight the potential application of shrub willow buffers for ecosystem service provision and support of ecosystem processes; however, understanding the relationship between the microbial community, crop type, and landscape is important for understanding the sustainability of the design.

Mechanical characteristics of wood-bark interface of shrub willow

The mechanical behavior of the wood-bark interface of shrub willow was tested to investigate the influence of key factors: harvest season, moisture content, and cultivars. The mechanical properties enable the design and optimization of the performance of debarking equipment for short-rotation woody stems and can help improve understanding of the mechanical performance of the wood-bark interface. Results show that the low moisture content samples have a significantly higher shear modulus, G (Mean =0.34 GPa) and modulus of toughness Ut (Mean = 12.84 kPa). However, the degree of ductility (0.02) and the ratio of ultimate strain εu to strain ε50 (2.18) are lower for low moisture content samples. Different willow cultivars have no significant influence on the mechanical properties of the wood-bark interface tested. Results also reveal that the values of ultimate strain εu (0.11), modulus of toughness Ut (16.09 kPa), and degree of ductility (0.031) are significantly higher for samples collected in the dormant season compared to the growing season. Covariance analysis reveals that aspect ratio of the sample has a significant effect on shear modulus, G (p = 0.041), ultimate strain, εu (p = 0.008), modulus of toughness (p = 0.012) and degree of ductility (p = 0.001). Identifying the combination of these desirable properties provides a framework to achieve the maximum debarking efficiency and effectiveness for short-rotation woody crops.

Yield and biomass quality of shrub willow hybrids in differing rotation lengths and spacing designs

To study the effects of planting design and harvest rotation on shrub willow bioenergy crops, 10 shrub willow genotypes were established in 2009 in side-by-side randomized complete block trials, one with a double-row design and the other a single-row design. Both double-row and single-row designs were established with the same stand density, ~14,000 plants ha−1. The single-row design was harvested four times on a 2-year rotation from 2009 to 2017. The double-row plots were harvested twice on a 4-year rotation. Biomass yield, growth parameters, wood composition, specific gravity, and calorific values were evaluated. Mean annualized yield over 8 years from the single-row design was 9.98 Mg ha−1 yr−1 whereas mean annualized yield for the double-row spacing design was 9.32 dry Mg ha−1 yr−1. Cumulative biomass production averaged across all genotypes from four biennial, single-row harvests resulted in 79.9 Mg ha−1 compared with two quadrennial double-row harvests of 74.5 Mg ha−1. A triploid hybrid, LA970253, produced the greatest mean annual yield in the single-row design of 14.0 dry Mg ha−1 yr−1, followed by another triploid, ‘Fabius’, which had the greatest yield in the double-row design of 12.5 dry Mg ha−1 yr−1. In both planting designs, hemicellulose and cellulose content increased over time, while lignin and ash content decreased. Calorific values ranged from 17.62 to 19.02 MJ kg−1 with no significant differences between designs or genotypes. The results from this study suggest that some genotypes respond better to shorter rotations, but over multiple rotations there is no difference in total yield.

Herbivores reduce seedling recruitment in alpine plant communities

Through changes in climate and other environmental factors, alpine tundra ecosystems are subject to increased cover of erect shrubs, reduced predictability of rodent dynamics and changes in wild and domesticated herbivore densities. To predict the dynamics of these ecosystems, we need to understand how these simultaneous changes affect alpine vegetation. In the long term, vegetation dynamics may depend critically on seedling recruitment. To study drivers of alpine plant seedling recruitment, we set up a field experiment where we manipulated the opportunity for plant–plant interactions through vegetation removal and introduction of willow transplants, the occurrence of herbivory through caging of plots, and then sowed 14 species into the plots. We replicated the experiment in three common alpine vegetation types (heath, meadow andSalixshrubland) and recorded seedling emergence and survival over five years. Strong effects of vegetation removal and substantial differences in recruitment among dominant vegetation types suggested important effects of local vegetation on the recruitment success of vascular‐plant seedlings. Similarly, herbivore exclusion had strong positive effects on recruitment success. This effect arose primarily via reduced seedling mortality in plots from which herbivores had been experimentally excluded and became noticeably stronger over time. In contrast, we detected no consistent effects of experimental willow shrub introduction on seedling recruitment. These results demonstrate that large and small herbivores can affect alpine plant seedling recruitment negatively by trampling and feeding on seedlings. Importantly, the effects became stronger over time, suggesting that effects of herbivory on seedling recruitment accumulates over time and may relate to recruitment phases beyond initial seedling emergence.

Сообщества с кустарниковыми ивами в подзоне типичных тундр восточноевропейского сектора Арктики

Сообщества с кустарниковыми ивами в подзоне типичных тундр восточноевропейского сектора Арктики

Сообщества с Myrica gale L. на болотах побережья Финского залива (Санкт-Петербург и Ленинградская область)

Сommunities of Myrica gale L. (sweet gale), their ecology and geography in coastal mires of the Gulf of Finland within St. Petersburg and the Leningrad Region on the Southeastern border of their range are described based on 70 relevés, made in 1981–2018. This species is included in the Red Data Books of Russia (2008), Leningrad Region (2018), St. Petersburg (2018), and Republic of Karelia (2007). The distribution of the communities in the studied area is as follows (Fig. 1) — the Yuntolovskiy reserve (the largest population), vicinity of the Lisiy Nos ­settlement, forest-park “Gagarka”, Tarkhovskiy Mys, Yuntolovskiy fo­rest-park (within St. Petersburg); vicinity of the Pesochnoe ­settlement, the Bolshoy Berye­zovyy Isl., near the port “Primorsk” (the Nor­thern coast of the Gulf of Finland) and the vicinity of Bolshaya Izhora ­settlement (Southern coast of the latter) in the Leningrad Region area. Communities are found mainly in coastal mires of various types (raised bogs, transitional mires, fens) in the place of former lagoons and in inter-dune depressions in different trophic conditions; most diverse in the last two. Communities are assigned into 12 associations, two of which with the shrub layer formed by Myrica gale. Sphagnetum myricosum galis is the most common association in transitional mires (Table 3). The communities are two-layers: Myrica gale shrub one and closed moss layer of Sphagnum species of diffe­rent ecological groups. The association is subdivided into 3 subassociations by dominanting Sphagnum species and groups of determinant species: sphagnosum angustifolii, sphagnosum flexuosi, and sphagnosum teretis. The communities of this association are located­ in newly formed mires, and their species composition is in the process of formation. These are succession stages between the fens and transitional mires. The ass. Myricetum caricosum lasiocarpae (table 4) includes communities of fens with close (50 to 80 %) Myrica gale shrub layer. Carex lasiocarpa is the dominant of the herb layer, in some communities there is the lower herb sublayer of Comarum palustre. There is no moss layer. Association Myricetum comaroso–betulosum with sparse Betula pubescens 5–12 m high tree layer is also recorded in fens (Table 4). Communities of the ass. Salicetum myricoso–paludiherbosum with the dominance of shrub willows and Myrica gale are rather widespread in coastal fens. They have closed (up to 100 %) shrub layer formed by various willows and M. gale. The composition and cover of paludal herbaceous species is variable, the only constant, sometimes abundant, species is Comarum palustre. The association is subdivided into 3 subassociations (salicosum phylicifoliae, salicosum phylicifoliae-myrsinifoliae and salicosum rosmarinifoliae-myrsinifoliae) according to the dominating willows and mire grasses. Besides the above associations with high abundance of Myrica gale, this species occurs with low abundance in the communities of other, often widespread mire associations, as their coastal variants (Tables 2–4). The discussed community types in the Leningrad Region and St. Petersburg have regional features and differ in species composition from the sweet gale communities of Western and Northern Europe. Due to the rarity in the European part of Russia communities with both low abundance and dominance of Myrica gale need protection as well as their habitats.

ДИНАМИКА РАЗВИТИЯ ПОБЕГОВ КУСТАРНИКОВЫХ ИВ (SALIX, SALICACEAE)

The article presents the results of observations of the seasonal dynamics of the growth of annual shoots of two species of shrub willows: Salix triandra and Salix viminalis. Object: genetically aligned model inbred-clonal populations of S. triandra and S. viminalis. Material: growing shoots on annual cuttings. Methods: comparative morphogenetic, chronobiological, numerical analysis of the series of dynamics. Results. Clones of two species of shrub willows, phylogenetically distant from each other, demonstrated high productivity along the length of shoots on annual cuttings. On the shoots of the strongest clone of S. triandra, the length of mature shoots was 176–215 cm, on the shoots of the strongest clone of S. viminalis - 132–192 cm. As the shoots grow, the differences in length between them increase. No significant influence of the clone factor on the dynamics of the daily growth of S. triandra shoots was revealed, and the effect of the clone factor on the dynamics of the daily growth of S. viminalis shoots is insignificant. In the seasonal dynamics of the daily growth of shoots, regardless of their species and clonal affiliation, three stages of shoot development were identified: spring, early summer, and late summer. The transitions between stages are synchronized in clones regardless of species. Qualitative interspecific and interclonal differences in the seasonal dynamics of daily shoot growth were not revealed. Quantitative interspecific differences in the seasonal dynamics of daily increment were revealed only at the second stage of shoot development, with high values of daily increment. Significant interclonal differences in the seasonal dynamics of daily growth were not found: differences between the trajectories of shoot development are due to intraclonal variability within each species. Recommendations. When planning, creating and operating pure and mixed cultures of S. triandra and S. viminalis, take into account the fundamental similarity in the seasonal dynamics of the development of shoots of different species of shrub willows. When harvesting and planting cuttings, use a homogeneous mother material. Culling of weak cuttings that are lagging behind in development should be carried out in the first year of life.

Drift, dissipation and risk to wildlife following targeted herbicide applications on boreal transmission rights-of-way

Herbicide use on boreal transmission line rights-of-way has been relatively limited compared to more temperate regions and therefore challenges exist in estimating and communicating the associated risks. Herbicides directly enter the ecosystem through deposition on vegetation and soils and can be a vector of contamination to browsing herbivores. Triclopyr drift and foliage concentrations were quantified following basal bark (Garlon RTU) and low-volume foliar (Garlon XRT) field treatments to aspen (Populus tremuloides) saplings and willow (Salix bebbiana) shrubs, respectively. Greater drift concentrations localized at the stem base were observed following basal bark treatments. Conversely, concentrations in foliage following the low-volume foliar treatment (DT50 = 5.7 days and DT90 = 34.6 days) were much higher than following basal bark treatment, which also required two days to translocate into the leaves. However, dissipation was rapid from both application methods and triclopyr in foliage was less than 20 μg g−1 a year following application. A risk assessment revealed an acceptable level of risk for acute toxicity to wildlife browsing on contaminated leaves from the residues detected in this study; however, an unacceptable level of risk for chronic toxicity to long-term browsing moose. Site-specific data regarding browsing behaviour on herbicide treated rights-of-ways and species-specific reference values are needed to improve confidence in the tier-two risk assessment. Basal bark application is ideal when stem density is lower and toxic effects for herbivores is of concern and low-volume foliar applications are best suited in areas with higher stem density when off-target herbicide deposition is less acceptable.

Sprout Regeneration of Shrub Willows after Cutting.

Shrub willow (Salix L. spp.) is a promising bioenergy resource crop due to its high growth rates and superb regenerative ability. Sprouting capacity is influenced by many factors, such as parent tree species and size, which are important limiting factors for stump survival or sprout growth. In this study, we aimed to quantify the survival and regeneration performance of sprouts (including sprout height, sprout diameter, sprout number, leaf morphological traits, leaf chlorophyll content, and ground part dry biomass) from the stumps of two Salix species from three diameter classes (10–15, 16–19, and 20–30 mm). An attempt was made to explore why the stump size affects the regeneration of willows by analyzing the carbon and nitrogen proportion of stumps. Stump survival did not differ between the two Salix species. However, the sprout regeneration of S. triandra was much better than that of S. suchowensis. An increase in stump diameter caused increases in the number of sprouts produced per stump, the mean height and basal diameter of sprouts per stump, the leaf chlorophyll content, and the biomass of sprouts per stump. By contrast, stump diameter did not significantly affect stump survival. The results indicate that the larger stumps store more carbon and nitrogen than small-sized stumps, which may be one of the reasons why the larger willow stumps have a stronger resprouting ability. This study provides essential information regarding the sprout regeneration of short-rotation coppice willow plantations after harvest.

Fauna and ecology of Hymenoptera background species of terrestrial ecosystems in the Yenisei Siberia tundra and forest-tundra

This paper presents materials on the ecology and faunistic composition of four species of Hymenoptera: Urocerus gigas L., 1758; Vespula vulgaris L., 1758; Bombus polaris Curtis, 1835; Bombus hyperboreus Schonherr, 1809. Their number was calculated for 20172019, data on population density, seasonal activity and forage plants of Hymenoptera adults in the tundra and forest-tundra of Yenisei Siberia are presented. As a result of calculating in both natural conditions, numerous species are true wasps and bumblebees and the large horntail is a rare species and was recorded only in the forest-tundra. When studying the food base of the studied species, it was noted that Vespula vulgaris was most often found on the forest bellap Anthriscus sylvestris L., in thickets of willow shrubs, Salix polaris Wahlenb. Adult insects Urocerus gigas were found mainly on Siberian larch Larix sibirica L. and alder forest Alnus fruticosa Rupr. Individuals of Bombus polaris and Bombus hyperboreus were recorded on horned dandelion Taraxacum ceratophorum L., narrow-leaved fireweed Chamerion angustifolium L., common tansy Tanacetum vulgare L.