Willow Growth Research Articles

The Performance of Five Willow Cultivars under Different Pedoclimatic Conditions and Rotation Cycles

A plant’s genotype, their environment, and the interaction between them influence its growth and development. In this study, we investigated the effect of these factors on the growth and biomass yield of willows in short-rotation coppice (SRC) under different harvesting cycles (i.e., two- vs. three-year rotations) in Quebec (Canada). Five of the commercial willow cultivars most common in Quebec, (i.e., Salix × dasyclados Wimm. ‘SV1’, Salix viminalis L. ‘5027’, Salix miyabeana Seeman ‘SX61’, ‘SX64’ and ‘SX67’) were grown in five sites with different pedoclimatic conditions. Yield not only varied significantly according to site and cultivar, but a significant interaction between rotation and site was also detected. Cultivar ‘5027’ showed significantly lower annual biomass yield in both two-year (average 10.8 t ha−1 year−1) and three-year rotation (average 11.2 t ha−1 year−1) compared to other cultivars (15.2 t ha−1 year−1 and 14.6 t ha−1 year−1 in two- and three-year rotation, respectively). Biomass yield also varied significantly with rotation cycle, but the extent of the response depended upon the site. While in some sites the average productivity of all cultivars remained fairly constant under different rotations (i.e., 17.4 vs. 16 t ha−1 year−1 in two- and three-year rotation, respectively), in other cases, biomass yield was higher in the two- than in the three-year rotation or vice versa. Evidence suggests that soil physico-chemical properties are better predictors of willow SRC plantation performance than climate variables.

In Vitro evaluation of salt tolerance of poplars and willows

The irrational anthropogenic influence on soils often leads to negative consequences, one of which is salinization. Among various types of salinity, chloride salinity has the greatest negative effect. Accumulatiоn of chlorine ions by plant cells causes disturbances in their metabolism, as a result of cell membrane damage. Such changes have a negative effect on the tree growth. Poplar and willow are energy trees with rapid growth and a wide range of adaptations to environmental conditions. These plants are not halophytes, but some genotypes are relatively salt-tolerant. Growing them in saline areas will have not only the ecological effect of soil remediation and importance for the urban horticulture, but can also bring economic profits, particularly in areas excluded from agricultural usage due to their salinity. The aim of the study was to analyze the salt tolerance of aspen (Populus tremula), hybrid poplar clone 'INRA 717-184' (P. tremula × P. alba) and willow clone 'Olympiyskiy vohon' (Salix alba × S. fragilis) under in vitro cultivation on the medium with sodium chloride added in concentrations 25 mM, 50 mM and 100 mM. General plant state, intensity of their growth (by the shoots’ length) and root formation (by number of roots) on the 10th, 30th and 60th day of cultivation were estimated. The results demonstrated that salt tolerance significantly varied in different genotypes. In hybrid poplar clone 'INRA 717-184', the intensity of growth activity was decreased after long-term cultivation under all investigated concentrations of sodium chloride. In aspen plants, a significant decrease of the intensity of shoots growth by 94.3 % compared to control was found only after two months of cultivation, then concentration of NaCl in media was 100 mM. The intensity of willow growth was not affected at any experimental treatment by sodium chloride. A statistically significant decrease of the intensity of root formation after the 1-st and 2-nd months of cultivation was shown only for aspen clones planted in the culture medium with 100 mM of sodium chloride added. In general, willow clones demonstrated higher intensity of root formation than poplar clones

Positive impact of bio-stimulators on growth and physiological activity of willow in climate change conditions

Abstract The aim of this research was to evaluate the physiological activity and growth of willow (Salix viminalis L.) plants cultivated under the conditions of adverse temperature and soil moisture content, and to assess the effect of the foliar application of Biojodis (1.0%) and Asahi SL (0.03%) bio-stimulators, or a mixture of Microcistis aeruginosa MKR 0105 and Anabaena PCC 7120 cyanobacteria under such changing growth conditions. The obtained results showed different reactions to the applied constant or periodically changed temperature and soil moisture content. The plants which grew at periodically changed adverse temperature (from -5 to 40oC) or in scantily (20% m.c.) or excessively (60% m.c.) watered soils, grew slowly, in comparison with those growing at 20oC and in optimally moistened soil (30% m.c.). Foliar application of Biojodis and Asahi SL cyanobacteria increased the growth of willow at optimal and adverse temperature or in scantily and excessively moistened soil. The changes in plant growth were associated with the changes in electrolyte leakage, activity of acid or alkaline phosphatases, RNase, index of chlorophyll content in leaves and gas exchange. The above indicates that the foliar application of the studied cyanobacteria and bio-stimulators partly alleviates the harmful impact of adverse temperature and water stress on growth and physiological activity of willow plants

Conductivity gradients as inferred by electromagnetic-induction meter (EM38) readings within a salt-affected wetland in Saskatchewan, Canada

The change from deep-rooted grass and shrub vegetation to annual-cropping dryland farming has contributed to serious soil salinization challenges on the semi-arid North American Great Plains. In some cases, cultivation of the Great Plains has increased the availability of water, causing dominant sulfate salts to travel from the uphill areas to depressions where it will surface when water evaporates at the soil surface. A potential solution could include the replanting of the native deep-rooted vegetation, which requires knowledge of the spatial distribution of soil salinity. This study tested the soil factors influencing electromagnetic-induction meter (EM38) readings of soil salinity distribution around wetlands. The objectives were to: (1) predict growth and survival of Salix dasyclados Wimm. (cv. ‘India’) along a salinity gradient in a small wetland, and (2) investigate whether newly established willows affected water-table fluctuations, which would indicate their phreatophytic nature or their ability to obtain their water supply from the zone of saturation. Results indicated significantly lower salinity values for sampling points with EM38 readings above 175 and 250 mS m−1 for height and survival, respectively. In addition, diurnal fluxes of the water table in areas of good willow growth and lower salinity indicated that cultivar ‘India’ was phreatophytic in these areas and therefore has great potential for being used to combat saline seeps.

Influence of soil chemical and physical characteristics on willow yield in Connecticut

Willows (Salix) are the focus of investigation as renewable feedstock for bioenergy in the Northeastern region of the US. The potential increase of acreage for willow biofuel production requires new information about how yield is influenced by variances in soil factors. The objectives of this experiment were to compare yields across several different soil series and to identify factors that may influence plant productivity. Four cultivars of shrub willow were planted in 2011 at five sites in Connecticut. Biomass yields were measured at the end of the fourth growing season. The best conditions for willow growth were recorded on Watchaug soil series, where the highest yield values for ‘SX67’ and ‘SX61’ (17.3 and 14.4 Mg ha−1 yr−1, respectively) are setting benchmarks for the potential of willow yield in Connecticut. These two willows were the most productive cultivars across all sites. ‘Allegany’ and ‘SV1’ performed better on sites with specific soil characteristics, clearly demonstrating greater cultivar × site interactions. Important soil characteristics that correlated with willow growth were soil organic matter, pH, as well as phosphorus, iron, magnesium and aluminum availability. All cultivars responded similarly to aluminum toxicity: the yields increased when exchangeable soil aluminum levels were below 200 mg kg−1. The yields also increased for most cultivars when the phosphorus levels were high. The yields consistently reached a maximum when the phosphorus to aluminum ratio was greater than 0.05. This study showed that soil factors correlated with willow yields and revealed that soil amendments could be exploited for yield gains.

Climate warming as a driver of tundra shrubline advance

Abstract Climate warming is predicted to alter ecological boundaries in high‐latitude ecosystems including the elevational or latitudinal extent of tall shrubs in Arctic and alpine tundra. Over 60 studies from 128 locations around the tundra biome have investigated shrub expansion in tundra ecosystems; however, only six studies test whether shrublines are actually advancing up hill‐slopes or northward into tundra where tall shrubs are currently absent. We test the hypothesis that willow shrublines have expanded to higher elevations in relation to climate across a 50 × 50 km area in the Kluane Region of the southwest Yukon Territory, Canada by surveying of 379 shrubs at 14 sites and sampling of 297 of the surveyed shrubs at 10 sites. We compared growth and recruitment to climate variables to test the climate sensitivity of shrub increase using annual radial growth analysis, age distributions and repeat field surveys to estimate the current rate of shrubline advance. We found consistent and increasing rates of recruitment of alpine willows, with estimates of faster advancing shrublines on shallower hill‐slopes. Mortality was extremely low across the elevation gradient. Aspect, elevation and species identity did not explain variation in recruitment patterns, suggesting a regional factor, such as climate, as the driver of the observed shrubline advance. Annual radial growth of willows was best explained by variation in summer temperatures, and recruitment pulses by winter temperatures. Measured recruitment rates are ~20 ± 5 individuals per hectare per decade (M ± SE) and measured rates of increased shrub cover of ~5 ± 1% per decade (M ± SE) measured at the Pika Camp site between field surveys in 2009 and 2013. Our results suggest that shrubline will continue to advance over the next 50 years, if growing conditions remain suitable. However, if future conditions differ between summer and winter seasons, this could lead to contrasting trajectories for recruitment vs. growth, and influence the vegetation change observed on the landscape. Synthesis. Our findings in the context of a review of the existing literature indicate that elevational and latitudinal shrublines, like treelines, are advancing in response to climate warming; however, the trajectories of change will depend on the climate drivers controlling recruitment vs. growth.

Impacts of recreation management practices in a subalpine wetland system dominated by the willow plant, Salix planifolia

Wetland habitat in the subalpine Rocky Mountains is an area of high biodiversity and includes many species of willow. These willow-dominated communities are often used for both summer and winter recreation. The maintenance of winter recreation trails has the potential to disturb wetland vegetation and compromise the long-term persistence of the wetland. In Breckenridge, Colorado, willow plants are clipped in October to a uniform height to prevent stems from protruding through the snow onto the ski trails, and large grooming tractors compact the snow on the trails. Our objective was to investigate the impact of winter recreation trail maintenance on growth and reproductive output of Salix planifolia (common names: planeleaf or diamondleaf willow) and to determine impacts on community diversity in a willow-dominated wetland system. Catkin production, plant height, and branch elongation were evaluated in meter-squared quadrats within paired belt transects both inside and outside a ski trail during the growing seasons of 2008 and 2009. In addition, percent cover of total vegetation was estimated for each species to calculate species richness and diversity. We found that maintenance of winter trails reduced catkin production and limited willow growth. Additionally, winter trail maintenance may have promoted the introduction of invasive species within the willow community. The activities associated with winter trail maintenance could interfere with the long-term persistence of the willow community adjacent to ski trails and should be considered when planning new trails in or along a wetland ecosystem.

Comparison of the growth of fast-growing poplar and willow in two sites of Central Kazakhstan

In temperate climatic conditions, plantations of poplar and willow species provide sustainable production of biomass. Short rotation coppice plantations on agricultural lands have a great potential to increase the amount of biomass available for the production of biofuels, bioenergy and bioproducts. We studied and measured the growth of poplar and willow clones in two experimental research sites in Batys and Astaninskiy in the steppe zone of Astana in northern Kazakhstan. We measured tree heights, stem diameters at breast height and crown diameter. The mean height of 6-years-old trees of the “Kazakhstanskiy” hybrid poplar was 4.03 m in the Batys site, which is 1.6 m less than the height of poplars from the Astaninskiy experimental site that were measured in autumn. The results of this study show different reactions of selected clones/cultivars of poplar and willow to climatic conditions of northern Kazakhstan as well as their usability for biomass production in plantations under limiting hydrological conditions.

Effectiveness of cyanobacteria and green algae in enhancing the photosynthetic performance and growth of willow (Salix viminalis L.) plants under limited synthetic fertilizers application

The physiological response of plants to triple foliar biofertilization with cyanobacteria and green algae under the conditions of limited use of chemical fertilizers was investigated. Triple foliar biofertilization with intact cells of Microcystis aeruginosa MKR 0105, Anabaena sp. PCC 7120, and Chlorella sp. significantly enhanced physiological performance and growth of plants fertilized with a synthetic fertilizer YaraMila Complex (1.0, 0.5, and 0.0 g per plant). This biofertilization increased the stability of cytomembranes, chlorophyll content, intensity of net photosynthesis, transpiration, stomatal conductance, and decreased intercellular CO2 concentration. Applied monocultures augmented the quantity of N, P, K in plants, the activity of enzymes, such as dehydrogenases, RNase, acid or alkaline phosphatase and nitrate reductase. They also improved the growth of willow plants. This study revealed that the applied nontoxic cyanobacteria and green algae monocultures have a very useful potential to increase production of willow, and needed doses of chemical fertilizers can be reduced.

Mountain wetland restoration: The role of hydrologic regime and plant introductions after 15 years in the Colorado Rocky Mountains, U.S.A.

Twelve wetland complexes were buried and/or drained by golf course and ski area development in the Colorado Rocky Mountains in the 1980s and early 1990s. We restored all or portions of each wetland, including fens, wet meadows and riparian areas, during 1997–2002. Intensive pre- and post-construction monitoring was used to develop restoration plans and evaluate their success. We revisited the sites to analyze long-term restoration processes in 2013–2016. Prior to construction the depth to the water table was measured weekly in monitoring wells installed through the fill, and into the wetland surfaces during and following restoration. Reference sites for each wetland type were used to characterize water table depth and vegetation for each wetland type. Restoration included removal of fill material and drains to create land surfaces with water table depth and dynamics similar to the reference areas for each wetland type. We planted each site with nursery grown sedges, willows and herbaceous dicots. Post restoration monitoring of water table depth, vegetation composition, sedge shoot density and willow growth was analyzed.The water table depth and dynamics of each restored wetland was similar to suitable reference sites on short and long time scales, indicating a stable hydrologic regime. Carex utriculata reached its maximum shoot density 4–5 years after planting indicating rapid growth and high production. Willow stems were still increasing in height 15 years after planting and basal stem density was also increasing. Most planted herbaceous dicots disappeared, indicating the difficulty of establishing them from plantings. Exotic (non-native) plants have invaded all three wetland types, with their highest cover in riparian areas. Critical factors that led to success were careful hydrological analysis of reference and restoration sites prior to earthwork, creating appropriate land/ground water interactions, and establishing clonal rhizomatous sedges and native willows.

Aboveground and belowground mammalian herbivores regulate the demography of deciduous woody species in conifer forests

AbstractMammalian herbivory can have profound impacts on plant population and community dynamics. However, our understanding of specific herbivore effects remains limited, even in regions with high densities of domestic and wild herbivores, such as the semiarid conifer forests of western North America. We conducted a seven‐year manipulative experiment to evaluate the effects of herbivory by two common ungulates, Cervus elaphus (Rocky Mountain elk) and cattle Bos taurus (domestic cattle) on growth and survival of two woody deciduous species, Populus trichocarpa (cottonwood) and Salix scouleriana (Scouler's willow) in postfire early‐successional forest stands. Additionally, we monitored belowground herbivory by Thomomys talpoides (pocket gopher) and explored effects of both aboveground and belowground herbivory on plant vital rates. Three, approximately 7 ha exclosures were constructed, and each was divided into 1‐ha plots. Seven herbivory treatments were then randomly assigned to the plots: three levels of herbivory (low, moderate, and high) for both cattle and elk, and one complete ungulate exclusion treatment. Treatments were implemented for seven years. Results showed that cattle and elk substantially reduced height and growth of both cottonwood and willow. Elk had a larger effect on growth and subsequent plant height than cattle, especially for cottonwood, and elk effects occurred even at low herbivore densities. Pocket gophers had a strong effect on survival of both plant species while herbivory by ungulates did not. However, we documented significant interaction effects of aboveground and belowground herbivory on survival. Our study is one of the first to evaluate top‐down regulation by multiple herbivore species at varying densities. Results suggest that traditional exclosure studies that treat herbivory as a binary factor (either present or absent) may not be sufficient to characterize top‐down regulation on plant demography. Rather, the strength of top‐down regulation varies depending on a number of factors including herbivore species, herbivore density, interactions among multiple herbivore species, and varying tolerance levels of different plant species to herbivory.

Groundwater controls on biogeomorphic succession and river channel morphodynamics

Biogeomorphic succession describes feedbacks between vegetation succession and fluvial processes that, at the decadal timescale, lead to a transition from bare river-deposited sediment to fully developed riparian forest. Where the rate of stabilization by biogeomorphic succession is greater than the rate of ecological disturbance by fluvial processes, a river is likely to evolve into less dynamic states. While river research has frequently considered the physical dimensions of morphodynamics, less is known about physical controls on succession rates, and how these impact stream morphodynamics. Here we test the hypothesis that groundwater dynamics influence morphodynamics via the rate of biogeomorphic succession. We applied historic imagery analysis in combination with dendroecological methods for willows growing on young gravelly fluvial landforms along a steep groundwater-depth gradient. We determined the following: floodplain morphodynamics and plant encroachment at the decadal scale, pioneer willow growth rates, and their relationships to hydrological variables. Willow growth rates were correlated with moisture availability (groundwater, discharge, and precipitation variability) in the downwelling reach, while little correlation was found in the upwelling reach. After a reduction in ecological disturbance frequency, data suggest that where groundwater is upwelling, biogeomorphic succession is fast, the engineering effect of vegetation is quickly established, and hence channel stability increased and active channel width reduces. Where groundwater is downwelling, deeper and more variable, biogeomorphic succession is slower, the engineering effect is reduced, and a wider active width is maintained. Thus, groundwater is an important control on biogeomorphic feedbacks intensity and, through the stabilizing effect of vegetation, may drive long-term river channel morphodynamics.

Interactive effects of biochar and an organic dust suppressant for revegetation and erosion control with herbaceous seed mixtures and willow cuttings

AbstractLand reclamation efforts on “non‐soil” substrates frequently involve additions of organic material coupled with soil‐stabilizing dust suppressants to control erosion, but formal experiments, particularly of interactive effects, are lacking. We examined the effects of Entac™, a tall oil pitch emulsion, and pyrolyzed wood waste‐derived biochar on early plant establishment, growth, and survivorship, in 2 factorial greenhouse experiments: 1 using a seed mix widely used for roadside erosion control (the grasses Festuca rubra, Poa pratensis, Lolium perenne, and white clover [Trifolium repens]) and 1 using rooted cuttings of sand bar willow (Salix exigua). Biochar additions of 5, 10, and 20 t/ha enhanced biomass of clover by 14–250%, but had no significant effects on grasses. Entac additions inhibited early establishment and growth of both clover and grasses at all biochar treatment levels. Entac plus biochar treatments significantly enhanced survivorship of willows following a drought treatment in a greenhouse trial. In a field trial, Entac treatments had positive effects on willow diameter growth. Collectively, these results suggest that better soil moisture retention is the principal mechanism responsible for enhanced survivorship and growth of planted willows treated with Entac and biochar on sand substrates. Given Entac's inhibitive effects on early establishment of herbaceous species, and the abilities of Entac and biochar in combination to mitigate drought stress, these treatments may be particularly well suited for ecological restoration efforts using planted tree stock on coarse‐textured substrates and where exposure and ingress of non‐native herbaceous species are of concern.

Summer Temperature Drives Radial Growth of Alpine Shrub Willows on the Northeastern Tibetan Plateau

ABSTRACTShrub willows (Salix species) are widespread beyond the latitudinal and altitudinal treelines. Their ring width has been shown to be a reliable ecological indicator for changes in the harsh cold conditions in the Arctic, but little is known on their growth in alpine conditions. The shrubby Salix oritrepha grows above the treeline on the northeastern Tibetan Plateau (TP), making it an interesting woody species to explore responses of alpine communities to ongoing climate warming in this area. Since precipitation increases with increasing elevation (until 4670 m) in the study area, we hypothesize that the growth of S. oritrepha is mainly constrained by cold summer temperature. We sampled 35 S. oritrepha individuals above the juniper treeline (4200 m), and took basal wood cross sections for dendrochronological analyses. Few missing rings were detected at the shoot base when serial sectioning was applied. Ring width (RW) and basal area increment (BAI) standard chronologies were established. We found that BAI reflected a stronger climatic signal than RW. The radial growth was constrained by low July to August temperatures. We expect that climate warming would enhance the growth of alpine willows, which could alter the services provided by these high-elevation ecosystems.

A Closer Look: Stream Geomorphology and Ecohydrological Interactions in the Minnesota River Basin

A Closer Look: Stream Geomorphology and Ecohydrological Interactions in the Minnesota River Basin

Do moose redistribute nutrients in low-productive fen systems?

The reduction of human use in many grassland systems across Europe has led to bush encroachment and a loss of biodiversity. Low intensity grazing systems by livestock has often been used as a cost-effective management tool to counteract this process. However, not all semi-natural grasslands are suitable for this due to large distance from human settlements or adverse environmental conditions. In this study we address the question whether natural wild large ungulates can be a useful management tool as well. In nutrient-limited systems, large herbivores can affect vegetation dynamics by redistribution of nutrients next to their direct effects on the vegetation. They can preferentially forage plant species and deposit their pellets at other locations leading to nutrient redistribution. We studied whether moose (Alces alces) in the Biebrza National Park (Poland), plays a role in nitrogen dynamics. Microscopic analyses of faeces showed that 57% of the diet consisted of Salix cinerea, which was preferentially foraged upon indicated by a positive Jacobs’ selectivity index. Pellet density was significantly higher in patches of S. cinerea compared to the surrounding vegetation. Based on the chemical composition of moose pellets and the pellet density, we calculated that moose-derived N (faeces and urine) leads to a relevant N-input in willow patches compared to other sources of N in the system. We show that moose do not redistribute nitrogen between different vegetation types but instead speed up the local recycling of nitrogen in patches dominated by willows during the growing season. As a consequence, nutrients become quicker available here than in other parts of the system. We hypothesize that enhanced N-availability in willow patches may off-set the growth reduction caused by moose browsing on willows, which fits to the observed continuous expansion of willows in the study area despite high density of moose. This suggests that moose likely stimulate the growth of willow rather than the often supposed suppression of this woody species. In these systems, more labour-intensive management (f.e. mowing) is required to counteract bush encroachment.

Establishment and Early Growth of Willow at Different Levels of Weed Competition and Nitrogen Fertilization

To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora (Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow planting. The buckets were fertilized with 30 or 90 kg N ha−1. Willow with weeds sown after 15 days produced less biomass and smaller leaf area and had a lower maximum shoot height compared to willow planted without weeds and willow with weeds sown after 26 or 30 days. Fertilization with 90 kg N ha−1 gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation, fertilization should be delayed.

洪水営力による樹木管理後の幼木林動態を踏まえた樹林化抑制手法の考察

Gravel-bed rivers in Japan are now facing a multitude of problems relating to fluvial environment and flood control. These problems include the expansion of river beds with less disturbance by flooding and the growth of the riverine trees and the decrease of high-quality gravel-bed bars and the immobilization of low-flow channel. In particular, the gravel bed river that dominated by vigorous growth of Willows and Robinia pseudo-acacia, sometimes increase the riverine trees by vegetative propagation under the flood disturbance. In addition, expansion of the overgrowth density is likely to occur as the young riverine trees that easily fallen by flood disturbance. In this study, to target the gravel bed of Watarase river that Robinia pseudo-acacia, etc. grows in the river, evaluated the dynamics of young riverine trees after felling, and proposed the excavation shape of gravel-bed bar for forestation suppressing by using flood disturbance.

Transplanting Soil Microbiomes Leads to Lasting Effects on Willow Growth, but not on the Rhizosphere Microbiome.

Plants interact closely with microbes, which are partly responsible for plant growth, health, and adaptation to stressful environments. Engineering the plant-associated microbiome could improve plant survival and performance in stressful environments such as contaminated soils. Here, willow cuttings were planted into highly petroleum-contaminated soils that had been gamma-irradiated and subjected to one of four treatments: inoculation with rhizosphere soil from a willow that grew well (LA) or sub-optimally (SM) in highly contaminated soils or with bulk soil in which the planted willow had died (DE) or no inoculation (CO). Samples were taken from the starting inoculum, at the beginning of the experiment (T0) and after 100 days of growth (TF). Short hypervariable regions of archaeal/bacterial 16S rRNA genes and the fungal ITS region were amplified from soil DNA extracts and sequenced on the Illumina MiSeq. Willow growth was monitored throughout the experiment, and plant biomass was measured at TF. CO willows were significantly smaller throughout the experiment, while DE willows were the largest at TF. Microbiomes of different treatments were divergent at T0, but for most samples, had converged on highly similar communities by TF. Willow biomass was more strongly linked to overall microbial community structure at T0 than to microbial community structure at TF, and the relative abundance of many genera at T0 was significantly correlated to final willow root and shoot biomass. Although microbial communities had mostly converged at TF, lasting differences in willow growth were observed, probably linked to differences in T0 microbial communities.

The influence of communal sewage sludge on the content of macroelements in the stem of selected clones of willow (Salix viminalis L.)

The problem of uptaking macroelements by plants from sewage sludge is still actual and controversial question. Sewage sludge (the by-product of sewage purification) contains many precious macroelements like N or P, beside heavy metals. These nutrients are used for willow growth and development, and ultimately to obtain high yields of biomass. The paper presents results on the impact of municipal sewage sludge on the concentration of macroelements (N, P, Mg, Ca, Na and K) in the stem of several clones of willow. Field experiment was carried out at Experimental Station Pawlowice (Poland) during the years 2009–2010 on grey-brown soil. Trials were conducted according to two factors and the split-plot method. Following factors were investigated: I—various doses of sewage sludge: 75tha−1 fresh weight of sewage sludge (14.3Mgha−1d.m.) and 150Mgha−1 fresh weight (28.5Mgha−1d.m.) and II—clones (1001 Salix viminalis×dasycladis ssp. Baltica, 1047 Salix viminalis var gigantea, 1053 Orm Valne, 1054 Salix viminalis 082) of Salix viminalis L.