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This article compares different production, economic, and selected environmental aspects of agroforestry systems in a standard (alley cropping) and a newly proposed design with fast-growing trees grown in short-rotation coppice. Our models of agroforestry systems (AFSs) are as follows: (i) alley cropping AFS with cherry and walnut trees in single rows (tree strips) with 28 m-wide arable fields between them (crop strips), and (ii) coppiced tree belt AFS with poplars and willows and 25 m-wide arable fields between them (crop strips). To evaluate the production characteristics of trees, we used yield curves from experimental plantations in conditions of the Czech Republic from previous research projects. Cost data were collected from long-term experimental plantations and combined with current operation and energy prices. The article presents an economic methodology for assessing the competitiveness of biomass production in AFSs under the current identified market conditions. Our results show that AFSs with short-rotation coppice can have similar economic and production results as annual crops if grown on suitable sites and with appropriate quality of agronomy. In comparison, alley cropping AFSs with fruit trees would not be economically viable for farmers without a significant subsidy for establishment and maintenance in the first years after establishment. Concerning the latest economic and political developments, the product from SRC (energy woodchips) can be evaluated as strategic, increasing the producer's independence from purchased energy fuels. [ABSTRACT FROM AUTHOR]

Solid biomass can be used for energy generation and the production of various renewable bioproducts. The aim of this study was to determine the yield and characteristics of wood obtained as debarking residue from 14 genotypes of short-rotation woody crops (SRWCs). These included five Populus genotypes, one Robinia genotype, and eight Salix genotypes, harvested in both annual and quadrennial cycles. The results showed that the highest dry wood yield (12.42 Mg ha−1 y−1 DM) and yield energy value (244.34 GJ ha−1 y−1) were obtained from willow (cultivar Żubr) harvested in a quadrennial cycle. The best effect among the poplar genotypes was achieved for the Hybryda275, and it was particularly marked in the quadrennial harvest cycle. The poorest results were determined for black locust. The Robinia characteristics included the significantly lowest moisture content (31.6%), which was a positive attribute from the energy point of view, but, on the other hand, it had some adverse characteristics—the highest levels of sulfur (0.033% DM), nitrogen (0.38% DM), and ash (0.69% DM). More beneficial properties in this respect were determined for willow and poplar wood. Moreover, willow and poplar wood contained more cellulose—51.8 and 50.0% DM, respectively—compared with black locust. Extending the SRWC shoot harvest cycle from annual to quadrennial resulted in an increase in cellulose, lignin, and carbon, higher heating value, and a decrease in nitrogen, sulfur, ash, and moisture content. Therefore, extending the harvest cycle improved the parameters of SRWC wood as an energy feedstock. [ABSTRACT FROM AUTHOR]

Typically, coniferous sawdust from debarked stems is used to make pellets. Given the high lignin content, which ensures strong binding and high calorific values, this feedstock provides the best quality available. However, finding alternative feedstocks for pellet production is crucial if small-scale pellet production is to be developed and used to support the economy and energy independence of rural communities. These communities have to be able to create pellets devoid of additives and without biomass pre-processing so that the feedstock price remains low. The features of pellets made from other sources of forest biomass, such as different types of waste, broadleaf species, and pruning biomass, have attracted some attention in this context. This review sought to provide an overview of the most recent (2019–2023) knowledge on the subject and to bring into consideration potential feedstocks for the growth of small-scale pellet production. Findings from the literature show that poor bulk density and mechanical durability are the most frequent issues when making pellets from different feedstocks. All of the tested alternative biomass typologies have these shortcomings, which are also a result of the use of low-performance pelletizers in small-scale production, preventing the achievement of adequate mechanical qualities. Pellets made from pruning biomass, coniferous residues, and wood from short-rotation coppice plants all have significant flaws in terms of ash content and, in some cases, nitrogen, sulfur, and chlorine content as well. All things considered, research suggests that broadleaf wood from beech and oak trees, collected through routine forest management activities, makes the best feasible feedstock for small-scale pellet production. Despite having poor mechanical qualities, these feedstocks can provide pellets with a low ash level. High ash content is a significant disadvantage when considering pellet manufacture and use on a small scale since it can significantly raise maintenance costs, compromising the supply chain's ability to operate cost-effectively. Pellets with low bulk density and low mechanical durability can be successfully used in a small-scale supply chain with the advantages of reducing travel distance from the production site and storage time. [ABSTRACT FROM AUTHOR]

The current context of ecological transition and the fight against climate change have revived interest in short-rotation coppice (SRC) of woody crops for bioenergy or bioproduct purposes. To determine the growth and yield potential of different willow cultivars, plantations were established in five regions of Quebec (Canada) across a wide climatic gradient. The present study compares results obtained after six years of cultivation at two coppicing frequencies (two and three years). Although annual yields approaching 20 tons ha−1 have been recorded at several of the study sites, little difference in the productivity of the tested cultivars was found, except for Salix viminalis "5027", which was generally less productive. Overall productivity was weakest at La Morandière, the northernmost site. Neither frequency of coppicing lead to a difference in yields. At La Pocatière, one of the coldest regions in this study, yields of cultivars were comparable to those recorded at the southernmost sites. Moreover, the highest cumulative yield after six years was recorded at that site with the cultivar "SV1". The fact that yields at most sites remain high after several years is indicative of the production potential of willow crops in SRC for Eastern Canada. [ABSTRACT FROM AUTHOR]

Monoculture croplands are a major source of global anthropogenic emissions of nitrous oxide (N2O), a potent greenhouse gas that contributes to ozone depletion. Agroforestry has the potential to reduce N2O emissions. Presently, there is no systematic comparison of soil N2O emissions between cropland agroforestry and monoculture systems in Central Europe. We investigated the effects of converting the monoculture cropland system into the alley cropping agroforestry system on soil N2O fluxes at three sites (each site has paired agroforestry and monoculture) in Germany, where agroforestry combined crop rows and poplar short‐rotation coppice (SRC). We measured soil N2O fluxes monthly over 2 years (March 2018–January 2020) using static vented chambers. Annual soil N2O emissions from agroforestry ranged from 0.21 to 2.73 kg N ha−1 year−1, whereas monoculture N2O emissions ranged from 0.34 to 3.00 kg N ha−1 year−1. During the rotation of corn crop, with high fertilization rates, agroforestry reduced soil N2O emissions by 9% to 56% compared to monocultures. This was mainly caused by low soil N2O emissions from the unfertilized agroforestry tree rows. Soil N2O fluxes were predominantly controlled by soil mineral N in both agroforestry and monoculture systems. Our findings suggest that optimized fertilizer input will further enhance the potential of agroforestry for mitigating N2O emissions. [ABSTRACT FROM AUTHOR]

In plantations, nutrient extraction is likely to be higher with shorter rotations. This is because thinner stems have a higher proportion of nutrient-rich bark, and sapwood contains more nutrients than hardwood. Annual willow plantations may extract even more nutrients than long rotation forests. In short rotation forest systems, the diameter of the harvested stems may affect the amount of nutrients exported with the wood. The present study investigated the effect of stem diameter distribution on nutrient extraction and nutrient use efficiency (UE). Two Salix clones were planted at low or high densities, and irrigated or left rainfed. Stems were harvested annually, and three years after planting, N, P, K, and Ca concentrations in small, medium, and big stems were determined, as well as the proportion of each stem diameter class at harvest. N extraction was the highest, followed by Ca, K, and P extraction. Nutrient extraction and nitrogen use efficiency were influenced by the proportion of small, medium, and big stems. The clones showed differences in nutrient concentration and stem diameter distribution, and irrigation increased the proportion of large stems and nitrogen concentration. Although the NUE and PUE were not linearly related to yield, they were related to the distribution of stem diameter and nutrient concentration. Higher yield resulted in higher CaUE and KUE, but the extraction of these nutrients during harvest was fine-tuned by stem diameter distribution and tissue concentration. This highlights the significance of stem diameter distribution in assessing the nutrient costs of wood production for bioenergy. [Display omitted] • In annual willow coppice nutrient extraction is N>Ca>K>P. • Nutrient extraction is related to the proportion of small, medium and large stems. • Clones differ in stem diameter distribution and nutrient concentration. • Irrigation increases the proportion and N concentration of large stems. • It is possible to increase nutrient use efficiency through silvicultural practices. [ABSTRACT FROM AUTHOR]

We present the first assessment of the impact of land use change (LUC) to second-generation (2G) bioenergy crops on ecosystem services (ES) resolved spatially for Great Britain (GB). A systematic approach was used to assess available evidence on the impacts of LUC from arable, semi-improved grassland or woodland/forest, to 2G bioenergy crops, for which a quantitative 'threat matrix' was developed. The threat matrix was used to estimate potential impacts of transitions to either Miscanthus, short-rotation coppice (SRC, willow and poplar) or short-rotation forestry (SRF). The ES effects were found to be largely dependent on previous land uses rather than the choice of 2G crop when assessing the technical potential of available biomass with a transition from arable crops resulting in the most positive effect on ES. Combining these data with constraint masks and available land for SRC and Miscanthus (SRF omitted from this stage due to lack of data), south-west and north-west England were identified as areas where Miscanthus and SRC could be grown, respectively, with favourable combinations of economic viability, carbon sequestration, high yield and positive ES benefits. This study also suggests that not all prospective planting of Miscanthus and SRC can be allocated to agricultural land class (ALC) ALC 3 and ALC 4 and suitable areas of ALC 5 are only minimally available. Beneficial impacts were found on 146 583 and 71 890 ha when planting Miscanthus or SRC, respectively, under baseline planting conditions rising to 293 247 and 91 318 ha, respectively, under 2020 planting scenarios. The results provide an insight into the interplay between land availability, original land uses, bioenergy crop type and yield in determining overall positive or negative impacts of bioenergy cropping on ecosystems services and go some way towards developing a framework for quantifying wider ES impacts of this important LUC.

The goal of this research is an assessment of the possible use of peatlands biomass and straw for the production of mixed bio-pellets. Peaty soils are a specific type of soils formed as the result of wetlands drainage. Peat mining is completed by the factory if the layer of the peat is less than 1-2 meters and not enough deep for effective mechanical excavation. After the peat excavation is finished, the biggest problem is the use of these lands for other purposes. One of the perspective directions is rewetting of post-mining peatlands to stimulate the growth of common reed, cattail, fescue, sedge, and other grasses which may grow in natural conditions, and also improve conditions for the cultivation of other plants, including trees. The yield of wetland grass in Belarus varies from 8.1 to 14 DM g ha-1 per year. The yield of willow wood can reach 8-10 of DM g ha-1 per year. The highest prime cost of biomass is obtained for willow wood, but it will be lower with the enlargement of the plantation area. Pellets with a high content of wood residues (sawdust) have the best technological parameters including calorific value when compared to pellets from only peat and peat plus straw. Biomass production on degraded peaty soils has also an ecological effect. The cost of carbon quotas on the market varies from 20 to 25 euro per ton, and biomass production can provide additional profit in the case of CO2 emissions trading depending on the biomass content in the fuel.

The paper aims to analyze the biomass at one year growth, resulting from the cultivation of the INGER energy willow clone as a short rotation crop (SRC), in order to use it as a renewable fuel. The paper completes the data in the field of renewable energies in the context of decreasing fossil energy reserves worldwide and emphasizing the impact on renewable energies. The effect of a contaminated land on the survival rate of the planted seedlings and the effect of the energy willow culture on the composition of the contaminated soil are analyzed. The obtained results show that the biomass characteristics, such as the calorific power of about 18,21 kJ/g to18,90 kJ/g, and the ash content of about 2,25 %, are comparable with the ones of other lignocellulosic energy materials. The results found in this studyshowed that the woody biomass in the first vegetation year of energy willow can be used directly as a renewable fuel without the need for compaction in the form of briquettes or pellets.

Purpose: The combination of chemostabilization and phytoextraction provide an affordable and environmentally effective remediation technology for the heavy metals in contaminated soils. The purpose of this study was to investigate how biochar applications in heavily contaminated alluvium soils reduced the toxic effects of heavy metal (Cd, Pb, Zn) and their transport through the soil profile. Materials and methods: The 3-year experiment was conducted under controlled conditions in greenhouse. Extremely contaminated soil required high doses (5, 10, and 15% w/w) of biochar. Biochar was prepared from wood by high-temperature pyrolysis (800 °C). Salix smithiana Willd. was chosen as a model plant. Leachate describing the mobility of metals was collected five times during each vegetative period. Leachate was collected. Results and discussion: Biochar application enhanced the phytoextraction potential of willow plants in the first and second year of a pot experiment. High biochar applications (5, 10, and 15% w/w) reduced the phytotoxicity of metals in soil solution, improved biomass growth in Salix smithiana, and enhanced heavy metal uptake by plants in the amendment treatments. In the 3rd year, the pH of both the soil and leachate decreased by 1 unit. The decrease of pH led to the increase of Cd and Zn in the leachate and/or limited the growth of plants. Conclusions: Biochar seems to be an effective tool for heavy metal immobilization; however, further research is necessary to evaluate the mechanisms of biochar behavior and subsequent utilization for remediation of extremely contaminated alluvial soils. [ABSTRACT FROM AUTHOR]

Abstract This contribution provides better insights in the water relations and the physiological traits of four commercial poplar genotypes of different genetic background, 'Bakan', 'Oudenberg', 'Koster' and 'Grimminge'. The main continuous (nondestructive and providing continuous and automated data records) and discontinuous (destructive and not allowing automation) plant water status (PWS) indicators were monitored at a multigenotype, commercial‐scale short‐rotation coppice plantation in East‐Flanders (Belgium), and their relationships with the principal environmental variables were assessed. All measurements were performed during the entire 2016 growing season on the third year of the third rotation in multistemmed trees. The discontinuous PWS indicators were measured on 10 separate days with a different evaporative demand and soil water content, while the continuous PWS indicators were recorded from April to November. The genotypes responded differently to environmental drivers and to soil conditions, based on the PWS indicators, featuring a different water behaviour in relation to the level of isohydricity. Poplar genotypes 'Koster' and 'Bakan' showed the typical water‐conserving behaviour of isohydric species, while 'Grimminge' was more in line with the anisohydric ones. A principal component analysis showed that sap flow (Fs) was the most suitable PWS indicator. The Fs and therefore the sap flow‐based canopy transpiration (Ec) were tightly linked to the phenological stage of the trees as well as to vapour pressure deficit and photosynthetic photon flux density, based on relationships between Ec and environmental variables. A quantitative predictive model was developed to estimate the crop water requirements for specific genotypes, by calculating transpiration per unit of ground area with a few environmental variables, monitored with easy‐to‐handle sensors.

Increasing demand for biomass has led to an on‐going intensification of fuel wood plantations with possible negative effects on open land biodiversity. Hence, ecologists increasingly call for measures that reduce those negative effects on associated biodiversity. However, our knowledge about the efficiency of such measures remains scarce.We investigated the effects of gap implementation in short rotation coppices (SRCs) on carabid diversity and assemblage composition over 3 years, with pitfall traps in gaps, edges and interiors. In parallel, we quantified soil surface temperature, shrub‐ and herb cover.Edges had the highest number of species and abundances per trap, whereas rarefied species richness was significantly lower in short rotation coppice interiors than in other habitat types. Carabid community composition differed significantly between habitat types. The main environmental drivers were temperature for number of species and abundance and shrub cover for rarefied species richness.We found significantly higher rarefied species richness in gaps compared with interiors. Hence, we argue that gap implementation benefits overall diversity in short rotation coppices. Furthermore, the differences in species community composition between habitat types through increased species turnover support carabid diversity in short rotation coppices. These positive effects were largely attributed to microclimate conditions. However, to maintain positive effects, continuous management of herb layer might be necessary. [ABSTRACT FROM AUTHOR]

There is a growing interest in Ulmus pumila L. as a forest plant species in harsh environments, as well as a woody short‐rotation crop for biomass production in marginal lands. In countries where U. pumila is allochthonous, concerns have been raised on the easy spread of this species, on the grounds that it produces large quantities of wind‐dispersed fruits with high potential germination success. Knowledge of the phenological responses of this species to management practices is essential to evaluate the risk of invasion to adjacent lands. This work addresses the phenology of U. pumila according the BBCH scale and the effect of short‐rotation coppicing and plant density on phenological growth stages of this species. Results showed that there is little effect of plant density on the phenology of non‐managed trees grown in regular plantations. On the contrary, short‐rotation coppice influences greatly the vegetative and reproductive phenology of Siberian elm. High plant densities, winter harvesting and 2‐year rotation guarantee that fruit dispersal will not happen. [ABSTRACT FROM AUTHOR]

Abstract Biomass from short‐rotation coppice (SRC) of woody perennials is being increasingly used as a bioenergy source to replace fossil fuels, but accurate assessments of the long‐term greenhouse gas (GHG) balance of SRC are lacking. To evaluate its mitigation potential, we monitored the GHG balance of a poplar (Populus) SRC in Flanders, Belgium, over 7 years comprising three rotations (i.e., two 2 year rotations and one 3 year rotation). In the beginning—that is, during the establishment year and during each year immediately following coppicing—the SRC plantation was a net source of GHGs. Later on—that is, during each second or third year after coppicing—the site shifted to a net sink. From the sixth year onward, there was a net cumulative GHG uptake reaching −35.8 Mg CO2 eq/ha during the seventh year. Over the three rotations, the total CO2 uptake was −51.2 Mg CO2/ha, while the emissions of CH4 and N2O amounted to 8.9 and 6.5 Mg CO2 eq/ha, respectively. As the site was non‐fertilized, non‐irrigated, and only occasionally flooded, CO2 fluxes dominated the GHG budget. Soil disturbance after land conversion and after coppicing were the main drivers for CO2 losses. One single N2O pulse shortly after SRC establishment contributed significantly to the N2O release. The results prove the potential of SRC biomass plantations to reduce GHG emissions and demonstrate that, for the poplar plantation under study, the high CO2 uptake outweighs the emissions of non‐CO2 greenhouse gases.

In Europe, poplar and other fast-growing tree species are considered valuable resources for meeting the required wood demand of the rising bioeconomy. The agricultural technique of short rotation coppice (SRC) has gained relevance to ease the pressure of the demand for wood from forests. Previous studies have implemented the life cycle assessment (LCA) methodology to evaluate such systems' potential environmental impacts. These studies present different outcomes, though a general pattern on the potential benefit of SRC is observed. The variation of relevant methodological options, such as goal and scope, system boundary, functional unit, reference system, data source, characterization models, and impact categories assessed can significantly affect the results. A consequence of this discrepancy is its effect on results' interpretation, making the absolute comparison of case studies challenging and hindering the understanding of the potential impacts of SRC LCAs in support of developing a sustainable bioeconomy. Therefore, the current research attempts to understand the methodological implementation of LCA in assessing SRC value chains. Through literature research, studies are analyzed based on the four LCA phases. One of the results of this study shows how most of the articles focus on assessing the impact category related to climate change, while other environmental issues that are particularly relevant for agricultural woody biomass systems are seldomly evaluated. By discussing the state of the art of SRC LCA, this review paper attempts to suggest improvements that will allow future LCA studies to reach a more comprehensive understanding of the overall environmental impact of SRC systems. [ABSTRACT FROM AUTHOR]

Short rotation plantations (SRP), also called short rotation coppice, can contribute to bioeconomy by satisfying the rising demand for wood raw material while strengthening the rural economy. However, farmers all over Europe show limited adoption of SRP. Marginal lands are considered a promising option for producing SRP biomass and avoiding conflicts with food production. This study focuses on the Malacky region in Western Slovakia because of suitable land quality and a board production site close by providing a significant local market for the produced biomass. Qualitative interviews in 2018 explored personal and situational factors that influenced local farmers' (N = 19) willingness to adopt SRP. Slovakia's land fragmentation in combination with the required landowner's consent, competition with food production, and lack of identification with SRP were identified as prominent barriers. The economic benefit from using low quality lands and environmental benefits from SRP were identified incentives. Moreover, the study found agricultural cooperatives more open to SRP than agricultural business companies, as they are more interested in the economic benefits and prefer agricultural activity over fallow land. Because the study identified conflicting views about the possible impacts of SRP on the environment and the rural community, it is considered crucial to provide farmers with science-based facts on these issues. This aspect should also be acknowledged to increase acceptance of stakeholders, such as land owners, governmental actors, and the general public, which is needed to develop measures to encourage SRP. [ABSTRACT FROM AUTHOR]

In addition to the use as biofuel, the utilization of poplar wood as a raw material from short-rotation coppice (SRC) became increasingly important in recent years. Because poplar SRCs are harvested during dormant season, wood storage is of particular importance to guarantee wood processing industries a continuous wood supply. The study focuses on the change of physical and chemical properties of poplar wood by the application of different storage strategies over a 9-month period. Therefore, a total amount of 60 m3 test log piles were set up in 2018 for six different storage variants: compact piles, compact piles with water sprinkling and oxygen exclusion, each with logs in bark and debarked. The effects on wood moisture content, equilibrium moisture content and wood density (ρ0) and the changes in the chemical components lignin, cellulose, hemicellulose and extracts were determined and evaluated. As expected, the wood moisture content changed in a wide range over the storage period, depending on the variant. The levels of equilibrium moisture (changes from − 4% to − 13.1%) as well as wood density (changes from − 2.61% to − 9.01%) decreased for all variants between start and end of storage. Changes in chemical composition were observed for all storage variants, which indicates microbial activity supporting the assumption that the observed mass loss is driven by wood decay. Overall, changes were more homogeneous for logs in compact piles compared to the other storage methods. Considering the weather conditions during the investigated period, the results indicate that storage in compact piles with debarked logs is the best method for the conservation of poplar wood from SRC. [ABSTRACT FROM AUTHOR]

The main purpose of the study was to assess the impact of energy willow (Salix viminalis L.) crops on the vascular flora diversity of agroecosystems in Łódź voivodeship in central Poland. The studies were carried out in the years 2013 and 2014 on seven commercial plantations which were established in various soil conditions, on five soil agricultural complexes. In total, 50 phytosociological relevés were made using the Braun-Blanquet method. The evaluation was conducted on the basis of an inventory of vascular flora accompanying energy willow crops, involving determination of phytosociological classes and multifaceted analysis. For each species the following parameters were determined: family, geographical and historical group, apophyte origin, biological-stability, life-form, and status as an invasive, endangered, near-endangered, or protected species. The number of vascular plant species accompanying energy willow crops was high (133 species in total) and depended on the soil conditions (soil agricultural complex - SAC). The largest number of species (74) was found on silty and sandy soils, too wet or too dry (SAC 9), while the lowest (45) was on very dry sandy soils (SAC 7). These species belonged mainly to three phytosociological classes: Molinio-Arrhenatheretea, Stellarietea mediae, and Artemisietea vulgaris. In all habitats, most species (83%) were rare and more frequent (I and II constancy class). The species were mainly apophytes – native species (76.7%), and among them meadow plants, woodland and shrub species were predominant. An important part of flora was endangered species (Agrostemma githago L.). Ten invasive plant species which mostly occurred very rarely were also found. Salix viminalis L. crops favor the maintenance of agroecosystem biodiversity, as confirmed by the values calculated for the Shannon–Wiener, Simpson and inverse Simpson indexes. The floristic diversity on the Salix viminalis L. plantations proved to be slightly higher than on typical arable crop plantations.

Bioenergy crops are considered to have the potential for climate mitigation and socio-economic benefits owing to their capacity to sequester C and partially replace the consumption of fossil fuels. In this study, the effects on soil respiration of a recent conversion of arable land to high (H) and very high (VH) density short-rotation coppices (SRCs), as well as of agronomic treatments (fertilization with or without irrigation) and lane/row location, were investigated in an alluvial area in Italy. A survey of soil variability was carried out by collecting soil cores (0-60 cm depth) at 67 points to characterize surface and subsurface spatial distributions of pH, organic carbon, nitrogen and carbonates and identify comparable points for monitoring soil respiration. Soil CO2 emissions were monitored over the period April 2010-November 2011 at 27 locations covering the whole study site. The influence of land use (H-SRC, VH-SRC, corn and alfalfa) or treatments on soil respiration was evaluated considering both factors as fixed effects in a linear mixed model. Our results showed that (i) the high variability of soil properties even at small spatial scale has to be considered when selecting points for monitoring soil respiration in the field; (ii) the cumulative soil respiration over the study period at the VH-SRC was lower (1299 ± 30 g C m-2) than in croplands (1600 ±145 g C m-2) and higher along the rows than in the lanes; (iii) no significant differences in soil respiration were found between the H-SRC and corn field; (iv) two years after VH-SRC establishment, agronomic treatments did not appear to influence soil respiration; (v) land-use change affected the vertical soil organic carbon distribution and soil surface temperature, as reflected in soil respiration differences.

The paper aims to analyze the biomass at one year growth, resulting from the cultivation of the INGER energy willow clone as a short rotation crop (SRC), in order to use it as a renewable fuel. The paper completes the data in the field of renewable energies in the context of decreasing fossil energy reserves worldwide and emphasizing the impact on renewable energies. The effect of a contaminated land on the survival rate of the planted seedlings and the effect of the energy willow culture on the composition of the contaminated soil are analyzed. The obtained results show that the biomass characteristics, such as the calorific power of about 18,21 kJ/g to18,90 kJ/g, and the ash content of about 2,25 %, are comparable with the ones of other lignocellulosic energy materials. The results found in this studyshowed that the woody biomass in the first vegetation year of energy willow can be used directly as a renewable fuel without the need for compaction in the form of briquettes or pellets. [ABSTRACT FROM AUTHOR]

Due to social demands with regard to sustainability and ecological considerations, an aim of current research in short‐rotation coppices (SRC) is to find effective candidates for biological control of pest species. The great red poplar leaf beetle, Chrysomela populi L. (Coleoptera: Chrysomelidae), is one of the most harmful pests in the SRC. The endoparasitic mite Linobia coccinellae (Scopoli) (Acari: Astigmata, Hemisarcoptidae) lives under the elytra of C. populi and feeds on the beetles' hemolymph. The population dynamics of the mites and their impact on the fecundity and longevity of female beetles were examined in two experiments. To study the occurrence of the mites, beetles were collected from two poplar SRC sites in Germany on three dates. Infestation rates of collected male and female C. populi individuals increased over the course of the year and reached 78–97% in the last survey. Females were parasitized more often than males at any time. For the second part of the study, beetles were reared under laboratory conditions to study the development of the mites and their impact on the hosts. For this purpose, half of the females were actively seeded with five adult females of L. coccinellae and the other half was used as a control. There was no significant impact on longevity or reproductive traits of the beetles. Despite the high rates of infestation, it appears that the mites do not have a serious effect on female beetles. Thus L. coccinellae, by itself, is not an effective biological control agent against C. populi. However, it remains to be investigated whether the mites increase the beetles' susceptibility to other biotic and abiotic factors, and so may contribute to an integrated pest management regime with multiple antagonists. [ABSTRACT FROM AUTHOR]

Key message: The use of reduced planting spacings is an important strategy to increase the carbon storage in the above-belowground biomass and should be recommended for future exploitation of forest energy plantations when the purpose intended is the production of biomass for energy. Context: Recent concerns about global warming have resulted in more concerted studies on quantifying carbon storage in forest systems. Forest energy plantations play an essential role in the carbon storage. Aims: We proposed to evaluate the carbon storage and partitioning in short-rotation forest plantations and to characterize the elemental composition and energetic properties of the forest species Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth, and Ateleia glazioviana Baill, grown under four planting spacings in Southern Brazil. Methods: A field study was conducted in order to evaluate forest carbon stock and wood composition using samples collected by direct method. The four spacings evaluated were 2.0 × 1.0, 2.0 × 1.5, 3.0 × 1.0, and 3.0 × 1.5 m. Results: The Eucalyptus grandis stored 327.1 Mg C ha−1 at 2.0 × 1.5-m spacing. When compared with the 3.0 × 1.5-m spacing, we observed a reduction of 29% in carbon stored. All forest species showed higher carbon storage in the following partitioning pattern: trunk>roots>branches>leaves>litter. Forest species energetic properties and elemental composition were not affected by planting spacing. On the other hand, variations according the tree portions were observed. For the carbon stocks in the soil, we observed an average accumulated carbon stock for the forest species studied of 77.4 Mg C ha−1 (0–40 cm). Conclusion: Forest managers can accelerate growth and increase the forest carbon storage and biomass yield by using reduced planting spacing that are smaller than the current pattern used by the majority of the forest producers, which is 3.0 × 1.5 m. For Eucalyptus grandis and Mimosa scabrella, the planting spacings recommended to produce biomass and improve carbon stocks were 2.0 × 1.5 and 2.0 × 1.0 m, respectively. [ABSTRACT FROM AUTHOR]

This contribution provides better insights in the water relations and the physiological traits of four commercial poplar genotypes of different genetic background, 'Bakan', 'Oudenberg', 'Koster' and 'Grimminge'. The main continuous (nondestructive and providing continuous and automated data records) and discontinuous (destructive and not allowing automation) plant water status (PWS) indicators were monitored at a multigenotype, commercial‐scale short‐rotation coppice plantation in East‐Flanders (Belgium), and their relationships with the principal environmental variables were assessed. All measurements were performed during the entire 2016 growing season on the third year of the third rotation in multistemmed trees. The discontinuous PWS indicators were measured on 10 separate days with a different evaporative demand and soil water content, while the continuous PWS indicators were recorded from April to November. The genotypes responded differently to environmental drivers and to soil conditions, based on the PWS indicators, featuring a different water behaviour in relation to the level of isohydricity. Poplar genotypes 'Koster' and 'Bakan' showed the typical water‐conserving behaviour of isohydric species, while 'Grimminge' was more in line with the anisohydric ones. A principal component analysis showed that sap flow (Fs) was the most suitable PWS indicator. The Fs and therefore the sap flow‐based canopy transpiration (Ec) were tightly linked to the phenological stage of the trees as well as to vapour pressure deficit and photosynthetic photon flux density, based on relationships between Ec and environmental variables. A quantitative predictive model was developed to estimate the crop water requirements for specific genotypes, by calculating transpiration per unit of ground area with a few environmental variables, monitored with easy‐to‐handle sensors. [ABSTRACT FROM AUTHOR]

Selecting superior clones is the first step for commercial short‐rotation coppice cultures to provide biomass and bioenergy. Till date, such selection for hybrid Populus clones in middle China is absent. Here we describe the growth, aboveground biomass production and cell wall composition of 27 hybrid poplar clones in Henan, China for two 3‐year rotations. Significant variation in these three characteristics over two triennial rotation coppices among the 27 poplar clones was observed. During two 3‐year rotation coppices, clones '276', '02‐17', and '599' showed relatively higher tree heights and larger basal diameters than those of the other clones. However, the most productive clones were '36' and '01‐30'. At the end of the second triennial rotation, the aboveground biomass production reached 18 Mg ha−1 year−1. For the cell wall composition analysis, the cellulose contents of clones '01‐243' and '2001' were relatively high, while the xylose contents of clones '01‐30' and '65' were relatively high. Cluster analysis based on height, basal diameter, biomass, heat value, cellulose content, and survival rate revealed five growth potential classes. Accordingly, clones '03‐332', '36', and '599' exhibited high biomass and growth and had the greatest potential to serve as excellent biomass producers in Henan, China. In addition, the expression patterns of 20 key regulatory genes were analyzed, and an integrated coexpression network was constructed. This field trial provides a comprehensive quantification and evaluation of the agronomic performance of 27 poplar clones in Henan, China. The results of this study and the analytical strategies provide an efficient mechanism for selecting clones that will perform well agronomically in local environments. The expression of key genes and the integrated coexpression network provide the molecular mechanisms of poplar biomass performance. [ABSTRACT FROM AUTHOR]

Considering the increasing use of wood biomass for energy and the related intensification of forest management, the impacts of different intensities of biomass harvesting on nutrient leaching risks must be better understood. Different nitrogen forms in the soil solution were monitored for 3 to 6 years after harvesting in hemiboreal forests in Latvia to evaluate the impacts of different biomass harvesting regimes on local nitrogen leaching risks, which potentially increase eutrophication in surface waters. In forestland dominated by Scots pine Pinus sylvestris L. or Norway spruce Picea abies L. (Karst.), the soil solution was sampled in: (i) stem-only harvesting (SOH), (ii) whole‐tree harvesting, with only slash removed (WTH), and (iii) whole‐tree harvesting, with both slash and stumps harvested (WTH + SB), subplots. In agricultural land, sampling was performed in an initially fertilised hybrid aspen (Populus tremula L.× P. tremuloides Michx.) short-rotation coppice (SRC), where above-ground biomass was harvested. In forestland, soil solution N (nitrogen) concentrations were highest in the second and third year after harvesting. Mean annual values in WTH subplots of medium to high fertility sites exceeded the mean values in SOH subplots and control subplots (mature stand where no harvesting was performed) for the entire study period; the opposite trend was observed for the low-fertility site. Biomass harvesting in the hybrid aspen SRC only slightly affected NO3–-N (nitrate nitrogen) and NH4+-N (ammonium nitrogen) concentrations in the soil solution within 3 years after harvesting, but a significant decrease in the TN (total nitrogen) concentration in the soil solution was found in plots with additional N fertilisation performed once initially.

Biomass from short‐rotation coppice (SRC) of woody perennials is being increasingly used as a bioenergy source to replace fossil fuels, but accurate assessments of the long‐term greenhouse gas (GHG) balance of SRC are lacking. To evaluate its mitigation potential, we monitored the GHG balance of a poplar (Populus) SRC in Flanders, Belgium, over 7 years comprising three rotations (i.e., two 2 year rotations and one 3 year rotation). In the beginning—that is, during the establishment year and during each year immediately following coppicing—the SRC plantation was a net source of GHGs. Later on—that is, during each second or third year after coppicing—the site shifted to a net sink. From the sixth year onward, there was a net cumulative GHG uptake reaching −35.8 Mg CO2 eq/ha during the seventh year. Over the three rotations, the total CO2 uptake was −51.2 Mg CO2/ha, while the emissions of CH4 and N2O amounted to 8.9 and 6.5 Mg CO2 eq/ha, respectively. As the site was non‐fertilized, non‐irrigated, and only occasionally flooded, CO2 fluxes dominated the GHG budget. Soil disturbance after land conversion and after coppicing were the main drivers for CO2 losses. One single N2O pulse shortly after SRC establishment contributed significantly to the N2O release. The results prove the potential of SRC biomass plantations to reduce GHG emissions and demonstrate that, for the poplar plantation under study, the high CO2 uptake outweighs the emissions of non‐CO2 greenhouse gases. [ABSTRACT FROM AUTHOR]

Abstract In short-rotation coppice, shoots grow at high density and compete for limiting resources with their neighbours. Interactions among shoots translate into individual size differences due to resource apportionment. In the present study we compared shoot dynamics of six hybrid poplars and three wild river genotypes of Populus nigra under the first three-year cycle of multi-stem short-rotation coppice. We investigated changes over time in diameter frequency distribution, mortality and biomass partitioning according to crown classes of the shoots. Unimodal shoot diameter distributions during rotation modelled by a two-parameter Weibull probability density distribution show that the values of the α scale parameter are higher in hybrid genotypes compared to wild black poplars (α ≥ 2.0 and α ≤ 2.0, respectively) in all three years. The values of the β shape parameter mostly decrease over time in hybrid genotypes and increase in wild black poplars in the narrow range from 1.42 to 2.38 and from 1.47 to 2.03, respectively. With regard to biomass partitioning among shoot crown classes, differences in size attributes are more pronounced in hybrids than native black poplar genotypes. In hybrid genotypes, 83.7% of the biomass is allocated to dominant shoots, while wild black poplars share 71.6% of the biomass in the dominant and 24.8% in the intermediate shoots. This disproportional biomass allocation among crown classes of hybrid compared to native genotypes could be related to their different origin of selection. Highlights • Two-parms Weibull PDF depicts shoot diameter distribution over time of poplars in SRC. • Weibull PDF diameter distributions change over time due to population dynamic. • Different biomass partitioning characterizes native wild and domesticated poplars. • Differences in size attributes are more pronounced in hybrids than native black poplar genotypes. [ABSTRACT FROM AUTHOR]

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.

Energy plantations create new habitats in agricultural landscapes with species compositions different from those in forests or farmlands. The purpose of our nine-year research project (2010–2018) was to evaluate the dependence of weed-species richness and their selected ecological aspects on stands of energy-plant species, and varieties in energy-tree and -grass plantations in conditions of Central Europe, on the basis of a case study. The permanent research plots were established in plantations containing two varieties of willow (Tordis and Inger), one poplar variety (Pegaso), and one clone of Miscanthus × giganteus. This evaluation included the species composition of understory flora, habitat preferences of different species, life cycle, life forms, ecological demands, and the harmfulness of these weed-species. The ground flora of energy plantations is predominantly composed of synanthropic plants of a weedy character with differences in species composition among different energy-tree and -grass species and varieties. The total number of vascular plant species was 98. The highest number of species (58) was recorded in the Tordis and Inger willow varieties, and the lowest was observed in the Pegaso poplar variety (45). Perennial species prevailed by their share, 10 of which were found in all four research plots. Therophytes and hemicryptophytes prevailed. Most species have high light requirements and are typical for mild-to-warm suboceanic areas, demanding freshly moist alkalic soils that are medium-to-rich in mineral nitrogen. Fifty percent of all observed species are considered weeds in Slovakia. The “very dangerous” category represented 46.94% of weeds, the “less dangerous” category 51.02%, and the “nondangerous” category represented 2.04% out of 49 species. The biggest share of “very dangerous weeds” was found in the poplar stand (38.78%), less in willow (32.65% and 28.57%), and the least in miscanthus stands (26.53%). The weeds of the Tordis variety were relatively poorly influenced by specific environmental conditions, and the weeds of the Inger variety were mainly defined by the soil reaction. Weeds in the undergrowth of both Miscanthus × giganteus and poplar trees (Pegaso) had the greatest affinity to mineral nitrogen content and temperature requirements.

Abstract Short-rotation coppice (SRC) using hybrid poplars for biomass production may be a productive alternative in Mediterranean zones. However, the degree of genetic control and the growth stability of poplar clones in high-density plantations remain unknown, and information is needed to reduce the selection time in SRC systems. The genetic variation and stability of growth traits with the age of hybrid clones (from interspecific crosses of Populus deltoides [D] , P. trichocarpa [T] , P. nigra [N] and P. maximowiczii [M]) were investigated under two planting densities (5000 and 10000 trees ha−1). The basal diameter and height of dominant shoots were measured at ages 1, 2 and 4 years. The total above-ground fresh weight of individual trees was also measured as an indicator of cumulative biomass at age 4 years. Clonal performance was not significantly changed by the planting density. Repeatability increased slightly from age 1 (0.58) to age 2 (0.65) but decreased by age 4 years (0.33). The highest clonal repeatability (0.54) value for above-ground fresh weight was observed for the T✕D cross, whereas the minimum value (0.27) was obtained when genotypes of all crosses were pooled. The age-to-age genetic correlations indicate high clonal stability over time. With respect to the complexities and time required for screening a large number of genotypes under SRC, the results of this study indicate that traits measured during the first growing season are stable indicators of clonal performance in SRC systems. Highlights • This study tests a large collection of hybrid poplar clones for Short rotation coppice (SRC). • Clonal performance was not significantly changed by the planting density. • There was a high clonal stability across time and sites. • Early selection might be as short as on one growing season for SRC systems. [ABSTRACT FROM AUTHOR]

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Abstract The 10-year juvenile records of three hybrid poplar and two aspen cultivars (Populus spp.) from a short rotation coppice (SRC) were assessed by measuring tree-ring width (annual radial increment, i r) and stable isotope ratios of carbon and oxygen (δ13C and δ18O) of α-cellulose. All cultivars showed common ‘juvenile trends’ that were modeled with nonlinear fit (NLF) functions. The i r of all cultivars culminated in the middle of the juvenile phase. Within the first ten years, δ13C showed a gradual decrease of approximately 2.5 ‰ in all cultivars and δ18O showed an asymptotic increase which was variable among the poplar cultivars and which was more pronounced in two hybrid poplars. Potential causes of the juvenile inter-annual variability of δ13C and δ18O were discussed. Likely, the maturation related changes in hydraulic architecture, the canopy closure and the resulting increase of the proportion of shaded crown segments which have lower photosynthetic capacities had an effect on δ13C. An additional effect of changes in N nutrition on δ13C is assumed at the present SRC trial because the NO 3 − concentration had significantly decreased after ten years. Interpretation of δ18O data remained difficult given the lack of soil water δ18O records. The maturation effect and the respective interaction have resulted in large temporal variability in the present three investigated tree ring traits. However, the impact of two drought vegetation periods (2003 and 2006) was still reflected by the juvenile tree ring records of all traits. Different juvenile trends in the records of the stable isotope ratios δ13C and δ18O, and the trend slopes, which may vary between genetically different cultivars, must be considered in tree ring investigations of SRC poplars. [ABSTRACT FROM AUTHOR]

Initial changes in soil structure and C stocks were studied under short-rotation coppices (SRC) planted on former cropland near Göttingen, Central Germany. Plantations were established either as monocultures with willow (Willow-SRC) or poplar (Poplar-SRC), or as an agroforestry system with willow strips and grassland alleys in between (Willow-AF). A neighbouring cropland served as a control. Three sampling campaigns were applied in this study. The first sampling was conducted at a fine scale to reveal the differences in soil C with depth ( i.e. 0–3, 3–6, 6–9, 9–12, 12–15, 15–20, 20–30 cm). Here, results indicated the main differences between plantations in 0–3, 3–20 and 20–30 cm layers. These soil depths were therefore chosen for the second sampling campaign to reveal differences in aggregate composition, C accumulation in aggregates and density fraction, and microbial biomass carbon (MBC) between plantations. Furthermore, quality of soil organic matter and amount of C mineralised by microorganisms were estimated by an incubation experiment. Results here indicated two times higher CO 2 emissions from the top layer than from the lower layers under SRCs, as well as higher MBC in SRCs (490–788.7 μg C g −1 ) than in cropland (266.4 μg C g −1 ). The results of the third sampling on the texture of respective soil horizons indicated a significant correlation (R 2 = 78%) of soil clay to C at 0–3 cm depth. It was concluded that aggregation and C in microbial biomass and free light fractions were the first indicators of soil quality improvement after conversion of arable land to SRC plantations. [ABSTRACT FROM AUTHOR]

This study aimed to determine the productivity and energy values of 10 poplar cultivars for use as potential fuel sources in Poland. The study was conducted over a seven-year cycle in northern Poland. The cultivars belonged to clones traditionally used for timber production, as well as new clones specific to short-rotation coppice (SRC) practices. Biomass production and biomass properties were measured, including elemental composition, the gross and net calorific values (heating value) of wood, and envelope density. For each cultivar, the synthetic fuel value index (FVI) was calculated. Biomass dry matter (DM) production differed noticeably between cultivars, and it was the highest for traditional cultivars (‘NE-42’ and ‘Fritzi Pauley’, amounting to 8 Mg ha −1 yr −1 ), and the lowest for new cultivars (DM was one-third that of the cultivars with the highest production). Two traditional cultivars (‘NE-42’ and ‘Fritzi Pauley’) had the highest FVI, representing potential biofuels, whereas two new SRC cultivars (‘AF-8’ and ‘AF-2’) had the lowest indexes. Overall, poplar plantations with short rotations could be considered as a potential additional source of renewable energy in Poland. However, the key factor is selection of appropriate genotypes for the specific climatic conditions. In conclusion, our study demonstrated the importance of testing cultivars under local climatic conditions before using them at a commercial scale. [ABSTRACT FROM AUTHOR]

Land management in Germany has been characterised by a continued intensification in recent decades. This development has come along with the replacement of landscape elements like hedges, bushes and single trees. Despite the high relevance of food supply, further social claims and requirements with regard to agricultural have land gained in importance over time. These include for example ecological aspects and the enhancement of the appearance of the landscape. Alley cropping systems with short-rotation wood can contribute to an increase of biodiversity and improved landscapes. Furthermore, the simultaneous growing of wood and crops can bring about economic benefits as well. Despite their ecological, social and economic advantages, only a very limited number of agroforestry systems has been established in Germany, mostly on experimental sites. Reasons for this may be economic disadvantages. This paper presents a comprehensive literature review about the economic effects of alley cropping agroforestry in comparison to traditional cropping. The results show that from an economic point of view agroforestry systems most is preferable for medium quality agricultural sites. Results also show that three to ten percent higher yields due to synergy effects between tree crops and field crops are needed to make alley cropping systems financially attractive. Furthermore, liquidity has to be taken into account due to the relatively high investment costs of the trees and delayed returns moreover. The results provide manifold starting for measures to increase the attractiveness of alley cropping systems. [ABSTRACT FROM AUTHOR]

We examined the effect of throughfall exclusion on aboveground woody biomass (AGB) productivity in a short-rotation woody coppice plantation. This study was carried out between the 3 rd and 7 th year (2011–2015) of the second rotation cycle in hybrid poplar plantation ( Populus nigra  ×  P. maximowiczii ) in the Czech Republic. A partial-throughfall exclusion (R) treatment and a control (C) treatment were applied. Throughfall exclusion was set to 40% in 2011–2012 and increased to 70% thereafter. The annual mean (standard error) AGB productivity for C and R during 2012–2015 were 11.2 (0.84) and 10.1 (0.89) Mg ha −1 y −1 of dry matter (DM), respectively. The lowest AGB productivity and most pronounced reduction (18.8%) in the annual AGB productivity by the R treatment occurred in 2014 - a year with the driest spring. The observed inter-annual variability in AGB productivity was not explained by precipitation nor by precipitation-treatment interaction. However, the annual AGB productivity variation depended (p = 0.002) on the throughfall totals during period May–July. The total harvestable biomass in 2015 reached 81.9 (7.2) and 75.0 (6.2) Mg ha −1 DM for the C and R treatments, respectively. Despite the non-negligible mean treatment difference (5.7 Mg ha −1 DM, i.e. 7.6%), the large between-plot variance and shifts in stand structure resulted in the nonsignificant differences. We suggest that once the root system is established, hybrid poplar plantations are relatively resilient to drought and might act as an income-stabilizing factor when traditional agricultural crops fail to deliver viable yields in drier climate. [ABSTRACT FROM AUTHOR]

The competitiveness of conventional and advanced (second generation) biofuels is a critical issue for the implementation of a sustainable transport strategy. We model biofuel competition under different feedstock cost development scenarios, assessing what costs and cost developments can be expected for energy crops in Germany and how these feedstock cost developments affect the competitiveness between biofuels. Perennial poplar was found to be the least-cost energy crop, with non-perennial silage maize being strongly competitive at increasing feedstock price developments. Assuming increasing feedstock costs for the future, neither conventional biodiesel from rape seed nor advanced biodiesel were found to be competitive in the long run. Feedstock costs were found to overshadow all other factors, leading to costs for advanced biodiesel to be between 27.0 and 53.6€ GJ −1 in 2030, which is above most expectations. Of the advanced biofuels, only synthetic natural gas was cost-competitive under some circumstances, but biomethane from silage maize and bioethanol from sugar beet were the strongest options, as they combine high yields with high conversion efficiencies while avoiding the high upfront costs of advanced biofuels and the risk of switching to perennial crops. However, such a transition leads to less mobile feedstocks being used than presently and in the case of gaseous fuels requires stimulation of the demand side in order to function. The high dependence on and increasing relevance of feedstock costs is characteristic for the biobased renewables only and is detrimental and inhibiting for investments and research and development efforts, in contrast to for e.g. wind and solar photovoltaics, and must be considered when designing policy for any sector of the bioeconomy. [ABSTRACT FROM AUTHOR]

Fast pyrolysis oil (FPO) produced from short-rotation willow was characterized by using high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and various bulk chemical analyses. The pyrolysis experiments were carried out on a bench-scale bubbling fluidized bed pyrolysis reactor operating at the temperature of 500 °C. The resulting pyrolysis oil was a single-phase liquid with relatively low oxygen content and had pH and total acid number values of 3.0 and 129 mg/g, respectively. A wealth of compositional information of the willow FPO was obtained using FT-ICR MS in combination with electrospray ionization (ESI) and atmospheric-pressure photoionization (APPI) techniques. While ESI preferentially ionized acidic extractives, small phenolics and anhydrosugars, APPI ionized clearly larger compounds, including neutral lipophilic extractives, triterpenoids and high molecular mass pyrolytic lignin, most of which are beyond conventional gas chromatography–mass spectrometry analyses. [ABSTRACT FROM AUTHOR]

Combining peatland rewetting with biomass cropping (paludiculture) is one strategy to remove nutrient surpluses from soil/water and stimulate peat-forming vegetation. This approach was tested in the Massaciuccoli Lake Basin (Tuscany, Italy), a coastal floodplain artificially drained for agricultural purposes since 1930, where land reclamation and continuous cropping have contributed to considerable peat degradation and water eutrophication due to nutrient enrichment of surface waters. An experimental trial was established in spring 2012 with three perennial rhizomatous grasses (PRG) ( Phragmites australis , Miscanthus × giganteus , Arundo donax ) and two woody species managed as short-rotation coppice (SRC) ( Salix alba “Dimitrios”, Populus × canadensis “Oudenberg”), aimed to provide biomass for various bioenergy supply chains. A conventionally cultivated annual crop (maize) was the control. The aim of this study was to compare the sustainability of the proposed paludiculture systems to that of conventional annual crops on the basis of yield and nutrient-removal capability. This two-year field study evaluated yields, nutrient concentrations and uptake (N and P) of the crops. Over the two years, A. donax had the highest mean biomass yield (35 Mg ha −1 ), N uptake (367 kg ha −1 ), and P uptake (54 kg ha −1 ). SRCs had the lowest nutrient uptake in both years. Among grasses, the highest N concentration was recorded in A. donax leaves in 2013 (N: 2.41%), while P concentration was greater in S. alba branches (P: 0.39%). The average aboveground biomass of maize was 17.5 Mg ha −1 , while the nutrient uptakes were equal to 194 and 27 kg ha −1 for N and P, respectively. Thus, the performances of paludiculture systems were generally encouraging and could represent an important alternative for restoring and managing former drained peatlands in a suitable product chain. [ABSTRACT FROM AUTHOR]

In order to investigate how the depth to which a cutting is inserted into the ground influences biomass of short-rotation coppice willows, 1-year-old cuttings from three clones each ofSalix pet-susuandSalix sachalinensiswere planted and harvested after two-seasons growth under natural conditions. All cuttings were 20 cm long, with either 18 or 10 cm below ground level (referred to as deep planting [DP] and shallow planting [SP], respectively, hereafter). Aboveground dry biomass from DP was 40% greater than from SP, although root biomass did not differ between the two treatments and shoot number per cutting was lower for DP than SP. The roots of the DP cutting were found deeper in the soil than those of SP cutting, suggesting that sustained soil water supply resulted in the higher aboveground biomass. [ABSTRACT FROM PUBLISHER]

Development of dedicated bioenergy crop production systems will require accurate yield estimates, which will be important for determining many of the associated environmental and economic impacts of their production. Shrub willow ( Salix spp) is being promoted in areas of the USA and Canada due to its adaption to cool climates and wide genetic diversity available for breeding improvement. Willow breeding in North America is in an early stage, and selection of elite genotypes for commercialization will require testing across broad geographic regions to gain an understanding of how shrub willow interacts with the environment. We analyzed a dataset of first-rotation shrub willow yields of 16 genotypes across 10 trial environments in the USA and Canada for genotype-by-environment interactions using the additive main effects and multiplicative interactions ( AMMI) model. Mean genotype yields ranged from 5.22 to 8.58 oven-dry Mg ha−1 yr−1. Analysis of the main effect of genotype showed that one round of breeding improved yields by as much as 20% over check cultivars and that triploid hybrids, most notably Salix viminalis × S. miyabeana, exhibited superior yields. We also found important variability in genotypic response to environments, which suggests specific adaptability could be exploited among 16 genotypes for yield gains. Strong positive correlations were found between environment main effects and AMMI parameters and growing environment temperatures. These findings demonstrate yield improvements are possible in one generation and will be important for developing cultivar recommendations and for future breeding efforts. [ABSTRACT FROM AUTHOR]

Short-rotation coppice ( SRC) has great potential for supplying biomass-based heat and energy, but little is known about SRC's ecological footprint, particularly its impact on the water cycle. To this end, we quantified the water use of a commercial scale poplar ( Populus) SRC plantation in East Flanders (Belgium) at tree and stand level, focusing primarily on the transpiration component. First, we used the AquaCrop model and eddy covariance flux data to analyse the different components of the stand-level water balance for one entire growing season. Transpiration represented 59% of evapotranspiration ( ET) at stand scale over the whole year. Measured ET and modelled ET were lower as compared to the ET of reference grassland, suggesting that the SRC only used a limited amount of water. Secondly, we compared leaf area scaled and sapwood area scaled sap flow ( Fs) measurements on individual plants vs. stand scale eddy covariance flux data during a 39-day intensive field campaign in late summer 2011. Daily stem diameter variation (∆ D) was monitored simultaneously with Fs to understand water use strategies for three poplar genotypes. Canopy transpiration based on sapwood area or leaf area scaling was 43.5 and 50.3 mm, respectively, and accounted for 74%, respectively, 86%, of total ecosystem ET measured during the intensive field campaign. Besides differences in growth, the significant intergenotypic differences in daily ∆ D (due to stem shrinkage and swelling) suggested different water use strategies among the three genotypes which were confirmed by the sap flow measurements. Future studies on the prediction of SRC water use, or efforts to enhance the biomass yield of SRC genotypes, should consider intergenotypic differences in transpiration water losses at tree level as well as the SRC water balance at stand level. [ABSTRACT FROM AUTHOR]

A paludicultural experiment was conducted in the Massaciuccoli Lake Basin (Tuscany, IT) to test this restoration strategy to reduce water eutrophication and subsidence phenomena of peat soils. The species tested were three perennial rhizomatous grasses (PRGs), Arundo donax , Miscanthus x giganteus , Phragmites australis , and two woody crops managed as short-rotation coppice (SRC), Populus x canadensis ‘Oudemberg’ and Salix alba ‘Dimitrios’, each of these species promising high productivity under wet conditions. The study aimed to test the combustibility of their harvested biomass as a function of crop age and harvest date. Parameters important for combustion and exhaust gas emissions were analyzed: ash content, concentration of chlorine (Cl), sulfur (S), nitrogen (N), phosphorus (P), carbon (C), hydrogen (H), calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na). Results indicated that the SRC crops appeared the most suitable for combustion. A general improvement in biomass quality with crop age was found for all crops tested, showing a significantly lower concentration of critical elements (Cl, N, S) and ash content in the 3rd year after planting. The biomass quality of PRGs was not significantly improved by a delayed harvest in February, as successfully practiced in northern Europe. In general, although concentrations of the most important critical elements were higher than expected for all crops, the calculated higher heating values were promising. Combustibility performances could be improved by finding an optimal mixture of SRC and PRG biomass. [ABSTRACT FROM AUTHOR]

Managed systems harvested at intermediate time-scales have advantages over annual short-cycled systems in maintaining top-down control of insect herbivores, and the flexible harvest regimes in these systems provide opportunities for habitat management that can stabilize predator-prey population dynamics across harvests - resulting in reduced risk of pest outbreaks., In a large-scale field experiment, we explored whether retaining refuges, that is preserving parts of the stand to reduce predator mortality, could reduce the risk of pest insect outbreaks in willow short-rotation coppice. Population densities of three omnivorous predator species and three outbreaking herbivorous leaf beetle species were monitored over four years after coppice (stem harvest) in eight stands with refuges (treatment) and eight stands without refuges (control). Predation pressure was estimated in years three and four., Contrary to our predictions, leaf beetle densities were higher in stands with refuges and predator densities were higher in stands without refuges. Leaf beetle egg mortality increased with total predator density, but did not differ between stands with and without refuges., These unexpected results can be attributed to interactions between dispersal and patch age. The altered phenology of coppiced stems may have triggered leaf beetle aggregation in refuges and migration from stands without refuges. A behavioural response to resource concentration in retained old patches likely transformed the predator refuge from a 'source' to a 'sink'., Synthesis and applications. This study shows that retaining refuges in willow short-rotation coppice to facilitate predator population recovery after harvest can come at the cost of more attractive herbivore habitats - and thus increased pest problems. We conclude that crop refuges in systems with intermediate disturbance regimes pose new challenges for conservation biological control, in particular the need to consider how patch age affects dispersal and recolonization of both pest and predators. [ABSTRACT FROM AUTHOR]

To achieve the goals of energy security and climate change mitigation in Denmark and the EU, an expansion of national production of bioenergy crops is needed. Temporal and spatial variation of yields of willow and Miscanthus is not known for Denmark because of a limited number of field trial data. The semi-mechanistic crop model BioCro was used to simulate the production of both short-rotation coppice ( SRC) willow and Miscanthus across Denmark. Predictions were made from high spatial resolution soil data and weather records across this area for 1990-2010. The potential average, rain-fed mean yield was 12.1 Mg DM ha−1 yr−1 for willow and 10.2 Mg DM ha−1 yr−1 for Miscanthus. Coefficient of variation as a measure for yield stability was poorest on the sandy soils of northern and western Jutland, and the year-to-year variation in yield was greatest on these soils. Willow was predicted to outyield Miscanthus on poor, sandy soils, whereas Miscanthus was higher yielding on clay-rich soils. The major driver of yield in both crops was variation in soil moisture, with radiation and precipitation exerting less influence. This is the first time these two major feedstocks for northern Europe have been compared within a single modeling framework and providing an important new tool for decision-making in selection of feedstocks for emerging bioenergy systems. [ABSTRACT FROM AUTHOR]