Short Rotation Coppice Willow Research Articles

Application of primary treated wastewater to short rotation coppice of willow and poplar in Mongolia: Influence of plants on treatment performance

The influence of short rotation willow coppice on wastewater treatment performance under Mongolian climatic conditions is still poorly understood. For this purpose, one bed planted with willow (Salix spec.) and Poplar (Populus spec.) trees and one unplanted bed (as control) were operated over two years with pre-treated domestic wastewater under the same operating condition (with a daily hydraulic load of 5mm). The results showed better wastewater treatment performance for the planted bed. An average mass removal rate of 241±14gm−2a−1 (86% removal efficiency), 130±26gm−2a−1 (93% removal efficiency), 82±11 gm−2a−1 (80% removal efficiency) and 7.1±1.2gm−2a−1 (85% removal efficiency) was observed for COD, BOD5, TN and TP respectively in planted bed over two study years. On the contrary in the unplanted bed, the average mass removal rate was found to be as 135±1 gm−2a−1 (59% removal efficiency), 121±28 gm−2a−1 (89% removal efficiency), 43±1gm−2a−1 (43% removal efficiency) and 3.7±0.2gm−2a−1 (46% removal efficiency) for COD, BOD5, TN and TP, respectively, over two study years. Additionally, the planted bed irrigated with pre-treated wastewater showed greater tree growth (height, biomass yield) as compared to the plants that were grown within the control area without any additional irrigation (i.e. natural growth). The results demonstrate that the presence of willow and poplar trees positively influences wastewater treatment performance and indicate that short rotation coppice irrigated with pre-treated wastewater can be an economically viable alternative for wastewater treatment and producing biomass for energy production in Mongolia.

Woody biofuel production from short rotation coppice in Italy: Environmental-impact assessment of different species and crop management

Short Rotation Coppices (SRC) can be a suitable solution for the production of biomass, mainly due to the easy-to-harvest good-quality feedstock. Besides technical, social and economic aspects, environmental issues are important to be taken into account when developing SRC. Although some studies focused on environmental sustainability of SRC were carried out only few compare different arboreous species using primary data.In this study, the environmental evaluation of SRC plantations carried out with 14 poplar and 6 willow clones was performed using primary data collected during experimental field tests over 12 years.Twelve impact potentials were evaluated using the characterization factors reported by the ILCD method: climate change (CC), ozone depletion (OD), Human toxicity, cancer effects (HTc), Human toxicity, non-cancer effects (HT), particulate matter (PM), photochemical ozone formation (POF), acidification (TA), freshwater eutrophication (FE), terrestrial eutrophication (TE), marine eutrophication (ME), freshwater ecotoxicity (FEx) and mineral, fossil and renewable resource depletion (MFRD).Both for poplar and for willow, among the different clones the environmental performance greatly vary mainly due to the yield. The choice of the most productive clones involves a reduction of the environmental impact of the produced biomass of about 35% (respect to the average results both for poplar and willow). However, biofuel production from willow SRC achieves lower environmental burdens respect to poplar SRC considering both the average biomass yield and the most productive clones.

Environmental performance of gasified willow from different lands including land‐use changes

AbstractA life‐cycle assessment (LCA) of a low‐input, short rotation coppice (SRC) willow grown on different Danish lands was performed. Woodchips are gasified, producer gas is used for cogeneration of heat and power (CHP), and the ash–char output is applied as soil amendment in the field. A hybrid model was developed for the estimation of greenhouse gas (GHG) emissions from indirect land‐use changes (iLUC) induced by willow cropping on arable land (iLUCfood). For this, area expansion results from a general equilibrium economic model were combined with global LUC trends to differentiate between land transformation (as additional agricultural expansion, in areas with historical deforestation) and occupation (as delayed relaxation, DR, in areas with historical land abandonment) impacts. A biophysical approach was followed to determine the iLUCfeed emissions factor from marginal grassland. Land transformation impacts were derived from latest world deforestation statistics, while a commercial feed mix of equivalent nutritive value was assumed to substitute the displaced grass as fodder. Intensification effects were included in both iLUC factors as additional N‐fertilizer consumption. Finally, DR impacts were considered for abandoned farmland, as a relative C stock loss compared to natural regeneration. ILUC results show that area related GHG emissions are dominant (93% of iLUCfood and 80% of iLUCfeed), transformation being more important (82% of iLUCfood) than occupation (11%) impacts. LCA results show that CHP from willow emits 4047 kg CO2‐eq (or 0.8 gCO2‐eq MJ−1) when grown on arable land, while sequestering 43 745 kg CO2‐eq (or −10.4 gCO2‐eq MJ−1) when planted on marginal pastureland, and 134 296 kg CO2‐eq (or −31.8 gCO2‐eq MJ−1) when marginal abandoned land is cultivated. Increasing the bioenergy potential without undesirable iLUC effects, especially relevant regarding biodiversity impacts, requires that part of the marginally used extensive grasslands are released from their current use or energy cropping on abandoned farmland incentivized.

First-Rotation Performance of Five Short-Rotation Willow Cultivars on Different Soil Types and Along a Large Climate Gradient

The establishment of short-rotation willow coppice plantations for bioenergy production is proposed as a land management practice to reduce the use of fossil fuels. However, there is little information on the performance of different willow (Salix spp.) cultivars on various types of soils and over climate gradients. This study aimed to determine which set of soil, climatic conditions, and cultivars are conducive to greater growth in eastern Canada. The performance of five willow cultivars was followed over three growing seasons on eight sites representing a large hydroclimatic gradient. Both geographic location and cultivar had a significant effect on annual yields. Annual yields were on average greater in the southern part of the climatic gradient. Across all cultivars, annual yields were positively correlated to average annual temperature (r = 0.23), total annual precipitation (r = 0.77), average growing season temperature (r = 0.21), average growing season precipitation (r = 0.47), and degree days (r = 0.18), as well as soil pH (r = 0.37) and soil extractible P (r = 0.38), and negatively correlated to soil clay content (r = 0.33). Cultivars of the SX group (i.e., Salix miyabeana SX61, SX64, and SX67) showed greater yield than did cultivars of the SV group (i.e., Salix × dasyclados SV1 and Salix viminalis SV5027). These results indicate that at the landscape level, climate variables, especially climate-related variables, largely explain the yield of the selected willow cultivars. Nonetheless, soil pH, extractable P, and clay content likely play an important role in plantation yield.

Hydrological modelling of changes in the water balance due to the impact of woody biomass production in the North German Plain

Several studies have implied that cultivation of willow and poplar short-rotation coppices influence the area’s water balance. Due to the high density of sites suitable for SRCs in the Northern German Plain, this study focusses on four different model areas representative of the climatic, soil, and morphological heterogeneity of this landscape. The river basins selected for the study are the Ems, Treene, Aland, and Uecker–Randow–Welse basins. The water balance modelling was performed with the Soil Water Assessment Tool (SWAT) and automatically calibrated with SWAT-CUP. The implemented scenarios were set to 10 % SRC cover on suitable sites, based on the area’s predicted need to meet domestic demands for woody biomass by 2020. Additionally, an extreme scenario of 100 % cultivation on all suitable sites was implemented to determine the maximum effect of SRC on the regional water balance as well as to allow for a direct comparison with annual crops, pasture, and deciduous forest. For parametrization, field measurements were used to characterize the key physiological parameters for willow and poplar in SWAT. The results for the 10 % SRC scenarios did not show a substantial impact on the investigated water balance components at the water basin level. But at the local level, the effects of conversion to SRC are more pronounced. In general, actual evapotranspiration of SRC is 16 % higher compared to annual crops and average groundwater recharge decreases by 48 %. Also, available water capacity in the soil increases by 26 % for SRCs in comparison with annual crops.

Effects of mechanical weed control or cover crop on the growth and economic viability of two short-rotation willow cultivars

Willow grown as short rotation coppice (SRC) is sensitive to weed competition, so herbicide treatment combined with mechanical weed control is recommended when establishing a plantation. This study compares that practice with two mechanical, row crop cultivator (RC) and row crop cultivator with torsion weeder (RCT), and two cultural treatments, cover crop (CC) and cut cover crop (CCC), to control weeds. Willow responses to these treatments were compared during the first three years after planting using two cultivars, Gudrun and Tordis with broad and narrow leaves, respectively. At harvest, the RCT treatment had produced 27% more biomass than the RC treatment (13.9 vs 11.0 Mg ha−1 dry matter) and approximately three times more than the cultural treatments. However, the standard control treatment, herbicides and row crop cultivator (HRC), produced more than all other treatments (17.3 Mg ha−1 dry matter). The two cultural treatments had higher plant mortality (CC 26.2% and CCC 32.8%) than the other treatments (HRC 2.7%, RC 7.0% and RCT 7.0%) after the first harvest cycle. No interaction between cultivar and treatment was found for willow shoot biomass, weed biomass or plant mortality. Overall, however, Gudrun had lower plant mortality and less weed biomass after the first harvest cycle than Tordis. All treatment and cultivar combinations gave positive financial annual returns when the whole life-span of the plantation was considered. This study suggests that without using herbicides, it is possible to establish a willow SRC plantation that produce enough to be economically viable.

Quantification and location of a renewable gas industry based on digestion of wastes in Ireland

Six EU gas grids have a target of 100% substitution of natural gas with renewable gas by 2050. This industry will start with biogas upgraded to biomethane. The biomethane resource and location of waste substrates (such as agricultural slurries, slaughterhouse waste, milk processing waste, and source separated household organic waste) were determined using the most recent spatially explicit data for Ireland. The total biomethane resource was estimated equivalent to: 7.6% of natural gas usage, 7% of energy in transport; 52% of the fuel usage in heavy goods vehicles in 2013. In terms of natural gas usage it corresponded to 26.5% of industrial gas use, and 52% of residential natural gas use. The resource as a source of thermal energy is equivalent to wood chips from 16.5% of arable land under short rotation coppice willow. Thematic maps illustrating the location of each resource were developed to highlight regions of significant biomethane production potential. The regions with the greatest resource of cattle slurry are located in the south and east of the country; sheep manure resources are concentrated on the western seaboard, while the largest biomethane resource from household organic waste is found in urban and city areas (63% of household organic waste biomethane resource).

Land‐use change to bioenergy: grassland to short rotation coppice willow has an improved carbon balance

AbstractThe effect of a transition from grassland to second‐generation (2G) bioenergy on soil carbon and greenhouse gas (GHG) balance is uncertain, with limited empirical data on which to validate landscape‐scale models, sustainability criteria and energy policies. Here, we quantified soil carbon, soilGHGemissions and whole ecosystem carbon balance for short rotation coppice (SRC) bioenergy willow and a paired grassland site, both planted at commercial scale. We quantified the carbon balance for a 2‐year period and captured the effects of a commercial harvest in theSRCwillow at the end of the first cycle. Soil fluxes of nitrous oxide (N2O) and methane (CH4) did not contribute significantly to theGHGbalance of these land uses. Soil respiration was lower inSRCwillow (912 ± 42 g C m−2 yr−1) than in grassland (1522 ± 39 g C m−2 yr−1). Net ecosystem exchange (NEE) reflected this with the grassland a net source of carbon with meanNEEof 119 ± 10 g C m−2 yr−1andSRCwillow a net sink, −620 ± 18 g C m−2 yr−1. When carbon removed from the ecosystem in harvested products was considered (Net Biome Productivity),SRCwillow remained a net sink (221 ± 66 g C m−2 yr−1). Despite theSRCwillow site being a net sink for carbon, soil carbon stocks (0–30 cm) were higher under the grassland. There was a largerNEEand increase in ecosystem respiration in theSRCwillow after harvest; however, the site still remained a carbon sink. Our results indicate that once established, significant carbon savings are likely inSRCwillow compared with the minimally managed grassland at this site. Although these observed impacts may be site and management dependent, they provide evidence that land‐use transition to 2G bioenergy has potential to provide a significant improvement on the ecosystem service of climate regulation relative to grassland systems.

High‐resolution spatial modelling of greenhouse gas emissions from land‐use change to energy crops in the United Kingdom

AbstractWe implemented a spatial application of a previously evaluated model of soilGHGemissions,ECOSSE, in the United Kingdom to examine the impacts to 2050 of land‐use transitions from existing land use, rotational cropland, permanent grassland or woodland, to six bioenergy crops; three ‘first‐generation’ energy crops: oilseed rape, wheat and sugar beet, and three ‘second‐generation’ energy crops:Miscanthus, short rotation coppice willow (SRC) and short rotation forestry poplar (SRF). Conversion of rotational crops toMiscanthus,SRCandSRFand conversion of permanent grass toSRFshow beneficial changes in soilGHGbalance over a significant area. Conversion of permanent grass toMiscanthus, permanent grass toSRFand forest toSRFshows detrimental changes in soilGHGbalance over a significant area. Conversion of permanent grass to wheat, oilseed rape, sugar beet andSRCand all conversions from forest show large detrimental changes in soilGHGbalance over most of the United Kingdom, largely due to moving from uncultivated soil to regular cultivation. Differences in netGHGemissions between climate scenarios to 2050 were not significant. Overall,SRFoffers the greatest beneficial impact on soilGHGbalance. These results provide one criterion for selection of bioenergy crops and do not considerGHGemission increases/decreases resulting from displaced food production, bio‐physical factors (e.g. the energy density of the crop) and socio‐economic factors (e.g. expenditure on harvesting equipment). Given that the soilGHGbalance is dominated by change in soil organic carbon (SOC) with the difference amongMiscanthus,SRCandSRFlargely determined by yield, a target for management of perennial energy crops is to achieve the best possible yield using the most appropriate energy crop and cultivar for the local situation.

Dry Matter Losses and Methane Emissions During Wood Chip Storage: the Impact on Full Life Cycle Greenhouse Gas Savings of Short Rotation Coppice Willow for Heat.

A life cycle assessment (LCA) approach was used to examine the greenhouse gas (GHG) emissions and energy balance of short rotation coppice (SRC) willow for heat production. The modelled supply chain includes cutting multiplication, site establishment, maintenance, harvesting, storage, transport and combustion. The relative impacts of dry matter losses and methane emissions from chip storage were examined from a LCA perspective, comparing the GHG emissions from the SRC supply chain with those of natural gas for heat generation. The results show that SRC generally provides very high GHG emission savings of over 90 %. The LCA model estimates that a 1, 10 and 20 % loss of dry matter during storage causes a 1, 6 and 11 % increase in GHG emissions per MWh. The GHG emission results are extremely sensitive to emissions of methane from the wood chip stack: If 1 % of the carbon within the stack undergoes anaerobic decomposition to methane, then the GHG emissions per MWh are tripled. There are some uncertainties in the LCA results, regarding the true formation of methane in wood chip stacks, non-CO2 emissions from combustion, N2O emissions from leaf fall and the extent of carbon sequestered under the crop, and these all contribute a large proportion of the life cycle GHG emissions from cultivation of the crop.

Limited adoption of short rotation coppice: The role of farmers' socio-cultural identity in influencing practice

UK energy policy promotes biomass energy crops as potentially significant contributors to renewable energy targets, but few farmers have planted these crops. Amongst the many possible explanations for this disconnect between policy ambitions and delivery on the ground, the role of farmers' socio-cultural identity has received little attention. This study focuses on the Lockerbie area in south-west Scotland, a potentially favourable location for perennial energy crops because (i) it is biophysically suitable for short rotation coppice (SRC) willow, and (ii) Britain's first wood-fueled power station provides a significant local market. A survey in 2009 explored farmers' perceptions of SRC willow, and the key reasons why they adopt or reject perennial energy crops. The results show that most farmers regard SRC willow as a financially risky, overly committing and inappropriate crop for their farms. Whilst financial factors are influential, even large potential profits would be insufficient to persuade many farmers to adopt SRC. Non-financial factors related to identity, lifestyle, farming culture and the perceived priority of food production powerfully shape the overwhelmingly negative attitudes of farmers to SRC. These findings suggest that biomass energy policy, especially regarding woody crops like SRC willow, needs to be more precisely tailored to influential social factors such as socio-cultural identity and local producer culture.

Effect of fertilisation on biomass yield, ash and element uptake in SRC willow

Optimal fertilization of short rotation coppice (SRC) willow is important both in terms of economic yield and environmental effect. We measured biomass yield and nutrient uptake in two willow clones, Inger and Tordis, grown on a coarse sandy soil and within six different fertilization regimes. Fertilization treatments were carried out during two two-year harvest rotations, beginning in the 2nd growth year of the plantation. Willow was fertilized as follows with names referring to type of fertilizer and total quantities of nitrogen (kg ha−1) in first and second year within both rotations: 1) Control0+0, 2) NPK120+0, 3) Slurry180+0, 4) NPK120+120, 5) NPK240+0, 6) Slurry360+0. Fertilization affected biomass yield significantly but interacted with rotation and clone. In first rotation, fertilization increased dry matter (DM) yield across clones significantly from 3.7 Mg ha−1 y−1 for Control0+0 to 6.5, 6.4 and 5.6 for Slurry360+0, NPK120+120 and NPK240+0, respectively. In second rotation, yield increased from 6.2 Mg ha−1 y−1 to 8.8, 8.2, 7.8 and 7.4 for Slurry360+0, NPK240+0, Slurry180+0 and NPK120+120, respectively. Biomass dry matter yield per ha increased linearly at 15 kg kg−1 of applied total-N in both rotations. The yield increase in response to fertilization was generally larger in Inger than in Tordis. In general, element concentration in the harvested biomass was either unaffected or slightly reduced by fertilization. In conclusion, yield response to fertilization appears to be primarily related to the quantity of N applied but the effect depended on fertilizer type, harvest rotation and willow clone.

Afforestation of former agricultural land with Salicaceae species – Initial effects on soil organic carbon, mineral nutrients, C:N and pH

Different species of Salicaceae are of interest for bioenergy production in Sweden. Surplus agricultural land is available and can be used for bioenergy plantations. Documentation of the effects of afforestation on soil properties is of importance for future recommendations on the choice of tree species and management measures.Hybrid aspen (Populus tremula×Populus tremuloides), poplar (Populus spp.) and willow (Salix spp.) were planted on former arable land at four sites in Sweden. Planting densities were 1500plantsha−1 for hybrid aspen and poplar, and 14,800plantsha−1 for short rotation coppice (SRC) willow. The present study comprised five years following plantation with the aim to quantify the afforestation effects on mineral soil variables, i.e. soil organic carbon (SOC), nitrogen (N), phosphorus (P), base cations (K, Mg, Ca), C:N ratios and pH. The soil variables were estimated by repeated sampling, i.e. prior to planting and at the end of the fifth season. A litter layer was present in the fifth year and included in the C estimates.The SOC pools were generally unchanged compared to pre-planting conditions. Total N pools had increased in SRC willow plantations and P pools had decreased in hybrid aspen and poplar plantations. Plant available K and Mg concentrations increased in the upper 0–10cm soil and decreased in the lower 10–30cm for all species, indicating redistribution by plant uptake and recycling through litter decay. Concentrations and pools of Ca were unchanged. The C:N ratio and pH were reduced with ca 10% and 0.1 units, respectively, for all species. No specific effect of species was observed in the mineral soil, but SRC willow had lower C:N ratio in aboveground litter compared to the other species. Thus, five years growth of Salicaceae on former agricultural land resulted mainly in general soil effects associated with the cessation of annual management measures, enhanced litter production from trees and ground vegetation, and probably also with altered soil physical conditions, for example humidity and temperature, in the growing plantations.

Development of a sink-source interaction model for the growth of short-rotation coppice willow and in silico exploration of genotype×environment effects.

Identifying key performance traits is essential for elucidating crop growth processes and breeding. In Salix spp., genotypic diversity is being exploited to tailor new varieties to overcome environmental yield constraints. Process-based models can assist these efforts by identifying key parameters of yield formation for different genotype×environment (G×E) combinations. Here, four commercial willow varieties grown in contrasting environments (west and south-east UK) were intensively sampled for growth traits over two 2-year rotations. A sink-source interaction model was developed to parameterize the balance of source (carbon capture/mobilization) and sink formation (morphogenesis, carbon allocation) during growth. Global sensitivity analysis consistently identified day length for the onset of stem elongation as most important factor for yield formation, followed by various 'sink>source' controlling parameters. In coastal climates, the chilling control of budburst ranked higher compared with the more eastern climate. Sensitivity to drought, including canopy size and rooting depth, was potentially growth limiting in the south-east and west of the UK. Potential yields increased from the first to the second rotation, but less so for broad- than for narrow-leaved varieties (20 and 47%, respectively), which had established less well initially (-19%). The establishment was confounded by drought during the first rotation, affecting broad- more than narrow-leaved canopy phenotypes (-29%). The analysis emphasized quantum efficiency at low light intensity as key to assimilation; however, on average, sink parameters were more important than source parameters. The G×E pairings described with this new process model will help to identify parameters of sink-source control for future willow breeding.

Small-scale harvesting machinery for short rotation willow coppice

Small-scale harvesting machinery for short rotation willow coppice

The Behaviour for SRC Willow Inger in Experimental Trial Ghilad, Romania

The use of bioenergy are increasing in many European countries and an important role will be played by biomass produced in willow SRC. Short Rotation Coppice (SRC) willow was developed in Sweden in 1970 and it is cultivated for the production of wood chips. In Romania there are not more than 800 hectares, half of them are in Banat area. In this context assessing the biomass yield in the different experimental trial are very important. Research have been made in three SRC willow experimental trials established in Ghilad, Timis County, Romania. The material consist in willow Inger. All three trails have been established in the year 2011 but harvested in different years. Measurements and observation were made on 15 plants at the end of the 2014 season. One plant from each experimental trial has been harvested and then weight in order to establish their aboveground and underground biomass. Research highlight significant differences according with a number of shoots per stump and shoot diameter according with harvested year. According with stump age and the number of harvests, significant differences were established for quantitative character diameter. There also have been put in evidence the differences between the aboveground and underground biomass for different willow age. This screening about biometric characteristic and aboveground biomass showed high value for willow SRC harvested every year. We have to notice that any economic aspect have not been evaluated

Carbon sequestration in willow (Salix spp.) plantations on former arable land estimated by repeated field sampling and C budget calculation

Short rotation coppice (SRC) plantations are of interest as producers of biomass for fuel, but also as carbon (C) sinks to mitigate CO2 emissions. Carbon sequestration in biomass and soil was estimated in 5-year-old replicated SRC plantations with willows (Salix spp.) on former arable land at five sites in Sweden. Total standing C stocks, i.e. C stored in woody biomass above- and belowground, fine root standing crop, litter, and soil organic carbon (SOC) were estimated by repeated field sampling and C budget calculation.Overall, the SRC willow plantations represented a C sink after five years. Estimated increase of total standing C stock was 15% on average compared to pre-planting conditions. There was no change in SOC when including all sites. Analyses within sites revealed a decrease in SOC at one site, although the decrease was compensated for by C stored in willow biomass. After removal of stem biomass, C in other plant pools was sufficient to compensate for the SOC decrease. Remaining C in stumps, stool, and coarse roots was estimated at ca 20% of stem C.There was a discrepancy between SOC sequestration rates from soil sampling and C budget calculation, −2.1–1.0 and 0.15–0.45 Mg ha−1 y−1, respectively. Mineralization of old organic material from previous land-use and input to SOC from understory vegetation were not included in the calculations, which may explain part of the differences. The importance of understory litter in C budgets for young plantations was apparent, as it comprised 24–80% of aboveground litter C.

Simulation of greenhouse gases following land‐use change to bioenergy crops using the ECOSSE model: a comparison between site measurements and model predictions

AbstractThis article evaluates the suitability of the ECOSSE model to estimate soil greenhouse gas (GHG) fluxes from short rotation coppice willow (SRC‐Willow), short rotation forestry (SRF‐Scots Pine) and Miscanthus after land‐use change from conventional systems (grassland and arable). We simulate heterotrophic respiration (Rh), nitrous oxide (N2O) and methane (CH4) fluxes at four paired sites in the UK and compare them to estimates of Rh derived from the ecosystem respiration estimated from eddy covariance (EC) and Rh estimated from chamber (IRGA) measurements, as well as direct measurements of N2O and CH4 fluxes. Significant association between modelled and EC‐derived Rh was found under Miscanthus, with correlation coefficient (r) ranging between 0.54 and 0.70. Association between IRGA‐derived Rh and modelled outputs was statistically significant at the Aberystwyth site (r = 0.64), but not significant at the Lincolnshire site (r = 0.29). At all SRC‐Willow sites, significant association was found between modelled and measurement‐derived Rh (0.44 ≤ r ≤ 0.77); significant error was found only for the EC‐derived Rh at the Lincolnshire site. Significant association and no significant error were also found for SRF‐Scots Pine and perennial grass. For the arable fields, the modelled CO2 correlated well just with the IRGA‐derived Rh at one site (r = 0.75). No bias in the model was found at any site, regardless of the measurement type used for the model evaluation. Across all land uses, fluxes of CH4 and N2O were shown to represent a small proportion of the total GHG balance; these fluxes have been modelled adequately on a monthly time‐step. This study provides confidence in using ECOSSE for predicting the impacts of future land use on GHG balance, at site level as well as at national level.

The priming potential of environmentally weathered pyrogenic carbon during land‐use transition to biomass crop production

AbstractSince land‐use change (LUC) to lignocellulosic biomass crops often causes a loss of soil organic carbon (SOC), at least in the short term, this study investigated the potential for pyrogenic carbon (PyC) to ameliorate this effect. Although negative priming has been observed in many studies, most of these are long‐term incubation experiments which do not account for the interactions between environmentally weathered PyC and native SOC. Here, the aim was to assess the impact of environmentally weathered PyC on native SOC mineralization at different time points in LUC from arable crops to short rotation coppice (SRC) willow. At eight SRC willow plantations in England, with ages of 3–22 years, soil amended 18–22 months previously with PyC was compared with unamended control soil. Cumulative CO2 flux was measured weekly from incubated soil at 0–5 cm depth, and soil‐surface CO2 flux was also measured in the field. For the incubated soil, cumulative CO2 flux was significantly higher from soil containing weathered PyC than the control soil for seven of the eight sites. Across all sites, the mean cumulative CO2 flux was 21% higher from soil incubated with weathered PyC than the control soil. These results indicate the potential for positive priming in the surface 5 cm of soil independent of changes in soil properties following LUC to SRC willow production. However, no net effect on CO2 flux was observed in the field, suggesting this increase in CO2 is offset by a contrasting PyC‐induced effect at a different soil depth or that different effects were observed under laboratory and field conditions. Although the mechanisms for these contrasting effects remain unclear, results presented here suggest that PyC does not reduce LUC‐induced SOC losses through negative priming, at least for this PyC type and application rate.

Five willow varieties cultivated across diverse field environments reveal stem density variation associated with high tension wood abundance.

Sustainable and inexpensive production of biomass is necessary to make biofuel production feasible, but represents a challenge. Five short rotation coppice willow cultivars, selected for high biomass yield, were cultivated on sites at four diverse regions of Quebec in contrasting environments. Wood composition and anatomical traits were characterized. Tree height and stem diameter were measured to evaluate growth performance of the cultivars according to the diverse pedoclimatic conditions. Each cultivar showed very specific responses to its environment. While no significant variation in lignin content was observed between sites, there was variation between cultivars. Surprisingly, the pattern of substantial genotype variability in stem density was maintained across all sites. However, wood anatomy did differ between sites in a cultivar (producing high and low density wood), suggesting a probable response to an abiotic stress. Furthermore, twice as many cellulose-rich G-fibers, comprising over 50% of secondary xylem, were also found in the high density wood, a finding with potential to bring higher value to the lignocellulosic bioethanol industry.