Global Change Biology Bioenergy最新文献

This study investigated the effects of pristine biochar (BC) and magnesium-treated biochar (Mg-BC), applied at 0%, 1%, and 2.5% (w/w), on the relationship between P fractions and GHG emissions in two degraded soils. Soil physiochemical properties were improved in response to BC and Mg-BC treatments. Enzyme activities increased with BC and Mg-BC treatments, where Mg-BC showed better effects. Similarly, increasing biochar did increase the labile-P pool while decreasing the moderately labile P (MP) and residual P pools in both soils, and the effects observed under Mg-BC treatment were more pronounced than those in the BC treatment. Compared to CK, BC and Mg-BC increased CO₂ emissions by 76%–138% and 44%–127% in red soil, and by 14%–33% and 8%–23% in black soil, respectively. In contrast, N₂O emissions decreased by 11%–29% and 17%–44% in red soil, and by 12%–23% and 16%–31% in black soil, respectively. Multivariate redundancy analysis revealed that biochar-induced improvement in labile P, enzyme activities, and soil properties were positively correlated with CO₂, whereas negatively associated with N₂O emission. The structural equation modeling (SEM) revealed that biochar type and dose had a minor influence on CO₂ emissions, but on the other hand, considerably decreased N₂O emissions (R² = 0.82–0.89) by increasing soil nutrients (SOC, NH₄, AP, and LP) in black soil, and pH, enzymes, and soil nutrients in red soil. Our results demonstrated that biochar application reduces N₂O emissions by improving soil pH, nutrients, and enzyme activities in degraded soils, with a greater impact under Mg-BC treatment.

This study investigated the effects of pristine biochar (BC) and magnesium-treated biochar (Mg-BC), applied at 0%, 1%, and 2.5% (w/w), on the relationship between P fractions and GHG emissions in two degraded soils. Soil physiochemical properties were improved in response to BC and Mg-BC treatments. Enzyme activities increased with BC and Mg-BC treatments, where Mg-BC showed better effects. Similarly, increasing biochar did increase the labile-P pool while decreasing the moderately labile P (MP) and residual P pools in both soils, and the effects observed under Mg-BC treatment were more pronounced than those in the BC treatment. Compared to CK, BC and Mg-BC increased CO₂ emissions by 76%–138% and 44%–127% in red soil, and by 14%–33% and 8%–23% in black soil, respectively. In contrast, N₂O emissions decreased by 11%–29% and 17%–44% in red soil, and by 12%–23% and 16%–31% in black soil, respectively. Multivariate redundancy analysis revealed that biochar-induced improvement in labile P, enzyme activities, and soil properties were positively correlated with CO₂, whereas negatively associated with N₂O emission. The structural equation modeling (SEM) revealed that biochar type and dose had a minor influence on CO₂ emissions, but on the other hand, considerably decreased N₂O emissions (R² = 0.82–0.89) by increasing soil nutrients (SOC, NH₄, AP, and LP) in black soil, and pH, enzymes, and soil nutrients in red soil. Our results demonstrated that biochar application reduces N₂O emissions by improving soil pH, nutrients, and enzyme activities in degraded soils, with a greater impact under Mg-BC treatment.

More and new sources of biomass are needed for renewable energy and renewable products for the bioeconomy. A leading new source of biomass is the highly sustainable perennial grass crop Miscanthus. The majority of the Miscanthus crop comprises a clone of Miscanthus × giganteus (M × g) of limited genetic variation and poor yield under dry growth conditions. The parental species of M × g, M. sacchariflorus and M. sinensis, are distributed over a large geographical range in Eastern Asia and may be used to improve on M × g. From breeding trials, we selected seven novel hybrids and two control genotypes including M × g. We grew these in a field experiment on drought-prone soil in Germany with and without irrigation. To identify superior Miscanthus types, we estimated radiation use efficiency (RUE), yield and water use efficiency (WUE) from within-season measurements made over three contrasting growing seasons. Temporal variations in RUE and WUE for different genotypes varied significantly and two novel hybrids, WAT6 and WAT8, achieved the highest yields. To achieve goodness of fit to yield measurements, genotype-specific parameters for process descriptions in the model MiscanFor were adjusted for the two superior genotypes. These parameters included earlier shooting and an increased threshold of overheating. When the model was run over ten years, despite generating the highest yield values, WAT8 accumulated less biomass than WAT6 over the longer term. The response of WUE to variation in soil capillary pressure and vapour pressure deficit was examined. WUE of M × g increased with the severity of water stress then declined again. The superior yielding genotypes were more able to sustain biomass accumulation and/or water use under the highest stress. We believe that combining physiology with crop modelling is a powerful way to inform genetic and agronomic improvements needed to secure the future supply of biomass for the bioeconomy.

Nitrogen (N) fertilizer is a common management practice to enhance the growth of bioenergy crops. Increasing aboveground yield and belowground carbon (C) (e.g., root biomass, microbial biomass, and organic carbon [OC]) is a win-win strategy to address energy and climate crises. However, it remains poorly understood how N additions affect belowground C dynamics, especially in deep soil layers where the majority of OC is stored. In this study, we investigated the effects of 12 years of N additions (0, 30, 60, 120, and 240 kg N ha⁻¹ year⁻¹) on Miscanthus × giganteus root traits, microbial biomass, enzyme activities, and OC pools across 0–120 cm soil depth profiles. High N additions at 120 and 240 kg N ha⁻¹ year⁻¹ increased root N contents and $��{\mathrm{NO}}_3^{-}�$ leaching, but decreased root biomass along the soil depth profiles. Biomass-specific activities of cellulose- and lignin-degrading extracellular enzymes (both for C acquisition) increased, but microbial basal respiration and biomass C decreased at 120 and 240 kg N ha⁻¹ year⁻¹ at 0–20 cm. Despite the changes in soil N availability and microbial activities, the magnitudes of salt-extractable OC, particulate OC, and mineral-associated OC did not significantly vary with the N additions across the soil profiles. We only observed reductions in these soil OC pools as soil depth increased. Our findings demonstrate that increases in soil N availability and root N contents do not always translate into notable changes in belowground C storage and stability under Miscanthus × giganteus after 12 years of N additions.

Understanding nitrogen-use strategies in Miscanthus sinensis is essential for optimizing biomass production while minimizing environmental impact, and providing sustainable bioenergy and ecosystem services. Nitrogen recycling in M. sinensis is known to be efficient, but the extent of intra-specific variability and its translation into distinct functional strategies remain unknown to date. Our objective was to assess the intergenotypic variation in nitrogen uptake and recycling and their relation to biomass yield in a diploid M. sinensis progeny. Endogenous remobilization fluxes were calculated for 80 genotypes from seasonal nitrogen dynamics under nitrogen deficient conditions, showing substantial intergenotypic variation, ranging from 0.2 to 85 kg N ha⁻¹ in spring and 5 to 158 kg N ha⁻¹ in autumn. Recycling efficiency, defined as the remobilized nitrogen relative to maximum nitrogen quantity, did not correlate with biomass yield, indicating that nitrogen recycling was independent of plant size. Exogenous nitrogen uptake varied widely (5–241 kg N ha⁻¹) and was strongly correlated with biomass yield (r = 0.72), making it the dominant factor influencing productivity, while principal component analysis highlighted the contribution of nitrogen recycling traits. Three functional groups emerged from hierarchical clustering on the principal components. The first group comprised nitrogen-acquisitive genotypes with high uptake and productivity, suitable for low-input bioenergy systems and potential ecosystem services like nitrate removal in water catchment areas. The second group followed a conservative strategy, with efficient belowground nitrogen storage and endogenous recycling, supporting resilience to environmental stress. The third group comprised nitrogen-deficient genotypes with low uptake, remobilization, and productivity. These findings demonstrate that substantial variation in nitrogen economy traits defined distinct functional groups in M. sinensis, providing a framework for breeding ideotypes that sustain biomass under nitrogen-limited conditions through enhanced uptake or remobilization, while delivering ecosystem services through contrasting remobilization strategies that can support nutrient retention, soil nitrogen conservation, and water quality regulation.

Miscanthus is a particularly promising lignocellulosic biomass as it can also grow under marginal conditions and can be used for a wide range of products including energy and material applications. The latter, including applications in the construction, textile, chemical, or agricultural sector, is becoming increasingly relevant today. In general, it is hypothesised that biobased products are advantageous in terms of their greenhouse gas (GHG) performance when compared to conventional—in particular fossil—alternatives. To investigate this, the life cycle assessment methodology is typically applied. However, assessments are subject to uncertainty and variability due to assumptions and methodological choices. Given the increasing interest in miscanthus-derived material applications, this study aims to draw more general conclusions about their GHG performance and relative mitigation potential. This should support a better understanding of their contribution to climate change mitigation objectives and guide the selection of promising products or product groups. A systematic review of peer-reviewed literature was conducted. In total, 20 studies reporting on 188 comparisons of the GHG performance of miscanthus-derived and alternative products were assessed. Most comparisons indicated potential GHG mitigation through miscanthus-derived products, with the majority ranging between 20% and 100% savings. Key parameters defining the relative performance include the selection of the reference product, consideration of soil carbon changes, changes in product and process design, as well as the incorporation of indirect Land Use Change (iLUC) impacts. Overall, we conclude that miscanthus-derived material applications have the potential to contribute to GHG emission mitigation if iLUC effects are minimised. Given the limited availability of agricultural land, miscanthus-derived products with high absolute GHG mitigation potential per unit of biomass used and long product lifetime are preferable. For future development, potential environmental trade-offs need to be monitored.

The cultivation of sterile giant miscanthus (Miscanthus × giganteus, M × g) for bioenergy and bioproducts has expanded into grain-cropped land in the United States (US) as local markets developed for this high-yielding perennial grass (10–30 Mg DM ha⁻¹). However, the magnitude of spatial and temporal variability in yield within US Corn Belt fields, along with impacts on economic return and sustainable land management, is poorly understood. This study established a diagnostic model relating remote sensing-derived vegetation indices to ground truth data from 105 hand-harvested stem biomass samples, which were strategically selected to represent the full range of vegetation index observations. The high-resolution satellite-sensed vegetation indices captured > 90% of the yield variation measured within fields. This model was then used to predict yield variability and assess economic performance across four of the first commercial M × g fields in the Corn Belt state of Iowa, US. Significant spatial variability in biomass dry matter (DM) yields (9.3–18.1 Mg DM ha⁻¹) and net profits ($83 to $1211.5 ha⁻¹) was observed. All fields were profitable in all site-years. When low profit occurred, it was explained by limited management experience of the crop in Iowa. The breakeven yield at a selling price of $130 Mg⁻¹ varied from 9.0–12.1 Mg ha⁻¹ at 15% moisture content (7.6–10.3 Mg DM ha⁻¹). Breakeven prices ranged from $73 to $122.4 Mg⁻¹, matching ranges used in the Department of Energy Billion Ton Report (US Department of Energy, 2023). Notably, M × g yield and profits were commensurate with grain crops particularly with favorable precipitation. This study provides insight on the M × g management “learning curve”, performance on marginal land and in drought conditions, and demonstrates that addressing yield gaps, reducing costs, and implementing precision agriculture strategies can enhance profitability. These findings emphasize the value of remote sensing technologies in guiding sustainable and competitive commercial-scale M × g production.

Increasing the production of bioproducts from lignocellulosic feedstocks requires improvement in both field production and biorefinery efficiency. When plant traits arise that improve field production but decrease biofuel yield, these trade-offs can represent challenges in the entire production process. To examine trade-offs between field and production traits, we examined factors underlying switchgrass resistance to fungal rust pathogens in field conditions and factors that impede yeast fermentation in the lab using repeated measurements on a switchgrass genetic diversity panel. We found that the same switchgrass genotypes that showed high fungal pathogen resistance also showed recalcitrance to yeast fermentation. These switchgrass genotypes were mostly from the Atlantic genetic group, which had high levels of specialized metabolites of the saponin class. Among 1589 metabolites identified through metabolomics, we found that saponins were among the most likely to explain variation in both rust infection and fermentation yield using random forest feature selection, and that only four of these were sufficient to explain 57.9% of the variation in rust susceptibility. Through follow-up testing in recalcitrant biomass, we found that the bacterium Zymomonas mobilis does not suffer the same inhibition as the yeast Saccharomyces cerevisiae, and that the addition of ergosterol (thought to be the fungal cellular target of saponin inhibition) rescues yeast fermentation. Several lines of evidence point to a central role for saponins as key metabolites protecting switchgrass from fungal pathogens and interfering with yeast fermentation, underscoring an ongoing need for collaboration between plant breeders and biofuel production scientists.

This work investigates the potential for logging residues (branches and tops that can be extracted during roundwood harvesting) to replace fossil-based feedstocks and energy use in industry, using Sweden as a case study. National and regional supply–demand balances are calculated and costs for extraction and transportation of logging residues to current and future users are estimated. The results show that there is an excess of unutilized logging residues in northern Sweden (just below 10 TWh/y), while the supply potential is already utilized in the south. In southern Sweden, the use of logging residues for district heating is extensive, while simultaneously, the refinery industry is undergoing a transition to renewable feedstocks. This creates a gap between the regional supply and demand of around 15 TWh/year going into the future. Meanwhile, the middle and northern parts of Sweden could be largely self-sufficient and rely on regional logging residues to supply the estimated future biomass demands of around 9 TWh/y. Thus, a regional supply–demand imbalance can be expected in the future, where the excess resource is located in the north, while large demands are expected in the south. With current utilization patterns, the costs for logging residue extraction and transportation are around 50% higher in the north than in the south of Sweden, mainly attributable to the shorter transportation distances. To supply refineries with logging residue-based feedstock from northern Sweden, costs for transportation can be reduced by about 5–10 €/MWh utilizing distributed methanol synthesis before long-distance ship and train transportation. However, the transportation cost reduction is small compared to the cost of the methanol synthesis step, highlighting that the added value for the refinery of receiving methanol compared to chipped logging residues needs to make up the difference to motivate a supply chain based on distributed methanol synthesis.