Global Change Biology Bioenergy最新文献

This study investigates uncertainties in greenhouse gas (GHG) emission factors related to switchgrass-based biofuel production in Michigan. Using three life cycle assessment (LCA) databases—US lifecycle inventory (USLCI) database, GREET, and Ecoinvent—each with multiple versions, we recalculated the global warming intensity (GWI) and GHG mitigation potential in a static calculation. Employing Monte Carlo simulations along with local and global sensitivity analyses, we assess uncertainties and pinpoint key parameters influencing GWI. The convergence of results across our previous study, static calculations, and Monte Carlo simulations enhances the credibility of estimated GWI values. Static calculations, validated by Monte Carlo simulations, offer reasonable central tendencies, providing a robust foundation for policy considerations. However, the wider range observed in Monte Carlo simulations underscores the importance of potential variations and uncertainties in real-world applications. Sensitivity analyses identify biofuel yield, GHG emissions of electricity, and soil organic carbon (SOC) change as pivotal parameters influencing GWI. Decreasing uncertainties in GWI may be achieved by making greater efforts to acquire more precise data on these parameters. Our study emphasizes the significance of considering diverse GHG factors and databases in GWI assessments and stresses the need for accurate electricity fuel mixes, crucial information for refining GWI assessments and informing strategies for sustainable biofuel production.

The UK sixth carbon budget has recommended domestic biomass supply should increase to meet growing demand, planting a minimum of 30,000 hectares of perennial energy crops a year by 2035, with a view to establishing 700,000 hectares by 2050 to meet the requirements of the balanced net zero pathway. Miscanthus is a key biomass crop to scale up domestic biomass production in the United Kingdom. A cohesive land management strategy, based on robust evidence, will be required to ensure upscaling of miscanthus cultivation maximizes the environmental and economic benefits and minimizes undesirable consequences. This review examines research into available land areas, environmental impacts, barriers to uptake, and the challenges, benefits, and trade-offs required to upscale miscanthus production on arable land and grassland in the United Kingdom. Expansion of perennial biomass crops has been considered best restricted to marginal land, less suited to food production. The review identifies a trade-off between avoiding competition with food production and a risk of encroaching on areas containing high-biodiversity or high-carbon stocks, such as semi-natural grasslands. If areas of land suitable for food production are needed to produce the biomass required for emission reduction, the review indicates there are multiple strategies for miscanthus to complement long-term food security rather than compete with it. On arable land, a miscanthus rotation with a cycle length of 10–20 years can be employed as fallow period for fields experiencing yield decline, soil fatigue, or persistent weed problems. On improved grassland areas, miscanthus presents an option for diversification, flood mitigation, and water quality improvement. Strategies need to be developed to integrate miscanthus into farming systems in a way that is profitable, sensitive to local demand, climate, and geography, and complements rather than competes with food production by increasing overall farm profitability and resilience.

Biochar possesses unique characteristics, including a substantial surface area, a high carbon content, sufficient capacity for cation exchange, and a robust structure. However, biochar contains hazardous pollutants like volatile organic compounds that harm soil properties and functionality. Although several studies on biochar production from various feedstocks have been undertaken in recent years, several issues about feedstock preparation, economic feasibility, influencing factors, and the proper utilization of biochar production processes need to be addressed. This paper thus addresses these issues by providing potential solutions identified through a comprehensive review. Slow pyrolysis of lignocellulosic biomass and Acacia nilotica yields biochar from 20 to 52 wt% at various temperatures and residence times. Biochar yield varies from 29 to 48.3 wt% when waste tires and corn stalks are rapidly pyrolyzed at higher temperatures and for shorter periods. Torrefaction of algal biomass at moderate temperatures with different residence times can result in a substantial yield of 50–60 wt%. However, the variability and heterogeneity of waste feedstocks pose potential challenges affecting biochar's quality and properties. Given its widespread use in carbon sequestration, soil remediation, wastewater purification, and organic waste composting, the mechanisms of biochar production in environmental usage need to be investigated.

Plagiomnium acutum has a high value of landscape application and medicinal value, but there is a lack of related research on propagation and cultivation techniques. The deadwood substrate has rich nutrients and superior water retention properties, which will be conducive to promoting the growth of moss. Nevertheless, the underlying mechanisms by which deadwood influences moss growth are not yet fully unclear. In this study, we pulverized deadwood from five decay classes of Pinus massoniana into three distinct particle sizes. Through a pot experiment, we investigated the effects of decay class and physicochemical properties on the growth and physiology of Plagiomnium acutum, aiming to identify the most suitable growth substrate. The results indicated that both the decay class and particle diameter of deadwood significantly affect the substrate's physicochemical characteristics and the growth indexes of P. acutum, with the decay class exerting a more pronounced effect. The water-holding porosity, water-holding capacity, total nitrogen, total phosphorus, total potassium and lignin content of the substrate positively affected the growth of P. acutum, while the bulk density, void ratio, total carbon, carbon-to-nitrogen ratio, condensed tannin content and cellulose content had negative impacts. A comprehensive evaluation using a fuzzy membership function indicated that deadwood with higher decay classes (IV and V) was more conducive to the growth of P. acutum. Specifically, substrates from decay class IV with particle sizes of 10–20 mm provided the most favorable conditions for P. acutum and were recommended as the optimal cultivation substrate. The results of this study provide theoretical basis and technical support for the propagation and cultivation of P. acutum, and provide a foundation for further development of the industrial, pharmaceutical and environmental biotechnology potential of P. acutum.

In emerging markets, investment costs tend to be associated with uncertainty, especially if the investment is policy driven. Globally, nations have agreed to reduce greenhouse gas emissions to keep the temperature increase below 1.5°C by 2100. Australia faces challenges in achieving its Paris Agreement Nationally Determined Contributions and Agenda 2030 commitments, mostly given the extraction profile of its economy. Introducing renewable carbon from forest residues in the niche markets could increase the competitiveness of the forest industry not only in terms of reduced energy costs but also in terms of ‘greening’ the primary product. Growing interest in the bioenergy market, linked with large volumes of available biomass feedstocks including forest residues, presents opportunities in Australia. Yet, ambiguity about costs and concerns about biomass supply throttle the investment potential. This paper aims to estimate a range of forest residue costs along the supply chain for the Australian market by projecting the biomass supply costs from a mature bioenergy market onto it using a benchmarking process reinforced by expert opinion. A three-round Delphi method in which experts indicated direction and range of costs along the forest biomass supply chain revealed that roadside costs of forest residues (other than stumps), and biomass transportation costs, are lower than or equal to and equal to or higher than, the EU costs respectively. Experts ranked investment and supply-side support as priority areas for the development of forest bioenergy in Australia. The expert estimations of forest residue cost ranges along the supply chain offer the first layer for framing a national policy for forest bioenergy within the broader bioeconomy.

Switchgrass (Panicum virgatum L.) is a prominent bioenergy crop with robust resilience to environmental stresses. However, our knowledge regarding how precipitation changes affect switchgrass photosynthesis and its responses to light and CO₂ remains limited. To address this knowledge gap, we conducted a field precipitation experiment with five different treatments, including −50%, −33%, 0%, +33%, and +50% of ambient precipitation. To determine the responses of leaf photosynthesis to CO₂ concentration and light, we measured leaf net photosynthesis of switchgrass under different CO₂ concentrations and light levels in 2020 and 2021 for each of the five precipitation treatments. We first evaluated four light and CO₂ response models (i.e., rectangular hyperbola model, nonrectangular hyperbola model, exponential model, and the modified rectangular hyperbola model) using the measurements in the ambient precipitation treatment. Based on the fitting criteria, we selected the nonrectangular hyperbola model as the optimal model and applied it to all precipitation treatments, and estimated model parameters. Overall, the model fit field measurements well for the light and CO₂ response curves. Precipitation change did not influence the maximum net photosynthetic rate (P_max) but influenced other model parameters including quantum yield (α), convexity (θ), dark respiration (R_d), light compensation point (LCP), and saturated light point (LSP). Specifically, the mean P_max of five precipitation treatments was 17.6 μmol CO₂ m⁻² s⁻¹, and the ambient treatment tended to have a higher P_max. The +33% treatment had the highest α, and the ambient treatment had lower θ and LCP, higher Rd, and relatively lower LSP. Furthermore, precipitation significantly influenced all model parameters of CO₂ response. The ambient treatment had the highest P_max, largest α, and lowest θ, R_d, and CO₂ compensation point LCP. Overall, this study improved our understanding of how switchgrass leaf photosynthesis responds to diverse environmental factors, providing valuable insights for accurately modeling switchgrass ecophysiology and productivity.

Harvest time is an important variable that determines the yield of miscanthus biomass, its possible end uses, and the nutrient offtake from the field. Green harvests result in a higher yield and greater nutrient removal from the field. Brown miscanthus harvests, carried out in late winter or early spring, result in lower yields and a lower nutrient offtake, whereby the harvested biomass is better suited to use in combustion. To look at the long-term impact of green harvests on miscanthus, this experiment followed the yield development of two miscanthus hybrids subjected to green and brown harvests over a period of seven years at one site in Southern Germany. The standard commercial hybrid Miscanthus × giganteus (Mxg) was compared with a novel late-ripening Miscanthus sinensis hybrid: Syn55. Average yields of Mxg were 19.9 t ha⁻¹ for green harvests and 13.2 t ha⁻¹ for brown harvests compared to 13.9 and 12.9 t ha⁻¹ for green and brown harvested Syn55, respectively. Yields of Mxg were very different for green and brown harvests; green harvested Mxg had very high nutrient offtake, while brown harvested Mxg had the lowest nutrient offtakes of all treatments. Syn55 showed a less marked difference between green and brown harvests likely due to its tendency to retain its leaves over winter. Syn55 was however not tolerant of a green harvest, with yields of brown harvested stands surpassing the yield of green harvested stands in several years. Although Mxg demonstrated consistently high yields when harvested in October, some signs of yield decline were detected in both hybrids when harvested green, which was due to insufficient carbohydrate relocation. Alternating green and brown harvests are recommended to allow stands to replenish carbohydrate stores and to form a litter layer.

Miscanthus ×giganteus (giant miscanthus), first found as a naturally occurring hybrid, has shown promise as a bioenergy/biomass crop throughout much of the temperate world. This allotriploid (2n = 3x = 57) hybrid resulted from a cross between tetraploid Miscanthus sacchariflorus (2n = 4x = 76) and diploid Miscanthus sinensis (2n = 2x = 38) and is particularly desirable due to its low fertility that minimizes reseeding and potential invasiveness. However, there is limited genetic diversity in commonly grown cultivars of triploid M. ×giganteus and breeding and development efforts to improve and domesticate this crop have been minimal. Here, we report on newly developed M. ×giganteus hybrids compared with the industry standard M. ×giganteus '1993-1780'. Dry biomass yields of new hybrids ranged from 19.5 to 32.4 Mg/ha/year for the fourth growing season, compared with 21.0 Mg/ha/year for M. ×giganteus '1993-1780'. Plant reproductive fertility remained low for all accessions with overall fertility [(seed set × seed germination)/100] ranging from 0.3% to 4.5% for new hybrids compared to 0.4% for M. ×giganteus '1993-1780'. Culm density and height varied among accessions and were positively correlated with increased biomass. Based on compositional analyses, theoretical ethanol yields ranged from 9, 740 to 16,278 L/ha/year for new hybrids compared to 10,406 L/ha/year for M. ×giganteus '1993-1780'. Relative feed value indices were low overall and ranged between 66.0 and 72.8 for new hybrids compared to M. ×giganteus '1993-1780' with 71.3. The genetic diversity of new hybrids, compared with existing cultivars, was characterized using whole genome sequences. Based on pair-wise distances, cluster analysis clearly showed increased diversity of new hybrids compared with earlier selections. These results document new triploid hybrids of M. ×giganteus with enhanced biomass and theoretical ethanol yields in combination with broader genetic diversity and lowreproductive fertility.

Miscanthus × giganteus (miscanthus) is considered a beneficial biomass energy crop because of its carbon (C) sequestration potential and low fertilizer requirements, but few studies in the United States have measured long-term C sequestration of miscanthus on suboptimal agricultural lands over a decadal scale, and none have been conducted in southeast Ohio. The objective of this study was to measure the soil C sequestration on abandoned agricultural land with a miscanthus crop that is harvested annually, the long-term changes in plant and soil nitrogen (N), and the photosynthetic capacity in the tenth year of growth. This study was conducted over a 10-year period from 2013 through 2023. A significant amount of C was accumulated in the soil (p < 0.05) and the mean C sequestration rates were 0.83 and 1.37 Mg C ha⁻¹ year⁻¹ at two different sites. The amount of C accumulated in the miscanthus plots by the tenth year was also greater than soil C in unmanaged grassland soils, but the difference was not statistically significant (p > 0.05). There was no statistically significant change in the amount of N found in soil and plants over 10 years (p > 0.05), but the variability in plant N was greater in some years relative to others. Even though miscanthus was grown without N fertilizers in this study, soil N at 0–30 cm depth was not depleted over 10 years of crop management. The photosynthetic capacity of miscanthus measured in this study indicated that the plants were thriving after 10 years, and C assimilation for growth was consistent with the findings of prior work that evaluated the maximum photosynthetic rates of this species. The combination of significant soil C sequestration, sustained soil N, and high photosynthetic rates has important implications for the sustainability of miscanthus as a biomass crop.