Global Change Biology Bioenergy最新文献

Anaerobic digesters are expected to significantly reduce CH₄ emissions from dairy manure management by capturing them for use as biogas. Anaerobic digestion is the current major mitigation strategy for agricultural CH₄ emissions in California's climate policy. However, verification of the effectiveness of anaerobic digesters to reduce CH₄ emissions has not been conducted at scale in California. We made atmospheric measurements from a mobile platform and used dispersion modeling to estimate CH₄ emissions from a liquid manure storage complex at a typical California dairy before and after digester installation across nine field campaigns. The anaerobic digester reduced CH₄ emissions by an average of 82% ± 16%, comparing paired months to predigester values. Prior to the digester, atmospheric CH₄ mole fractions showed a persistent hotspot near the manure settling basin cells of 28.6 ± 8.9 ppm. After the digester, atmospheric CH₄ mole fractions from manure storage were greatly reduced. We observed strong temporal variability across measurement campaigns due to weather, on-farm management practices, and digester operations. Estimated emissions greatly exceeded those based on inventory calculations used by the California Air Resources Board (CARB) but were in line with expected relative emissions reduction from digester installation. Scaling these results to 139 dairies with digester projects statewide suggests that similarly operating digesters would reduce CH₄ emissions by 1.6 ± 0.3 MMT CO₂e (65 ± 12 Gg CH₄), 39% of the emissions reduction goal for livestock manure management set by California law. This work demonstrates the effectiveness of anaerobic digesters to reduce dairy manure management CH₄ emissions in practice, along with the importance of understanding operations and management for interpreting on-farm CH₄ emissions studies.

Cellulose, a major component of plant cell walls and a critical bioeconomy resource, is synthesized by cellulose synthase complexes (CSCs). Understanding the assembly and function of CSCs, driven by cellulose synthase (CESA) proteins, is essential for enhancing biomass and tailoring cellulose properties for various applications. This study integrates evolutionary analysis, structural modeling, and functional data to elucidate the sequence-structure–function relationships of CESAs. We analyzed key interface residues within plant-conserved regions, transmembrane helices, and zinc-finger domains, revealing functional specialization through variations among duplicated CESAs, subfamilies, and plant groups. Our findings indicate that CESA gene duplication and interface residue divergence, coupled with tissue-specific and environment-dependent expression and post-translational modifications, drive CSC diversification. These alterations in CESAs may redefine CSC assembly. Heterologous expression of an evolutionarily distant CESA, such as Sorghum bicolor secondary wall CESA8 in Arabidopsis, may favor the formation of exogenous homomeric CSCs, leading to increased cellulose synthesis and enhanced plant growth. This increase in cellulose synthesis is associated with pectin demethylation, a process known to promote plant cell expansion. Based on these findings and previous studies, we propose a working model for enhanced biomass production. In this model, interface alterations in CESAs redefine CSC assembly, allowing overexpressed CESAs to form homomeric complexes that enhance cellulosic biomass production.

Biochar carbon removal (BCR) is widely recognized as a globally feasible technique for removing CO₂ from the atmosphere and storing carbon in a stable form within the environment. The hydrogen-to-carbon (H/C) molar ratio serves as the primary proxy for classifying biochar into different quality categories and is a key parameter in decay models used to estimate its long-term stability. In the context of climate credit systems that rely on biochar for carbon sequestration, an accurate assessment of biochar's carbon pools and permanence is crucial. The results of this study confirm that the H/C molar ratio is a robust bulk geochemical proxy for biochar carbonization. However, its use as a standalone benchmark for biochar permanence should be approached with caution. To ensure a more comprehensive assessment, the H/C molar ratio should be combined with the random reflectance (R_o) method, which provides spatially resolved insights into the degree of carbonization within a biochar sample. Relying exclusively on a single bulk H/C molar ratio may, in some cases, lead to inaccurate determinations of biochar's carbon storage security. Such limitations could undermine the credibility of climate credit systems that depend on biochar for permanent carbon dioxide removal. Therefore, integrating both H/C ratio and R_o analysis is essential for accurately evaluating biochar stability and its long-term carbon sequestration potential.

As global interest in enhancing energy security, reducing energy costs, and promoting rural economic development grows, the use of forest residues for bioenergy has gained attention. While bioenergy derived from forest residues can help meet power needs and support policy goals, significant uncertainty remains regarding the greenhouse gas (GHG) emissions associated with their production and use. This study aims to explore the key drivers of these uncertainties by reviewing estimates of GHG emissions from forest residue use for energy, as presented in peer-reviewed journals, reports, and gray literature. The findings reveal a wide range of GHG emission outcomes, with some studies suggesting net emissions and others indicating net removals. This uncertainty stems from the complexity of time scales, variety of forest management approaches and feedstock quality, assumptions about alternative scenarios, and varying approaches to emissions accounting. Recognizing that each method has its unique attributes, we propose an ideal framework that integrates multiple approaches to provide a more comprehensive assessment of the potential net GHG outcomes of using forest residues for energy.

Dissimilatory nitrate reduction to ammonium (DNRA) process is an important factor in the removal and retention of nitrogen (N) in cropland soil. However, the effects of cropland management on DNRA rate and nrfA gene abundance are poorly understood on a global scale. A global synthesis based on 29 published papers and 158 observations was conducted to examine the effects of cropland management (including biochar, manure, straw amendment and N fertilization) and identified the controlling factors affecting the DNRA process. We found biochar amendment enhanced DNRA rate by 85%, while manure and straw amendment enhanced DNRA rate by 442% and 160%. Both biochar and straw amendment significantly increased nrfA gene abundance. Biochar significantly increased DNRA rate and nrfA gene abundance in acidic soils in cool climate zones. Manure application increased DNRA rate when N input was low and in coarse-textured Regosols. Similar to biochar and manure amendment, low N application rate under straw amendment increased DNRA rate in acidic and coarse-textured soils. The nrfA gene abundance was increased in cool climate and clay loam-textured soils. Management effects were improved in the long term (> 10 years) experiments. Pearson correlation indicated the crucial roles of alkaline, cool environments and available N in controlling DNRA processes following biochar and straw amendment. Our results also showed the vital roles of alkaline, humid environments and available N controlling the DNRA process under manure amendment and N fertilization. Our study further highlights management practices could enhance N retention through DNRA processes and therefore lower N loss from cropland soil.

Palm oil is an efficient feedstock for biodiesel production due to its high oil yield and cost-effectiveness, positioning it as a key component in the global biofuel industry. However, the expansion of oil palm plantations has raised substantial environmental and socio-economic concerns. This review critically assesses the environmental impacts of palm oil biodiesel, including greenhouse gas emissions, deforestation, biodiversity loss, and the degradation of water and soil resources. Additionally, it explores the “food versus fuel” debate, emphasizing how competition for land and resources between biodiesel production and food cultivation affects global food security, particularly in developing nations. What distinguishes this review is its focus on Southeast Asian producer countries, particularly Indonesia and Malaysia, where biodiesel policies and land-use changes intersect with food and environmental systems in unique ways. Unlike previous studies, this article delves into the often-overlooked consequences of peatland conversion, highlighting its role in exacerbating carbon emissions and biodiversity loss. By providing a detailed analysis of the socio-economic trade-offs and sustainability challenges linked to palm oil biodiesel, the review offers insights into the complex interplay between renewable energy, food security, and environmental stewardship. It also evaluates technological innovations and best practices that can mitigate negative impacts. Furthermore, the review critically examines certification initiatives like the roundtable on sustainable palm oil (RSPO) and the indonesian sustainable palm oil (ISPO) and their effectiveness in promoting sustainable practices. By integrating case studies, this article demonstrates practical applications of these principles, offering actionable recommendations for policymakers, industry stakeholders, and researchers in the field.

Plant strategies to acquire nutrients from limited environments help shape ecosystem carbon (C) and nitrogen (N) cycling and response to environmental change. The effects of plant strategies on ecosystem dynamics are largely uncharacterized in bioenergy agroecosystems, where the impacts could determine bioenergy's ability to meet its sustainability goals of storing C and reducing N loss. We used FUN-BioCROP (Fixation and Uptake of Nitrogen-Bioenergy Carbon, Rhizosphere, Organisms and Protection), a plant–microbe interaction model of coupled plant nutrient uptake and soil organic matter decomposition, to simulate the effects of nutrient acquisition strategies on soil microbial activity and ecosystem nutrient cycling in bioenergy feedstocks miscanthus (Miscanthus × giganteus) and sorghum (Sorghum bicolor (L.) Moench). We examined the model's ability to reproduce the relative effects of belowground nutrient uptake on microbial activity using a reanalysis of empirical data showing that miscanthus root exudation provoked a larger soil microbial response than sorghum. From baseline model simulations, we found that the ability of miscanthus to retranslocate N resulted in higher N uptake at a lower C cost than the sorghum/soybean rotation and that soil C and N pools increased under perennial (miscanthus) and decreased under annual (sorghum/soybean) cultivation. The model also predicted that greater root exudation increased soil C accumulation, highlighting the role of roots in forming stable soil C. Overall, the baseline model was unable to reproduce field observations of miscanthus root exudation stimulating microbial activity more than sorghum. To improve the model, we updated the soil microbial parameters in miscanthus to have faster decomposition, a higher C/N ratio, and greater carbon use efficiency. These changes improved the simulated soil microbial response to miscanthus root exudation, supporting the hypothesis that miscanthus soils foster a microbial community that is more responsive to root exudation than that of sorghum.

Field pennycress (Thlaspi arvense L.) is an annual in the Brassicaceae family and is currently being developed as an oilseed intermediate crop suitable for renewable biodiesel and jet fuel. It displays many desirable characteristics for this role including cold tolerance, a rapid life cycle, and a seed fatty acid profile conducive to bioenergy generation. These traits make field pennycress favorable for winter oilseed cultivation in the inland Pacific Northwest (iPNW). Simultaneously, intermediate crops are an increasingly recognized component of both agronomic sustainability and soil health management. Intermediate crops enhance soil microbial diversity, which benefits both soil and plant health. To understand the impact of field pennycress on soil microbial diversity, two natural accessions and seven experimental accessions were grown at three sites in Eastern Washington. Aboveground biomass and rhizosphere soil were then collected. Soil genomic DNA was extracted from rhizosphere samples and used to generate an amplicon library for bacterial (16S) and fungal (ITS) rRNA sequences. The resulting libraries were analyzed in QIIME2, which revealed that not only did the fad2 deficient line from the Spring32-10 background have significantly increased aboveground biomass production compared to other pennycress genotypes, but also displayed significantly higher β-diversity in the rhizosphere community specifically at the site experiencing the driest conditions. ANCOM analysis showed that multiple sequences similar to beneficial plant and soil health enhancing organisms such as Trichoderma spirale, Pseudomonas spp., and Methylobacterium goesingense were found to be enriched in the microbiome of the fad2 Spring32-10 background also at that site. To add additional context to rhizosphere community data, root exudates from two pennycress genotypes were captured in magenta boxes and analyzed using HPLC. Future work will expand our understanding of the mechanisms by which field pennycress creates diversity in the rhizosphere, thus expanding our ability to cultivate this crop in the iPNW.

Epigenetic regulation in annual plants is recognized as a key component of recurring stress acclimation and adaptation, but reports on perennial tree species are limited. In this study, two contrasting tree species, Populus trichocarpa and Populus deltoides, and an F1 hybrid cross between them showed species-specific epigenetic and physiological responses to heat stress (42°C) following priming (35°C). By analyzing whole-genome methylation, transcriptomics, proteomics, metabolomics, and photosynthesis parameters, we found that P. deltoides expresses specific epigenetic signatures in response to heat, resulting in improved photosynthetic efficiency compared to P. trichocarpa. Conversely, P. trichocarpa displayed stress signaling and defense mechanisms that could not sustain a net assimilation rate despite maintaining higher gas exchange. Heat stress following priming in hybrid plants increased transcript levels of thermotolerance-related transcription factors, such as SPL12. Selected regions in the promoter of SPL12 showed differential methylation between direct heat stress and priming followed by heat stress. As a result, upregulation of downstream genes and associated increases in protein and metabolite abundance for stress adaptation were exhibited. Consequently, hybrid plants showed enhanced photosynthesis and gas exchange rates, a trait lacking in P. trichocarpa. These results imply that priming may not be universally effective in enhancing plant performance under stress, particularly in perennial tree species. However, priming can acclimate the perennial tree species P. deltoides to withstand elevated temperature stress better. Our study has demonstrated that priming-based stress adaptation is species-specific but can be attained through crossbreeding, indicating its potential use in breeding programs.