Carbon Sequestration Capability Research Articles

Full-Scale Fire Experiments on Cross-Laminated Timber Residential Enclosures Featuring Different Lining Protection Configurations

AbstractThe adoption of timber, specifically cross-laminated timber (CLT), as a primary construction material is gaining traction due to its carbon sequestration capabilities, environmental advantages, and potential for precision manufacturing. However, the combustibility of wood raises legitimate concerns about fire safety in timber-based residential buildings. This paper investigates the fire performance of timber in a residential context, attempting to fill knowledge gaps and outline strategies for improving fire robustness in timber-built dwellings. Through comprehensive experimental studies on residential-type enclosures constructed with CLT panels, this research explores different configurations and the effects of varying degrees of non-combustible protective lining. The findings underscore the significance of considering timber surface exposure and adopting effective encapsulation strategies in CLT buildings. It has been estimated that the exposure of timber walls leads to a proportional increase in heat release rate, corresponding to the area of exposed timber surfaces and their charring rates. Consequently, the external flame has a larger projection, resulting in a much greater heat flux to the façade. Furthermore, threshold conditions for initial flaming self-extinguishment of timber defined in literature of 44.5 ± 1.2 kW/m2 have been found to be applicable to the experiments conducted in this research. Finally, it has been observed that partial encapsulation, where the protective lining will likely fall off during a fire, may hinder rather than increase the likelihood of self-extinguishment. This work contributes towards a nuanced understanding of fire dynamics in timber structures, offering insights for safer and more effective design strategies for CLT-based construction.

A Coupled InVEST-PLUS Model for the Spatiotemporal Evolution of Ecosystem Carbon Storage and Multi-Scenario Prediction Analysis

In investigating the spatiotemporal patterns and spatial attributes of carbon storage across terrestrial ecosystems, there is a significant focus on improving regional carbon sequestration capabilities. Such endeavors are crucial for balancing land development with ecological preservation and promoting sustainable, low-carbon urban growth. This study employs the integrated InVEST-PLUS model to assess and predict changes in ecosystem carbon storage under various land use scenarios within the Chengdu urban cluster, a vital region in Central and Western China, by 2050. The results indicate the following. (1) A linkage between land use dynamics and ecosystem carbon storage changes: over two decades, a 7.5% decrease in arable land was observed alongside a 12.3% increase in urban areas, leading to an 8.2% net reduction in ecosystem carbon storage, equating to a loss of 1.6 million tons of carbon. (2) Carbon storage variations under four scenarios—natural development (NDS), urban development (UDS), farmland protection (FPS), and ecological protection (EPS)—highlight the impact of differing developmental and conservation policies on Chengdu’s carbon reserves. Projections until 2050 suggest a further 5% reduction in carbon storage under NDS without intervention, while EPS could potentially decrease carbon storage loss by 3%, emphasizing the importance of strategic land use planning and policy. This research provides a solid theoretical foundation for exploring the relationship between land use and carbon storage dynamics further. In summary, the findings highlight the necessity of incorporating ecological considerations into urban planning strategies. The InVEST-PLUS model not only sheds light on current challenges but also presents a method for forecasting and mitigating urbanization effects on ecosystem services, thus supporting sustainable development goals.

Carbon sequestration potential of plantation forests in New Zealand - no single tree species is universally best

BackgroundPlantation forests are a nature-based solution to sequester atmospheric carbon and, therefore, mitigate anthropogenic climate change. The choice of tree species for afforestation is subject to debate within New Zealand. Two key issues are whether to use (1) exotic plantation species versus indigenous forest species and (2) fast growing short-rotation species versus slower growing species. In addition, there is a lack of scientific knowledge about the carbon sequestration capabilities of different plantation tree species, which hinders the choice of species for optimal carbon sequestration. We contribute to this discussion by simulating carbon sequestration of five plantation forest species, Pinus radiata, Pseudotsuga menziesii, Eucalyptus fastigata, Sequoia sempervirens and Podocarpus totara, across three sites and two silvicultural regimes by using the 3-PG an ecophysiological model.ResultsThe model simulations showed that carbon sequestration potential varies among the species, sites and silvicultural regimes. Indigenous Podocarpus totara or exotic Sequoia sempervirens can provide plausible options for long-term carbon sequestration. In contrast, short term rapid carbon sequestration can be obtained by planting exotic Pinus radiata, Pseudotsuga menziesii and Eucalyptus fastigata.ConclusionNo single species was universally better at sequestering carbon on all sites we tested. In general, the results of this study suggest a robust framework for ranking and testing candidate afforestation species with regard to carbon sequestration potential at a given site. Hence, this study could help towards more efficient decision-making for carbon forestry.

Improving the carbonation performance of sulfate-activated material cured waste sediments by calcined Mg-Al hydrotalcite: Influence of CLDH dosages, carbonation concentrations and cycles

A method was proposed to strengthen the carbonation resistance of the waste sludge matrix by replacing part of cement with industrial by-products such as ground-granulated blast-furnace slag (GGBFS) and fly ash (FA) via the structural recrystallization and anion exchangeability of calcined Mg-Al hydrotalcite in a humid carbon dioxide environment. The mechanical and workability results showed that although the addition of CLDH weakened the flow extension of the mixture samples, they accelerated the solidification and hardening of the samples and increased the development of compressive strength in a slightly carbonized environment (e.g., C5T3L0.3 and C5T3L0.6). Furthermore, XRD, TG, BSE, and MIP techniques were used to analyze the composition of the hydration products and the distribution of the pore structure of the CLDHs-containing samples at different carbonation times and carbonation concentrations. The results indicated that CLDHs had good carbon sequestration capability. The addition of CLDH helped to refine the pores, and a slightly carbonized product like calcium carbonate could enhance the strength development by filling the pores, but too much had side effects. The outcomes of the study also provided an alternative way of thinking about the anti-carbonation behavior of cement pastes.

Full phenology cycle carbon flux dynamics and driving mechanism of Moso bamboo forest.

Moso bamboo forests, widely distributed in subtropical regions, are increasingly valued for their strong carbon sequestration capacity. However, the carbon flux variations and the driving mechanisms of Moso bamboo forest ecosystems of each phenology period have not been adequately explained. Hence, this study utilizes comprehensive observational data from a Moso bamboo forest eddy covariance observation for the full phenological cycle (2011-2015), fitting a light response equation to elucidate the evolving dynamics of carbon fluxes and photosynthetic characteristics throughout the entire phenological cycle, and employing correlation and path analysis to reveal the response mechanisms of carbon fluxes to both biotic and abiotic factors. The results showed that, First, the net ecosystem exchange (NEE) of Moso bamboo forest exhibits significant variations across six phenological periods, with LSOFF demonstrating the highest NEE at -23.85 ± 12.61 gC·m-2·5day-1, followed by LSON at -19.04 ± 11.77 gC·m-2·5day-1 and FGON at -17.30 ± 9.58 gC·m-2·5day-1, while NFOFF have the lowest value with 3.37 ± 8.24 gC·m-2·5day-1. Second, the maximum net photosynthetic rate (Pmax) and apparent quantum efficiency (α) fluctuated from 0.42 ± 0.20 (FGON) to 0.75 ± 0.24 mg·m-2·s-1 (NFOFF) and from 2.3 ± 1.3 (NFOFF) to 3.3 ± 1.8 μg·μmol-1 (LSOFF), respectively. Third, based on the path analysis, soil temperature was the most important driving factor of photosynthetic rate and NEE variation, with path coefficient 0.81 and 0.55, respectively, followed by leaf area index (LAI), air temperature, and vapor pressure difference, and precipitation. Finally, interannually, increased LAI demonstrated the potential to enhance the carbon sequestration capability of Moso bamboo forests, particularly in off-years, with the highest correlation coefficient with NEE (-0.59) among the six factors. The results provide a scientific basis for carbon sink assessment of Moso bamboo forests and provide a reference for developing Moso bamboo forest management strategies.

Insights into anaerobic digestion of microalgal biomass for enhanced energy recovery

This review paper delves into the intricate challenge of transforming microalgal biomass into biofuel through anaerobic digestion, elucidating its significance for sustainable energy production and waste management. Despite the promise anaerobic digestion holds, obstacles like inhibitory substances, process stability issues, and residue management complexities persist. Microalgal biomass, characterized by high biogas yields and carbon sequestration potential, emerges as a viable solution to enhance anaerobic digestion efficiency. Employing a comprehensive literature selection process, the review synthesizes recent studies to shed light on breakthroughs and pinpoint areas for future investigation. Key findings underscore advancements in microalgal biomass utilization, with strategic strain selection and innovative pretreatment methods resulting up to 25% increase in biogas production. Additionally, the assimilation of co-digestion techniques yields enhanced overall process efficiency. Microalgal biomass demonstrates remarkable carbon sequestration capabilities, sequestering up to 60% of CO2 during the anaerobic digestion process. Furthermore, the analysis reveals that despite inhibitory substances posing challenges, innovative approaches have reduced inhibition by 15%, promoting more stable and efficient digestion. Implications of the review findings stress the need to scale laboratory successes to industrial applications while maintaining environmental sustainability. Identified gaps include challenges in inhibitory substance management and process stability, with future research directions advocating for multidisciplinary approaches to unlock the full potential of microalgal biomass in anaerobic digestion. In conclusion, the review contributes significantly to understanding the intricate relationship between microalgal biomass and anaerobic digestion, highlighting the importance of continued research and development to address existing challenges and advance towards a more regenerative bioeconomy.

Effects of fresh-salt water interaction on spatial variations of soil organic carbon in reed wetland of Yellow River Estuary.

Estuarine wetlands exhibit significant interaction between fresh and salt water, with long-term carbon sequestration capability. We set up 60 sampling sites in the reed wetlands of the fresh-salt water interaction zone of the Yellow River Estuary, covering four different zones of the weak-intensity fresh-salt water interaction zone (WIZ), medium-intensity fresh-salt water interaction zone (MIZ), high-intensity interaction fresh-salt water zone (HIZ) and strong-intensity fresh-salt water interaction zone (SIZ). We investigated how fresh-salt water interaction affected the spatial variation of soil organic carbon (SOC) storage. The results showed that the area of reed wetland accounted for 17.8% of the total area of the fresh-salt water interaction zone the Yellow River Estuary, which mainly distributed in the WIZ and MIZ. The SOC content of reed wetland in the fresh-salt water interaction zone ranged from 1.09 to 3.65 g·kg-1, the SOC density was between 1.85-5.84 kg·m-2, and the SOC storage was (17.32±3.64)×104 t. The SOC content and SOC density decreased with increasing fresh-salt water interaction. There were significant differences in surface SOC content between different subzones of the fresh-salt water interaction zone. The surface SOC content decreased significantly with the increases of fresh-salt water interaction intensity. SOC density was positively correlated with SOC, TN, NH4+-N, and biomass, but negatively correlated with salt ions, soil bulk density, pH, and EC. SOC storage in the 0-30 cm soil layer accounted for 50.9%-64.2% of that in the 0-60 cm soil layer, while SOC storage in the 0-60 cm soil layer occupied 19.1%-37.7% of that in the 0-400 cm soil layer. The results could provide a scientific basis for accurately evaluating SOC storage of estuarine wetlands, improving carbon sink function and wetland management.

Life Cycle Assessment of Carbon Capture by an Intelligent Vertical Plant Factory within an Industrial Park

Bio-based carbon capture and utilization emerges as a critical pathway to mitigate carbon dioxide (CO2) emissions from industrial activities. Within this context, plant factories become an innovative solution for biological carbon capture within industrial parks, fed with the substantial carbon emissions inherent in industrial exhaust gases to maximize their carbon sequestration capabilities. Among the various plant species suitable for such plant factories, Pennisetum giganteum becomes a candidate with the best potential, characterized by its high photosynthetic efficiency (rapid growth rate), perennial feature, and significant industrial value. This paper studies the feasibility of cultivating Pennisetum giganteum within an intelligent plant factory situated in an industrial park. An automated and intelligent plant factory was designed and established, in which multiple rounds of Pennisetum giganteum cultivations were performed, and life cycle assessment (LCA) was carried out to quantitatively evaluate its carbon capture capacity. The results show that the primary carbon emission in the plant factory arises from the lighting phase, constituting 67% of carbon emissions, followed by other processes (15%) and the infrastructure (10%). The absorption of CO2 during Pennisetum giganteum growth in the plant factory effectively mitigates carbon emissions from industrial exhaust gases. The production of 1 kg of dry Pennisetum giganteum leads to a net reduction in emissions by 0.35 kg CO2 equivalent. A plant factory with dimensions of 3 m × 6 m × 2.8 m can annually reduce carbon emissions by 174 kg, with the annual carbon sequestration per unit area increased by 56% compared to open-field cultivation. Furthermore, large-scale plant factories exhibit the potential to offset the carbon emissions of entire industrial parks. These findings confirm the viability of bio-based carbon capture using intelligent plant factories, highlighting its potential for carbon capture within industrial parks.

Methane and nitrous oxide emissions and related microbial communities from mangrove stems on Qi'ao Island, Pearl River Estuary in China

Mangrove forests, crucial carbon-rich ecosystems, are increasingly vulnerable to soil carbon loss and greenhouse gas (GHG) emissions due to human disturbance. However, the contribution of mangrove trees to GHG emissions remains poorly understood. This study monitored CO2, CH4, and N2O fluxes from the stems of two mangrove species, native Kandelia obovata (KO) and exotic Sonneratia apetala (SA), at three heights (0.7 m, 1.2 m, and 1.7 m) during the dry winter period on Qi'ao Island, Pearl River Estuary, China. Heartwood samples were analyzed to identify potential functional groups related to gas fluxes. Our study found that tree stems acted as both sinks and sources for N2O (ranging from −9.49 to 28.35 μg m−2 h−1 for KO and from −6.73 to 28.95 μg m−2 h−1 for SA) and CH4. SA exhibited significantly higher stem CH4 flux (from −26.67 to 97.33 μg m−2 h−1) compared to KO (from −44.13 to 88.0 μg m−2 h−1) (P < 0.05). When upscaled to the community level, both species were net emitters of CH4, contributing approximately 4.68 % (KO) and 0.51 % (SA) to total CH4 emissions. The decrease in stem CH4 flux with increasing height, indicates a soil source. Microbial analysis in the heartwood using the KEGG database indicated aceticlastic methanogenesis as the dominant CH4 pathway. The presence of methanogens, methanotrophs, denitrifiers, and nitrifiers suggests microbial involvement in CH4 and N2O production and consumption. Remarkably, the dominance of Cyanobacteria in the heartwood microbiome (with the relative abundance of 97.5 ± 0.6 % for KO and 99.1 ± 0.2 % for SA) implies roles in carbon and nitrogen fixation for mangroves coping with nitrogen limitation in coastal wetlands, and possibly in CH4 production. Although the present study has limitations in sampling duration and area, it highlights the significant role of tree stems in GHG emissions which is crucial for a holistic evaluation of the global carbon sequestration capability of mangrove ecosystems. Future research should broaden spatial and temporal scales to enhance the accuracy of upscaling tree stem gas fluxes to the mangrove ecosystem level.

Carbon sequestration potential of Tamanu (Calophyllum inophyllum) in Gunung Kidul, Yogyakarta

Indigenous tree species play an important yet underestimated role in tropical ecosystems’ carbon sequestration, mitigating global climate change. Tamanu (Calophyllum inophyllum), an indigenous tree species, is studied for its carbon sequestration capacity in Gunung Kidul, Yogyakarta, Indonesia, an environmentally diverse location. Our comprehensive investigation included aboveground and belowground biomass, soil carbon concentration, and understory carbon content. The study found that tamanu stands can store carbon in their biomass, understorey, and soil, i.e., 54.2, 0.5, and 64 tons/ha, respectively. It was also shown that soil stores the most carbon because the Tamanu planted in this study area is still relatively young and has a relatively large space. This study also revealed the understory plants’ often overlooked role, increasing these ecosystems’ carbon sequestration capability. The need for comprehensive conservation programs considering carbon storage above and below ground is highlighted. The above discoveries contribute to creating efficient local climate mitigation policies and the global effort to combat climate change.

Life Cycle Assessment of the Construction Process in a Mass Timber Structure

Today, the application of green materials in the building industry is the norm rather than the exception and reflects an attempt to mitigate the sector’s environmental impacts. Mass timber is growing rapidly in the construction field because of its long span, speed of installation, lightness and toughness, carbon sequestration capabilities, renewability, fire rating, acoustic isolation, and thermal resistance. Mass timber is close to overtaking steel and concrete as the preferred material. The endeavor of this research is to quantitatively assess the ability of this green material to leverage the abatement of carbon emissions. Life cycle assessment (LCA) is a leading method for assessing the environmental impacts of the building sector. The recently completed Adohi Hall mass timber building on the University of Arkansas campus was used as a case study in an investigation to quantify greenhouse gas (GHG) emissions throughout the construction phase only. The energy used in building operations is the most dominant source of emissions in the building industry and has galvanized research on increasing the efficiency of building operations, but reduced emissions have made the impacts of embodied carbon (EC) components more noticeable in the building life cycle. While most studies have focused on the manufacturing stage, only a few to date have focused on the construction process. Consequently, few data are available on the environmental impacts associated with the installation of mass timber as a new green material. The present study began with the quantification of the materials and an inventory of the equipment used for construction. Then, this study determined the EC associated with running the equipment for building construction. The GHG emissions resulting from the transportation of materials to the site were also quantified. Based on data collected from the construction site, the results of this study indicate that earthwork ranks first in carbon emissions, followed by mass timber installation and construction. In third place is ready-mix poured concrete and rebar installation, followed by Geopiers. A comparison of these results with those in the existing literature shows that the EC generally associated with the building construction phase has been underestimated to date. Furthermore, only emissions associated with the fuel usage of the main equipment were considered.

Agroforestry and Its Potential for Sustainable Land Management and Climate Action: A Review

Agroforestry, the integration of trees and shrubs with crops and/or livestock, stands as a pivotal strategy in sustainable land management and climate action. This review synthesizes current knowledge and practices of agroforestry, focusing on its diverse systems, contributions to sustainable land management, role in climate change mitigation and adaptation, and the challenges and future prospects, with a special emphasis on the Indian context. Agroforestry systems, classified into silvopastoral, agrosilvicultural, and silvoarable, along with specialized practices like alley cropping and forest farming, demonstrate significant adaptability across various climatic and geographical regions. These systems have shown promising results globally, evident in case studies highlighting their effectiveness in different environmental settings. In the realm of sustainable land management, agroforestry is instrumental in soil conservation, enhancing soil fertility, and nutrient cycling. It also plays a critical role in biodiversity conservation and the enhancement of ecosystem services, such as water regulation and pollination. Socioeconomically, agroforestry contributes to improving livelihoods and economic resilience, as demonstrated in various local community case studies. In addressing climate change, agroforestry systems are notable for their carbon sequestration capabilities. Compared to traditional agricultural practices, these systems exhibit a higher potential for carbon storage, both above and below ground. They also enhance resilience to climate extremes, offering adaptive strategies for farmers and communities facing climatic variability. Policy and global initiatives increasingly recognize agroforestry's role in climate action, with international agreements and organizations fostering its integration into national policies. The implementation of agroforestry is not without challenges. Technical complexities, the need for site-specific knowledge, economic and policy barriers, and sociocultural factors pose significant hurdles. For India, a country with diverse agro-ecological zones, these challenges are coupled with opportunities for research, technological innovation, policy improvement, and global-local collaborations. The future prospects for agroforestry are vast, particularly in the Indian context, where it can significantly contribute to sustainable agriculture and rural development. Continued research, policy support, and collaborative efforts are essential to fully realize the potential of agroforestry in environmental conservation, climate change mitigation, and socioeconomic development.

Leveraging google earth engine cloud computing for large-scale arctic wetland mapping

Climate-driven permafrost degradation and an intensification of the hydrological cycle are rapidly altering the intricate ecohydrological processes of Arctic wetlands, threatening their long-term carbon sequestration capabilities. Addressing this concern through effective management holds immense potential for climate regulation, mitigation, and adaptation efforts. As such, there is growing need for timely spatial inventory data identifying Arctic wetlands with sufficient accuracy, resolution, and detail. Wetland mapping at large scales necessitates the processing of large volumes of Earth observation (EO) data, a challenge known as “Big Data”. Consequently, in this study, we present a cloud-based methodology exploiting the remarkable collection of EO data and computational power of Google Earth Engine (GEE) to map Arctic wetlands at 10 m spatial resolution. Our workflow evaluated temporally aggregated optical and radar satellite imagery and novel hydro-physiographic layers as inputs into a robust Random Forest (RF) machine learning (ML) algorithm. Both pixel and object-based classification approaches were assessed, whereby ML models were calibrated with a training dataset of sufficient and comprehensive samples. The study was conducted over Canada’s Southern Arctic ecozone (830,000 km2). GEE enabled the efficient preprocessing and classification of large volumes of EO data and resulted in excellent yet similar statistical performance for both pixel and object-based approaches, achieving overall accuracies of > 89 % and mean F1-scores of > 0.79. Moreover, McNemar tests indicated that these classifications were not statistically different, which has significant implications regarding computing time and processing efficiencies. These results demonstrate the efficacy and scalability of our cloud-based GEE methodology, and as such can support future endeavors around Pan-Arctic wetland mapping and monitoring.

Consumer perceptions of the co-benefits of biosolids and carbon sequestration in a fertiliser aimed at the urban retail market

New markets for biosolids-derived products are urgently required to provide cost-effective solutions for water utilities to address the increasing production of municipal sewage waste. One potential outlet for biosolids is the domestic retail fertiliser market. Biosolids-derived fertilisers could be marketed to consumers by highlighting their environmental benefits, including carbon sequestration potential. This study used a two-part research approach to assess the feasibility of biosolids-derived fertiliser in the current market and to gauge the extent to which retail consumers value carbon sequestration features in fertilisers. First, a hedonic price analysis of existing fertilisers in the market explored consumer preferences and whether they currently pay extra for “sustainable” or “organic-certified” products. Second, a discrete choice experiment was designed to elicit consumers’ willingness-to-pay for biosolids-derived fertilisers and those clearly labelled with their carbon sequestration capability. The hedonic price analysis determined that organic or natural fertilisers sell at similar or slightly higher prices than synthetic alternatives. The choice experiment revealed that consumers would pay 17% more for fertilisers labelled with their carbon capture capacity. Purchasers of organic fertilisers perceived biosolids-derived fertilisers as valuable organic alternatives. In contrast, buyers of synthetic fertilisers were willing to pay slightly less for biosolids-derived alternatives. These findings suggest that some consumers are willing to purchase biosolids-derived fertilisers at prices comparable to current alternatives and place higher value on fertilisers offering environmental benefits, such as carbon sequestration. These results indicate that urban retail markets could be a strategic outlet for biosolids by producing biosolids-derived fertilisers.

Inner Mongolia grasslands act as a weak regional carbon sink: A new estimation based on upscaling eddy covariance observations

Clarifying temporal and spatial variations of carbon exchanges of arid and semi-arid grasslands, the most widespread terrestrial ecosystem in the Northern China, is critical to evaluate regional and national carbon balance. However, estimating the carbon sequestration capability of arid and semi-arid grasslands still remains a challenge due to large interannual variability and high sensitivity to human activities. In this study, based on 696 site-months of long-term eddy covariance observations from 7 sites, we estimated the regional carbon fluxes of the arid and semi-arid grasslands in Inner Mongolia, China with the random forest (RF) approach. The estimated carbon fluxes encompassed net ecosystem productivity (NEP), gross primary productivity (GPP) and ecosystem respiration (ER), at a spatial resolution of 0.1°×0.1°. We found that Inner Mongolia grasslands acted as a weak carbon sink with a mean NEP of 2.43 ± 6.71 Tg C y−1 from 1982 to 2018. Fluctuations of precipitation during the peak growing season and leaf area index were the most important drivers for the interannual variations of regional carbon fluxes. During the dry period of 1999 to 2011, the grasslands switched from carbon sink to source resulting from a great drought-induced reduction in GPP than ER. Comparison of our RF carbon fluxes with the global datasets (FLUXCOM, CMIP6 models, and atmospheric inversion data of JenaCO2) showed that these products had limited agreement in terms of spatial and temporal variations, particularly for interannual variabilities of carbon fluxes, which highlights the importance of local long-term observations for regional evaluation and simulation of carbon budget.

Coupled weather-biosphere model (WRF-VPRM) response to extreme land cover scenarios over Ganga basin: a cross-component analysis

Deforestation can have both biophysical and biochemical effects. In our study we evaluate the impacts of extreme idealized land cover scenarios over Ganga basin, India using an online coupled weather-biosphere model. We present an analysis of the carbon stored, based on introduced afforestation (AFF) and deforestation (DEF) in the Ganga basin of India. WRF-VPRM model simulations were carried out at horizontal resolution of 20 km using optimized downscaling configuration. For DEF case, we found two-fold increase in surface temperatures whereas, AFF scenario exhibited cooling effect. The average carbon sequestration capability for AFF was 0.3 g C m−2 day−1 more than control run (CTL). The CTL simulations exhibited carbon sequestration capability of −0.15 g C m−2 day−1 which for a year accounts for around 59.3 Mt C yr−1. AFF scenario showed relative increase in net sequestration compared to DEF scenario. Most importantly, the model simulations showed that the croplandscan increase net carbon sequestration rather than just deciduous forest type. Our study highlights the possible effects of land use management practices on atmospheric CO2 variability.

A dataset of carbon and water fluxes of the typical grasslands in Duolun County, Inner Mongolia during 2006-2015

Grassland is an important terrestrial ecosystem for the exchange of mass and energy between land and atmosphere, playing an important role in global carbon cycle. However, the direction and size of its carbon sink are still in dispute. The eddy covariance technique can be sued to continuously determine ecosystem-level carbon, water and energy exchanges between vegetation and atmosphere. The long-term observations of carbon and water fluxes can help quantify the carbon sequestration capability of grassland ecosystems and its response to climate change. This dataset consists of two half-hourly data files, including the carbon, water and heat fluxes data file and the meteorological variables data file. All of the flux data were processed according to the flux data processing procedure specified by ChinaFLUX. The observational quality of this dataset is good, with a complete data observation integrity of over 95% throughout the year and a high energy balance ratio (1.04 ± 0.07). This decadal flux dataset from 2006 to 2015 provides a high-quality and continuous long-term eddy flux observation data valuable for the research of diurnal dynamics, seasonal and interannual variations of carbon and water fluxes, which is significant for evaluating the role of China’s temperate typical grasslands in regional and global carbon and water cycles.

A dataset of observational key parameters in carbon and water fluxes in a semi-arid steppe, Inner Mongolia (2012 – 2020): based on a long-term manipulative experiment of precipitation pattern

Warming has led to remarkable changes in global precipitation pattern, which will significantly affect vegetation growth and ecosystem function of the semiarid grasslands in Northern China. As a key processe of ecosystem function, carbon and water flux determines the carbon sequestration capability and resource utilization strategies of ecosystems. Therefore, understanding the responses of ecosystem carbon and water fluxes to precipitation pattern changes and their controls will be helpful for the evaluation in the carbon sequestration capacity of grassland ecosystems. However, there is a lack of long-term experiments and observational data on the responses of carbon and water processes to precipitation pattern changes in grassland ecosystems. Based on the long-term precipitation pattern manipulative experiment (including seven precipitation amount and rain event frequency treatments), we collected seasonal dynamics of ecosystem carbon and water fluxes by the static chamber method connecting with infrared gas analyzer during 2012-2020 in Xilin Gol grassland, Inner Mongolia. The dataset consists of two data files, namely the meteorological environmental data file (including annual precipitation, air temperature, soil moisture, and soil temperature) and the carbon and water fluxes data file (including ecosystem gross primary productivity, ecosystem respiration, net ecosystem carbon exchange, evapotranspiration, carbon use efficiency, and water use efficiency). Preliminary data analysis has shown that the drought treatment could significantly reduce the carbon and water fluxes, while water addition treatment had no significant effect on them. All the parameters recovered to the control level in the first year after the treatment cessation. This dataset is expected to provide important data support for the understanding of the responses of carbon and water cycles and their coupling processes to future precipitation regime in grasslands of Northern China.

Wood Pellet Production in the U.S. South and Exportation for ‘Renewable’ Energy in Europe

In recent years, European demand for wood pellets has surged due to a misconception of carbon neutrality. The current legal frameworks posit that simply replacing a harvested tree renders the burning of wood pellets for energy use renewable energy. This oversimplification does not consider a number of factors, including the difference in carbon sequestration capabilities between original, natural forests and replacement monoculture plantations, the cumulative impact of CO2 emissions in the atmosphere, and the years required for a replacement tree to sequester as much carbon as the harvested tree. The EU and U.K. can currently utilize emissions “reductions” due to burning wood pellets to reach domestic renewable energy goals along with commitments under the Paris Agreement. The corresponding increase in demand for wood pellets in Europe has resulted in a hotspot of wood pellet production in the U.S. South with several significant consequences. This Note presents the environmental justice and climate change impacts of the growing wood pellet industry in historically marginalized communities in the U.S. South, with a close look at the Enviva wood pellet plant in Hamlet, North Carolina. It provides an overview of the inadequacies of U.S., EU, U.K., and international environmental law in protecting both the global climate and local communities from the impacts of wood pellet production and combustion. This Note then builds on calls to change IPCC and EU carbon accounting rules for wood harvested for energy use to propose a solution to the environmental justice side of the wood pellet dilemma in international environmental law: namely, adding environmental justice safeguards to the UNFCCC Paris Agreement.

Variations in CO2 and CH4 Exchange in Response to Multiple Biophysical Factors from a Mangrove Wetland Park in Southeastern China

Mangrove ecosystems can be both significant sources and sinks of greenhouse gases. The restoration of mangrove forests is increasingly used as a natural climate solution tool to mitigate climate change. However, the estimates of carbon exchanges remain unclear, especially from restored mangroves. In this study, we observed the temporal variations in carbon dioxide (CO2) and methane (CH4) fluxes and their biophysical controls for 4 years, based on a closed-path eddy covariance (EC) system. The measurements were conducted in a mangrove wetland park with 14-year-old restored mangroves surrounded by open waters in Guangdong Province, China. The EC measurements showed that the mangrove ecosystem acted as a CO2 source with a net CO2 ecosystem exchange (NEE) of 305 g C m−2 from January 2019 to May 2020 by the 5-m tower measurement. After the tower was adjusted to 10 m, the mangrove showed a CO2 sink with an NEE of −345 g C m−2 from June 2020 to December 2022. The change in tower height influenced the interpretation of interannual trends on NEE. There were no significant interannual trends in the gross primary productivity (GPP) and the ecosystem respiration (Re) values. The change from CO2 source to sink may be attributed to the decrease in land surface proportion by the tower replacement, which reduces the proportion of the mangrove canopy respiration and, therefore, captures lower CO2 fluxes from open waters. The restored mangroves indicated strong CH4 sources of 23.2–26.3 g C m−2 a−1. According to the random forest analysis, the land surface proportion, radiation, and relative humidity were the three most important predictors of NEE, while the CH4 flux was most sensitive to air temperature. Compared to the natural and long-term restored mangroves, this 14-year-old restored mangrove had not yet achieved a maximum carbon sequestration capability. Our study highlights the need for the careful design of long-term observations from restored mangroves and proposes future needs in the context of carbon neutrality.