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Forest soils play a critical role in carbon (C) reservoirs and climate change mitigation globally. Exploring the driving factors of soil organic carbon (SOC) concentration and stability in forests on a large spatial scale can help us evaluate the role of forest soils in regulating C sequestration. Based on SOC quantification and solid-state 13 C nuclear magnetic resonance spectroscopy, we investigated the SOC concentration and SOC chemical stability (indicated by alkyl-to-O-alkyl ratio and hydrophobic-to-hydrophilic ratio) in top 0-5 and 5-10 cm soils from 65 Chinese natural forest sites and explored their driving factors. Results showed that SOC concentration in 0-5 cm soils were highest in mixed forests but SOC chemical stability in 0-5 cm soils were highest in coniferous forests, while SOC concentration and chemical stability in 5-10 cm soil layers did not differ across forest types. SOC concentration in 0-5 cm was directly related to soil pH and soil bacterial diversity. Structural equation models showed that aridity indirectly affected SOC concentration in 0-5 cm by directly affecting soil pH. While SOC chemical stability in 0-5 cm soils was higher with increased aridity. According to the correlations, the potential mechanisms could be attributed to higher proportion of coniferous forests in more arid forest sites, lower relative abundance of O-alkyl C, higher MgO and CaO contents, and higher bacterial diversity in soils from more arid forest sites. Our study reveals the important role of aridity in mediating SOC concentration and chemical stability in top 0-5 cm soils in Chinese natural forests on a large-scale field investigation. These results will help us better understand the different mechanisms underlying SOC concentration and stability in forests and assess the feedback of forest SOC to future climate change., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Arbuscular mycorrhizal fungi (AMF) establish symbiotic relationships with roots of most plants, contributing to plant water uptake and soil carbon (C) sequestration. However, the interactive contribution and of long-term field AMF inoculation and water conservation on maize yield and soil organic carbon (SOC) sequestration in drylands remain largely unknown. After 7-year long-term field inoculation with AMF Funneliformis mosseae, AMF suppression by fungicide benomyl, and no-AMF/no-benomyl control, and two water conservation practices of half-film and full-film mulching (∼50 % and ∼100 crop planted area covered with plastic film), this study thus applied in situ 13 CO 2 -C labeling and high-throughput sequencing to quantify newly photosynthetically assimilated C into different soil C pools including soil aggregates and respiration, and their effects on maize growth and productivity. Results showed that 7-year long-term AMF inoculation significantly increased the relative abundance of F. mosseae in rhizosphere soil and root AMF colonization, indicating that F. mosseae successfully dominated in AMF communities. Compared to no-AMF/no-benomyl control, AMF colonization significantly increased shoot biomass and maize yield by 17.9 % and 20.3 % while mitigated the less water conservation effects of half-film mulching on maize performance. The SOC content under field AMF inoculation SOC was increased from 7.9 to 8.4 g kg -1 and also the mean weight diameter of aggregates (1.21 to 1.35), e.g. aggregate stability. After 1 and/or 40 days 13 C labeling, the enhanced 13 C translocations into macro-aggregates with decreased 13 C emissions from microbial decomposition under field AMF inoculation had contributed to SOC conservation in bulk soil. These results suggest that AMF inoculation in dryland crops is promising to increase crop yield while promoting more atmospheric CO 2 fixation in soil aggregates. A long-term field AMF inoculation will enhance our understanding of applying beneficial mycorrhizal fungi to enhance soil C sequestration and also crop yield via plant-fixed atmospheric CO 2 in semi-arid and arid farmlands., Competing Interests: Declaration of competing interest The authors declare no known competing financial interests or personal relationships that could influence the work reported in this manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Soil organic carbon (SOC) sequestration is increasingly emphasized as a climate mitigation solution, as scientists, policy makers, and land managers prioritize enhancing belowground C storage. To identify key underlying drivers of total SOC distributions, we compiled a global dataset of soil C stocks held in three chemical forms, reflecting different mechanisms of organic C protection: free particulate organic C (fPOC), physically protected particulate organic C (oPOC), and mineral-protected soil organic C (mSOC). In our dataset, these three SOC pools were differentially sensitive to the effects of climate, soil mineralogy, and ecosystem type, emphasizing the importance of distinguishing between physical and chemical C protection mechanisms. C stocks in all three pools varied among ecosystems: cropland soils stored the least amount in each pool, with forest and grassland soils both containing significantly more fPOC (40%-60% greater in each ecosystem) than croplands. oPOC stocks did not significantly differ from zero in croplands but were substantial in forest and grassland soils. Meanwhile, mSOC stocks were the greatest in grasslands and shrublands (90%-100% greater than croplands). In cropland soils, there were no major effects of tillage on C storage in any of the three pools, while manure addition enhanced mSOC stocks, especially when added with inorganic N. Thus, the human land use intensity in croplands appears to reduce SOC storage in all major pools, depending upon management; retaining native vegetation should be emphasized to maintain current global SOC stocks., (© 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd.)

The biological pump supplies carbon to the oceans' interior, driving long-term carbon sequestration and providing energy for deep-sea ecosystems 1,2 . Its efficiency is set by transformations of newly formed particles in the euphotic zone, followed by vertical flux attenuation via mesopelagic processes 3 . Depth attenuation of the particulate organic carbon (POC) flux is modulated by multiple processes involving zooplankton and/or microbes 4,5 . Nevertheless, it continues to be mainly parameterized using an empirically derived relationship, the 'Martin curve' 6 . The derived power-law exponent is the standard metric used to compare flux attenuation patterns across oceanic provinces 7,8 . Here we present in situ experimental findings from C-RESPIRE 9 , a dual particle interceptor and incubator deployed at multiple mesopelagic depths, measuring microbially mediated POC flux attenuation. We find that across six contrasting oceanic regimes, representing a 30-fold range in POC flux, degradation by particle-attached microbes comprised 7-29 per cent of flux attenuation, implying a more influential role for zooplankton in flux attenuation. Microbial remineralization, normalized to POC flux, ranged by 20-fold across sites and depths, with the lowest rates at high POC fluxes. Vertical trends, of up to threefold changes, were linked to strong temperature gradients at low-latitude sites. In contrast, temperature played a lesser role at mid- and high-latitude sites, where vertical trends may be set jointly by particle biochemistry, fragmentation and microbial ecophysiology. This deconstruction of the Martin curve reveals the underpinning mechanisms that drive microbially mediated POC flux attenuation across oceanic provinces., (© 2024. The Author(s).)

Consumers can directly (e.g., consumption) and indirectly (e.g., trophic cascades) influence carbon cycling in blue carbon ecosystems. Previous work found that large grazers have nuanced effects on carbon stocks, yet, small, bioturbating-grazers, which remove plant biomass and alter sediment properties, remain an understudied driver of carbon cycling. We used field-derived and remote sensing data to quantify how the purple marsh crab, Sesarma reticulatum, influenced carbon stocks, flux, and recovery in salt marshes. Sesarma caused a 40%-70% loss in carbon stocks as fronts propagated inland (i.e., ungrazed to recovered transition), with front migration rates accelerating over time. Despite latitudinal differences, front migration rate had no effect on carbon stocks, flux, or time to replacement. When we included Sesarma disturbance in carbon flux calculations, we found it may take 5-100 years for marshes to replace lost carbon, if at all. Combined, we show that small grazers cause a net loss in carbon stocks as they move through the landscape, and irrespective of migration rate, these grazer-driven impacts persist for decades. This work showcases the significant role of consumers in carbon storage and flux, challenging the classic paradigm of plant-sediment feedbacks as the primary ecogeomorphic driver of carbon cycling in blue carbon ecosystems., (© 2024 The Author(s). Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

Deciphering riverine dissolved carbon dynamics is pivotal for a comprehensive picture of the global carbon cycle. Through rigorous in-situ sampling across the Pearl River Basin (PRB), our investigation reveals the Pearl River networks function as a significant carbon source, with the annual carbon dioxide (CO 2 ) emission of 2.57 ± 1.94 Tg C, which offsets 10 ± 8 % of the forest carbon sequestration or 65 ± 49 % carbon sink via chemical weathering in the PRB. Based on the mass balance of 222 Rn, we initially reveal that the contributions of water flux from the hyporheic zone increased with the river orders (Hack Order) across both dry and wet seasons. Conversely, the evasion rates of dissolved CO 2 (CO 2 *) and dissolved inorganic carbon (DIC) from the hyporheic zone into river channels exhibited a decline with the increasing river orders. The hyporheic exchange contributes 4 - 11 % of the lateral and vertical DIC losses, thereby is a key mechanism in the riverine carbon cycle. Furthermore, CO 2 * derived from the hyporheic zone was ∼4 times of riverine CO 2 emissions and this CO 2 * flux from the hyporheic zone was buffered into carbonates/bicarbonates in river channels, due to the high riverine pH resulted from carbonate weathering in the basin. These results not only highlight the substantial role of carbonates and hyporheic processes in modulating riverine carbon fluxes but also signify their broader implications on understanding riverine carbon dynamics at both regional and global scales., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Landscapes evolution have significantly altered the Earth's energy balance and biogeochemical cycles, thereby exacerbating climate change. This, in turn, affects surface characteristics and the provision of ecosystem services, especially carbon storage. While recent centuries have witnessed unprecedented landscape changes, limited long-term studies have offered insights into the comparison between present-day features and historical conditions. This study utilized historical reconstruction data and remote sensing imagery to assess landscape evolution and its consequences for carbon stocks over 300 years. Employing multiple regression and random forest models were selected to quantify the influence of key landscape metrics on carbon stocks in the Dongting Lake basin, allowing for a thorough analysis across different sub-basins and land types. The results revealed that intensified human disturbances led to increased landscape fragmentation (+82%), regularity (+56%), and diversity (+37%) within the basin. Moreover, carbon stocks decreased from 4.13 Gt to 3.66 Gt, representing an 11.4% loss, with soil carbon stock experiencing the most considerable reduction (0.24 Gt, 51%). These changes in carbon stock metrics corresponded to shifts in landscape patterns, both undergoing significant transitions at the turn of the 21st century. Meanwhile, fragmentation and regularity played a vital role in explaining carbon stock changes, as their increase contributes to greater carbon losses. Likewise, an increase in landscape diversity correlated with decreased carbon stocks, challenging the prevailing notion that enhanced diversity promotes carbon stocks. The influence of landscape patterns on carbon stocks varies notably across distinct land types. An increase in the dominance of farmland and built-up land led to decreased carbon stocks, while the opposite holds true for forestland. Similarly, a decrease in regularity for farmland, forestland, and built-up land benefits carbon storage, while grassland demonstrates the opposite trend. These findings offer insights for countries and regions in the early stages of development or approaching development, suggesting improvements in land use practices and strategies to address climate change. This involves offsetting land-based carbon emissions through changes in landscape spatial configuration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Nitrogen and phosphorus are universally recognized as limiting elements in the eutrophication processes affecting the majority of the world's lakes, reservoirs, and coastal ecosystems. However, despite extensive research spanning several decades, critical questions in eutrophication science remain unanswered. For example, there is still much to understand about the interactions between carbon limitation and ecosystem stability, and the availability of carbon components adds significant complexity to aquatic resource management. Mounting evidence suggests that aqueous CO 2 could be a limiting factor, influencing the structure and succession of aquatic plant communities, especially in karstic lake and reservoir ecosystems. Moreover, the fertilization effect of aqueous CO 2 has the potential to enhance carbon sequestration and phosphorus removal. Therefore, it is important to address these uncertainties to achieve multiple positive outcomes, including improved water quality and increased carbon sinks in karst lakes and reservoirs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Gaining a comprehensive understanding of the effect of land use/land cover (LULC) and soil depth on soil carbon storage, through the manipulation of external carbon input and turnover processes, is crucial for accurate predictions of regional soil carbon storage. Numerous research investigations have been conducted to examine the impact of LULC on the storage and cycling of carbon in the surface soils of coastal wetlands. Nevertheless, there remains a dearth of understanding concerning the implications of this phenomenon on subterranean soils, a crucial factor in discerning the capacity for carbon sequestration in coastal wetlands and implementing measures for their preservation. The study focused on the Yellow River Delta (YRD) in China, which serves as a representative model system. It aimed to assess the impact of LULC as well as soil depth on carbon storage. This was achieved by a combination of remote sensing interpretation and field samplings. The findings of the study indicate that there was an increase in soil organic carbon storage with both the area covered and the depth of the soil across the four different land use types, namely forest, grass, tidal flat, and cultivated land. Cultivated land was identified as the predominant LULC type, encompassing 41.73% of the entire YRD. Furthermore, it accounted for a substantial carbon storage of 76.08%. In comparison to soil layers at depths of 0-20 cm and 20-40 cm, 40-60 cm was discovered to have the maximum carbon storage, accounting for 42.29% of total carbon storage. Furthermore, one of the main factors influencing carbon storage is salinity, which shows a negative association with carbon storage. Moreover, the aforementioned findings underscore the significance of the conjoined physical and chemical properties induced by LULC in influencing the dynamics of soil carbon. This suggests that the inclusion of deep soil carbon in the estimation and restoration of soil carbon storage is necessary. This inclusion will support the realization of the United Nations' "Toward Zero Carbon" effort and facilitate the implementation of China's national carbon neutrality objectives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Soil organic carbon (SOC) is the largest carbon pool in terrestrial ecosystems and plays a crucial role in mitigating climate change and enhancing soil productivity. Microbial-derived carbon (MDC) is the main component of the persistent SOC pool. However, current formulas used to estimate the proportional contribution of MDC are plagued by uncertainties due to limited sample sizes and the neglect of bacterial group composition effects. Here, we compiled the comprehensive global dataset and employed machine learning approaches to refine our quantitative understanding of MDC contributions to total carbon storage. Our efforts resulted in a reduction in the relative standard errors in prevailing estimations by an average of 71% and minimized the effect of global variations in bacterial group compositions on estimating MDC. Our estimation indicates that MDC contributes approximately 758 Pg, representing approximately 40% of the global soil carbon stock. Our study updated the formulas of MDC estimation with improving the accuracy and preserving simplicity and practicality. Given the unique biochemistry and functioning of the MDC pool, our study has direct implications for modeling efforts and predicting the land-atmosphere carbon balance under current and future climate scenarios., Competing Interests: Competing interests statement:The authors declare no competing interest.

Spatial distribution and edaphic influences on soil organic carbon (SOC) are key determinants of carbon sequestration potential, and analysis of aggregate-protected SOC gives an in-depth understanding of the stability of carbon stored in soils. The present study evaluated the edaphic effects on the SOC in four different forest types-tropical evergreen forest, tropical moist deciduous forest, tropical dry deciduous forest and shola forest-in the southern high hills agro-ecological zone of Western Ghats, India. SOC stocks at depths of up to 1 m varied significantly across forest types, with the highest levels observed in the shola forest type (441.08 Mg C/ha) and the lowest in the dry deciduous forest (138.17 Mg C/ha). Around 70% of SOC was found in upper layers (0-30 cm) in all the studied forest types. Evaluation by a fixed-effect model showed that forest type, soil depth and aggregate size significantly affected SOC storage in these systems. An assessment of the relative importance and effect of 14 edaphic factors on SOC content in different forest types using the random forest model showed that the algorithm could explain 93.68%, 41.72%, 45.53% and 75.2% variability of SOC concentration across shola, dry deciduous, moist deciduous and evergreen systems, respectively. Across all forest types, except for dry deciduous forests, soil texture was found to be the primary factor influencing SOC, surpassing all other edaphic parameters. Ionic interactions by way of metal oxides like Ca 2+ , Al 3+ , Fe 3+ , Mg and H + influenced the SOC in tropical forest systems. The insights into SOC dynamics and the edaphic factors regulating them offer valuable guidance for forest management in tropical regions, particularly regarding climate change mitigation., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Cropping systems are considered the largest source of agricultural GHG emissions. Identifying key categories and factors affecting cropping systems is essential for reducing these emissions. Most studies have focused on the carbon budget of cropping systems from the perspective of a single crop or crop category. Comprehensive studies quantifying the carbon budget of diversified cropping systems, including farmland and garden crops, are still limited. This study aims to fill this gap by quantifying the carbon budget of diversified cropping systems, clarifying their carbon attributes, and identifying key crop categories and influencing factors within different classifications of the system. This study analyzed the carbon budget of a diversified cropping system consisting of 19 crops in Yunnan Province, southwestern China, using a crop-based net greenhouse gas balance methodology based on the "cradle-to-farm" life cycle idea. Crops were categorized into three levels of categories to assess the potential impact of categorization within the cropping system on its carbon balance. Results showed that Yunnan's diversified cropping system is a significant carbon sink, with net sequestration of 33.1 Mt CO 2 eq, total emissions of 37.4 Mt CO 2 eq, and total sequestration of 70.5 Mt CO 2 eq. Cereals, vegetables, and hobby crops were the main contributors to carbon emissions, accounting for 41.61%, 21.87%, and 15.37%, respectively. Cereal crops also made the largest contribution to carbon sequestration at 53.18%. Bananas had the highest emissions per unit area (11.45 t CO 2 eq ha -1 ), while walnuts had the highest sequestration (20.64 t CO 2 eq ha -1 ). In addition, this study highlights effective strategies to reduce greenhouse gas emissions, such as reducing nitrogen fertilizer use, minimizing reactive nitrogen losses, and controlling methane emissions from rice fields. By elucidating the impact of carbon dynamics and crop categories, this study provides insights for sustainable agricultural practices and policies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Many researchers have evaluated the fishery carbon sink potential of bivalve aquaculture, with most studies focusing on the Life Cycle Assessment (LCA) of individual bivalves, and there is currently no consensus on whether bivalves are carbon sinks or carbon sources. It is worth noting that most studies have not considered the impact of bivalve aquaculture on ecosystems when evaluating its carbon sink potential. In this context, based on existing literature, this article aims to comprehensively review the effects of bivalve aquaculture on carbon storage in the water column and sediment of aquaculture areas. In general, our findings revealed that moderate and low stocking densities of bivalve aquaculture do not lead to significant changes in the abundance of phytoplankton, but it does indeed alter the phytoplankton community structure from dominated by huge diatom with lower carbon densities to dominated by small phytoplankton with higher carbon densities. Therefore, bivalve aquaculture may increase the total carbon storage in the water column. In addition, bivalve aquaculture also increases the sedimentation rate of suspended particles, increasing the rate of carbon burial, especially in low-energy environment and shallow water areas. The findings of this article fill the knowledge gap of fishery carbon sink in bivalve aquaculture from an ecosystem perspective., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Seagrass meadows are globally recognized as critical natural carbon sinks, commonly known as 'blue carbon'. However, seagrass decline attributed to escalating human activities and climate change, significantly influences their carbon sequestration capacity. A key aspect in comprehending the impact of seagrass decline on carbon sequestration is understanding how degradation affects the stored blue carbon, primarily consisting of sediment organic carbon (SOC). While it is widely acknowledged that seagrass decline affects the input of organic carbon, little is known about its impact on SOC pool stability. To address this knowledge, we examined variations in total SOC and recalcitrant SOC (RSOC) at a depth of 15 cm in nine seagrass meadows located on the coast of Southern China. Our findings revealed that the ratio of RSOC to SOC (RSOC/SOC) ranged from 27 % to 91 % in the seagrass meadows, and the RSOC/SOC increased slightly with depth. Comparing different seagrass species, we observed that SOC and RSOC stocks were 1.94 and 3.19-fold higher under Halophila beccarii and Halophila ovalis meadows compared to Thalassia hemprichii and Enhalus acoroides meadows. Redundancy and correlation analyses indicated that SOC and RSOC content and stock, as well as the RSOC/SOC ratio, decreased with declining seagrass shoot density, biomass, and coverage. This implies that the loss of seagrass, caused by human activities and climate change, results in a reduction in carbon sequestration stability. Further, the RSOC decreased by 15 %, 29 %, and 40 % under unvegetated areas compared to adjacent Halophila spp., T. hemprichii and E. acoroides meadows, respectively. Given the anticipated acceleration of seagrass decline due to climate change and increasing coastal development, our study provides timely information for developing coastal carbon protection strategies. These strategies should focus on preserving seagrass and restoring damaged seagrass meadows, to maximize their carbon sequestration capacity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Watershed ecosystems play a pivotal role in maintaining the global carbon cycle and reducing global warming by serving as vital carbon reservoirs for sustainable ecosystem management. In this study, we based on the "quantity-mechanism-scenario" frameworks, integrate the MCE-CA-Markov and InVEST models to evaluate the spatiotemporal variations of carbon stocks in mid- to high-latitude alpine watersheds in China under historical and future climate scenarios. Additionally, the study employs the Geographic Detector model to explore the driving mechanisms influencing the carbon storage capacity of watershed ecosystems. The results showed that the carbon stock of the watershed increased by about 15.9 Tg from 1980 to 2020. Fractional Vegetation Cover (FVC), Digital Elevation Model (DEM), and Mean Annual Temperature (MAT) had the strongest explanatory power for carbon stocks. Under different climate scenarios, it was found that the SSP2-4.5 scenario had a significant rise in carbon stock from 2020 to 2050, roughly 24.1 Tg. This increase was primarily observed in the southeastern region of the watersheds, with forest and grassland effectively protected. Conversely, according to the SSP5-8.5 scenario, the carbon stock would decrease by about 50.53 Tg with the expansion of cultivated and construction land in the watershed's southwest part. Therefore, given the vulnerability of mid- to high-latitude mountain watersheds, global warming trends continue to pose a greater threat to carbon sequestration in watersheds. Our findings carry important implications for tackling potential ecological threats in mid- to high-latitude watersheds in the Northern Hemisphere and assisting policymakers in creating carbon sequestration plans, as well as for reducing climate change., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Accurately assessing the changes in soil organic carbon storage （SOCS） before and after the Grain for Green Project （GFG） in the Loess Plateau （LP） and exploring the relationship between its spatial and temporal distribution and the influencing factors were important references for the development of regional recycling as well as the formulation of ecological protection policies. Based on the data of climate, human activities, and SOCD in the surface （0-20 cm） and deep （0-100 cm） soil before and after GFG in the LP from 2001 to 2020, we investigated the changes in SOCD at different spatial and temporal scales by using the methods of trend analysis, the kriging method, and variance partitioning analysis. The results showed that： ① Before and after the GFG, the surface SOCS of the whole region increased by 8 338.7×10 4 t； the deep SOCS increased by 1 160.02×10 4 t. ② In each bioclimatic subregion, the whole-region average SOCD of Ⅰ （Semi-Humid Forest Region）, Ⅱ （Semi-Humid Semi-Arid Forest and Grassland Region）, and Ⅲ （Semi-Arid Typical Grassland Region） showed a significant increasing trend, with a decreasing trend in Ⅳ （arid semi-arid desert grassland area） and Ⅴ （arid desert area）. ③ The average surface SOCS increase in different ecosystems was ranked as follows： cropland > grassland > woodland > shrubs > bare land and sparse vegetation. The deep soil increase was ranked as follows： grassland > cropland > woodland > shrubs > bare land and sparse vegetation. ④ Climate factors were the most important driving factors for changes in SOCD； the annual average temperature and precipitation were significantly positively correlated with changes in SOCD. The results of the study could provide data support for regional ecological management and land use policy formulation to promote high quality development of the ecological environment in the LP.

The alpine meadows of the Qinghai-Tibet Plateau have significant potential for storing soil carbon, which is important to global carbon sequestration. Grazing is a major threat to its potential for carbon sequestration. However, grazing poses a major threat to this potential by speeding up the breakdown of organic matter in the soil and releasing carbon, which may further lead to positive carbon-climate change feedback and threaten ecological security. Therefore, in order to accurately explore the driving mechanism and regulatory factors of soil organic matter decomposition in grazing alpine meadows on the Qinghai-Tibet Plateau, we took the grazing sample plots of typical alpine meadows as the research object and set up grazing intensities of different life cycles, aiming to explore the relationship and main regulatory factors of grazing on soil organic matter decomposition and soil microorganisms. The results show the following: (1) soil microorganisms, especially Acidobacteria and Acidobacteria, drove the decomposition of organic matter in the soil, thereby accelerating the release of soil carbon, which was not conducive to soil carbon sequestration in grassland; (2) the grazing triggering effect formed a positive feedback with soil microbial carbon release, accelerating the decomposition of organic matter and soil carbon loss; and (3) the grazing ban and light grazing were more conducive to slowing down soil organic matter decomposition and increasing soil carbon sequestration., (© 2024. The Author(s).)

As major terrestrial carbon sinks, forests play an important role in mitigating climate change. The relationship between the seasonal uptake of carbon and its allocation to woody biomass remains poorly understood, leaving a significant gap in our capacity to predict carbon sequestration by forests. Here, we compare the intra-annual dynamics of carbon fluxes and wood formation across the Northern hemisphere, from carbon assimilation and the formation of non-structural carbon compounds to their incorporation in woody tissues. We show temporally coupled seasonal peaks of carbon assimilation (GPP) and wood cell differentiation, while the two processes are substantially decoupled during off-peak periods. Peaks of cambial activity occur substantially earlier compared to GPP, suggesting the buffer role of non-structural carbohydrates between the processes of carbon assimilation and allocation to wood. Our findings suggest that high-resolution seasonal data of ecosystem carbon fluxes, wood formation and the associated physiological processes may reduce uncertainties in carbon source-sink relationships at different spatial scales, from stand to ecosystem levels., (© 2024. The Author(s).)

Soil organic carbon (SOC) accrual, and particularly the formation of fine fraction carbon (OC fine ), has a large potential to act as sink for atmospheric CO 2 . For reliable estimates of this potential and efficient policy advice, the major limiting factors for OC fine accrual need to be understood. The upper boundary of the correlation between fine mineral particles (silt + clay) and OC fine is widely used to estimate the maximum mineralogical capacity of soils to store OC fine , suggesting that mineral surfaces get C saturated. Using a dataset covering the temperate zone and partly other climates on OC fine contents and a SOC turnover model, we provide two independent lines of evidence, that this empirical upper boundary does not indicate C saturation. Firstly, the C loading of the silt + clay fraction was found to strongly exceed previous saturation estimates in coarse-textured soils, which raises the question of why this is not observed in fine-textured soils. Secondly, a subsequent modelling exercise revealed, that for 74% of all investigated soils, local net primary production (NPP) would not be sufficient to reach a C loading of 80 g C kg -1 silt + clay, which was previously assumed to be a general C saturation point. The proportion of soils with potentially enough NPP to reach that point decreased strongly with increasing silt + clay content. High C loadings can thus hardly be reached in more fine-textured soils, even if all NPP would be available as C input. As a pragmatic approach, we introduced texture-dependent, empirical maximum C loadings of the fine fraction, that decreased from 160 g kg -1 in coarse to 75 g kg -1 in most fine-textured soils. We conclude that OC fine accrual in soils is mainly limited by C inputs and is strongly modulated by texture, mineralogy, climate and other site properties, which could be formulated as an ecosystem capacity to stabilise SOC., (© 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd.)

Enhanced silicate rock weathering (ERW) is an emerging strategy for carbon dioxide removal (CDR) from the atmosphere to mitigate anthropogenic climate change. ERW aims at promoting soil inorganic carbon sequestration by accelerating geochemical weathering processes. Theoretically, ERW may also impact soil organic carbon (SOC), the largest carbon pool in terrestrial ecosystems, but experimental evidence for this is largely lacking. Here, we conducted a 2-year field experiment in tropical rubber plantations in the southeast of China to evaluate the effects of wollastonite powder additions (0, 0.25, and 0.5 kg m -2 ) on both soil organic and inorganic carbon at 0-10 cm depth. We found that ERW significantly increased the concentration of SOC and HCO 3 - with low- and high-level wollastonite applications. ERW had positive effects on the accrual of organic carbon in mineral-associated organic matter (MAOM) and macroaggregate fractions, but not on particulate organic matter. Path analysis suggested that ERW increased MAOM mainly by increasing the release of Ca, Si, and Fe, and to a lesser extent by stimulating root growth and microbial-derived carbon inputs. Our study indicates that ERW with wollastonite can promote SOC sequestration in stable MOAM in surface soils through both the soil mineral carbon pump and microbial carbon pump. These effects may have been larger than the inorganic CDR during our experiment. We argue it is essential to account for the responses of SOC in the assessments of CDR by ERW.3 - with low- and high-level wollastonite applications. ERW had positive effects on the accrual of organic carbon in mineral-associated organic matter (MAOM) and macroaggregate fractions, but not on particulate organic matter. Path analysis suggested that ERW increased MAOM mainly by increasing the release of Ca, Si, and Fe, and to a lesser extent by stimulating root growth and microbial-derived carbon inputs. Our study indicates that ERW with wollastonite can promote SOC sequestration in stable MOAM in surface soils through both the soil mineral carbon pump and microbial carbon pump. These effects may have been larger than the inorganic CDR during our experiment. We argue it is essential to account for the responses of SOC in the assessments of CDR by ERW., (© 2024 John Wiley & Sons Ltd.)

This paper introduces an energy transition model featuring a carbon-intensive manufacturer that adopts sustainable insurance, participates in a cap-and-trade scheme, and implements carbon capture and storage (CCS) transit, all aimed at achieving the net-zero carbon emission target. The model utilizes a down-and-out call (DOC) approach to evaluate the manufacturer's equity, considering the bankruptcy risk prior to maturity due to carbon intensity. The equity of the life insurer providing funds is assessed using a capped DOC method to address the capped credit risk from the manufacturer. The findings reveal that increased adoption of CCS transit diminishes manufacturer equity, heightens default risk, and reduces insurer equity, with these effects exacerbated by advanced CCS technology and stringent cap-and-trade caps. Both stringent cap-and-trade schemes and rapid advancements in CCS transit practices, particularly with the use of advanced CCS technology, deviate from the net-zero target. A critical policy implication is the necessity for the precise calibration of cap-and-trade schemes and the pace of CCS transit adoption to ensure alignment with net-zero targets., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Trait heritability and the response to selection depend on genetic variation, a prerequisite to developing sorghum varieties with desirable agronomic traits and high carbon sequestration for sustainable crop production and soil health. The present study aimed to assess the extent of genetic variability and associations among agronomic and carbon storage traits in selected sorghum genotypes to identify the best candidates for production or breeding. Fifty genotypes were evaluated at Ukulinga, Bethlehem and Silverton sites in South Africa during the 2022/23 growing season. The following agronomic and carbon storage traits were collected: days to 50% heading (DTH), days to 50% maturity (DTM), plant height (PH), total plant biomass (PB), shoot biomass (SB), root biomass (RB), root-to-shoot biomass ratio (RS), grain yield (GY), harvest index (HI), shoot carbon content (SCc), root carbon content (RCc), grain carbon content (GCc), total plant carbon stock (PCs), shoot carbon stock (SCs), root carbon stock (RCs), and root-to-shoot carbon stock ratio (RCs/SCs), and grain carbon stock (GCs). Higher genotypic coefficient of variations (GCVs) were recorded for GY at 45.92%, RB (39.24%), RCs/SCs (38.45), and RCs (34.62). Higher phenotypic coefficient of variations (PCVs) were recorded for PH (68.91%), followed by GY (51.8%), RB (50.51%), RS (41.96%), RCs/SCs (44.90%), and GCs (41.90%). High broad-sense heritability and genetic advance were recorded for HI (83.76 and 24.53%), GY (78.59 and 9.98%), PB (74.14 and 13.18%) and PCs (53.63 and 37.57%), respectively, suggesting a marked genetic contribution to the traits. Grain yield exhibited positive association with HI (r = 0.76; r = 0.79), DTH (r = 0.13; r = 0.31), PH (r = 0.1; r = 0.27), PB (r = 0.01; r = 0.02), RB (r = 0.05; r = 0.06) based on genotypic and phenotypic correlations, respectively. Further, the path analysis revealed significant positive direct effects of SB (0.607) and RB (0.456) on GY. The RS exerted a positive and significant indirect effect (0.229) on grain yield through SB. The study revealed that PB, SB, RB, RS, RCs, and RCs/SCs are the principal traits when selecting sorghum genotypes with high yield and carbon storage capacity., (© 2024. The Author(s).)

Urban blue-green infrastructure (BGI) offers a multitude of ecological advantages to residents, thereby playing a pivotal role in fortifying urban resilience and fostering the development of climate-resilient cities. Nonetheless, current research falls short of a comprehensive analysis of BGI's overall potential for carbon reduction and its indirect carbon reduction impact. To fill this research gap, we utilized the integrated valuation of ecosystem services and trade-offs model and remote sensing estimation algorithm to quantify the direct carbon sequestration and resultant indirect carbon reduction facilitated by the BGI within the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) (China). To identify the regions that made noteworthy contributions to carbon offsets and outliers, spatial autocorrelation analysis was also employed. The findings of this study reveal that in 2019, the BGI within the study area contributed an overall carbon offset of 1.5 × 10 8 t·C/yr, of which 3.5 × 10 7 and 11.0 × 10 7 t·C/yr were the result of direct carbon sequestration and indirect carbon reduction, respectively. The GBA's total CO 2 emissions were 1.1 × 10 8 t in 2019. While the direct carbon sequestration offset 32.0% of carbon emissions, the indirect carbon reduction mitigated 49.9% of potential carbon emissions. These results highlight the critical importance of evaluating BGI's indirect contribution to carbon reduction. The findings of this study provide a valuable reference for shaping management policies that prioritize the protection and restoration of specific areas, thereby facilitating the harmonized development of carbon offset capabilities within urban agglomerations.

This study aims to assess the amount of organic carbon stored in soils, as it is an intention of knowing the sustainable soil management, by using two common methods for determining soil organic matter (SOM), namely oxidation with acidified wet dichromate (Walkley-Black method-WB) and loss on ignition (LOI). The study was carried with soil samples collected from a depth of 0 to 30 cm in the Saharan arid region of Ghardaïa (Algeria), with different land uses: agricultural, forest and pastoral. The results obtained from the LOI and WB methods were subjected to statistical analysis, and the relations between both methods were tested to investigate their relationship. The mean percentage of SOM values were 1.86, 2.42, 1.54 by using LOI, but, lower values of 0.34, 0.33, 0.36 were determined by using WB method, for agricultural, forest and pastoral soils respectively. A weak linear relationship between the two analytical procedures was obtained (R 2 of 0.19 and 0.13 for agricultural and forest soils), while a medium relationship (R 2  = 0.65) was found for pastoral soils when using linear adjustment. However, the opposite behaviour was found when we use the logarithmic adjustment. The study outcomes indicated discrepancies in the measurements of SOM values between the two methods, been higher those estimated with LOI. Finally, in order to identify the best methodology to measure soil organic matter in arid soils, more research is required in these extreme arid regions as they are a gap in world soil organic matter maps., (© 2024. The Author(s).)

Submerged macrophytes are integral to the functioning of shallow lakes through their interaction with microorganisms. However, we have a limited understanding of how microbial communities in shallow lakes respond when macrophytes are restored after being historically extirpated. Here, we explored the interactions between prokaryotic communities and carbon utilization in two lakes where submerged macrophytes were restored. We found restoration reduced total carbon in sediment by 8.9 %-27.9 % and total organic carbon by 16.7 %-36.9 % relative to control treatment, but had no effects on carbon content in the overlying water. Sediment microbial communities were more sensitive to restoration than planktonic microbes and showed enhanced utilization of simple carbon substrates, such as Tween 40, after restoration. The increase in carbon utilization was attributed to declines in the relative abundance of some genera, such as Saccharicenans and Desertimonas, which were found weakly associated with the utilization of different carbon substrates. These genera likely competed with microbes with high carbon utilization in restored areas, such as Lubomirskia. Our findings highlight how restoring submerged macrophytes can enhance microbial carbon utilization and provide guidance to improve the carbon sequestration capacity of restored shallow lakes., Competing Interests: Declaration of competing interest All authors declare that there are no competing financial interests or personal relationships that might seem to have influenced the findings presented in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Biodiversity is essential for the functioning of ecosystems and the provision of services. In recent years, the role of plantations in mitigating climate change through carbon sequestration has been highlighted. In the Mediterranean area, high-density poplar plantations in short-rotation with resprouting management (SRC) have been established for biomass purposes on mostly irrigated agricultural land, coexisting with rainfed and irrigated agricultural crops. This study aims to assess the contribution of these plantations to this type of agroforest ecosystem in terms of biodiversity. For this purpose, both flora and fauna diversity were evaluated both within and outside of the plantation. Additionally, the accumulated carbon in the biomass, as well as in the accompanying vegetation within the plantation, was assessed. Different indices were used to evaluate both the intrinsic diversity of the forest plantation and the degree of substitution and complementarity between the different communities of the landscape. Our findings reveal distinct biodiversity patterns in the land-use scenarios sampled. Specifically, we observed significantly higher flora-species richness in SRC plantations than in the adjacent agricultural land, whereas fauna richness showed a similar but slightly higher level in the forested area. A moderate level of complementarity between land uses was found for insects and mammals (around 45 %), contrasting with high complementarity for birds (87 %) and flora (90 %). This suggests substantial turnover and replacement among these ecological environments. Our results indicate that a second rotation (4 year) plantation could accumulate a total of 61.6 Mg C ha -1 , and even though adventitious flora represents <2 % of the total carbon accumulated, its importance in providing ecosystem services is considerable. Hence, these findings evidence the fact that SRC poplar plantations can enhance biodiversity in Mediterranean agroforest ecosystems and actively contribute to various provisioning ecosystem services, including carbon sequestration, reflecting a multi-objective approach that extends beyond biomass production., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Fernando Montes reports financial support was provided by Spain Ministry of Science and Innovation. Hortensia Sixto reports financial support was provided by Spain Ministry of Economy, Industry and Competitiveness. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Soil organic carbon (SOC) plays a vital role in global carbon cycling and sequestration, underpinning the need for a comprehensive understanding of its distribution and controls. This study explores the importance of various covariates on SOC spatial distribution at both local (up to 1.25 km) and continental (USA) scales using a deep learning approach. Our findings highlight the significant role of terrain attributes in predicting SOC concentration distribution with terrain, contributing approximately one-third of the overall prediction at the local scale. At the continental scale, climate is only 1.2 times more important than terrain in predicting SOC distribution, whereas at the local scale, the structural pattern of terrain is 14 and 2 times more important than climate and vegetation, respectively. We underscore that terrain attributes, while being integral to the SOC distribution at all scales, are stronger predictors at the local scale with explicit spatial arrangement information. While this observational study does not assess causal mechanisms, our analysis nonetheless presents a nuanced perspective about SOC spatial distribution, which suggests disparate predictors of SOC at local and continental scales. The insights gained from this study have implications for improved SOC mapping, decision support tools, and land management strategies, aiding in the development of effective carbon sequestration initiatives and enhancing climate mitigation efforts.

The fraction of net primary productivity (NPP) allocated to belowground organs (f BNPP ) in grasslands is a critical parameter in global carbon cycle models; moreover, understanding the effect of precipitation changes on this parameter is vital to accurately estimating carbon sequestration in grassland ecosystems. However, how f BNPP responds to temporal precipitation changes along a gradient from extreme drought to extreme wetness, remains unclear, mainly due to the lack of long-term data of belowground net primary productivity (BNPP) and the fact that most precipitation experiments did not have a gradient from extreme drought to extreme wetness. Here, by conducting both a precipitation gradient experiment (100-500 mm) and a long-term observational study (34 years) in the Inner Mongolia grassland, we showed that f BNPP decreased linearly along the precipitation gradient from extreme drought to extreme wetness due to stronger responses in aboveground NPP to drought and wet conditions than those of BNPP. Our further meta-analysis in grasslands worldwide also indicated that f BNPP increased when precipitation decreased, and the vice versa. Such a consistent pattern of f BNPP response suggests that plants increase the belowground allocation with decreasing precipitation, while increase the aboveground allocation with increasing precipitation. Thus, the linearly decreasing response pattern in f BNPP should be incorporated into models that forecast carbon sequestration in grassland ecosystems; failure to do so will lead to underestimation of the carbon stock in drought years and overestimation of the carbon stock in wet years in grasslands., (© 2024 John Wiley & Sons Ltd.)

Coastal wetland ecosystems make an important contribution to the global carbon pool, yet their extent is declining due to aquaculture-related land use changes. We conducted an extensive investigation into the carbon stock and area coverage of macrophytes in a tropical coastal Ramsar wetland, Kolleru in Andhra Pradesh, India. A total of 72 quadrats of size 1 × 1 m 2 were laid in the wetland, 19 species of macrophytes were collected and analyzed for carbon content using a CNHS analyzer. To assess changes in the wetland macrophytes, Normalized Difference Vegetation Index (NDVI) was estimated using Landsat time series data from 1975 to 2023. The importance value index (IVI) of macrophytes scored highest for the Ipomoea aquatica (41.4) and the lowest for Ottelia alismoides (1.9). Non-metric multidimensional scaling (NMDS) significantly (r = 0.1905, p = 0.0361) revealed a clear separation of macrophytes in ordination space. ANOVA indicated highly significant (p < 0.0001) variations in the carbon content of aboveground and belowground components of macrophytes. Among the different macrophytes, the highest carbon content was found in Phragmites karka (0.6 g. g -1 ) and the lowest was recorded in Utricularia stellaris (0.2 g. g -1 ). On an average, emergents in the Kolleru wetland sequester 1525 ± 181 g C m -2  yr -1 , rooted floating species sequester 858 ± 101 g C m -2  yr -1 , submerged macrophytes sequester 480 ± 60 g C m -2  yr -1 , and free-floating macrophytes sequester 221 ± 90 g C m -2  yr -1 . Land cover mapping revealed a decrease in spread of aquatic vegetation from 225.2 km 2 in 1975 to 100.6 km 2 in 2023. Although macrophytes are vital carbon sinks, the wetland conversion into fishponds has resulted in a loss of 55.3 % of carbon storage. Therefore, immediate restoration of macrophyte cover is vital for the proper functioning of carbon sequestration and mitigation of climate change impacts., Competing Interests: Declaration of competing interest The author declares that there is no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Artificial forest restoration is widely recognized as a crucial approach to enhance the potential of soil carbon sequestration. Nevertheless, there is still limited understanding regarding the dynamics of aggregate organic carbon (OC) and the underlying mechanisms driving these dynamics after artificial forest restoration. To address this gap, we studied Pinus tabuliformis forests and adjacent farmland in three recovery periods (13, 24 and 33 years) in the Loess Plateau region. Samples of undisturbed soil from the surface layer were collected and divided into three aggregate sizes: >2 mm (large aggregate), 0.25-2 mm (medium aggregate), and <0.25 mm (small aggregate). The aim was to examine the distribution of OC and changes in enzyme activity within each aggregate size. The findings revealed a significant increase in OC content for all aggregate sizes following the restoration of Pinus tabuliformis forests. After 33 years of recovery, the OC of large aggregates, medium aggregates and micro-aggregates increased by (30.23 ± 9.85)%, (36.71 ± 21.60)% and (37.88 ± 16.07)% respectively compared with that of farmland. Moreover, the restoration of Pinus tabuliformis forests lead to increased activity of hydrolytic enzymes and decreased activity of oxidative enzymes. It is noteworthy that the regulation of carbon in all aggregates is influenced by soil P-limitation. In large aggregates, P-limitation promotes the enhancement of hydrolytic enzyme activity, thereby facilitate OC accumulation. Conversely, in medium and small aggregates, P-limitation inhibits the increase in oxidative enzyme activity, resulting in OC accumulation. The results emphasize the importance of P-limitation in regulating OC accumulation during the restoration of Pinus tabulaeformis forest, in which large aggregates play a leading role., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Xinhui Han reports financial support was provided by the national key research and development sub-project of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The seabed of the Antarctic continental shelf hosts most of Antarctica's known species, including taxa considered indicative of vulnerable marine ecosystems (VMEs). Nonetheless, the potential impact of climatic and environmental change, including marine icescape transition, on Antarctic shelf zoobenthos, and their blue carbon-associated function, is still poorly characterised. To help narrow knowledge gaps, four continental shelf study areas, spanning a southern polar gradient, were investigated for zoobenthic (principally epi-faunal) carbon storage (a component of blue carbon), and potential environmental influences, employing a functional group approach. Zoobenthic carbon storage was highest at the two southernmost study areas (with a mean estimate of 41.6 versus 7.2 g C m -2 ) and, at each study area, increased with morphotaxa richness, overall faunal density, and VME indicator density. Functional group mean carbon content varied with study area, as did each group's percentage contribution to carbon storage and faunal density. Of the environmental variables explored, sea-ice cover and primary production, both likely to be strongly impacted by climate change, featured in variable subsets most highly correlating with assemblage and carbon storage (by functional groups) structures. The study findings can underpin biodiversity- and climate-considerate marine spatial planning and conservation measures in the Southern Ocean., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Water and carbon, essential for Earth's well-being, face imminent threats from human activities that fuel climate change. This study investigates nature-based solutions, focusing on the carbon-water nexus of ex-mining lake-converted constructed wetlands, specifically in Malaysia's Paya Indah Wetlands (PIW). Addressing research gaps, it assesses the ecosystem services of these wetlands, emphasising integrated evaluations for informed land management and employing a top-down conservation approach. Methodologically, spatial assessments, soil and water sampling, carbon quantification, water quality index calculations, land cover classification and stakeholder surveys were conducted. Results underscore the significant carbon sequestration and water quality improvement potential of constructed wetlands, with soil and sediment carbon accumulation reaching 1553.11 Mg C ha -1 (equivalent to 5700 Mg CO 2 ha -1 ), translating to an annual sequestration capacity of 67.5 Mg C ha -1 year -1 . Water quality index values ranged from 58 to 81 (Classes II to III). PIW's establishment led to a reduction of over 90% in barren land, with increases in water bodies (36%) and vegetation-covered land (38%), boosting wildlife populations by 30%. Spatial variations in organic carbon density and water quality underscore the complexity of the carbon-water nexus and its impacts on ecosystem health and water security. Despite land use changes, PIW demonstrates resilience, contributing to climate change mitigation. Stakeholder perceptions vary, emphasising the need for adaptive strategies. The study proposes transdisciplinary conservation initiatives and adaptive plans, stressing the pivotal role of ex-mining lake-converted constructed wetlands in enhancing climate resilience., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Khai Ern Lee reports financial support was provided by the Malaysian Ministry of Higher Education., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Plant and microbially derived carbon (C) are the two major sources of soil organic carbon (SOC), and their ratio impacts SOC composition, accumulation, stability, and turnover. The contributions of and the key factors defining the plant and microbial C in SOC with grassland patches are not well known. Here, we aim to address this issue by analyzing lignin phenols, amino sugars, glomalin-related soil proteins (GRSP), enzyme activities, particulate organic carbon (POC), and mineral-associated organic carbon (MAOC). Shrubby patches showed increased SOC and POC due to higher plant inputs, thereby stimulating plant-derived C (e.g., lignin phenol) accumulation. While degraded and exposed patches exhibited higher microbially derived C due to reduced plant input. After grassland degradation, POC content decreased faster than MAOC, and plant biomarkers (lignin phenols) declined faster than microbial biomarkers (amino sugars). As grassland degradation intensified, microbial necromass C and GRSP (gelling agents) increased their contribution to SOC formation. Grassland degradation stimulated the stabilization of microbially derived C in the form of MAOC. Further analyses revealed that microorganisms have a C and P co-limitation, stimulating the recycling of necromass, resulting in the proportion of microbial necromass C in the SOC remaining essentially stable with grassland degradation. Overall, with the grassland degradation, the relative proportion of the plant component decreases while than of the microbial component increases and existed in the form of MAOC. This is attributed to the physical protection of SOC by GRSP cementation. Therefore, different sources of SOC should be considered in evaluating SOC responses to grassland degradation, which has important implications for predicting dynamics in SOC under climate change and anthropogenic factors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Vegetation restoration in karst areas has shifted from expanding planting areas to the collective enhancement of various ecological functions, especially carbon sequestration. Identifying and regulating key plant functional traits involved in the carbon cycle is an effective approach to increase carbon sequestration. However, reports on the significant contribution of petiole traits to the carbon cycle are scarce. Eucalyptus globulus and Bauhinia purpurea plantations in Liujiang river basin were investigated in this study. Petiole traits, understory characteristics, and soil organic carbon have been measured. The aim is to explore key effect of petiole traits for increasing soil carbon sequestration and to provide scientific evidence for the high-quality development of plantations in karst areas. The results indicate that in Eucalyptus globulus plantations, when the understory vegetation coverage is below 50 %, petioles tend to elongate rather than thicken, leading to an increase in specific petiole length. In Bauhinia purpurea plantations, petioles consistently tend to increase diameter. However, when specific leaf area decreases, specific petiole length increases. In both plantations, an increase in specific petiole length accelerates leaf shedding. It leads to increased litter accumulation so that soil carbon content increases. In Eucalyptus globulus plantations, to enhance soil carbon sequestration as an ecological goal, it is recommended to keep the soil total nitrogen below 1.20 mg/g, to control understory vegetation coverage below 50 %, and to limit the extension of Bidens pilosa. In Bauhinia purpurea plantations, within 100 m of altitude, the soil total nitrogen can be controlled below 1.00 mg/g to increase soil organic carbon from large leaf shedding due to the increase of specific petiole length. At lower altitudes, increasing soil total nitrogen can enhance understory vegetation coverage, allowing soil organic carbon to originate from both leaf shedding and understory vegetation residues., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Given global climate change and the projected increases in the greenhouse effect, enhancing the carbon storage capacity of forest ecosystems is especially critical. To fully realize the potential carbon sequestration, it is imperative to understand the drivers affecting carbon storage in forest ecosystems, particularly with disturbances that disrupt existing balance. In this study, we explored the effects of stem-only harvest at various thinning intensities on forest structure and carbon density in middle-aged natural secondary forests, located in the northern temperate zone. Carbon density included aboveground carbon density (ACD), soil organic carbon stocks (SOCD), and total carbon density (TCD), which was the sum of ACD and SOCD. We employed the random forest analysis method to identify significant variables influencing changes in carbon density. Structural equation modelling (SEM) was then used to determine the drivers of changes in forest carbon density. The results showed that moderate thinning (20 %-35 % trees removed), is an effective management practice for increasing the TCD in forests. Although heavy thinning (35.1 %-59.9 % trees removed) accelerated individual growth, it did not fully offset the carbon removed due to thinning. It is noteworthy that light thinning (0-19.9 % trees removed) not only reduced the species richness but also caused a significant number of tree deaths. Large live trees were an important direct determining factor of ACD, but not the only one. In addition, thinning indirectly influenced ACD by reducing canopy density and deformed tree density. The increase in dead tree density had an adverse impact on SOCD, and this phenomenon increased with the passage of recovery time. Conversely, greater thinning intensity enhanced SOCD. Moreover, TCD was directly influenced by tree height, large live trees, and stand density. Furthermore, thinning altered the conifer ratio, thereby influencing tree growth and indirectly controlling the TCD. We believe that this knowledge will be highly beneficial for successful forest management and enhancing the carbon sequestration capacity of forest ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microbial carbon utilization efficiency (CUE) is a crucial indicator for evaluating the efficiency of soil carbon sequestration and transformation, which is applied to quantify the proportion of soil carbon extracted by microbes for anabolism (growth) and catabolism (respiration). Previous studies have shown that the degradation of Moso bamboo forests (Phyllostachys edulis) destroyed the aboveground bamboo structure, reduced vegetation carbon storage, and weakened ecosystem carbon sequestration capacity. Interestingly, soil organic carbon stocks are gradually increasing. However, the mechanism by which degradation-induced changes in soil and vegetation characteristics affect microbial CUE and drive soil carbon sequestration remains unclear. Here we selected four stands with the same origin but different degradation years (intensive management, CK; 2 years' degradation, DM1; 6 years' degradation, DM2; and 10 years' degradation, DM3) based on the local management profiles. The principle of space-for-time substitution was used to investigate the changes in microbial CUE along a degradation time and to further identify the controlling biotic and abiotic factors. Our finding showed that microbial CUE increased by 12.27 %, 31.01 %, and 55.95 %, respectively, compared with CK; whereas microbial biomass turnover time decreased from 23.99 ± 1.11 to 17.16 ± 1.20 days. Promoting microbial growth was the main pathway to enhance microbial CUE. Massive inputs of vegetative carbon replenished soil carbon substrate content, and altered microbial communities and life history strategy, which in turn promoted microbial growth and increased microbial CUE. These findings provide theoretical support for the interactions between carbon dynamics and microbial physiology in degraded bamboo forests, and reinforce the importance of vegetation and microbial properties and soil carbon substrates in predicting microbial CUE., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024. Published by Elsevier B.V.)

Soil organic matter has been well acknowledged as a natural solution to mitigate climate change and to maintain agricultural productivity. Microbial necromass is an important contributor to soil organic carbon (SOC) storage, and serves as a resource pool for microbial utilization. The trade-off between microbial births/deaths and resource acquisition might influence the fate of microbial necromass in the SOC pool, which remains poorly understood. We coupled soil microbial assembly with microbial necromass contribution to SOC on a long-term, no-till (NT) farm that received maize (Zea mays L.) stover mulching in amounts of 0 %, 33 %, 67 %, and 100 % for 8 y. We characterized soil microbial assembly using the Infer Community Assembly Mechanisms by Phylogenetic-bin-based null model (iCAMP), and microbial necromass using its biomarker amino sugars. We found that 100 % maize stover mulching (NT100) was associated with significantly lower amino sugars (66.4 mg g -1 SOC) than the other treatments (>70 mg g -1 SOC). Bacterial and fungal communities responded divergently to maize stover mulching: bacterial communities were positive for phylogenetic diversity, while fungal communities were positive for taxonomic richness. Soil bacterial communities influenced microbial necromass contribution to SOC through determinism on certain phylogenetic groups and bacterial bin composition, while fungal communities impacted SOC accumulation through taxonomic richness, which is enhanced by the positive contribution of dispersal limitation-dominated saprotrophic guilds. The prevalence of homogeneous selection and dispersal limitation on microbial cell wall-degrading bacteria, specifically Chitinophagaceae, along with increased soil fungal richness and interactions, might induce the decreased microbial necromass contribution to SOC under NT100. Our findings shed new light on the role of microbial assembly in shaping the dynamics of microbial necromass and SOC storage. This advances our understanding of the biological mechanisms that underpin microbial necromass associated with SOC storage, with implications for sustainable agriculture and mitigation of climate change., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In the face of 21st-century challenges driven by population growth and resource depletion, understanding the intricacies of climate change is crucial for environmental sustainability. This review systematically explores the interaction between rising atmospheric CO 2 concentrations and soil microbial populations, with possible feedback effects on climate change and terrestrial carbon (C) cycling through a meta-analytical approach. Furthermore, it investigates the enzymatic activities related to carbon acquisition, gene expression patterns governing carbon and nitrogen metabolism, and metagenomic and meta-transcriptomic dynamics in response to elevated CO 2 levels. The study reveals that elevated CO 2 levels substantially influence soil microbial communities, increasing microbial biomass C and respiration rate by 15 % and upregulating genes involved in carbon and nitrogen metabolism by 12 %. Despite a 14 % increase in C-acquiring enzyme activity, there is a 5 % decrease in N-acquiring enzyme activity, indicating complex microbial responses to CO 2 changes. Additionally, fungal marker ratios increase by 14 % compared to bacterial markers, indicating potential ecosystem changes. However, the current inadequacy of data on metagenomic and meta-transcriptomic processes underscores the need for further research. Understanding soil microbial feedback mechanisms is crucial for elucidating the role of rising CO 2 levels in carbon sequestration and climate regulation. Consequently, future research should prioritize a comprehensive elucidation of soil microbial carbon cycling, greenhouse gas emission dynamics, and their underlying drivers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microbial necromass carbon (MNC) contributes significantly to the formation of soil organic carbon (SOC). However, the microbial carbon sequestration effect of biochar is often underestimated and influenced by nutrient availability. The mechanisms associated with the formation and stabilization of MNC remain unclear, especially under the combined application of biochar and nitrogen (N) fertilizer. Thus, in a long-term field experiment (11 years) based on biochar application, we utilized bacterial 16S rRNA gene sequencing, fungal ITS amplicon sequencing, metagenomics, and microbial biomarkers to examine the interactions between MNC accumulation and microbial metabolic strategies under combined treatment with biochar and N fertilizer. We aimed to identify the critical microbial modules and species involved, and to analyze the sites where MNC was immobilized from various components. Biochar application increased the MNC content by 13.9 %. Among the MNC components, fungal necromass contributed more to MNC, but bacteria were more readily enriched after biochar application. The microbial life-history strategies that affected MNC formation under the application of various amounts biochar were linked to the N application level. Under N added at 226.5 kg ha -1 , communities such as Actinobacteria and Bacteroidetes with high-growth yield strategies were prevalent and contributed to MNC production. By contrast, under N added at 113.25 kg ha -1 with high biochar application, Proteobacteria with strong resource acquisition strategies were dominant and MNC accumulation was lower. The mineral-associated organic carbon pool was rapidly saturated with the addition of biochar, so the contribution of fungal necromass carbon may have been reduced by reutilization, thereby resulting in the more rapid preservation of bacterial necromass carbon in the particulate organic carbon pool. Overall, our findings indicate that microbial life history traits are crucial for linking microbial metabolic processes to the accumulation and stabilization of MNC, thereby highlighting the their importance for SOC accumulation in farmland soils, and the need to tailor appropriate biochar and N fertilizer application strategies for agricultural soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The Ulva prolifera bloom is considered one of the most serious ecological disasters in the Yellow Sea in the past decade, forming a carbon sink in its source area within a short period but becoming a carbon source at its destination. To explore the effects of different environmental changes on seawater dissolved carbon pools faced by living U. prolifera in its originating area, U. prolifera were cultured in three sets with different light intensity (54, 108, and 162 μmol m -2  s -1 ), temperature (12, 20, and 28 °C) and nitrate concentration gradients (25, 50, and 100 μmol L -1 ). The results showed that moderate light (108 μmol m -2  s -1 ), temperature (20 °C), and continuous addition of exogenous nitrate significantly enhanced the absorption of dissolved inorganic carbon (DIC) in seawater by U. prolifera and most promoted its growth. Under the most suitable environment, the changes in the seawater carbonate system were mainly dominated by biological production and denitrification, with less influence from aerobic respiration. Facing different environmental changes, U. prolifera continuously changed its carbon fixation mode according to tissue δ 13 C results, with the changes in the concentrations of various components of DIC in seawater, especially the fluctuation of HCO 3 - and CO 2 concentrations. Enhanced light intensity of 108 μmol m -2 could shift the carbon fixation pathway of U. prolifera towards the C -1 pathway compared to temperature and nitrate stimulation. Environmental conditions at the origin determined the amount of dissolved carbon fixed by U. prolifera. Therefore, more attention should be paid to the changes in marine environmental conditions at the origin of U. prolifera, providing a basis for scientific management of U. prolifera.4 pathway compared to temperature and nitrate stimulation. Environmental conditions at the origin determined the amount of dissolved carbon fixed by U. prolifera. Therefore, more attention should be paid to the changes in marine environmental conditions at the origin of U. prolifera, providing a basis for scientific management of U. prolifera., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Both natural revegetation and cropping have great impact on long-term soil carbon (C) sequestration, yet the differences in their underlying mechanisms remain unclear. In this study, we investigated trends in soil organic C (SOC) accumulation during natural revegetation (VR) and cropping processes over 24 years, and explored the contributions of microbial necromass and plant-derived C to SOC formation and their primary controls. Over the course of 24 years of land use/cover change (LUCC) from 1995, SOC content exhibited a more substantial increase in VR (0.31 g kg -1  a -1 ) than in cropland (0.14 g kg -1  a -1 ) during Stage II (>10 y after LUCC), and recalcitrant organic carbon explained more of the SOC variation than easily oxidizable carbon. The higher SOC content in VR was attributed to a greater contribution of plant-derived C (14-28 %) than that in cropland (3-11 %) to SOC and a consistently lower ratio of cinnamyl (C)- to vanillyl (V)-type phenols in VR across all the assessed years. Although there were higher proportion of microbial necromass of SOC (41-84 %) in cropland than in VR, the differences were not significant. The dominant bacterial phylum of Chloroflexi and soil nitrogen content were the primary biotic and abiotic factors regulating microbial-derived and plant-derived C in both cropland and VR. However, soil phosphorus content was the main factor in cropland, while climatic factors such as mean annual precipitation were more important in VR. These results provided evidence that long-term natural revegetation enhanced SOC sequestration by greater contribution of plant-derived C to SOC formation compared to cropping. These findings underscore the synergistic contribution of vegetation and microorganisms to long-term SOC sequestration, offering insights into the different mechanisms of carbon formation during VR and cropping processes, and providing support for optimizing land management to achieve global carbon neutrality goals., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hongling Qin reports financial support was provided by the National Ecosystem Science Data Center. Baoli Zhu reports financial support was provided by the National Key Research and Development Program of China. Baoli Zhu reports financial support was provided by Hunan Science Fund for Distinguished Young Scholars. Hongling Qin reports was provided by the Natural Science Foundation of Hunan. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Carbon storage and the aboveground biomass of farmland provide practical significance for understanding global changes and ensuring food production and quality. Based on soil carbon storage, aboveground biomass, climate, geochemistry, and other data from 19 farmland ecological stations in China, we analysed the distribution characteristics of farmland carbon storage in topsoil and aboveground biomass. We notably revealed the response direction and degree of climate and geochemical factors to farmland carbon storage in topsoil and aboveground biomass. The results indicated that the average carbon stocks of farmland in different regions ranged from 0.28 to 7.91 kg m -2 , the average fresh weight of the aboveground biomass (FAB) ranged from 1370.64 to 5997.28 g m -2 , and the average dry weight of the aboveground biomass (DAB) ranged from 119.95 to 852.35 g m -2 . The least angle regression (LARS) and the best subsection selection regression (BSS) showed that evapotranspiration and extreme low temperatures were significant climatic factors affecting carbon sequestration and aboveground biomass on long-time scales. The linear mixed-effects model (LMM) further showed that AN and AP had significant long-term effects on carbon sequestration and aboveground biomass (p < 0.05), with AN having the highest contribution to SOC %, FAB, and DAB. The structural equation model (SEM) showed that carbon sequestration and aboveground biomass in agricultural fields were significantly positively correlated (p < 0.05). Moreover, the climate had a less direct contribution to carbon sequestration and above-ground biomass compared to geochemistry (PC c  < 0.1G ), and its effect was more indirect. When the geochemical variables were removed, the correlation between climate and carbon and aboveground biomass variables decreased significantly. We conclude that it is possible that extremes climate and geochemistry control carbon sequestration and above-ground biomass in long-term cropland through interactions in the context of global change, which provides new insights into the evolution of soil organic carbon in long-term cropland and the scientific formulation of policies to increase food production and preserve quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Rhizodeposition encompasses the intricate processes through which plants generate organic compounds via photosynthesis, store these compounds within aboveground biomass and roots through top-down transport, and subsequently release this organic matter into the soil. Rhizodeposition represents one of the carbon (C) cycle in soils that can achieve long-term organic C sequestration. This function holds significant implications for mitigating the climate change that partly stems from the greenhouse effect associated with increased atmospheric carbon dioxide levels. Therefore, it is essential to further understand how the process of rhizodeposition allocates the photosynthetic C that plants create via photosynthesis. While many studies have explored the basic principles of rhizodeposition, along with the associated impact on soil C storage, there is a palpable absence of comprehensive reviews that summarize the various factors influencing this process. This paper compiles and analyzes the literature on plant rhizodeposition to describe how rhizodeposition influences soil C storage. Moreover, the review summarizes the impacts of soil physicochemical, microbial, and environmental characteristics on plant rhizodeposition and priming effects, and concludes with recommendations for future research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Rice-crayfish farming systems (RCs) can help mitigate climate change by enhancing soil organic carbon (SOC) sequestration. However, the mechanisms that govern the responses of microbial residues carbon (MRC), a key component of SOC, in RCs are not fully understood. We conducted a 6-year field experiment comparing RCs and rice monoculture systems (RMs). Specifically, we explored how MRC formation and stabilization differ between the two systems and how those differences are linked to changes in the metabolic processes of microbes. Results showed that MRC levels in RCs were 5.2 % and 40.0 % higher in the topsoil and subsoil, respectively, compared to RMs, indicating depth-dependent effects. Notably, MRC accumulation and stabilization in RCs were promoted through a cascade of processes of dissolved organic carbon (DOC) accessibility-microbial metabolism-mineral protection. In addition, the mechanism of MRC accumulation in subsoil differed between the two systems. Specifically, RMs improved accessibility of DOC by reducing humification and aromaticity of subsoil DOC, which helped microbes access to resources at lower cost. This decreased the respiration rate of microbes, thereby increasing microbial carbon pump (MCP) efficiency and thus promoting MRC accumulation. By contrast, the crayfish in RCs facilitated carbon exchange between topsoil and subsoil through their burrowing behaviors. This increased carbon allocation for microbial metabolism in the subsoil, supporting a larger microbial population and thus enhancing the MCP capacity, while reducing MRC re-decomposition via enhanced mineral protection, further increasing subsoil MRC accumulation. That is, MRC accumulation in the subsoil of RCs was predominantly driven by microbial population numbers (MCP capacity) whereas that of RMs was mostly driven by microbial anabolic efficacy (MCP efficiency). Our findings reveal a key mechanism by which RCs promoted soil MRC accumulation and stabilization, highlighting the potential role of DOC accessibility-microbial metabolism-mineral protection pathway in regulating MRC accumulation and stabilization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Uncertainty in the global carbon (C) budget has been reduced for most stocks, though it remains incomplete by not considering aquatic and transitional zone carbon stocks. A key issue preventing such complete accounting is a lack of available C data within these aquatic and aquatic-terrestrial transitional ecosystems. Concurrently, quantifiable results produced by restoration practices that explicitly target C stock accumulation and sequestration remain inconsistent or undocumented. To support a more complete carbon budget and identify impacts on C stock accumulation from restoration treatment actions, we investigated C stock values in a Mediterranean-montane riparian floodplain system in California, USA. We quantified the C stock in aboveground biomass, large wood, and litter in addition to the C and total nitrogen in the upper soil profile (5 cm) across 23 unique restoration treatments and remnant old-growth forests. Treatments span 40 years of restoration actions along seven river kilometers of the Cosumnes River, and include process-based (limited intervention), assisted (horticultural planting and other intensive restoration activities), hybrid (a combination of process and assisted actions), and remnant (old-growth forests that were not created with restoration actions) sites. Total C values measured up to 1100 Mg ha -1 and averaged 129 Mg ha -1 with biomass contributing the most to individual plot measurements. From 2012 to 2020, biomass C stock measurements showed an average 32 Mg ha -1 increase across all treatments, though treatment specific values varied. While remnant forest plots held the highest average C values across all stocks (336 Mg ha -1 ), C values of different stocks varied across treatment type. Process-based restoration treatments held more average biomass C (120 Mg ha -1 ) than hybrid (23 Mg ha -1 ) or assisted restoration treatments (50 Mg ha -1 ), while assisted restoration treatments held more average total C in soil and litter (58 Mg ha -1 ) than hybrid (35 Mg ha -1 ) and process-based restoration treatments (37 Mg ha -1 ). Regardless of treatment type, time was a significant factor for all C stock values. These findings support a more inclusive global carbon budget and provide valuable insight into restoration treatment actions that support C stock accumulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The increase in climate-related extreme events and ecosystem degradation demands consistent and sustainable climate mitigation efforts. Seagrass playing a key role in nature-based carbon sequestration mitigation strategy. Here, we investigated the role of coral reef connectivity in blue carbon dynamics with seagrass meadows with coral reef connectivity (SC areas) and without coral reef connectivity (SG areas) in Palk Bay, India. The high sediment organic carbon was recorded in SC areas (90.26 ± 25.68 Mg org.C/ha) and lower in SG areas (66.96 ± 12.6 Mg org.C/ha). The maximum above-ground biomass (AGB) was recorded in Syringodium isoetifolium (35.43 ± 8.50) in SC areas and the minimum in Halophila ovalis (7.59 ± 0.90) in SG areas, with a similar trend observed in below-ground biomass (BGB). Our findings highlight the importance of coral reefs in enhancing the blue carbon potential of seagrass ecosystems and underscore the need for integrated conservation and restoration strategies for coral reefs and seagrasses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Composting is one of the primary methods for organic waste recycling in China. This study aims to analyze the product quality of organic fertilizer enterprises from the perspective of actual production and the relationship between production process variations and organic matter content in organic fertilizers based on 348 samples from 229 organic fertilizer companies across 22 provinces. Results showed that fertilizers produced through composting processes contain higher organic matter, averaging 45.42 %, compared to commercial organic fertilizers and bio-organic fertilizers. Raw materials, equipment, methods, operational scale, and personnel structure are key factors affecting the content of organic matter in products. Optimizing equipment and processes in Chinese organic fertilizer companies could increase organic matter content to 49.3 %, potentially reducing annual carbon emissions by an estimated 3.07 to 6.97 billion kg of CO 2 equivalent, thereby supporting the realization of dual carbon goals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Shanghai's extensive coastline and offshore marine areas feature diverse ecosystems. This study aimed to determine the current status, spatial distribution, and total capacity of marine carbon storage in Shanghai. Surveys were conducted on oyster reefs, phytoplankton, and fish populations from August to November 2022, with samples collected to quantify biomass and carbon content. The carbon storage of oyster reefs, phytoplankton, and fish was found to be 2.045 × 10 5 tC, 5113.19 kgC, and 56.6014 tC, respectively. The spatial distributions exhibited significant heterogeneity, influenced by substrate type, nutrient concentrations, and fishing activities. The total marine carbon storage capacity in Shanghai's offshore waters was estimated at 2.045 × 10 5 tC, highlighting a pathway for achieving regional carbon neutrality goals. This study enriches baseline data, elucidates carbon sequestration functions and spatial patterns, and provides scientific support for marine ecological protection and blue carbon resource utilization. Future research should investigate spatiotemporal variation mechanisms and potential regulation pathways., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Spartina alterniflora has rapidly and extensively encroached on China's coastline over the past decades. Among the coastal areas invaded by S. alterniflora, at most 93% are mudflats. However, the effect of S. alterniflora invasion on soil organic carbon (SOC) stocks of coastal mudflats has not been systematically studied on a national scale. Here, we quantified the nationwide changes in SOC stocks in coastal mudflats associated with S. alterniflora invasion between 1990 and 2020. We found that S. alterniflora invasion significantly enhanced SOC stocks in coastal China. Nonetheless, the benefit of S. alterniflora invasion of coastal SOC stock may be weakened by continuing human intervention. We found that S. alterniflora invading mudflats added 2.3 Tg SOC stocks to China's coastal blue carbon, while 1.78 Tg SOC stocks were lost mainly due to human activities, resulted in a net SOC stock gain of 0.52 Tg C. These findings overturned the traditionally thought that S. alterniflora invasion would reduce ecosystem services by highlighting that the historical invasion of S. alterniflora has broadly and consistently enhanced blue carbon stock in coastal China., (Copyright © 2024 Science China Press. Published by Elsevier B.V. All rights reserved.)