Enhance Carbon Storage Research Articles

Factors driving carbon accumulation in forest biomass and soil organic carbon across natural forests and planted forests in China

IntroductionForests play a pivotal role within the global carbon cycle. However, how to enhance carbon storage in existing forests remains unclear.MethodsIn this study, we conduct a comprehensive analysis of data from 2,948 forest sites across China. Utilizing structural equation modeling (SEM), we investigate the intricate relationship between climate, tree species diversity, stand structure, function traits, initial biomass carbon stocks (BCi), soil organic carbon stocks (Soil C content), and carbon accumulation in biomass (ΔBC) and soil organic carbon stocks (ΔSOC) within both natural forests (NF, n = 1,910) and planted forests (PF, n = 1,038).ResultsOur findings underscore the critical influence of tree species diversity and stand structure drivers of both direct and indirect carbon accumulation, with distinct drivers emerging based on the carbon pools in NF and PF. Specifically, increasing tree species diversity from its minimum to maximum value through management-results in a 14.798 tC/ha reduction in BC and 0.686 tC/ha in SOC in NF. Conversely, amplifies BC and SOC in PF by 0.338 tC/ha and 0.065 tC/ha, respectively. Enhancing stand structure-such as stand density-results in a 231.727 tC/ha reduction in BC and SOC in NF, and a 10.668 tC/ha in BC and 64.008 tC/ha increment in SOC in PF.DiscussionOverall, our results indicate that higher tree species diversity, stand density and age-group limits further carbon accumulation in BC and SOC in current NF. In contrast, low tree species diversity and stand density limits the development of carbon storage potential in planted forests. To enhance carbon sequestration capacity, China should change its current policy of completely banning logging of natural forests. Natural forests need thinning and reduced tree species diversity, while planted forests should increase tree species diversity and stand density.

Enhancing land cover and carbon storage through rehabilitation of degraded lands into Wono: a case study of a small-scale private forest in Dengok Village, Gunungkidul, Yogyakarta, Indonesia (1972-2021)

The implementation of degraded land rehabilitation programs and community-based forest management certification is widely recognised to enhance the status of wono land cover and aid in climate change mitigation. The expansion of the restoration efforts can be monitored using satellite images to track the progress of operations by observing changes in land cover area. Community forest certification also can enhance the success of land restoration endeavours. Therefore, this study aimed to show the change in forest land cover and the amount of carbon stored from 1972 to 2021. Landsat imagery was used to depict land cover conditions in 1972, 1982, 1993, 2000, 2008, 2014, and 2021, before and after the implementation of restoration and community forest certification programs. The Normalized Difference Vegetation Index approach was employed for satellite images captured in 1972 and 1982, while the Forest Canopy Density method was employed for images in 1993, 2000, 2008, 2014, and 2021, to illustrate the progressive increase in wono land cover. Meanwhile, carbon storage was analysed from 1972 to 2021 using national carbon storage conversion. The results indicated that restoration activity and the establishment of community forest certification increased wono area and carbon storage, which totalled 55.90 ha and 5,499.04 t C between 1972 and 2021. Augmenting carbon storage within wono land cover constituted an effective strategy for mitigating climate change.

Engineered Materials, Machine Learning Enhance Carbon Storage Well Integrity

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214844, “Engineered Materials and Machine Learning for Carbon Storage Well Integrity,” by Jacob Pollock, Oceanit Laboratories, and Hani Elshahawi, SPE, NoviDigiTech. The paper has not been peer reviewed. _ The success of CO2 injection operations, and the endurance of long-term storage, are partially dependent on well design and the materials used for well construction. The authors describe a stack of technologies they have developed that enable enhanced well robustness, monitoring of carbon-storage facilities, and modeling of their performance. The combination of these technologies enables the tracking of downhole and subsurface fluid distribution and flow. Furthermore, the scalable technologies can be used to exploit remaining reservoirs while preventing CO2-plume migration. Introduction Besides site selection and geological features that influence plume migration, well-construction design and materials have a major effect on successful storage. Injection wells are drilled into the storage site and completed with multiple cemented casing strings, with access to the reservoir through perforations or gravel packs. Cement supports and protects the metal casings from corrosive fluids while isolating the storage reservoir from freshwater aquifers by sealing off the wellbore annulus (Fig. 1). Cement integrity and durability are critical to successful carbon capture, storage, and use (CCUS) operations. Despite their importance, current cement-evaluation methods suffer from limited resolution, poor discrimination, and ambiguous interpretation. The authors have developed steel/cement interfacial bonding nanotechnology that enhances both mechanical bonding and acoustic coupling, along with acoustic metamaterials for sensing cement and tracking particles. The acoustic band gap of the materials was demonstrated to improve acoustic contrast and provide information about the cement environment based on frequency and amplitude. Furthermore, data-processing and machine-learning methods have been developed to interpret subsurface readings with more accuracy and deeper insight. Neural networks can be used to interpret the results of smart material detection and sensing, providing new information that was previously unattainable. Engineered Materials for Well Construction New classes of construction components with enhanced properties may be self-healing or passively sensing or may have outstanding physical properties such as mechanical strength. Nanoscale treatments can alter the surface characteristics of materials, endowing them with engineered interfacial behavior. Passive-sensing materials can alter incoming energy waves that can be detected to discern information about material condition and environment. These technologies can improve the properties of well-construction materials for carbon storage, increasing integrity and allowing monitoring of well and reservoir states. The results of successful laboratory and field trials of each technology described in this section are provided in the complete paper.

Stand spatial structure is more important than species diversity in enhancing the carbon sink of fragile natural secondary forest

Increasing attention for adjusting forest structural and species diversity has been paid to enhance carbon storage. However, the relative importance of stand spatial structural diversity and species diversity to restored stand carbon stocks remains unclear. To address this issue, we conducted a sample plot setup in the Loess Plateau with the aim of exploring the effects of stand spatial structural diversity and species diversity on forest carbon stocks. Therefore, we determined index parameters for species diversity (Simpson, Shannon-Wiener, and Pielou) and spatial structural diversity (Angular scale, Mingling, Aggregation, and Competition) within the oak forest ecosystem. We examined carbon storage in all vegetation organs and different soil layers. Additionally, we employed a structural equation model to develop a model that illustrates the effects of stand spatial structure and species diversity on ecosystem carbon storage. The results reveal that stand spatial structure and species diversity influence the ecosystem carbon storage through biomass (trees and litter) and soil carbon (0–100 cm). Stand spatial structure exhibits positive direct effects (path coefficients: 0.764 and 0.890), while species diversity shows negative direct effects (−0.320 and −0.206) on biomass and soil carbon, respectively. Finally, the total effect of spatial structure diversity on forest carbon storage surpasses that of species diversity. Therefore, stand spatial structure should be adjusted preferentially during forest management in fragile ecological environment. Our results provide important insights into the climate change mitigation potential associated with the structure-based management of forests.

Intercropping in rainfed Mediterranean olive groves contributes to improving soil quality and soil organic carbon storage

Given the current degradation problems that Mediterranean soils endure, the implementation of alley cropping in olive orchards has been suggested as a sustainable strategy to increase agricultural productivity and improve carbon storage and soil fertility. Therefore, the objective of this study was to evaluate in the short term (3 years) the effect of alley cropping with minimum tillage versus conventional tillage in a traditional rainfed olive grove on soil organic carbon, total nitrogen concentrations, and stocks. Changes in soil quality through a stratification index, and the success of the 4‰ strategy in these soils with this type of management were also evaluated. Three intercropping strategies were tested: Crocus sativus (D-S), Vicia sativa and Avena sativa in rotation (D-O), and Lavandula x intermedia (D-L), all with minimum tillage versus olive with conventional tillage without intercropping, which was used as a control. Intercropping increased soil organic carbon in topsoil (0–10 cm) by 41.1, 28.5, and 30.5% for D-S, D-O, and D-L, respectively, compared to conventional tillage. At a depth of 10–30 cm, the soil organic carbon and the soil organic carbon stock increased slightly, although significant differences were found only in D-L. In the diversified plots, total nitrogen did not vary. However, total nitrogen increased in olive with conventional tillage due to fertilisation. Concerning soil quality, no significant differences were observed when evaluating the soil carbon and nitrogen stratification index in any of the treatments. However, the implementation of intercropping reached the objectives set by the 4‰ initiative in these soils with an increase in soil carbon per hectare and per year of 80, 87.4, and 86.4% for D-S, D-O, and D-L, respectively. Therefore, based on these results, in the short term, intercropping treatment enhances carbon storage in these soils, effectively achieving the objectives of the 4‰ initiative.

Enhancing Carbon Capture and Storage Deployment in the EU: A Sectoral Analysis of a Ton-Based Incentive Strategy

The EU considers carbon capture and storage (CCS) technology as an option for achieving climate goals, but its cost remains appreciable. Therefore, the purpose of this research was to investigate the implementation of a ton-based incentive system for CCS in the EU using Croatia as an example based on an analysis of the existing legislative framework in the EU and relevant tax credit provisions in the USA. A novel methodology for the design of the incentive system is presented in the form of partial allocation of the state’s auction revenues from the EU emissions trading system (ETS) into the CCS fund for five years. The CCS fund assets then incentivize the capture site for 10 years. The incentives are determined for each emitter in cement, electricity, paper and pulp, glass, oil refining, and petrochemical sectors based on varying European Union allowance (EUA) prices, CCS fund sizes, and CO2 emission scenarios. In addition to designing the methodology, a novel method for forecasting CO2 emissions is applied using geometric Brownian motion. The calculated incentives are categorized as underperforming, optimal, or overperforming, with upper and lower limits set to 80 and 10 EUR/t. The results are optimistic, since all sectors can be efficiently incentivized within the defined boundaries, meaning that the incentive system can be applied to all member states. The contracting of the incentives is proposed through carbon contracts for difference to avoid irregularities. Also, regulatory amendments are proposed so that emitters with emissions higher than 100 kt would have to consider CCS. Finally, the contributions are presented by proving the feasibility of the incentive system together with demonstrating its applicability to all member states.

The Changes in Cropland Pattern Enhanced Carbon Storage in Northwest China

Northwest China has experienced dramatic changes in agricultural land area in recent years. The effects of these changes on carbon storage are unknown, and this ambiguity hinders land development policies related to carbon emissions. In this study, we evaluated the effects of annual cropland changes (expansion and abandonment) during 2000 to 2020 on carbon storage in Northwest China by using land use data, carbon density data, and statistical yearbooks using the Intergovernmental Panel on Climate Change (IPCC) method. The results indicated that the area of cropland increased by 1.47 × 106 ha from 2000 to 2020, in that the area of cropland expansion and abandonment are 3.58 × 106 and −2.11 × 106 ha, respectively. Cropland expansion was mainly from other land and grassland, and the conversion of cropland to grassland made up the largest proportion of cropland abandonment, followed by built-up land. The cropland changes resulted in a total carbon sequestration of 4.05 Tg (0.20 Tg C year−1), including a 17.66 Tg decrease and 21.71 Tg increase in carbon storage due to, respectively, cropland expansion and cropland abandonment, in which the conversion of forest to cropland (−8.60 Tg) and cropland to forest (11.16 Tg) were the main causes of the increase and decrease in carbon storage. Specifically, regional carbon storage due to cropland changes exhibited an increasing variation characteristic during 2000 to 2007, a gradually decreasing variation characteristics during 2007 to 2014, and fluctuated stabilization since then (during 2014 to 2020). In addition, the highest carbon emission was found in Xinjiang (−3.68 Tg), followed by Ningxia (−0.21 Tg) province, while Shanxi (3.44 Tg), Gansu (3.17 Tg) and Qinhai (1.33 Tg) had carbon accumulation. Overall, cropland changes acted as a carbon sink in Northwest China from 2000 to 2020. We suggest that the development of high-carbon-density lands or the conversion of low-carbon-density lands are critical to increasing future carbon sequestration due to cropland change.

The effect of mixed forest identity on soil carbon stocks in Pinus massoniana mixed forests

Increased productivity generally promotes the accumulation of soil organic carbon (SOC) stocks. The productivity of mixed forests is mainly influenced by plant species richness (PSR), mixed forest age (MFA), and mixed species proportion (MSP). However, the influence of PSR, MFA, and MSP on SOC stocks along the soil profiles in Pinus massoniana mixed forests remains to be determined. We conducted a meta-analysis employing paired observations of SOC stocks from 1010 paired mixed and pure stands of P. massoniana from 110 publications. The findings revealed that SOC stocks were highly dependent on MFA and increased with increasing MFA in various soil layers, rather than the expected influence of PSR. MFA contributed 48.97 %, 83.20 %, and 38.41 % to the increased SOC stocks in the topsoil, midsoil, and subsoil, respectively. Furthermore, MSP also significantly affected the increase in SOC stock in the topsoil and midsoil when 40 % < MSP ≤ 60 %. Over the next 60 years, subsoil SOC accumulation will be limited by increased PSR and MSP in mixed forests. Mixing between P. massoniana and broadleaf tree species (especially Schima superba and Lespedeza bicolor) significantly enhanced SOC stocks along the soil profiles. SOC stocks along the soil profiles decreased with increasing dominant mixed tree species richness (e.g., broadleaf, deciduous broadleaf, arbuscular mycorrhizal, and the sum of conifer and broadleaf trees). Incorporating lower PSR (e.g., 2 ≤ N ≤ 10) and dominant mixed tree species richness (e.g., N = 2) practices may be optimization options for increasing SOC stocks. Overall, based on the expected goals, including optimizing productivity, enhancing carbon storage, mitigating climate change, and promoting biodiversity conservation, we emphasize the importance of incorporating MFA, MSP, tree species identity, and subsoil into forest management.

Study on the impact of vegetation change on ecosystem services in the Loess Plateau, China

Vegetation change has a non-negligible role in the impact of ecosystem services (ESs). Quantitative assessment of vegetation ecosystem services is the basis for sustainable regional development. Using the Chinese Loess Plateau (LP) as the study area, this study firstly analysed the spatial and temporal characteristics of vegetation change and used a Geodetector model to reveal the driving mechanism. Next, this study applied the InVEST model to quantitatively assess the four services of carbon storage, habitat quality, soil conservation and water yield, and explored the vegetation ecosystem service balance through vegetation type transfer. The results showed that (1) there was a trend towards an increase in the area of all vegetation types, with sparse vegetation being the most pronounced. Areas of damaged vegetation were concentrated in urban and peripheral areas, as well as wasteland and bare ground. (2) Annual precipitation, soil types and cumulative afforestation area ratio were the main drivers of vegetation change on the LP. (3) Restoration of woodland enhanced carbon storage, habitat quality and soil retention services for vegetation on the LP, while water yield decreased by 31.66%. The restoration of vegetation area did not enhance all ecosystem services. This study may provide a reference and basis for the sustainable management of regional ecosystems.

Using the InVEST-PLUS Model to Predict and Analyze the Pattern of Ecosystem Carbon storage in Liaoning Province, China

Studying the spatiotemporal distribution pattern of carbon storage, balancing land development and utilization with ecological protection, and promoting urban low-carbon sustainable development are important topics under China’s “dual carbon strategy” (Carbon emissions stabilize and harmonize with natural carbon absorption). However, existing research has paid little attention to the impact of land use changes under different spatial policies on the provincial-scale ecosystem carbon storage. In this study, we established a carbon density database for Liaoning Province and obtained the spatial and temporal distribution of carbon storage over the past 20 years. Then, based on 16 driving factors and multiple spatial policies in Liaoning Province, we predicted land use and land cover changes (LUCC) under three scenarios for 2050 and analyzed the spatiotemporal distribution characteristics and response mechanisms of carbon storage under different scenarios. The results showed that (1) LUCC directly affected carbon storage, with a 35.61% increase in construction land and a decrease in carbon storage of 0.51 Tg over the 20-year period. (2) From 2020 to 2050, the carbon storage varied significantly among the natural trend scenario (NTS), ecological restoration scenario (ERS), and economic priority scenario (EPS), with values of 2112.05 Tg, 2164.40 Tg, and 2105.90 Tg, respectively. Carbon storage in the ecological restoration scenario exhibited positive growth, mainly due to a substantial increase in forest area. (3) The spatial pattern of carbon storage in Liaoning Province was characterized by “low in the center, high in the east, and balanced in the west”. Therefore, Liaoning Province can consider rationally formulating and strictly implementing the spatial policy of ecological protection in the future land planning so as to control the disorderly growth of construction land, realize the growth of ecological land area, effectively enhance carbon storage, and ensure the realization of the goal of “dual carbon strategy”.

Storing Carbon in Forest Biomass and Wood Products in Poland—Energy and Climate Perspective

Huge amounts of carbon being sequestered in forest ecosystems make them an important land carbon sink at the global scale. Their ability to withdraw carbon dioxide (CO2) from the atmosphere, whose concentration is gradually increasing due to anthropogenic emissions, renders them important natural climate-mitigation solutions. The urgent need for transition from high to zero net emission on country, continental, and global scales, to slow down the warming to an acceptable level, calls for the analysis of different economic sectors’ roles in reaching that ambitious goal. Here, we examine changes in CO2 emission and sequestration rates during recent decades focusing on the coal-dominated energy sector and Land Use, Land-Use Change, and Forestry (LULUCF) as well as wood production at the country level. The main purpose of the presented study is to examine the potential of storing carbon in standing forest biomass and wood products in Poland as well as the impact of disturbances. The ratio of LULUCF absorption of CO2 to its emission in Poland has ranged from about 1% in 1992 to over 15% in 2005. From a climate-change mitigation point of view, the main challenge is how to maximize the rate and the duration of CO2 withdrawal from the atmosphere by its storage in forest biomass and wood products. Enhancing carbon sequestration and storage in forest biomass, via sustainable and smart forestry, is considered to be a nature-based climate solution. However, not only forests but also wood-processing industries should be included as important contributors to climate-change mitigation, since harvested wood products substitute materials like concrete, metal, and plastic, which have a higher carbon footprint. The energy perspective of the paper embraces two aspects. First, CO2 sequestration in forests and subsequently in harvested wood products, is an effective strategy to offset a part of national CO2 emissions, resulting largely from fossil fuel burning for energy-production purposes. Second, wood as biomass is a renewable energy source itself, which played an important role in sustaining energy security for many individual citizens of Poland during the unusual conditions of winter 2022/2023, with a scarce coal supply.

Enhanced carbon storage in semi-arid soils through termite activity

Termites are keystone species in natural ecosystems and their role in the C cycle is potentially substantial but poorly understood. Large (20–40 m) mounds (heuweltjies) of the harvester termite Microhodotermes viator occupy up to a quarter of the semi-arid west coast region of South Africa but their C storage potential is unknown. This study determined the organic and inorganic C fractions, C stocks, and their correlation with each other, depth, and biogenic features in these mounds. Trenches (30–60 m) were excavated through 3 mounds: Buffels River (m.a.p < 100 mm), Klawer (m.a.p 100–200 mm) and Piketberg (m.a.p 300–400 mm) and grid sampled. Mound soils had significantly higher soil organic carbon (SOC) and inorganic carbon (SIC) than surrounding soils. Total C was strongly correlated (ρ > 0.9; p < 0.001) with SIC in the arid mounds and SOC (ρ > 0.75; p < 0.001) in the higher rainfall mound. There was no consistent relationship between SOC and SIC distributions throughout the mounds, which is likely related to solubility-linked translocations of carbonates. For all mounds, SOC was highest in topsoils with a second clear peak in subsoils (>1 m) that was associated with biogenic features, termite channels and burrows. Subsoils contributed substantially (36–41 %) to the total C stock. Total C stocks for the intermediate rainfall mound (Klawer) were estimated at 14.6 tons per mound, with 1.1 tons SOC. In this region, mounds occupy 27 % of the total area but contribute 44 % of the total SOC stock to a depth of 80 cm. This highlights the disproportionate contribution termite mounds make to carbon stocks of these semi-arid environments and demonstrates the importance of deep (<1 m) soil carbon for C modelling. Termite activity needs to be recognized as a major contributor to C stock variability both laterally and at depth and accounted for in land-use change (CO2-LULUCF) models.

Can we manage microbial systems to enhance carbon storage?

Climate change is an urgent environmental issue with wide-ranging impacts on ecosystems and society. Microbes are instrumental in maintaining the balance between carbon (C) accumulation and loss in the biosphere, actively regulating greenhouse gas fluxes from vast reservoirs of organic C stored in soils, sediments and oceans. Heterotrophic microbes exhibit varying capacities to access, degrade and metabolise organic C-leading to variations in remineralisation and turnover rates. The present challenge lies in effectively translating this accumulated knowledge into strategies that effectively steer the fate of organic C towards prolonged sequestration. In this article, we discuss three ecological scenarios that offer potential avenues for shaping C turnover rates in the environment. Specifically, we explore the promotion of slow-cycling microbial byproducts, the facilitation of higher carbon use efficiency, and the influence of biotic interactions. The ability to harness and control these processes relies on the integration of ecological principles and management practices, combined with advances in economically viable technologies to effectively manage microbial systems in the environment.

Effects of Biochar and Organic Additives on CO2 Emissions and the Microbial Community at Two Water Saturations in Saline–Alkaline Soil

The nutrient-limiting conditions in saline–alkali soil as well as the salinity and alkalinity stress are successfully alleviated by water management measures and the addition of organic matter. However, the impacts of these two strategies on the microbe-driven CO2 emissions in saline–alkaline soils are not yet clear. Therefore, a 150-day incubation experiment was conducted in this study to evaluate the short-term effects of water regulation and the addition of organic matter with different characteristics on CO2 emissions and microbial community characteristics in saline–alkali soils under non-flooding conditions. This study was conducted at two water saturations, i.e., 50% WFPS and 80% WFPS. In addition, five organic matter treatments were conducted: CK: control; N: urea; SN: Straw + urea; SNH: Straw + urea + microbial agent; and SNB: Straw + urea + biochar. The results demonstrated that compared with 50% WFPS, 80% WFPS significantly increased cumulative CO2 emission by 27.66%, but significantly decreased salt content and the fungal Chao1 and Shannon indices. The application of the biochar and microbial agent decreased the cumulative CO2 emissions of the SN treatment by 27.39% and 14.92%, respectively. When sufficient carbon supply is available, the decrease in fungal diversity may reduce CO2 emission. The findings demonstrated that SNH and SNB at 80% WFPS might decrease CO2 emissions under straw carbon intake as well as the loss of labile organic carbon (LOC). Additionally, these treatments can alleviate microbial stress caused by salinity, which has a favorable impact on enhancing carbon storage in salinity-affected dryland soils.

A new framework for identifying ecological conservation and restoration areas to enhance carbon storage

Limited attention has been given to improving carbon storage by identifying ecological conservation and restoration areas (ECRAs). In this research, we proposed a new framework for identifying ECRAs by incorporating future carbon storage changes into ecological security patterns (ESPs), including several models of the Patch-generating Land Use Simulation (PLUS), Integrated Valuation of Ecosystem Service and Tradeoffs (InVEST), Minimum Cumulative Resistance (MCR) and circuit theory. This new framework was applied in Jiangsu Yangtze River Economic Belt, East China. To evaluate the effectiveness of this new framework, we compared two scenarios: an ecological priority scenario (EPS) where future carbon storage change was not considered and an ecosystem carbon sequestration scenario (ECSS) where future carbon storage change was explicitly incorporated. Under the EPS, ecological conservation areas and ecological restoration areas were 11169.87 km2 and 221.11 km2, respectively. Under the ECSS, the ecological conservation areas and ecological restoration areas were 14768.76 km2 and 244.89 km2, respectively. Carbon storage will be most likely to increase around lakes and the Yangtze River, and the identified key areas under the ECSS will be more adaptable to future environmental changes than the EPS. This new framework can effectively enhance both ecological function and carbon sequestration, providing effective support for policymakers in landscape management and low-carbon development in other regions facing similar challenges. In the meantime, more caution is needed for the possible limitations, such as without adequate consideration of uncertainties of changes in population, land use, and economy in the future.

Climate and vegetation codetermine the increased carbon burial rates in Tibetan Plateau lakes during the Holocene

The Tibetan Plateau (TP), also known as the “Asian Water Tower,” includes thousands of lakes containing sizable lacustrine sediments that have been proven to be important carbon pools of inland ecosystems. To develop an in-depth understanding of the status of TP lake carbon storage and its response to global changes and human activities, we accurately quantified the change trend of long-term organic carbon burial in lakes over the TP, compared levels of differentiation within the TP, and explored related driving factors of the carbon accumulation rates (CARs) by compiling 24 lake sediment cores. The results show that the lake CAR over the TP presented a rising trend during the Holocene, with an average of 6.50 g C m−2 yr−1 and levels ranging from 1.75 to 18.41 g C m−2 yr−1. The eastern TP (ETP), with warmer and wetter climate conditions and more vegetation coverage, had almost twice the CAR as that of the central and western TP (CWTP). We demonstrate that climate and vegetation could be the main drivers of the lake CAR on the TP despite environmental heterogeneity contributing to subregional discrepancies. During the early Holocene, superior summer temperatures and precipitation favored vegetation development, providing abundant material for lake carbon deposition. In the middle Holocene, together with vigorous vegetation, decreasing summer temperatures led to a decline in mineralization, which enhanced carbon storage efficiency and resulted in an increase in the CAR across the ETP. In contrast, for the CWTP, herbaceous-dominated vegetation continued to expand during the early-mid Holocene, which constrained detritus supply, thus maintaining a relatively stable CAR. However, intensive human activities could be responsible for the CAR peak in the late Holocene on the TP, especially since 2000 cal yr BP. In addition to the anthropogenic impacts, variations in CAR among lakes resulting from local factors lead to large uncertainties in future C predictions for the whole region of TP.

Opportunities for blue carbon restoration projects in degraded agricultural land of the coastal zone in Queensland, Australia

Restoring degraded agricultural lands to their original coastal wetland cover is an approach for enhancing blue carbon storage. This approach enhances carbon sequestration in biomass and soils whilst reducing greenhouse gas emissions and delivering other conservation benefits such as enhancing biodiversity, improving water quality, and protecting coastlines from sea level rise. In Queensland, Australia, tens of thousands of hectares of coastal land have been converted to agriculture since the 1900s, often through drainage. We evaluated the characteristics of degraded agricultural land to identify opportunities for blue carbon restoration projects. Degraded agricultural land was identified through visual inspection of satellite imagery. Our analysis revealed degradation was associated with historical Melaleuca-dominated wetland vegetation and current land uses other than intensive agriculture. Field sampling of a subset of paired degraded and non-degraded sites found that water content, organic carbon, and electrical conductivity were significantly higher at degraded sites. We also observed standing water, drainage structures, and dead trees at degraded sites. From our analyses, we inferred land degradation is likely caused by waterlogging, salinisation, and land management choices. Degraded land historically vegetated by Melaleuca-dominated wetlands could be targeted for blue carbon restoration projects that protect remaining soil carbon and enhance carbon storage, restore ecosystem services, and provide new income streams for landowners. Further characterisation of the distribution of degraded lands may contribute to prioritisation of sites suitable for restoration.

Enhanced Carbon Storage Process from Flue Gas Streams Using Rice Husk Silica Nanoparticles: An Approach in Shallow Coal Bed Methane Reservoirs

Carbon capture and storage (CCS) is considered a key process to reach net-zero emission by the 2050 aim of limiting global warming. Coal bed methane (CBM) is considered potential geological reservoirs for underground CCS due to the CO2–CH4 exchange feasibility by adsorptive phenomena. Global implementation has been focused only on deep reservoirs to provide methane recovery. Thus, this work proposes a modified CCS process based on silica nanoparticle inclusion for shallow CBM reservoirs (<300 m). The nanomaterials were evaluated at high pressure in two main stages including i) CO2 sorption on a single CO2 stream and ii) CO2 selectivity on a flue gas stream (N2–CO2 mixture). This work includes silica nanomaterial synthesized from rice husk as agro-waste sources with better technical-economic feasibility framed in a circular economy to reduce costs and maximize the use of available resources. Rice husk silica (RSi) nanoparticles were doped with 1.0, 3.0, and 5.0 wt % of urea (Si–U), diethylamine (Si-DE), triethylamine (Si-TE), and ethylenediamine (Si-EM) to enhance the CO2 sorption. First, CO2 sorption was evaluated at 30 °C and between 0.084 and 3 MPa using a CO2 stream to determine the best-doped amount of each N-source. Then, the best nanoparticles were used to impregnate CBM at 10 and 20 wt %, and the subsequent CO2 storage on the flue gas stream (70% v/v N2 and 30% v/v CO2) was done. The results showed that CO2 sorption on RSi increases with the N-group coating in the order RSi-DE < RSi-TE < RSi-U < RSi-EM. Also, the best-doped amount for each N-source was 3 wt %. For CBM impregnation, the nanofluid containing 20 wt % of RSi-EM3 presented the best yield increasing the CO2 sorption from 0.05 to 0.75 mmol g–1, meaning an increase of more than 1000% in the sorption capacity.

Management of tree fodder banks for quality forage production and carbon sequestration in humid tropical cropping systems – An overview

Livestock forms an integral component of humid tropical cropping systems, providing food and financial security, employment, and insurance against crop failure for small scale farmers. However, livestock sector is seriously constrained by the drastic decline in fodder base and high cost of feeds, incurring huge economic loss to farmers. Hence fodder production should be intensified in cropping system by including alternate feeds like nutrient rich fodder trees and shrubs to supplement conventional fodder. Fodder trees serve as a potential source of quality green fodder to livestock especially during lean periods. Moreover, tree leaves can be cheaper feed supplements than the commercial concentrates and can easily be grown by the small-holder farmers. Leucaena, mulberry, kadamba, calliandra, agathi, moringa and gliricidia are promising fodder tress by virtue of their nutritive foliage, fast growing nature with higher biomass production, amenable to heavy pruning, good coppicing ability and easy management. Moreover, these trees can be grown in close hedgerows as fodder banks in integration with existing crops to maximize productivity in land crunch humid tropical areas. Enhancing tree cover in cropping systems also offers ecosystem services like enhanced carbon storage and associated global warming issues. Forage and nutrient yields, and carbon accretion can be substantially elevated and crop–tree competition can be minimized by appropriate stand management practices and proper regulation of overstorey and understorey components. Extensive studies conducted on tree fodder bank establishment, management and their productive and protective functions in humid tropical cropping systems of South India are reviewed in this paper.

Effects of pyrolysis temperature and feedstock type on biochar characteristics pertinent to soil carbon and soil health: A meta‐analysis

AbstractBiochar amendment to soil is utilized globally as an approach to enhance carbon storage and to improve soil functioning. However, biochar characteristics and related improvements of soil functioning depend on biochar production conditions. Systematic evaluation of corresponding biochar characteristics is needed for more targeted and efficient biochar application strategies. Herein, we systematically review the effects of biochar pyrolysis temperature (175–950°C) and feedstock (corn stover, switchgrass and wood) on selected biochar characteristics (carbon content, H/C ratio, nitrogen content, pH, specific surface area, ash content and pore volume). These specific characteristics were selected as being pertinent to soil organic carbon sequestration and soil health improvement. Despite numerous studies on these topics, few have numerically quantified the effects of pyrolysis temperature. Our results show that high pyrolysis temperature (&gt;500°C) increased carbon content and pore volume for wood biochar compared with low pyrolysis temperature (≤500°C). The high pyrolysis temperature decreased the H/C ratio and nitrogen content but increased pH, specific surface area and ash content regardless of feedstock. Compared with corn stover biochar and switchgrass biochar, wood biochar had higher carbon content and larger specific surface area but lower nitrogen and ash contents regardless of pyrolysis temperature. The higher biochar carbon content might be derived from higher lignin and cellulose contents of wood feedstock. Wood feedstock had 76%–109% more lignin and 27%–47% more cellulose than corn stover and switchgrass. Corn stover biochar had higher pH, and switchgrass biochar had larger pore volume than wood biochar. Our study indicates that the targeted production of biochar with specific characteristics can be facilitated by the selection of pyrolysis temperature and feedstock type. For amending soil with biochar, more operationally defined biochar production conditions and feedstock selection might be a way forward to wider acceptance and better predictability of biochar performance under field conditions.