Potential carbon sequestration in China’s forests

Sea-level rise enhances carbon accumulation in United States tidal wetlands

The carbon sequestration potential is affected by cropping system and management practices, but soil organic carbon (SOC) sequestration potential under fertilizations remains unclear in north China. This study examined SOC change, total C input to soil and, via integration of these estimates over years, carbon sequestration efficiency (CSE, the ratio of SOC change over C input) under no fertilization (control), chemical nitrogen fertilizer alone (N) or combined with phosphorus and potassium fertilizers (NP, NK, PK and NPK), or chemical fertilizers combined with low or high (1.5×) manure input (NPKM and 1.5NPKM). Results showed that, as compared with the initial condition, SOC content increased by 0.03, 0.06, 0.05, 0.09, 0.16, 0.26, 0.47 and 0.68 Mg C ha-1 year-1 under control, N, NK, PK, NP, NPK, NPKM and 1.5NPKM treatments respectively. Correspondingly, the C inputs of wheat and maize were 1.24, 1.34, 1.55, 1.33, 2.72, 2.96, 2.97 and 3.15 Mg ha-1 year-1 respectively. The long-term fertilization-induced CSE showed that about 11% of the gross C input was transformed into SOC pool. Overall, this study demonstrated that decade-long manure input combined with chemical fertilizers can maintain high crop yield and lead to SOC sequestration in north China. © 2016 Society of Chemical Industry.

Carbon sequestration in soils has a huge potential to decrease the rate of CO2 emission to the atmosphere. However, little is known about Soil Organic Carbon (SOC) stock and fluxes in savannas. This study quantified the SOC of major plant communities in the southern guinea savanna ecological zone of Nigeria to determine their carbon sequestration potential for climate change mitigation. Field and laboratory procedures were employed to estimate carbon stock. Soil samples were collected by resampling from 40 permanent sampling plots for the years 2013, 2017, and 2021, respectively. Eighty composite soil samples were taken at two depths (0-15cm and 15-30cm). SOC concentration was estimated in the laboratory using the wet-oxidation Walkley-Black method. Findings revealed that between 2013 and 2021, the mean bulk density at 0–15 cm increased from 1.29 to 1.38 g cm-3, while at 15-30cm depth ranged from 1.30 to 1.36 g cm-3, signifying an increasing trend of soil compaction. Conversely, the mean SOC at 0–15 cm decreased from 20.11 to 14.06 Mg ha-1 while 15-30cm ranged from 15.84 to 11.92 Mg ha-1, implying carbon loss. The mean SOC concentration was mostly higher in the 0-15 cm layer than in the 15-30 cm layer. Savanna Woodland recorded the highest SOC (23.41 Mg ha-1) in 2013, while the Recent fallow land recorded the lowest (7.25 Mg ha-1) in 2021. Between 2013 and 2021, carbon emissions occurred at an annual loss rate of 8.87 Mg ha-1 yr-1. It was concluded that the restoration of the various plant communities has the potential to sequester about 79.84 Mg ha-1 of SOC at an annual rate of 8.87 Mg ha-1, which will provide effective climate change mitigation. This study recommends sustainable management practices for soil carbon sequestration, such as forest protection, fire management, afforestation, the use of organic fertilizers, and soil amendments.

Potential for soil carbon sequestration of eroded areas in subtropical China

2 - Crop management practices for carbon sequestration

Foreword PART I. Urban Ecosystems and Climate Change 1. Urban Ecosystems and Climate Change R. Lal 2. Adapting Urban Land Use in a Time of Climate Change Optimising Future Land-use Patterns to Decrease Flood Risks E.van Leeuwen, E. Koomen 3. Comparison of Methods for Estimating Carbon Dioxide Storage by Sacramento's Urban Forest E. Aguaron, E.G. McPherson 4. Terrestrial Carbon Management In Urban Ecosystems And Water Quality K. Lorenz, R. Lal PART II. Urban Forests 5. Carbon Stocks in Urban Forest Remnants: Atlanta and Baltimore as Case Studies I. D. Yesilonis, R. V. Pouyat 6. Urban Trees for Carbon Sequestration B.C. Scharenbroch 7. Carbon Storage in Some Urban Forest Soils of Columbus, Ohio, USA K. Lorenz, R. Lal PART III. Turfgrass and Home Lawns 8. Carbon Dynamics and Sequestration in Urban Turfgrass Ecosystems Y. Qian, R. Follett 9. Carbon sequestration potential in urban soils S. Brown, E. Miltner, and C. Cogger 10. Carbon Sequestration in Turfed Landscapes: A Review E.A. Guertal 11. Microbial Control of Soil Carbon Accumulation in Turfgrass Systems W. Shi, D. Bowman, T. Rufty 12. Using Soil Health Indicators to Follow Carbon Dynamics in Disturbed Urban Environments- A Case Study of Gas Pipeline Right-of-Way Construction R. R. Schindelbeck, H. M. van Es 13. Carbon Sequestration in Golf Course Turfgrass Systems and Recommendations for the Enhancement of Climate Change Mitigation Potential A. L. Selhorst, R. Lal 14. Modeling Carbon Sequestration in the U.S. Residential Landscape G. Zirkle, R. Lal, B. Augustin, R. Follett PART IV. Current Trends in Urban Ecosystems 15. Improving Soil Quality for Urban Agriculture in the North Central U.S. J. Beniston, R. Lal 16. Carbon Cycle of Urban Ecosystems G. Churkina 17. Legacy Effects of Highway Construction Disturbance and Vegetation Management on Carbon Dynamics in Forested Urban Verges T. L. L. Trammell, M. M. Carreiro PART V. Sustainable Management of Urban Ecosystems 18. Global Urbanization and Demand for Natural Resources C. Yeh, S. Huang 19. Toward Greening of Urban Landscapes R. Lal

Abstract:Revegetation is vital for enhancing soil carbon sequestration. However, the impacts of revegetation and terracing measures on soil organic carbon (SOC) and SOC sequestration (SOCS), and the differences in the effects of revegetation on SOC and SOCS when implemented on sloped fields versus terraced fields, are still unclear. Thus, we conducted a field survey on cropland (CL), grassland (GL), and forestland (FL) on both sloped fields and terraced fields in Wuqi county, China’s Loess Plateau. The results showed that SOC content in FL at 0–10 cm, 10–20 cm, 20–40 cm, 40–60 cm depths were 1.70, 1.28, 1.28, and 1.19 times respectively higher than in CL. Similarly, SOC content in GL at the same depths were 1.30, 1.13, 1.18, and 1.20 times higher than in CL. In terraced, SOC content at 40–60 cm, 60–80 cm, 80–100 cm depths were 1.22, 1.28, and 1.20 times respectively higher than on sloped fields. Revegetation primarily significantly affected SOC at 0–10 cm depth on sloped fields (GL: p = 0.04; FL: p < 0.01), and more deeply (0–100 cm) on terraced fields (GL at 40–80 cm: p < 0.05; FL: p < 0.01). Furthermore, revegetation on sloped fields generated the highest SOCS at 0–40 cm depth, with a subsequent decrease as depth increased to 40–100 cm depth. Conversely, on terraced, SOCS increased with soil depth within the 0–100 cm depth. These results indicated that revegetation primarily enhanced SOCS in the surface soil (0–40 cm), and terracing measures stabilized the SOCS in the surface soil and further enhanced them in deeper soil horizons (0–100 cm). Therefore, in the context of soil erosion control and ecological restoration, the combined implementation of vegetation restoration and engineering measures can effectively stabilize and enhance SOCS, thereby fully leveraging the role of soil in mitigation climate change.Keywords: Soil and water conservation measures; Carbon sequestration; Land use change；Vegetation restoration; Engineering measures; Deep soil organic carbon

Carbon sequestration (CS) has been increasingly viewed as one of the crucial issues/strategies to address the challenging issues of global warming led climate change effects besides imparting sustainability to productivity. In agricultural land use systems, increased CO2 emission into the atmosphere is through repeated and frequent cultivation of croplands, crop residues, biomass burning, shifting cultivation, cultivation of low biomass producing crop cultivars, land degradation, deforestation, etc. The results of current review revealed that agricultural soils have lost about 30–75% of their inherent soil organic carbon (SOC) pool which is quite alarming. The U.N. panel (IPCC) in its current report published that to contain warming at 1.5oC, there will be a need to reduce the global net CO2 emissions (manmade) by about 45% by the year 2030 from 2010 levels and further to reach ‘net zero’ by 2050. The potential of carbon sequestration with cautious management of world cropland include 0.08±0.12 Pg/yr by erosion control, 0.02±0.03 Pg/yr by preservation of harshly problematic/degraded soils, 0.02±0.04 Pg/yr by repossession of salt-affected soils, 0.15±0.175 Pg/yr by taking up of minimum/conservation tillage and crop left-over administration, 0.18±0.24 Pg/yr by execution of better cropping system and 0.30±0.40 Pg/ yr as C balance via biofuel production. The total potential of carbon sequestration by the world cropland is about 0.75±1.0 Pg/yr. Each 1 Mg/ha rise in soil organic carbon pool in the root zone under the soil would enhance yields of crops by 20–70 kg/ha in case of wheat, 10–50 kg/ha in rice, and 30–300 kg/ha in corn, augmenting production of cereals and legumes in the developing countries by 32 and 11 million Mg/yr, respectively. Therefore, CS apart from mitigating global warming potential also succors the farming community and the nation in advancing food security on sustainable basis.

Digital soil maps of soil organic carbon (SOC) sequestration potential resulting from a hypothetical 10% relative increase in long‐term vegetation cover are presented at 100‐m resolution across the state of New South Wales (NSW) in southeast Australia. This land management outcome is considered realistically achievable for many land managers, using strategies such as revegetation, grazing management or crop residue management. A mean state‐wide potential increase of 5.4 Mg ha −1 over the 0‐ to 30‐cm depth interval was derived. Assuming a 20‐year period of re‐equilibration, this equates to an average SOC increase of 0.27 Mg ha −1 year −1 . Sequestration potential is systematically influenced by a combination of climate, soil parent material and current vegetation cover, for example only 1.6 Mg ha −1 SOC under dry conditions in sandy, infertile soil material with sparse vegetation cover, compared with 15.9 Mg ha −1 under wet conditions in clay‐rich, fertile soil material with moderate–high vegetation cover. The outputs could be used to identify locations of highest sequestration potential and thereby help prioritize areas and inform decisions on sequestration programmes. Future application of the method at field scale with high levels of accuracy, together with strategic sampling, may provide statistically reliable estimates of carbon sequestration, for application in carbon trading schemes such as Australia's Emissions Reduction Fund. The modelling involved a conceptually transparent ‘space‐for‐time substitution’ process. Multiple linear regression (MLR) and random forest (RF) modelling techniques were applied, but only MLR gave consistently meaningful results. The apparent failing of RF in this application warrants further examination.

Understanding the long-term and quantitative effects of different fertilization practices on carbon sequestration and nitrogen loss is important when establishing the best fertilization regime. In this study, the DeNitrification–DeComposition (DNDC) model was validated first for the change of soil organic carbon (SOC) at the site mode and at the regional mode, and then it was used to simulate the effects of three fertilization practices including rice straw (RS) returning, chemical fertilizer application (CF), and green manure planting (GM) on C and N dynamics in paddy soils from a subtropical area of China. The prevailing fertilization practices in the study area were set as the baseline scenario, and alternative scenarios were assigned by varying only one of the three fertilization practices. All three fertilization practices increased SOC content but had different effects on rice yield, N2O emission, and nitrate leaching loss. Compared with a baseline RS rate of 15 %, the SOC contents less than RS rates of 30, 50, and 80 % were increased on average by 12.84, 29.48, and 53.50 %, respectively. SOC content also increased as the CF rate rose from 70 to 130 % of the baseline scenario and then leveled off from 130 to 160 %. SOC contents under GM were higher than that without GM by 35.74 %. Both the N2O emissions and the nitrate leaching were increased with the increasing CF rate, while they decreased under GM treatment. However, RS increased the N2O emissions but decreased the nitrate leaching. The polygon-based modeling method with the DNDC could accurately evaluate the general trend of SOC dynamics and nitrogen loss from paddy soils.

Changes in long-term land use alter deep soil microbial necromass and organic carbon stabilization.

This report describes the feasibility, calibration, and safety considerations of a non-destructive, in situ, quantitative, volumetric soil carbon analytical method based on inelastic neutron scattering (INS). The method can quantify values as low as 0.018 gC/cc, or about 1.2% carbon by weight with high precision under the instrument's configuration and operating conditions reported here. INS is safe and easy to use, residual soil activation declines to background values in under an hour, and no radiological requirements are needed for transporting the instrument. The labor required to obtain soil-carbon data is about 10-fold less than with other methods, and the instrument offers a nearly instantaneous rate of output of carbon-content values. Furthermore, it has the potential to quantify other elements, particularly nitrogen. New instrumentation was developed in response to a research solicitation from the U.S. Department of Energy (DOE LAB 00-09 Carbon Sequestration Research Program) supporting the Terrestrial Carbon Processes (TCP) program of the Office of Science, Biological and Environmental Research (BER). The solicitation called for developing and demonstrating novel techniques for quantitatively measuring changes in soil carbon. The report includes raw data and analyses of a set of proof-of-concept, double-blind studies to evaluate the INS approach in the first phase of developing the instrument. Managing soils so that they sequester massive amounts of carbon was suggested as a means to mitigate the atmospheric buildup of anthropogenic CO{sub 2}. Quantifying changes in the soils' carbon stocks will be essential to evaluating such schemes and documenting their performance. Current methods for quantifying carbon in soil by excavation and core sampling are invasive, slow, labor-intensive and locally destroy the system being observed. Newly emerging technologies, such as Laser Induced Breakdown Spectroscopy and Near-Infrared Spectroscopy, offer soil-carbon analysis; however, these also are invasive and destructive techniques. The INS approach permits quantification in a relatively large volume of soil without disrupting the measurement site. The technique is very fast and provides nearly instantaneous results thereby reducing the cost, and speeding up the rate of analysis. It also has the potential to cover large areas in a mobile scanning mode. These capabilities will significantly advance the tracking carbon sequestration and offer a tool for research in agronomy, forestry, soil ecology and biogeochemistry.

Soil organic carbon (SOC) sequestration is vital for maintaining the function of grassland ecosystems under grazing conditions, yet the relationship between different carbon fractions and carbon sequestration remains unclear. This study investigated SOC dynamics under a 5‐year controlled grazing gradient (ranging from grazing exclusion to extremely heavy grazing) in the Qilian Mountains, China. It aimed to elucidate the variations in SOC and its fractions and further discuss the mechanisms of SOC sequestration under grazing. The results showed that with increasing grazing intensity, SOC and all carbon fractions exhibited a significant declining trend, except for dissolved organic carbon (DOC). The decline in SOC was directly influenced by aboveground biomass and available phosphorus. Furthermore, organic carbon dynamics were regulated by the mineral protection mechanism represented by particulate organic carbon (POC) and mineral‐associated organic carbon (MAOC), whereas other carbon fractions did not exhibit significant effects. However, Partial Least Squares Structural Equation Modeling (PLS‐SEM) revealed distinct regulatory pathways for the two; specifically, the reduction in POC induced by changes in vegetation characteristics was a significant cause of the SOC decline. In contrast, MAOC, serving as the primary reservoir for carbon sequestration, was mainly regulated by soil factors. Overall, the insensitivity of MAOC to grazing pressure rendered it the most stable carbon fraction. Meanwhile, the contribution of MAOC to long‐term carbon preservation exceeded that of POC, highlighting the critical significance of stable organic carbon for the long‐term retention of SOC. These findings suggest that maintaining grazing at moderate levels can preserve the labile organic carbon inputs required for nutrient cycling, while the stable carbon fraction (MAOC) ensures the long‐term carbon sink function of alpine meadows.

The cool temperate climate, dominance of perennial land use, and relatively large proportion of peat and organically rich soils, make the northern European regions to have a large potential of soil organic carbon (SOC) sequestration. However, with predicted global warming soils in these areas may become sources of atmospheric CO2. Quantitative and reliable assessment methods and understanding of the spatial variability of SOC pools are required to make accurate mean estimate of available C and integrate variability into predictive models of SOC reserves and sequestration potential. Advanced analytical methods such as near-infrared spectroscopy and carbon isotope techniques can be used to estimate retention time and C turnover rates in soils. The rehabilitation of peat lands has shown a potential for SOC sequestration ranging from 25 to 45 gCm−2 yr−1 in Scandinavian countries. The potential of SOC sequestration in agricultural and forestry ecosystems depends on the land use and management practice adopted. Furthermore, the proven land management practices (e.g. conservation tillage, reduced soil erosion, restoring wetlands and degraded lands) coupled with improved cultivation practices (e.g. judicious fertilizer use, crop rotations and cover crops) can make the soil of this region as C sink.

Abstract. Grassland soil organic carbon (SOC) is sensitive to anthropogenic activities. Increased anthropogenic disturbance related to overgrazing has led to widespread alpine grassland degradation on the Tibetan Plateau. The degraded grasslands are considered to have great potential for carbon sequestration after adoption of improved management practices. Here, we calibrated and employed the Century model to investigate the effects of overgrazing and improved managements on the SOC dynamics in alpine meadows. We calibrated the Century model against plant productivity at the Haibei Research Station. SOC stocks for validation were obtained in 2009–2010 from degraded alpine meadows in two communes. We found that Century model can successfully capture grassland SOC changes. Overall, our simulation suggests that degraded alpine meadow SOC significantly increased with the advent of restoration management from 2011 to 2030. Carbon sequestration rates ranged between 0.04 Mg C ha−1 yr−1 in lightly degraded winter grazing grasslands and 2.0 Mg C ha−1 yr−1 in moderately degraded summer grazing grasslands. Our modelling work also predicts that improve management in degraded Tibetan grasslands will contribute to an annual carbon sink of 0.022–0.059 Pg C yr−1. These results imply that restoration of degraded grasslands in the Tibetan Plateau has great potential for soil carbon sequestration to mitigate greenhouse gases.