Regional Carbon Sequestration Research Articles

Analysis of the Spatiotemporal Changes in Cropland Occupation and Supplementation Area in the Pearl River Delta and Their Impacts on Carbon Storage

In recent years, the “dual carbon” issue has become a major focus of the international community. Changes in land use driven by anthropogenic activities have a profound impact on ecosystem structure and carbon cycling. This study quantitatively assesses the spatiotemporal changes in cropland occupation and supplementation in the Pearl River Delta from 2000 to 2020 using the InVEST model, analyzing the spatial clustering of carbon storage changes caused by variations in cropland area. The PLUS model was employed to simulate land-use patterns and the spatial distribution of carbon storage in four future development scenarios. The results indicate the following: (1) From 2000 to 2020, the net change rate of cropland area in the Pearl River Delta was −0.81%, with a decrease of 16.49 km2 in cropland area, primarily converted to built-up land and forest land. (2) Carbon storage in the Pearl River Delta exhibited a pattern of lower values in the center and higher values in the periphery. The terrestrial ecosystem carbon storage in the Pearl River Delta was 534.62 × 106 t in 2000, 518.60 × 106 t in 2010, and 512.57 × 106 t in 2020, showing an overall decreasing trend. The conversion of cropland and forest land was the main reason for the decline in total regional carbon storage. (3) The area of carbon sequestration lost due to cropland occupation was significantly greater than the area of carbon loss compensated by new cropland, indicating an imbalance in the quality of cropland occupation and supplementation as a crucial factor contributing to regional carbon loss. (4) Under the ecological priority scenario, the expansion of built-up land and the reduction in ecological land such as cropland and forest land were effectively controlled, resulting in the minimal loss of carbon storage. The soil organic carbon pool of cropland is the most active carbon pool in terrestrial ecosystems and has a significant impact on carbon storage. Clarifying the relationship between “cropland protection measures–land use changes–ecosystem carbon storage” will improve cropland protection policies, provide references for regional carbon sequestration enhancement, and support sustainable socio-economic development.

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

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

Modulation of regional carbon uptake by AMOC and alkalinity changes in the subpolar North Atlantic under a warming climate

IntroductionThe slowdown of the Atlantic Meridional Overturning Circulation (AMOC) and associated consequences on ocean carbon uptake could have large implications for the Earth’s climate system and its global carbon cycle.MethodsThis study analyzes ten Earth System Models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and reveals that the regional carbon uptake in the subpolar North Atlantic under a high CO2 emission scenario moderately correlates with the decline in AMOC at 40°N. AMOC transports warm and salty subtropical waters to the subpolar regions.ResultsModels with stronger AMOC slowdown generally exhibit weaker surface warming and larger decline of surface salinity and alkalinity. We consider two plausible mechanisms linking the AMOC slowdown to the decline of regional CO2 uptake: the reduction in surface alkalinity and diminished subduction. The decline of surface salinity and alkalinity reduces the ocean’s capacity to buffer acids leading to a reduced CO2 uptake. This important contribution is unique to the North Atlantic. Diminished convective mixing and subduction of surface water can further decrease the downward transport of anthropogenic carbon, as also shown in previous research. The centennial trends of pCO2 are decomposed into four components driven by temperature, salinity, alkalinity and dissolved inorganic carbon, revealing that alkalinity and dissolved inorganic carbon are both significant contributors. The alkalinity-driven pCO2 essentially follows surface salinity, establishing the linkage between AMOC slowdown and alkalinity decline.DiscussionOur results indicate that alkalinity changes are important for the interplay between AMOC and the regional carbon sequestration ability across the late 20th and the entirety of the 21st century in the subpolar North Atlantic.

Construction of carbon sequestration ecological network in Linyi City based on supply and demand of ecosystem service.

The increasing carbon emissions is one of the important reasons for global warming. As a key area of carbon emissions, carbon sequestration capacity of cities is urgently needed to be improved. Carbon sequestration ser-vices can be transferred between supply and demand areas due to the circulation of atmosphere. With Linyi City as an example, we used the minimum cumulative resistance model to extract the matching path of supply and demand, and constructed a carbon sequestration ecological network. The results showed that the regions with high supply of carbon sequestration services were located in the north and south of the study area, and that current total supply could solve about 60% of the total demand. Although the spatial distribution of supply and demand was uneven, 54% of the areas that could meet the surrounding carbon sequestration demand were still idle. The optimized supply-demand matching paths could maintain good transmission efficiency of material and energy, with lower costs. Paths with strong potential carbon sequestration capacity were located in the central and northwest part of the research area. In the construction of carbon sequestration ecological network, it is necessary to strengthen the protection and restoration of the supply side of carbon sequestration services, realize carbon reduction and strengthen carbon sequestration on the demand side, and optimize the matching path of supply and demand. This method provided services to the demand areas through the oversupply of ecosystem services, optimized the overall resource allocation, which could advance regional carbon sequestration capacity.

Assessing Forest-Change-Induced Carbon Storage Dynamics by Integrating GF-1 Image and Localized Allometric Growth Equations in Jiangning District, Nanjing, Eastern China (2017–2020)

Forest and its dynamics are of great significance for accurately estimating regional carbon sequestration, emissions and carbon sink capacity. In this work, an efficient framework that integrates remote sensing, deep learning and statistical modeling was proposed to extract forest change information and then derive forest carbon storage dynamics during the period 2017 to 2020 in Jiangning District, Nanjing, Eastern China. Firstly, the panchromatic band and multi-spectral bands of GF-1 images were fused by using four different methods; Secondly, an improved Mask-RCNN integrated with Swin Transformer was devised to extract forest distribution information in 2020. Finally, by using the substitution strategy of space for time in the 2017 Forest Management and Planning Inventory (FMPI) data, local carbon density allometric growth equations were fitted by coniferous forest and broad-leaved forest types and compared, and the optimal fitting was accordingly determined, followed by the measurements of forest-change-induced carbon storage dynamics. The results indicated that the improved Mask-RCNN synergizing with the Swin Transformer gained an overall accuracy of 93.9% when mapping the local forest types. The carbon storage of forest standing woods was calculated at 1,449,400 tons in 2020, increased by 14.59% relative to that of 2017. This analysis provides a technical reference for monitoring forest change and lays a data foundation for local agencies to formulate forest management policies in the process of achieving dual-carbon goals.

Drought offsets the vegetation greenness-induced gross primary productivity from 1982 to 2018 in China

Recent studies have shown that climate stress may cause asynchronous changes between greenness and productivity, but the mechanism how greenness and productivity respond to drought remains unclear. The significant greening of vegetation in China has attracted worldwide attention; nevertheless, it is unclear whether large-scale greening will translate into productivity in the context of recent droughts. In this study, we used the vegetation index dataset to extract long-term trends in vegetation greenness and productivity from 1982 to 2018, and then chose the multi-scale Standardized Precipitation Evapotranspiration Index (SPEI) index to measure how vegetation greenness and productivity change in response to drought. The results show that significant vegetation greening did not cause a simultaneous increase in productivity during 1982–2018. Vegetation greenness and productivity trends were relatively consistent before 2000 and diverged after 2000, especially during the prolonged drought of 2000–2009. The opposite trend between greenness and productivity in humid ecosystems during drought periods mainly caused this trend difference. In humid ecosystems, short-term drought promotes vegetation greening, while long-term drought has no significant impact on greenness. However, the inhibitory effect of drought on productivity deepens with an increase in drought duration. Therefore, prolonged droughts offset vegetation greenness-induced gross primary productivity. We also found that prolonged drought causes a significant decrease in greenness but has little effect on productivity in arid ecosystems, possibly because vegetation productivity is more sensitive to soil water than atmospheric drought. Our results highlight the complexity of vegetation growth in the context of climate change. Furthermore, it is crucial to pay attention to the impact of climate stress on regional carbon sequestration functions, considering the significant carbon sink potential of forest areas in southern China.

Research on regional terrestrial carbon storage based on the pattern-process-function

The evolution of ecological pattern caused by human activities has altered the terrestrial carbon cycle process, and it is important to explore systematic approaches to study the relationship between ecological pattern and carbon sequestration function within regions. From the new perspective of the pattern-process-function in landscape ecology, this study couples NPP-InVEST, GeoDa, MOP-PLUS, and GeoDetector models to construct a conceptual cascade framework of “Land use pattern-Evolution process-Carbon sequestration function” (LEC), which provides a new epistemology and methodology for increasing carbon sink and mitigating down carbon source. Based on natural and socioeconomic elements, the use of LEC is illustrated in the Beijing-Tianjin-Hebei (BTH) region, the land use pattern, evolution process, and carbon sequestration function from 2000 to 2020 were analyzed, the trends of carbon storage in 2030 under four development scenarios were simulated, the driving mechanism of carbon sequestration function was studied, and the carbon sequestration function enhancement strategy based on the LEC was proposed. The results indicate that the land use pattern determines the spatial distribution and aggregation of carbon sequestration function, and the evolution process forms a low-carbon zone with construction land expansion, leading to a reduction in carbon storage. However, the ecological protection simulation scenario increases the high-carbon zone, which effectively slows down the decreasing trend of carbon sequestration function. Based on a comprehensive understanding of LEC, regional carbon storage can be enhanced through scientific allocation, priority protection, and efficient utilization of land use pattern. LEC contributes to the sustainability of complex natural-social-economic systems and provides an innovative approach for regional landscape pattern optimization policy formulation and carbon sequestration function enhancement.

Spatio-temporal Evolution and Multi-scenario Simulation of Carbon Storage in Karst Regions of Central Guizhou Province：Taking Puding County as An Example

Regional land use change is the main cause for the change in karst carbon storage. It is important to analyze the spatial and temporal evolution and future spatial distribution trends of carbon storage in typical counties in central Guizhou's karst region， such as Puding County， to improve regional carbon storage， optimize land ecological security patterns， and promote low-carbon sustainable urban development. The PLUS-InVEST model was coupled， based on the interpreted land use data and future land prediction， the spatial and temporal evolution characteristics of land use change and carbon storage in Puding County from 1973 to 2020 were inverted， and the spatial pattern evolution of land use and carbon storage change under different scenarios in 2060 were simulated and predicted. The results showed： ① from 1973 to 2020， the overall carbon storage in Puding County increased by 6.61×105 t， showing an upward trend. The spatial distribution showed a significant increase in the northeastern and southwestern parts of Puding County and a significant decrease in the south-central parts. The change was due to the increase in carbon storage in dryland to shrubland and forest land and the decrease in carbon storage in areas where paddy fields are converted to construction land. ② The land use change in Puding County in the historical period was mainly reflected in the continuous expansion of construction land and the increased fluctuation of the proportion of forest land and shrub forest land， and the change in land use in different scenarios projected in 2060 retained the change characteristics of the historical period. ③ In 2060， the carbon storage in Puding County under the scenarios of natural evolution， ecological protection， and economic development increased by 2.93×105， 5.40×105， and 1.11×105 t， respectively， compared with that in 2020. Of these， the increase in ecological protection scenarios was the most significant， with the transfer of dryland to shrubland being the main reason for the increase in regional carbon sequestration capacity. These results can serve as a scientific reference for land use management decisions and the formulation of emission reduction and sink increase policies in Puding County. The future land use planning of karst areas should be guided by the goal of "carbon neutrality" in 2060， take appropriate ecological protection measures， strictly control the rapid expansion of construction land to paddy fields， optimize the land use structure， and effectively improve the level of regional carbon storage.

Net carbon sequestration implications of intensified timber harvest in Northeastern U.S. forests

AbstractU.S. forests, particularly in the eastern states, provide an important offset to greenhouse gas (GHG) emissions. Some have proposed that forest‐based natural climate solutions can be strengthened via a number of strategies, including increases in the production of forest biomass energy. We used output from a forest dynamics model (SORTIE‐ND) in combination with a GHG accounting tool (ForGATE) to estimate the carbon consequences of current and intensified timber harvest regimes in the Northeastern United States. We considered a range of carbon pools including forest ecosystem pools, forest product pools, and waste pools, along with different scenarios of feedstock production for biomass energy. The business‐as‐usual (BAU) scenario, which represents current harvest practices derived from the analysis of U.S. Forest Service Forest Inventory and Analysis data, sequestered more net CO2 equivalents than any of the intensified harvest and feedstock utilization scenarios over the next decade, the most important time period for combatting climate change. Increasing the intensity of timber harvest increased total emissions and reduced landscape average forest carbon stocks, resulting in reduced net carbon sequestration relative to current harvest regimes. Net carbon sequestration “parity points,” where the regional cumulative net carbon sequestration from alternate intensified harvest scenarios converge with and then exceed the BAU baseline, ranged from 12 to 40 years. A “no harvest” scenario provides an estimate of an upper bound on forest carbon sequestration in the region given the expected successional dynamics of the region's forests but ignores leakage. Regional net carbon sequestration is primarily influenced by (1) the harvest regime and amount of forest biomass removal, (2) the degree to which bioenergy displaces fossil fuel use, and (3) the proportion of biomass diverted to energy feedstocks versus wood products.

Exploring ecological carbon sequestration advantage and economic responses in an ecological security pattern: A nature-based solutions perspective

Nature-based solutions (NbS) underscore a holistic approach centered around ecosystems to address challenges. Under the “carbon peaking and carbon neutrality "goal, the identification of core ecological carbon sequestration (ECS) areas within ecosystems lacks an effective grading model. Furthermore, the insufficient delineation of the relationship between carbon sink potential and economic development has impeded scientific planning and effective management. This study introduces an innovative hierarchical model for identifying ECS core areas, combined with an NbS framework. This study employs the InVEST-Zonation-MSPA modeling approach to construct the hierarchical model for ECS core areas. In the process of establishing the ecological security pattern (ESP), it measures the ECS advantage and employs the multiscale geographically weighted regression (MGWR) model to explain the spatial variations in economic responses to ECS advantage levels. The study considered Yunnan Province, which has rich ecological carbon sinks in the highland mountains of southwest China, as the study area. The key findings are: (1) The distribution pattern of priority levels for ecosystem services related to ECS shows a three-tiered pattern. Factors such as urban expansion and infrastructure development have reduced priority areas in ECS. (2) In the construction of the ESP, scenario A and scenario B identified 16.71 % and 14.64 % of priority areas as core ecological source areas, respectively. A linear relationship exists between minimum cumulative resistance (MCR) and the ECS advantage index (ECSAI). An equation was developed to explain 30.9 % of the variability in ECSAI, indicating that ECSAI increases to some extent with increasing MCR. (3) The hierarchical classification of ECS core areas is based on a priority protection area foundation formed jointly by ecological and carbon sequestration landscape priorities. Four levels of core areas (I, II, III, IV) are defined, representing 3.9 %, 6.2 %, 2.7 %, and 37.3 % of the total area respectively. (4) Economic factors exhibit significant spatial heterogeneity in their impact on ECS across counties. This study provides a quantitative analytical method for balancing carbon sequestration priorities with economic development. The results guide regional ecological conservation and carbon sequestration management.

Analysis and prediction of the spatiotemporal characteristics of land-use ecological risk and carbon storage in Wuhan metropolitan area

In the context of global warming, understanding the spatiotemporal dynamic of carbon storage, land-use related ecological risks, and how ecological risks are correlated with carbon storage, is vitally significant for enhancing regional carbon-sequestration capacity, promoting the rational exploitation of land and green and low-carbon development. Using land-use data, this study employed the InVEST and PLUS models to analyze and forecast spatiotemporal variation in land-use, land-use ecological risks, and terrestrial ecosystem carbon storage in the Wuhan metropolitan area under multiple-scenarios. Spearman’s correlation and spatial autocorrelation analyses were used to explore spatial correlations between carbon storage and land-use ecological risk. The following was found: (1) From 2000 to2020, the area of arable land, grassland, water body, and unused land reduced. In contrast, the area of forestland and built-up land increased. Similar land-use changes were observed in 2030 under the natural development scenario. The area of forestland, grassland, and water body increased, and the expansion of built-up land is effectively controlled under the ecological protection scenario. (2) Land-use ecological risks in the study area first declined and then increased over the research period, with an overall increase. (3) From 2000 to 2030, the carbon storage within the Wuhan metropolitan area declined. In the 2030 ecological protection scenario, the reduction in carbon storage is lower than under the natural development scenario. Through the lens of land-use categories, the entire carbon storage was, in descending order, arable land, forestland, built-up land, grassland, unused land, and water body. (4) Land-use ecological risk and carbon storage were negatively correlated and dominated by Low-High and High-Low aggregation zones. This study can serve as a reference for the future optimal layout of land-use and sustainable development of ecosystems in metropolitan areas.

Carbon metabolism in "production-living-ecological" space in urban agglomeration based on land use change.

To grasp the impact of carbon metabolism on the evolution of "production-living-ecological" (PLE) space due to land usechange in the Changsha-Zhuzhou-Xiangtan (CZT) urban agglomeration, this study delves into the temporal and spatial distribution of PLE space carbon metabolism by constructing a carbon flow model. We evaluate the influence of positive and negative carbon flows on carbon metabolism using ecological network analysis and utility assessment. Furthermore, we delve into the driving factors behind carbon metabolism through redundancy analysis (RDA). The findings of this study included mainly the following aspects. (1) From 2000 to 2020, the net carbon flow in the CZT urban agglomeration consistently remained negative, with the primary source of negative carbon flow being the transition from ecological space to production space. (2) Within the ecological utility network, the dominant ecological relationship shifted from a period of control and exploitation relationship (counted for 61.91%) between 2000 and 2005 to one of competition relationship that counted for 83.33% in 2005-2010, 47.62% in 2010-2015, and 66.67% in 2015-2020. Mutualism relationship, present in the 2000-2005 period, completely disappeared in subsequent years. (3) The value of the utility function M was 0.88, 0.36, 0.48, and 0.40 in four stages (all less than 1), which meant that PLE space evolution on regional carbon metabolism was negative. (4) The key drivers influencing carbon metabolism in PLE space were mainly Change in the Comprehensive Land Use Index (CL), Change in the Proportion of Manufacturing Land (CM), Change in the Proportion of Forestland (CF), and Change in the Proportion of Cultivated Land (CC). Carbon metabolism holds a critical role in the urban material and energy cycle. Studying carbon metabolism within PLE space carries great importance for regional carbon cycling, carbon emission and sequestration, efforts to mitigate climate change, and the maintenance of regional sustainable development.

Estimation and simulation of carbon sequestration in typical dryland areas of China under future climate change scenarios

Climate anomalies and human disturbances exert complex effects on regional carbon sequestration (CS), causing ecosystem CS to either increase or decrease due to factors such as vegetation greening, climate extremes, land use/land cover (LULC) changes, and farming systems. This study employs the patch-level land use simulation model to forecast changes in various land-use types in the Xinjiang Uyghur Autonomous Region, China, between 2020 and 2060 under different climatic conditions. The Intergovernmental Panel on Climate Change has proposed shared socioeconomic pathways (SSPs) as potential socioeconomic and environmental trajectories that might influence the region’s future land-use patterns. Three salient findings emerged: (1) LULC displayed considerable variation across future climate scenarios, with a notable rise in forest and grassland cover and a marked decrease in cropland areas under the SSP126 scenario. Conversely, the SSP585 scenario witnessed a substantial cropland expansion, paralleled by a decrease in forest and grassland areas; (2) CS exhibited significant disparities across different future climate scenarios. Xinjiang achieved a peak CS of 9.81 Pg between 2020 and 2060 under the SSP126 scenario, marking an increase of 335.22 Tg in 2060 compared to that in 2020. The SSP585 scenario registered the lowest CS at 9.41 Pg, indicating a decline of 50.07 Tg in 2060 relative to 2020; (3) The impacts of longitude and latitude on CS in Xinjiang predominantly arose from shifts in forest area and vegetation cover based on latitude, which positively influenced CS. In contrast, a decrease in vegetation cover and a subsequent decline in CS were evident with increasing longitude, particularly in the Altai, Tianshan, and Kunlun Mountains. These findings hold significant implications for formulating CS management strategies for terrestrial ecosystems and enhancing ecological preservation in Xinjiang.

Regional Contribution and Attribution of the Interannual Variation of Net Primary Production in the Yellow River Basin, China

Net primary production (NPP) serves as a crucial indicator of the ecosystem’s capacity to capture atmospheric CO2. Gaining insights into the dynamics of NPP and its driving mechanisms is pivotal for optimizing ecosystem carbon sink resource management. Since the implementation of the Grain-for-Green Program (GFGP) in 1999, the Yellow River Basin (YRB) has been one of the most significant areas for ecological restoration in China. However, our knowledge regarding the interannual variability (IAV) of NPP and the underlying driving forces in this region remains incomplete. In this study, we utilized a light use efficiency model to assess the spatiotemporal dynamics, IAV, and driving factors of NPP in the YRB during the period from 1999 to 2018. Our findings revealed that the average annual NPP in the YRB approximated 189.81 Tg C. Over the study duration, NPP significantly increased in 79.63% of the basin with an overall increasing rate of 6.76 g C m−2 yr−1. The most prominent increase was observed in the key GFGP implementation area, predominantly in the semi-humid region. Notably, the middle altitude region (1–1.5 km), semi-humid region, and grassland emerged as the primary contributors to the basin’s total vegetation carbon sequestration. However, it is worth emphasizing that there was substantial IAV in the temporal trends of NPP, with the semi-humid region being the most influential contributor (62.66%) to the overall NPP IAV in the YRB. Further analysis of the driving mechanisms unveiled precipitation as the primary driver of NPP IAV in the YRB with a contribution of 62.9%, followed by temperature (23.07%) and radiation (14.03%). Overall, this study deepened our understanding of the IAV and driving mechanisms of NPP in the YRB under ecological restoration, and provided scientific support for optimizing the management of regional carbon sequestration resources.

Agricultural Production Can Be a Carbon Sink: A Case Study of Jinchang City

In the context of China’s commitment to the “double carbon” goal, promoting agricultural carbon emission reduction is currently an important research topic. Assessing the carbon sequestration level of crops has a positive impact on enhancing agricultural carbon sinks and reducing carbon emissions. The carbon budget for agricultural planting on the arid oasis of Jinchang, northwest China, is quantitatively calculated from 2018 to 2020. The average value of total carbon absorption by crops in Jinchang was greater than the average value of total carbon emissions in the past three years. In 2020, the total carbon absorption was the highest (1,744,725 t CO2-eq), and the carbon emission was 102,641 t CO2-eq. The crops had a strong carbon absorption function. Among the investigated crops, the largest average annual carbon sequestration was found in corn, which accounted for 45% of the total carbon sequestration in the city. Among the carbon emission pathways, chemical fertilizer and agricultural film were the main carbon sources, accounting for more than 40% of total carbon emissions. The carbon budget analysis in the region clearly showed that the structure of agricultural cropping and the planting area proportion of crops significantly affected the carbon balance of the whole agricultural region and that increasing the proportion of the area planted with corn was beneficial in enhancing regional carbon sequestration.

Soil organic carbon stock in China’s tea plantations and their great potential of carbon sequestration

China is the biggest tea producer in the world, and soils in the tea plantations play important roles in the carbon cycle, and regional and national carbon neutrality. The knowledge regarding the variation and the key drivers of soil organic carbon (SOC) stock in tea plantations could provide a scientific basis for assessing the potential of regional and national carbon sequestration and neutrality. This is also helpful for the sustainable management of tea plantations. However, little information is available on soil organic carbon (SOC) stock and influential factors in tea plantations. Thereby, SOC density (SOCD) and stock were estimated based on 1723 datasets collected from 322 published studies. Subsequent estimations reveal that the total SOC stock in China’s tea plantations is 207.13 Tg with 124.58 Tg SOC stored in top soil layer (0–20 cm), and the average SOCD is 59.17 Mg ha−1 ranging from 0.9 Mg ha−1 to 589.54 Mg ha−1. The SOCD showed a significant three-dimension zonal pattern and was significantly influenced by managerial practices. Tea plantations managed in ecological ways and/or with long stand age even showed higher SOCD than that in neighbored forests. The lower average but wide range of SOCD in tea plantations indicates their great potential in carbon sequestration. This makes tea plantations critically important in regional and national carbon accounting and carbon neutrality, and cannot be ignored in future research and policymaking initiatives.

Dynamic Changes and Driving Mechanisms of Net Primary Production (NPP) in a Semi-Arid Region of China

The objective of this study is to analyze the spatiotemporal dynamics of net primary production (NPP) change combined with land use and to further explore the driving factors of NPP change, allowing us to provide a scientific reference point for optimizing the land-use structure and improving regional carbon sequestration capacity. The average annual NPP ranged from 200 to 300 gC/m2•a in the period of 2001–2020 in our study area. We used trend analysis and linear regression analysis to explore the spatial and temporal dynamic changes in annual NPP and analyzed the driving mechanism in a semiarid region (western Jilin Province) of China in the period of 2001–2020. The results showed that NPP presented a trend of fluctuating growth, and the spatial distribution of NPP showed that NPP values of cultivated land, forest and grassland were generally higher than those of other land-use types. The high value in the southeastern region and low value in the northwestern region were identified because there were large areas of cultivated land distributed in the southeastern part of the study area in the period of 2001–2020. The main driving factors that affected NPP were annual precipitation, CO2 emissions, GDP and hours of sunshine. NPP was positively correlated with annual precipitation, CO2 emissions and GDP, and it had a significant negative correlation with hours of sunshine. Our study provides important support for research into land-use structure and improvements to the regional carbon sequestration capacity, making an important contribution to regional sustainable development.

Vegetated coastal ecosystems in the Southwestern Atlantic Ocean are an unexploited opportunity for climate change mitigation

Vegetated coastal ecosystems (mangroves, seagrasses, and saltmarshes, often called Blue Carbon ecosystems) store large carbon stocks. However, their regional carbon inventories, sequestration rates, and potential as natural climate change mitigation strategies are poorly constrained. Here, we systematically review organic carbon storage and accumulation rates in vegetated coastal ecosystems across the Central and Southwestern Atlantic, extending from Guyana (08.28°N) to Argentina (55.14°S). We estimate that 0.4 Pg organic carbon is stored in the region, which is approximately 2-5% of global carbon stores in coastal vegetated systems, and that they accumulate 0.5 to 3.9 Tg carbon annually. By ecosystem type, mangroves have the largest areal extent and contribute 70-80% of annual organic carbon accumulation, with Brazil hosting roughly 95% of mangrove stocks. Our findings suggest that organic carbon accumulation in the region is equivalent to 0.7 to 13% of global rates in vegetated coastal ecosystems, indicating the importance of conserving these ecosystems as a nature-based approach for mitigating and adapting to climate change.

NPP Variability Associated with Natural and Anthropogenic Factors in the Tropic of Cancer Transect, China

The regions near the Tropic of Cancer are a latitudinal geographical zone with typical climatic, topographic, and human landscape features. It is necessary to explore the region’s net primary productivity (NPP) dynamics as it combines complex topography, various vegetation types, and intense human activities. The study sets the transect near the Tropic of Cancer (TCT) and uses the Carnegie–Ames–Stanford (CASA) model to estimate the NPP from 2000 to 2020. After using the RESTREND method, the paper calculates and compares the relative contributions of climate variability and anthropogenic activities to NPP changes. Finally, the geographical detector (Geodetector) model is applied to evaluate how anthropogenic and natural factors affect spatial distribution patterns and NPP changes. The results indicated that the average annual NPP is 820.39 gC·m−2·yr−1 during the 21 years. In addition, when the NPP varies, it increases over the entire study area, with a slope of 4.81 gC·m−2·yr−1, particularly in the western region. Across the entire research area, 63.39% and 77.44% of the total pixels positively contribute to climate variability and human activities in NPP, with a contribution of 0.90 and 3.91 gC·m−2·yr−1, respectively. Within the western, central, and eastern regions, anthropogenic activities have a stronger impact on NPP than climate variability, particularly pronounced in the eastern region. Furthermore, vegetation cover is the dominant factor in the spatial patterns and NPP trends across the TCT and the three regions. In contrast, climate factors are shown to be less influential in NPP distribution than in the western region. The results also demonstrated that the effect of population density and the GDP on NPP gradually rises. Two-factor interaction is much larger than any individual factor, with the dominant interaction factor being vegetation cover with climatic factors. Lastly, the findings revealed that anthropogenic activities positively promote NPP accumulation across the TCT, thus highlighting the importance of human activity-led ecological restoration and ecological protection measures that contribute to regional carbon sequestration and carbon balance.

Spatial and temporal variations of net ecosystem productivity in Xinjiang Autonomous Region, China based on remote sensing.

Net ecosystem productivity (NEP), which plays a key role in the carbon cycle, is an important indicator of the ecosystem's carbon budget. In this paper, the spatial and temporal variations of NEP over Xinjiang Autonomous Region, China from 2001 to 2020 were studied based on remote sensing and climate re-analysis data. The modified Carnegie Ames Stanford Approach (CASA) model was employed to estimate net primary productivity (NPP), and the soil heterotrophic respiration model was used to calculate soil heterotrophic respiration. Then NEP was obtained by calculating the difference between NPP and heterotrophic respiration. The annual mean NEP of the study area was high in the east and low in the west, high in the north and low in the south. The 20-year mean vegetation NEP of the study area is 128.54 gC·m-2, indicating that the study area is a carbon sink on the whole. From 2001 to 2020, the annual mean vegetation NEP ranged between 93.12 and 158.05 gC·m-2, and exhibited an increasing trend in general. 71.46% of the vegetation area showed increasing trends of NEP. NEP exhibited a positive relationship with precipitation and a negative relationship with air temperature, and the correlation with air temperature was more significant. The work reveals the spatio-temporal dynamics of NEP in Xinjiang Autonomous Region and can provide a valuable reference for assessing regional carbon sequestration capacity.