Changes In Carbon Stocks Research Articles

Quantifying forest stocking changes in Sundarbans mangrove using remote sensing data

The Sundarbans, the world's largest mangrove ecosystem, faces significant challenges from forest stocking changes due to natural and anthropogenic factors. Scientific studies on these changes are not available. This study uses remote sensing techniques to quantify long-term changes in mangrove forest canopy height, aboveground biomass (AGB), and forest carbon stocks. Shuttle Radar Topography Mission (SRTM) and Global Ecosystem Dynamics Investigation (GEDI) LiDAR data sets. We assessed canopy height and forest stocking changes, and changes in AGB carbon fluxes over the last two decades in the Sundarbans mangrove. Calibrated SRTM data provided tree canopy height (TCH) estimates for 2000, while calibrated GEDI LiDAR data facilitated assessments of TCH for 2023. The findings show substantial changes in TCH, AGB, and carbon stock distribution in the Sundarbans mangrove between 2000 and 2023. TCH in the 5-10 m class notably increased from 58.3% in 2000 to 70.8% in 2023, while TCH above 15 m decreased, and those under 5 m regrew. Higher AGB carbon classes (>50 tons ha⁻1) decreased, with only the lowest class (<50 tons ha⁻1) increasing, indicating notable forest carbon stock reduction due to deforestation and forest degradation. Approximately 1571 Kt of AGB carbon were lost over 23 years, around 4% of the total stock. The driving forces of forest stocking changes could be changes in the dynamic energy balance from the estuarine river system and the tidal waves, relative sea-level change, increases of salinity in various zones of Sundarbans mangrove, other anthropogenic factors, etc. This research provides valuable insights into Sundarbans mangrove dynamics, aiding global forest degradation and forest growth in understanding forest stocking change and their role in terrestrial carbon flux and global climate change. The results will be helpful for the forest manager in identifying the locations where there is forest degradation or enhancement of forest growing stock and planning any silvicultural operations that are needed in the forest. This is also useful for climate change scientists to understand probable man-made or natural driving forces of the changes in forest stocking in the Sundarbans mangrove forests. It underscores the urgency of integrating deforestation and forest degradation into climate strategies for effective carbon management and conservation efforts, that align with carbon sequestration goals, contributing to broader climate change mitigation strategies.

Bulk density and coarse fragment content of the French soil monitoring network for better assessment of changes of soil organic carbon stocks

Bulk density (BD) and coarse fragments (CF) are often missing in soil monitoring networks. In the French Soil Quality Monitoring Network BD and CF have been measured in two campaigns in sites distributed in a grid over mainland France. The objective of this work is to evaluate i) how BD and CF have changed, ii) how volumetric methods and land use affect the observed trends, and iii) to simulate the impact of BD and CF changes on the estimations of changes of soil organic carbon stocks (SOCS). The results showed no significant change of (Δ) CF between campaigns in either the topsoil or subsoil, while there was a significant decrease of BD only in the topsoil (−3.1 ± 0.9 %). When methods were constant in both campaigns, BD decreased in croplands and grasslands topsoil and it did not change in forests. We could explain a rather low part of the ΔBD variance (R2 = 0.21), mostly linked to the within-site variability of CF and to changes in some methodological aspects between campaigns. We simulated changes in topsoil SOCS, assuming SOC content constant over time; we found negative estimates that were the largest in soils with low CF content (−0.2 ± 0.06 % yr−1 an-1) as well as differences between using site-specific average CF values over both campaigns and using site-specific values of each campaign [-0.17 ± 0.04 % yr−1 vs −0.05 ± 0.06 % yr−1, respectively]. These differences were caused by rocky soils, and were not significant when using only sites with low CF content. Our work highlights some limitations in assessing BD changes using broad-scale soil monitoring networks. These findings have important consequences on the methods used to assess changes in SOCS and their uncertainties at broad-scale. They are timely and relevant given the current proposals to implement soil health monitoring at national, continental and global scale.

Analyzing and Predicting LUCC and Carbon Storage Changes in Xinjiang’s Arid Ecosystems Under the Carbon Neutrality Goal

Land use/cover change (LUCC) significantly alters the carbon storage capacity of ecosystems with a profound impact on global climate change. The influence of land use changes on carbon storage capacity and the projection of future carbon stock changes under different scenarios are essential for achieving carbon peak and neutrality goals. This study applied the PLUS-InVEST model to predict the land use pattern in China’s arid Xinjiang Region in 2020–2050. The model assessed the carbon stock under four scenarios. Analysis of the historical LUCC data showed that the carbon storage in Xinjiang in 2000–2020 in five-year intervals was 85.69 × 108, 85.79 × 108, 85.87 × 108, 86.01 × 108, and 86.71 × 108 t. The rise in carbon sequestration capacity in the study area, attributable to the expansion of cropland, water, and unused land areas, brought a concomitant increment in the regional carbon storage by 1.03 × 108 t. However, prediction results for 2030–2050 showed that carbon storage capacity under the four scenarios would decrease by 0.11 × 108 and increase by 1.2 × 108, 0.98 × 108 t, and 1.28 × 108 t, respectively. The findings indicate that different land transfer modes will significantly affect Xinjiang’s carbon storage quantity, distribution, and trend. This research informs the past, present, and future of carbon storage in arid ecosystems of Xinjiang. It offers a reference for Xinjiang’s development planning and informs the efforts to achieve the carbon peak and neutrality goals.

Beyond MRV: Combining remote sensing and ecosystem modeling for geospatial monitoring and attribution of forest carbon fluxes over Maryland, USA

Abstract Members of the U.S. Climate Alliance, a coalition of 24 states committed to achieving the emissions reductions outlined in the 2015 Paris Agreement, are considering policy options for inclusion of forest carbon in climate mitigation plans. These initiatives are generally limited by a lack of relevant data on forest carbon stocks and fluxes past-to-future. Previously, we developed a new forest carbon modeling system that combines high-resolution remote sensing, field data, and ecological modeling to estimate contemporary above-ground forest carbon stocks, and projected future forest carbon sequestration potential for the state of Maryland. Here we extended this work to provide a consistent geospatial approach for monitoring changes in forest carbon stocks over time. Utilizing the same data and modeling system developed previously for planning, we integrated historical input data on weather and disturbance to reconstruct the history of vegetation dynamics and forest above-ground carbon stocks annually over the period 1984-2016 at 30 m resolution and provided an extension to 2023. Statewide, forested land had an average annual net above ground carbon sink of 1.37 TgC yr-1, comparable to prior estimates. However, unlike the prior estimates, there was considerable variation around this mean. The statewide net above ground flux ranged interannually from -0.65 - 2.77 Tg C yr-1. At the county scale, the average annual net above ground flux ranged spatially from 0.01 - 0.13 Tg C yr-1 and spatiotemporally from -0.43 - 0.24 Tg C yr -1. Attribution analyses indicate the primary importance of persistent and regrowing forests, vegetation structure, local disturbance, and rising CO2 to the mean flux, and the primary importance of weather to the large-scale interannual variability. These results have important implications for state climate mitigation planning, reporting and assessment. With this approach, it is now possible to monitor changes in forest carbon stocks spatiotemporally over policy relevant domains with a consistent framework that is also enabled for future planning.

Soil organic carbon stocks as driven by land use in Mato Grosso State: the Brazilian Cerrado agricultural frontier

To address national and global demand for agro-based products, agricultural expansion has rapidly become a norm in Brazil since 1950s to date. In recent decades, agricultural expansion and technological advancement have placed the country among the top producers and exporters of agricultural products. The paradigm shifts in farming system from conventional to integrated approach has brought significant changes in land use, which consequently influenced carbon sequestration and soil organic carbon (SOC). This is more prevalent in the State of Mato Grosso, one of the most producers of food in Brazil. On this background, we hypothesized that though forests have potential for SOC stock, which decreases due to conversion to cropland but in longer-term with sustainable management, carbon might accrual significantly in cropland. Therefore, this paper aimed to unveil the nexus between long term land use and carbon stock changes and estimate future SOC stocks in Mato Grosso State of Brazil. To achieve this aim, a hybridization of machine learning and the InVEST prediction models was applied to estimate the land use changes and the SOC stocks between 1990 and 2020 and estimate for 2050. The study revealed that between 1990, 2020, and 2050, croplands increased significantly by at least 78%, pastures decreased by 32%, while forests decreased marginally by about 4% due to agricultural expansions. However, in 1990 and 2020, the SOC stock was slightly up to 147.34 Mg ha−1, it recorded an increase after a longer-time (i.e., in 2050). This increase was substantially under the forests, and marginally in the croplands. Climate-smart agricultural systems such as crop-livestock forest, integrated crop-livestock, and other conservation agricultural practices have great potential to contribute to sustainable development by increasing the levels of carbon in agricultural soils especially, after a longer period. Therefore, agricultural policies geared towards low carbon agriculture should be fully integrated into the various government decision making processes as this will guarantee food security and maximize soil carbon sequestration and stocks in the long term. Simultaneously, it is crucial to promote the dissemination of best practices for implementing and sustaining conservation efforts, thereby safeguarding the carbon stocks established to prevent their depletion. This will also support the Brazilian government in achieving its Nationally determined contributions (NDCs) through agricultural soils.

Higher temperature accelerates carbon cycling in a temperate montane forest without decreasing soil carbon stocks

Global warming is expected to accelerate the cycling of soil organic carbon (SOC) and the assimilation of new carbon, but the net effect of those counteracting accelerations and their ultimate effects on SOC are still uncertain. This hinders the prediction of long-term changes in biospheric carbon stocks and SOC-climate feedbacks. Here, we studied the long-term effect of temperature on carbon cycling across a 3.2 °C altitudinal temperature gradient in a temperate forest ecosystem in New Zealand. Across the gradient, soil respiration rates increased with increasing temperature from 9.0 to 10.4 tC ha−1 yr−1, but SOC stocks down to 85 cm depth also tended to increase, from 154 to 176 tC ha−1, albeit non-significantly (P = 0.06). This system was able to maintain higher soil respiration rates at higher temperatures without reducing SOC because the higher respiration rates were sustained by higher litterfall rates. Aboveground litterfall increased from 1.8 to 2.4 tC ha−1 yr−1 and estimated belowground C inputs increased from 7.2 to 8.0 tC ha−1 yr−1 along the temperature gradient. These higher fluxes were associated with significantly (P < 0.05) increased biomass at higher temperatures. As a direct measure of the effect of temperature on carbon cycling processes, we also calculated the turnover rate of forest litter which increased about 1.4-fold across the temperature gradient. This study demonstrates that higher temperatures along the thermal gradient increased plant carbon inputs through enhanced gross primary production, which counteracted SOC losses through temperature-enhanced soil respiration. These results suggest that temperature sensitivities of both plant carbon inputs and SOC losses must be considered for predicting SOC-climate feedbacks.

Analysing the Driving Forces of Carbon Stock Change for Climate Change Mitigation

Analysing the Driving Forces of Carbon Stock Change for Climate Change Mitigation

Thinning Impacts on Carbon and Water Budgets in a Temperate Deciduous Forest Ecosystem

Among various forest management activities, thinning is a prevalent treatment that affects tree growth and living biomass. Increased moisture and light availability may also enhance the mineralization of litter and dead wood organic matter, impacting soil carbon stocks. Thinning may also affect the services forests provide, including water production and nutrient cycling. The impacts of thinning on water yield and carbon stocks have been well documented around the globe while targeting mainly one of these ecosystem services. Our experimental paired catchment study covers both and puts forward long term results. We assessed the carbon stock changes caused by two slight thinning treatments together with the impacts on water yield in experimental paired catchments of 71.9 (W–I) and 77.5 hectares (W–IV) in Istanbul, Türkiye. The null hypothesis was that the slight thinnings did not affect the water yield and carbon stocks significantly. On the carbon stock part, we calibrated and parametrized the CBM–CF3 model with field measurements to simulate changes in carbon stocks of mixed deciduous forest stands. The intensities of the treatments (thinnings) were 11% and 18% of the basal area, performed in 1986 and 2011, respectively. We found that, while C stocks decreased by around 30 tons per hectare during the 1986–2020 period, the water yield was enhanced by approximately 25 mm/yr in the treatment catchment compared to the control watershed during the four-year post-treatment period. This amount of streamflow increase was around 10 percent of the average water yield of the catchments. It was concluded that there was a detectable increase in water yield during the following four years of the slight thinning treatments, while the reduction in abovegound carbon stocks continued for more than three decades.

Spatiotemporal Pattern Analysis and Prediction of Carbon Storage Based on Land Use and Cover Change: A Case Study of Jiangsu Coastal Cities in China

Accurate estimation of terrestrial ecosystem carbon storage and the scientific formulation of ecological conservation and land use policies are essential for promoting regional low-carbon sustainable development and achieving the goal of “carbon neutrality.” In this study, the FLUS–InVEST model was used to evaluate the carbon stocks of the Jiangsu coastal zone in China from 1995 to 2020 and scientifically forecast the changes in carbon stocks in 2030 under three scenarios: natural exploitation, ecological protection, and economic development. The results are as follows: (1) From 1995 to 2020, carbon storage in the coastal zone initially remained stable before declining, a trend closely linked to the accelerated urbanization and economic growth of Jiangsu Province. (2) By 2030, carbon storage under the three scenarios exhibits a pattern of “S1 decrease–S2 increase–S3 decrease,” with a more significant increase in construction land under the natural development and economic development scenarios compared to the ecological protection scenario. (3) The sensitivity of carbon storage to land use changes varies across scenarios. In the natural development scenario, carbon storage is most affected by forest reduction and construction land expansion. In the ecological protection scenario, it is more responsive to increases in non-construction land. In the economic development scenario, the expansion of construction land leads to the most significant decrease in carbon storage. Therefore, when formulating future territorial spatial planning policies and urban development strategies, it is essential to consider ecological protection and economic development scenarios comprehensively, taking into account carbon sequestration capabilities. This approach will ensure effective conservation and restoration of damaged ecosystems while safeguarding the robust development of urban economies and societies.

A bibliometric analysis of 100 years of research on Himalayan cedar: research trends, gaps, and future implications

Himalayan Cedar (Cedrus deodara), a member of the family Pinaceae is well-known for its ecological, economic, and cultural significance. It is native to the Western Himalayan region and listed as Least Concern in the IUCN list of threatened species. In the present study, a bibliometric analysis of more than a hundred years of research on C. deodara is carried out. Total 616 documents published from 1916 to 2024 were retrieved from the Scopus database and analyzed using biblioshiny and VoS viewer. A comprehensive overview of publication trends, country-wise publications, bibliographic coupling, citation analysis, keyword analysis, and collaborative research networks are presented. The research findings revealed that publications have increased significantly in recent decades and primarily multidisciplinary. Forest ecology, pharmacology, phytochemistry, climate change, environmental science, and taxonomy were among the major thrust areas. However, recent studies are mostly focused on carbon stock, biomass, dendrochronology, and climate change. Out of the 362 publication sources, Bradford’s law identified six journals as core sources for publication. Lotka’ law revealed that only 8% of authors have published more than two documents on C. deodara. The present study provides a comprehensive evaluation and visualization of C. deodara based bibliometric research carried out during the past 100 years. Further, the study provides collective information and a research framework for scholars, the general public, and decision-makers by identifying research gaps and future research areas.

Multi-Scenario Simulation of Land Use and Assessment of Carbon Stocks in Terrestrial Ecosystems Based on SD-PLUS-InVEST Coupled Modeling in Nanjing City

In the context of achieving the goal of carbon neutrality, exploring the changes in land demand and ecological carbon stocks under future scenarios at the urban level is important for optimizing regional ecosystem services and developing a land-use structure consistent with sustainable development strategies. We propose a framework of a coupled system dynamics (SD) model, patch generation land-use simulation (PLUS) model, and integrated valuation of ecosystem services and trade-offs (InVEST) model to dynamically simulate the spatial and temporal changes of land use and land-cover change (LUCC) and ecosystem carbon stocks under the NDS (natural development scenario), EPS (ecological protection scenario), RES (rapid expansion scenario), and HDS (high-quality development scenario) in Nanjing from 2020 to 2040. From 2005 to 2020, the expansion rate of construction land in Nanjing reached 50.76%, a large amount of ecological land shifted to construction land, and the ecological carbon stock declined dramatically. Compared with 2020, the ecosystem carbon stocks of the EPS and HDS increased by 2.4 × 106 t and 1.5 × 106 t, respectively, with a sizable ecological effect. It has been calculated that forest and cultivated land are the two largest carbon pools in Nanjing, and the conservation of both is decisive for the future carbon stock. It is necessary to focus on enhancing the carbon stock of forest ecosystems while designating differentiated carbon sink enhancement plans based on the characteristics of other land types. Fully realizing the carbon sink potential of each ecological functional area will help Nanjing achieve its carbon neutrality goal. The results of the study not only reveal the challenges of ecological conservation in Nanjing but also provide useful guidance for enhancing the carbon stock of urban terrestrial ecosystems and formulating land-use planning in line with sustainable development strategies.

Characteristics of Spatial and Temporal Changes in Carbon Stocks in the Middle and Upper Reaches of the Huaihe River Basin and Future Multi-scenario Simulation Prediction

The Huaihe River Basin is located in the north-south climate transition zone of China. The change of carbon storage in this area is of great significance for predicting the future ecological protection, mitigating climate change, and maintaining sustainable development of the Huaihe River Basin. The middle and upper reaches of Huaihe River Basin （above Bengbu station） were taken as the research area. Based on the land use data from 1980 to 2020, the PLUS model was used to simulate and predict the land use types in the study area from 2030 to 2100 under the scenarios of SSP1-2.6, SSP2-4.5, SSP5-8.5, and the continuation of land use status. The carbon module in the InVEST model was used to simulate and predict the carbon storage from 1980 to 2020 and the carbon storage from 2030 to 2100 under various scenarios, and the spatial and temporal changes of carbon storage in the middle and upper reaches of the Huaihe River Basin were compared and analyzed. The results showed that： ① From 1980 to 2020, the basin showed a decrease in both cultivated land and grassland,and the area of forest,water, construction, and unused land all increased, among which the area of cultivated land continued to decrease, with a total decrease of 4 699 km2 in 40 a. Construction land continued to increase, with a total increase of 4 592 km2 in 40 a. ② The carbon storage in the basin showed a downward trend, with a total reduction of 1.05×107 t from 1980 to 2020. ③ In the four scenarios, the area of each land type had different degrees of change, and that of the SSP1-2.6 scenario was relatively small out of the four scenarios. ④ Compared with the carbon storage in 2020, the carbon storage in the SSP1-2.6 scenario increased by 8.7×104 t, the carbon storage in the SSP2-4.5 scenario decreased by 1.42×107 t, the carbon storage in the SSP5-8.5 scenario decreased by 1.34×107 t, and the carbon storage in the current continuation scenario decreased by 1.22×107 t. The study can provide a scientific basis for land use structure management and ecological protection in the middle and upper reaches of the Huaihe River Basin （above Bengbu station） in the future.

Changes in soil organic carbon stocks and mineralization following the replacement of secondary evergreen broadleaf forests with tea (Camellia sinensis L.) plantations

AbstractTea plantation ecosystems have a strong potential to sequester carbon (C) and reduce CO2 emissions. However, the effects of different tea planting periods on soil organic carbon (SOC) stocks and mineralization and related mechanisms are unclear. To address this knowledge gap, we investigated the effects of replacing evergreen broadleaf forests with tea plantations on SOC stocks and mineralization rates by examining alterations in SOC pools and composition, microbial community composition, functional genes related to C‐cycling and enzyme activities. The SOC content in forest, 30‐, 50‐ and 100‐year‐old tea plantations were 1.91%, 2.37%, 2.87% and 3.69%, respectively, in the 0–20 cm soil depth (100‐year‐old &gt; 50‐year‐old &gt; 30‐year‐old &gt; forest). Cumulative CO2–C emissions increased by 38.1% (114 mg C kg−1 soil), 49.9% (157 mg C kg−1 soil), and 100.2% (171 mg C kg−1 soil) compared to forest soil (228 mg C kg−1 soil) after tea had been grown for 30, 50 and 100 years, respectively; however, cumulative CO2 emissions did not differ significantly between the 30‐ and 50‐year‐old plantations. The rate of SOC mineralization was positively related to particulate organic carbon (POC), water‐soluble organic carbon (WSOC), microbial biomass C (MBC), and O‐alkyl C contents, as well as β‐glucosidase/cellobiohydrolase activities and GH48/cbhI abundance; by contrast, the SOC mineralization rate was negatively correlated with the aromatic C content. More importantly, bacteria and fungi related to SOC mineralization, such as WPS‐2 and Acidobacteria, and Sordariomycetes, Tremellomycetes, Mortierellomycetes and Agaricomycetes, respectively, had high relative abundances. Our results indicate that replacing forests with tea plantations enhanced both SOC stocks and mineralization rates and that this effect was positively correlated with tea cultivation time. We reveal that an increased length of the tea planting period was conducive to increasing SOC stocks, and mitigating C losses in tea plantation soils is crucial for establishing an ecologically low‐C tea plantation system.

An Appraisal of the Potential of Sequestering Carbon through Pomegranate Orchards in India

Pomegranate is an important arid and semi-arid fruit crop of Indian origin. Land use change from agriculture to pomegranate orchards not only enhances farmers’ income but also helps in sequestering carbon and provides additional ecosystem services. Assessing carbon stocks and stock changes in fruit orchards is crucial under the United Nations Framework Convention on Climate Change and the Kyoto Protocol. In this context, we conducted a study to estimate carbon stocks in pomegranate orchards in India. We developed an exclusive allometric equation to estimate pomegranate tree biomass and collected extensive samples of trees, litter, weeds, and soil. We grouped pomegranate-growing areas by similarity in variety, soil, and climate, and then calculated the carbon held in these pools. Finally, we computed the carbon sequestered by pomegranates per hectare, providing valuable insights for climate change mitigation efforts. The national-level carbon storage in pomegranate orchards was then computed by multiplying the area occupied by pomegranate in these regions by the amount of carbon sequestered in one ha of land. Nearly 42.49 mt of carbon is sequestered in the pomegranate orchards of the country with 18.42 mt (43.36% of the total CS) stored in tree biomass and 24.1 mt (56.71% of the total CS) stored in soil. This study underscores the important role of pomegranate orchards in India, not only as a lucrative agro-economic venture for farmers but also as a significant contributor to carbon sequestration and overall ecosystem services. Such insights are essential for guiding sustainable land use practices and aligning agricultural efforts with global climate change mitigation strategies.

Predicting land cover changes and carbon stock fluctuations in Fuzhou, China: A deep learning and InVEST approach

Predicting the spatiotemporal dynamics of land cover and its carbon stock holds significant importance in guiding regional sustainable development, enhancing regional carbon stocks, and addressing global climate change. However, there is insufficient research on the quantitative relationships between various land cover types and carbon stock changes, as well as their future spatial predictions. Focusing on the core area of Fuzhou City, China, this study constructs a streamlined framework by coupling deep learning and the InVEST model to predict urban land cover and carbon stock changes in 2025 and 2035. The results show that: (1) The prediction model for land cover change has high applicability and can produce the simulated images with high accuracy. Impervious surface is expected to increase by 53 km2 in 2025 and 131 km2 in 2035 compared to 2020, resulting in considerable reductions in forest and cropland. (2) Carbon stocks of the study area are expected to decrease by 1.68 × 106t in 2035 compared to 2020 due to large amounts of high-carbon-density forests and croplands being converted into low-carbon-density impervious surfaces. (3) Multiple regression analysis reveals that forests have the largest impact on carbon stocks in the area, with a magnitude 5.25 times greater than impervious surfaces and 11.5 times greater than cropland, whereas impervious surfaces are the second most influential land cover type on carbon stock changes. Therefore, expanding forest areas becomes an essential initiative as forests could offset the carbon stock loss caused by impervious surface growth. This study provides scientific references for optimizing land-use planning and formulating policies for the development of low-carbon cities.

Soil carbon stock changes in a crop-livestock-forestry integration in Southern Goiás State, Brazil

Soil carbon stock changes in a crop-livestock-forestry integration in Southern Goiás State, Brazil

A global analysis of the effects of forest thinning on soil N stocks and dynamics

Forest thinning is a critical management measure for changing the forest community structure and improving the soil microclimate and nitrogen (N) cycle. However, differences in forest types, thinning intensity, recovery time, and climate conditions make the accumulation of soil N under forest thinning uncertain; especially the soil N accumulation rate is still lacking. This study systematically discusses the effects of forest thinning on the rate of soil N stock change (RNC) and analyzes the relationship between the RNC and the rate of soil carbon (C) stock change (RCC) by synthesizing 387 global data points. Forest thinning significantly increased the soil N stock, with the RNC being +0.07 Mg/ha yr−1. The RNCs in coniferous and mixed forests (+0.07 and +0.09 Mg/ha yr−1, respectively) were higher than that in broadleaf forest (−0.03 Mg/ha yr−1). Heavy forest thinning inhibited soil N accumulation; however, light forest thinning and long-term recovery were more conducive to improving it. The RNC decreased with increasing precipitation and temperature under forest thinning. Additionally, the RNC was positively correlated with the RCC. Overall, heavy forest thinning decreases the soil N accumulation rate in the global forest ecosystem; conversely, long-term recovery increases it. Reducing the forest thinning intensity and extending the recovery time can accelerate soil N accumulation and thus reduce greenhouse gas emissions.

Analysis of Temporal and Spatial Carbon Stock Changes and Driving Mechanism in Xinjiang Region by Coupled PLUS-InVEST-Geodector Model

Based on the goal of "dual-carbon" strategy, it is important to explore the impacts of land use change on carbon stock and the drivers of spatial differentiation of carbon stock in Xinjiang. Here, we predicted the land use types in Xinjiang in 2035 under different scenarios and analyzed the impacts of land use on carbon stock, which is of great theoretical and practical importance for policy formulation, land use structure adjustment, and carbon neutrality target achievement in Xinjiang. The coupled PLUS-InVEST-Geodector model was used to explore the spatial and temporal patterns of carbon stock change under the scenarios of rapid development, natural change, arable land protection, and ecological protection in Xinjiang in 2035 and to quantitatively reveal the attribution of influences on the changes in carbon stock from the perspectives of land use change and the combination of nature-socioeconomic-accessibility. The results showed that： ① From 1990 to 2020, the area of arable land and construction land in Xinjiang increased, and in terms of the transfer direction, it was mainly shifted from unutilized land to grassland. ② On the time scale, the carbon stock in Xinjiang showed the fluctuation of "decrease-increase-decrease," with an overall increasing trend. The transfer of unutilized land to grassland was the main reason for the increase in carbon stock； on the spatial scale, the carbon stock in the Altai Mountains in the north, the Tianshan Mountains in the middle, and the Kunlun Mountains in the south was higher, whereas the carbon stock in the Tarim Basin and the Junggar Basin was lower. ③ In 2035, the carbon stock of the natural development and rapid development scenarios decreased by 27.24 Tg and 71.17 Tg compared with 2020, respectively, and the ecological protection and arable land protection scenarios increased by 492.55 Tg and 46.67 Tg. The ecological protection scenario could significantly increase the carbon stock of the Xinjiang Region compared with that in the other scenarios, and the distribution pattern of the carbon stock in the four scenarios was more or less the same as that in 2020. In addition to land transformation, soil erosion intensity was the main driver of spatial differentiation of carbon stocks in Xinjiang （q value of 0.3501）, followed by net primary productivity of vegetation. The results of multifactor interactions showed that the spatial differentiation of carbon stocks in Xinjiang was the result of the joint action of multiple factors. All the factors had a synergistic enhancement under the interactions. The interaction between soil erosion intensity and the net primary productivity of vegetation was the main driver of the spatial differentiation of carbon stocks in Xinjiang.

Abandonment Leads to Changes in Forest Structural and Soil Organic Carbon Stocks in Moso Bamboo Forests.

The important role of soil carbon pools in coping with climate change has become widely recognized. Moso bamboo (Phyllostachys pubescens) is an economically important bamboo species in South China; however, owing to factors such as rising labor costs and increasingly stringent environmental policies, Moso bamboo forests have recently been abandoned. The present study aimed to investigate the effects of abandonment on structural factors and soil organic carbon (SOC) stocks in Moso bamboo forests. We investigated Moso bamboo forests subjected to intensive management or abandonment for different durations and measured forest structural characteristics, mineral properties, soil nutrients, and other soil properties. Although abandonment did not significantly affect the height and diameter at breast height, it increased culm densities, biomass, and SOC stocks. The drivers of SOC stocks depended on soil depth and were mainly controlled by carbon decomposition mediated by soil properties. In the topsoil, mineral protection and soil total nitrogen (TN) exerted significant effects on SOC stocks; in the subsoil, soil TN was the main driver of SOC stocks. As the controlling factors of SOC stocks differed between the subsoil and topsoil, more attention should be paid to the subsoil. Overall, these findings refine our understanding of the structural characteristics and SOC stocks associated with Moso bamboo forest abandonment, serving as a reference for the follow-up management of these forests.

Insights into effects of conventional and biodegradable microplastics on organic carbon decomposition in different soil aggregates

The impacts of microplastics on soil ecological functions such as carbon recycling and soil structure maintenance have been extensively focused. However, the mechanisms underlying the impacts of microplastics on soil carbon transformation and soil microbial community at soil aggregate scale have not been clarified yet. In this work, the effects and action mechanisms of traditional microplastic polypropylene (PP) and degradable microplastic polylactic acid (PLA) on carbon transformation in three sizes of soil aggregates were investigated. The results showed that both PP and PLA promoted CO2 emission, and the effect depended on the type and content of microplastics, and the size of soil aggregates. Changes in soil carbon stocks were mainly driven by changes in organic carbon associated with macroaggregates. For macroaggregates, PP microplastics decreased soil organic carbon (SOC) as well as dissolved organic carbon (DOC). These changes were reversed in microaggregates and silt and clay. Interestingly, PLA increased the SOC, DOC and CO2 emissions in bulk soil and all three aggregates with a dose-effect response. These changes were associated with soil microbes, functional genes and enzymes associated with the degradation of labile and recalcitrant carbon fractions. Furthermore, PP and PLA reduced bacterial community diversities and shifted bacterial community structures in both the three aggregates and in bulk soil. Alterations of functional genes induced by microplastics were the key driving factors of their impacts on carbon transformation in soil aggregates. This research opened up a new insight into the mechanisms underlying the impacts of microplastics on soil carbon transformation, and helped us make rational assessments of the risks and the disturbances of microplastics on soil carbon cycling.