Search Results (105)

This study investigates the spatial heterogeneity of carbon pools in young Betula sp. stands on former arable lands in the southern Moscow region, Russia. The findings could be useful for the current estimates and predictions of the carbon balance in such forest ecosystems. The research focuses on understanding the interactions between plant cover and the environment, i.e., how environmental factors such as stand density, tree diameter and height, light conditions, and soil properties affect ecosystem carbon pools. We also studied how heterogeneity in edaphic conditions affects the formation of plant cover, particularly tree regeneration and the development of ground layer vegetation. Field measurements were conducted on a permanent 50 × 50 m sampling plot divided into 5 × 5 m subplots, in order to capture variability in vegetation and soil characteristics. Key findings reveal significant differences in carbon stocks across subplots with varying stand densities and light conditions. This highlights the role of the spatial heterogeneity of soil properties and vegetation cover in carbon sequestration. The study demonstrates the feasibility of indirect estimation of carbon stocks using stand parameters (density, height, and diameter), with results that closely match direct measurements. The total ecosystem carbon stock was estimated at 80.47 t ha⁻¹, with the soil contribution exceeding that of living biomass and dead organic matter. This research emphasizes the importance of accounting for spatial heterogeneity in carbon assessments of post-agricultural ecosystems, providing a methodological framework for future studies. Full article

Soil organic carbon (SOC) pool plays an extremely important role in regulating the global carbon (C) cycle and climate change. Atmospheric nitrogen (N) and phosphorus (P) deposition caused by human activities has significant impacts on soil C sequestration potential of terrestrial ecosystem. To investigate the effects of N and P deposition on soil C sequestration and C-N coupling relationship in broad-leaved evergreen forests, a 6-year field nutrient regulation experiment was implemented in subtropical Castanopsis sclerophylla forests with four different N and P additions: N addition (100 kg N·hm⁻²·year⁻¹), N + P (100 kg N·hm⁻²·year⁻¹ + 50 kg P·hm⁻²·year⁻¹), P addition (50 kg P·hm⁻²·year⁻¹), and CK (0 kg N·hm⁻²·year⁻¹). The changes in the C and N contents and stable isotope distributions (δ¹³C and δ¹⁵N) of different soil organic fractions were examined. The results showed that the SOC and total nitrogen (STN) (p > 0.05) increased with N addition, while SOC significantly decreased with P addition (p < 0.05), and N + P treatment has low effect on SOC, STN (p > 0.05). By density grouping, it was found that N addition significantly increased light fraction C and N (LFOC, LFN), significantly decreased the light fraction C to N ratio (LFOC/N) (p < 0.05), and increased heavy fraction C and N (HFOC, HFN) accumulation and light fraction to total organic C ratio (LFOC/SOC, p > 0.05). Contrary to N addition, P addition was detrimental to the accumulation of LFOC, LFN and reduced LFOC/SOC. It was found that different reactive oxidized carbon (ROC) increased under N addition but ROC/SOC did not change, while N + P and P treatments increased ROC/SOC, resulting in a decrease in SOC chemical stability. Stable isotope analysis showed that N addition promoted the accumulation of new soil organic matter, whereas P addition enhanced the transformation and utilization of C and N from pre-existing organic matter. Additionally, N addition indirectly increased LFOC by significantly decreasing pH; significantly contributed to LFOC and ROC by increasing STN accumulation promoted by NO₃⁻-N and NH₄⁺-N; and decreased light fraction δ¹³C by significantly increasing dissolved organic C (p < 0.05). P addition had directly significant negative effect on LFOC and SOC (p < 0.05). In conclusion, six-year N deposition enhances soil C and N sequestration while the P enrichment reduces the content of soil C, N fractions and stability in Castanopsis sclerophylla forests. The results provide a scientific basis for predicting the soil C sink function of evergreen broad-leaved forest ecosystem under the background of future climate change. Full article

Soil organic carbon (SOC) is an important part of the global C pool and is sensitive to climate change. The SOC content and fractions of rice paddies along four elevations (250, 1150, 1600 and 1800 m) on the same slope in four seasons (spring, summer, autumn and winter) at Yuanyang Terrace in southwest China were investigated, and their relationship with environmental factors was analyzed. The contents of SOC, unprotected SOC (uPOM), physically protected SOC (pPOM) and biochemically protected SOC (bcPOM) in rice paddies at a low elevation (250 m), were significantly lower by 49–51% than those at relatively high elevations (1600 m and 1800 m). Among the SOC fractions, the highest proportion (33–50%) was uPOM, followed by pPOM and bcPOM (accounting for 17–40%), and the lowest proportion was chemically protected SOC (cPOM). In addition, there were interseasonal differences among the contents of SOC fractions, with a significantly higher content of SOC, uPOM and pPOM at an elevation of 1600 m in summer than in the other three seasons, whereas the cPOM content at an elevation of 250 m in spring was significantly higher than in the other three higher elevations. According to the redundancy analysis (RDA), total nitrogen was the key environmental factor, with an explanatory degree of 56% affecting the contents of SOC and its fractions. Thus, the SOC content increased with increasing elevation, and physical and biochemical protection were potential stabilization mechanisms responsible for their stability in the rice paddy of Yuanyang Terrace. These results provides empirical evidence for the elevational distribution patterns and seasonal dynamics of SOC fractions in rice paddies across Yuanyang Terrace. These findings highlight the importance of physical and biochemical protection mechanisms in stabilizing SOC in rice paddies, which could enhance long-term C sequestration and contribute to climate change mitigation in terraced agroecosystems. Full article

Soil degradation exerts profound impacts on soil ecological functions, global food security, and human development, making the development of effective technologies to mitigate degradation a critical research focus. Microorganisms play a leading role in rehabilitating degraded land, improving soil hydraulic properties, and enhancing soil structural stability. Mosses contribute to soil particle fixation through their unique rhizoid structures; however, the mechanisms underlying their interactions in mixed inoculation remain unclear. Therefore, this study addresses soil and water loss caused by rainfall erosion in the cold black soil region. We conducted controlled laboratory experiments cultivating Bacillus subtilis and cold-adapted moss species, evaluating the erosion mitigation effects of different biological treatments under gradient slopes (3°, 6°, 9°) and rainfall intensities (70 mm h⁻¹, 120 mm h⁻¹), and elucidating their carbon-based structural reinforcement mechanism. The results indicated that compared to the control group, Treatment C significantly increased the mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates by 121.6% and 76.75%, respectively. In separate simulated rainfall events at 70 mm h⁻¹ and 120 mm h⁻¹, Treatment C reduced soil loss by 95.70% and 96.75% and decreased runoff by 38.31% and 67.21%, respectively. Crucially, the dissolved organic carbon (DOC) loss rate in Treatment C was only 21.98%, significantly lower than that in Treatment A (32.32%), Treatment B (22.22%), and the control group (51.07%)—representing a 59.41% reduction compared to the control. This demonstrates the following: (1) Bacillus subtilis enhances microbial metabolism, driving carbon conversion into stable pools, while mosses reduce carbon leaching via physical barriers, synergistically forming a dual “carbon protection–structural reinforcement” barrier. (2) The combined inoculation optimizes soil structure by increasing the proportion of large soil particles and enhancing aggregate stability, effectively suppressing soil loss even under extreme rainfall erosion. This study elucidates, for the first time, the biological pathway through which microbe–moss interactions achieve synergistic carbon sequestration and erosion resistance by regulating aggregate formation and pore water dynamics. It provides a scalable “carbon–structure”-optimized biotechnology system (co-inoculation of Bacillus subtilis and moss) for the ecological restoration of the cold black soil region. Full article

Visible and near-infrared (Vis–NIR) spectroscopy enables the rapid prediction of soil properties but faces three limitations with conventional machine learning: information loss and overfitting from high-dimensional spectral features; inadequate modeling of nonlinear soil–spectra relationships; and failure to integrate multi-scale spatial features. To address these challenges, we propose ReSE-AP Net, a multi-scale attention residual network with spatial pyramid pooling. Built on convolutional residual blocks, the model incorporates a squeeze-and-excitation channel attention mechanism to recalibrate feature weights and an atrous spatial pyramid pooling (ASPP) module to extract multi-resolution spectral features. This architecture synergistically represents weak absorption peaks (400–1000 nm) and broad spectral bands (1000–2500 nm), overcoming single-scale modeling limitations. Validation on the LUCAS2009 dataset demonstrated that ReSE-AP Net outperformed conventional machine learning by improving the R² by 2.8–36.5% and reducing the RMSE by 14.2–69.2%. Compared with existing deep learning methods, it increased the R² by 0.4–25.5% for clay, silt, sand, organic carbon, calcium carbonate, and phosphorus predictions, and decreased the RMSE by 0.7–39.0%. Our contributions include statistical analysis of LUCAS2009 spectra, identification of conventional method limitations, development of the ReSE-AP Net model, ablation studies, and comprehensive comparisons with alternative approaches. Full article

Reasonable nitrogen fertilizer management and cultivation methods can enhance the nitrogen supply and carbon sequestration capabilities of soil, which is beneficial for meeting the growth requirements of crops and alleviating environmental issues. However, the existing research on optimizing nitrogen use efficiency and soil carbon sequestration in organic systems remains limited. Therefore, a field trial was conducted to elucidate the impacts of different cultivation patterns and nitrogen application rates on soil carbon and nitrogen pools, especially on how these factors affect the components of soil organic carbon. The treatments included conventional cultivation with low nitrogen treatment (CFN12), conventional cultivation with high nitrogen treatment (CFN18), organic cultivation with low nitrogen treatment (OFN12), and organic cultivation with high nitrogen treatment (OFN18). The results demonstrated that, relative to CFN18, OFN12 significantly increased the accumulation amounts of organic carbon and nitrogen in paddy soil. This was evident under multiple classifications of organic carbon, while it showed no advantage in the accumulation of mineral nitrogen. Notably, the organic cultivation mode increased the activities of enzymes involved in the carbon–nitrogen cycle in the cultivated layer and optimized the structure of humus, which gave the proportion of aggregates with a particle size greater than 0.5 mm more advantages. Correlation analysis demonstrated that the pertinent indices associated with soil carbon and nitrogen pools exhibited a highly significant positive correlation in the topsoil layer, accompanied by pronounced synergistic interactions among them. The PCA comprehensive scoring results indicate that OFN12 has the highest total score, indicating that it is beneficial for the improvement of soil fertility. This study offers practical insights for improving soil health, boosting plant growth, and enhancing climate mitigation through soil carbon storage, contributing to more sustainable agricultural practices. Full article

Ecological restoration has increasingly been employed to reverse land degradation and increase carbon (C) sink, especially in ecologically fragile karst areas. Microbial necromass carbon (MNC) constitutes a critical pool within soil organic carbon (SOC), contributing substantially to long-term C sequestration through mineral stabilization. However, its distribution patterns across soil profiles and grassland restoration stages in karst areas remain unclear. To address this knowledge gap, the contents of bacterial necromass C (BNC), fungal necromass C (FNC), and their contributions to SOC were estimated based on glucosamine and muramic acid contents across the soil profile (0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, and 80–100 cm) for four subalpine restoration stages (grazing enclosure for 5, 11, 17, and 25 years) in the karst region. Our findings demonstrated that both soil depth and grassland restoration stages effectively influenced the BNC and FNC contents. On average, the soil BNC, FNC, and total MNC at the depth of 80–100 cm reduced by 70.50%, 59.70%, and 62.18% compared with in topsoil (0–20 cm), respectively. However, the FNC/BNC ratio gradually increased with the increase in soil depth, which was 43.15% higher at 80–100 cm soil depth than in topsoil, suggesting that the accumulation efficiency of FNC was higher compared to BNC in the deep soil. The BNC, FNC, and MNC were positively correlated with the grassland restoration stage, while FNC/BNC ratio had a negative relationship with the restoration stage (R² = 0.45, p < 0.001). FNC contributed significantly more to SOC (28.6–36.4%) compared to BNC (7.7–9.9%) at all soil depths, indicating that soil fungal necromass has an essential effect on SOC sequestration. The results of the random forest model and distance-based redundancy analysis identified that pH, soil water content, and dissolved organic carbon were the three most essential predictors for the contribution of MNC to SOC. Our study highlights the importance of microbial necromass to SOC accumulation, providing significant scientific implications for the C pool management during the restoration of degraded grasslands in karst regions. Full article

The integration of manure and straw substantially affects soil organic carbon (SOC) dynamics, transformation, and long-term stabilization in agricultural systems. Dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MOC) are the three main components of the SOC pool, each influencing soil carbon dynamics and nutrient cycling. Current research gaps remain regarding how combined fertilization practices affect the inputs of plant-originated and microbe-derived carbon into SOC pools and stability mechanisms. Our investigation measured SOC fractions (DOC, POC, MOC), SOC mineralization rate (SCMR), microbial necromass carbon, lignin phenols, enzyme activities, and microbial phospholipid fatty acids (PLFAs) over a long-term (17 years) field experiment with four treatments: mineral fertilization alone (CF), manure-mineral combination (CM), straw-mineral application (CS), and integrated manure-straw-mineral treatment (CMS). The CMS treatment exhibited notably elevated levels of POC (7.42 g kg⁻¹), MOC (10.7 g kg⁻¹), and DOC (0.108 g kg⁻¹), as well as a lower SCMR value (1.85%), compared with other fertilization treatments. Additionally, the CMS treatment stimulated the buildup of both bacterial and fungal necromass while enhancing the concentrations of ligneous biomarkers (vanillin, syringyl, and cinnamic derivatives), which correlated strongly with the elevated contents of fungal and bacterial PLFAs and heightened activity of carbon-processing enzymes (α-glucosidase, polyphenol oxidase, cellobiohydrolase, peroxidase, N-acetyl-β-D-glucosidase). Furthermore, fungal and bacterial microbial necromass carbon, together with lignin phenols, significantly contributed to shaping the composition of SOC. Through random forest analysis, we identified that the contents of bacterial and fungal necromass carbon were the key factors influencing DOC and MOC. The concentrations of syringyl phenol and cinnamyl phenols, and the syringyl-to-cinnamyl phenols ratio were the primary determinants for POC, while the fungal-to-bacterial necromass carbon ratio, as well as the concentrations of vanillyl, syringyl, and cinnamyl phenols, played a critical role in SCMR. In conclusion, the manure combined with straw incorporation not only promoted microbial growth and enzyme activity but also enhanced plant- and microbial-derived carbon inputs. Consequently, this led to an increase in the contents and stability of SOC fractions (DOC, POC, and MOC). These results suggest that manure combined with straw is a viable strategy for soil fertility due to its improvement in SOC sequestration and stability. Full article

Film mulching and gravel mulching are effective methods for increasing crop yields in Northwest China but exacerbate soil organic carbon (SOC) mineralisation. Manure amendment is a viable method for offsetting carbon (C) losses from mulching. SOC stability is a key factor in determining the nutrient supply capacity of soils, as it affects the C sources available to microorganisms. However, the synergistic effects of film mulching and manure amendment on SOC stability and crop nutrient uptake are still unclear. Therefore, four treatments—no mulching (CK), gravel mulching (GM), film mulching (FM), and film mulching with manure amendment (FCM)—were established on the Loess Plateau. Experiments were conducted to measure plant and grain nitrogen (N), phosphorus (P), potassium (K) uptake, SOC, labile organic C fractions (LOCFs), stability-based organic C fractions (SOCFs), and the C management index (CMI) in 2019 and 2020. The results showed that the FM and FCM treatments significantly improved crop dry matter accumulation in both years compared to the control. The FCM treatment significantly increased the two-year NPK averages of plants to 44.9%, 50.7%, and 54.5% and significantly increased those of grains to 46.7%, 58.2%, and 30.4%. The FCM treatment significantly increased all LOCFs, water solution C (WSC), hot-water-extractable C (HWC), permanganate oxidisable C (POXC), and particulate organic C (POC) in the topsoil (0–20 cm) in both years. The fractions of the active C pool (AP) in the SOCFs, namely, very labile C (C_VL) and labile C (C_L), were significantly increased, suggesting that the FCM treatment significantly decreased C stability in the topsoil. The sensitivity index showed that, among all SOC fractions, POC (21.5–72.9%) and less labile C (C_LL) (20.8–483.8%) were the most sensitive fractions of LOCFs and SOCFs compared to SOC (1.93–35.8%). A random forest analysis showed that most labile C fractions and the CMI significantly contributed to crop N, P, and K uptake, especially POXC to crop N uptake, the CMI to crop P uptake, and the AP to crop K uptake. It was concluded that the FCM treatment synergistically enhanced SOC lability, crop NPK uptake, and labile C fractions, especially POXC, the AP, and the CMI, which serve as robust indicators for guiding precision nutrient management in semi-arid croplands. Full article

Boreal forests have historically been regarded as some of the largest terrestrial carbon (C) sinks. However, increased soil organic matter (SOM) decomposition due to forest harvesting and post-harvest silviculture (e.g., site preparation, planting, and managing for competing vegetation) may exacerbate the effects of climate warming and shift boreal forests from being C sinks to C sources. We used an established stand-scale, fully replicated, experimental study to identify how two levels of forest management (harvesting = Harvest Only, and harvesting with post-harvest silviculture = Harvest Plus) influence SOC dynamics at three boreal forest sites varying in soil texture. Each site was surveyed for forest floor (litter and F/H horizons) and mineral soils pre-harvest (0) and 5, 14, and 20 years post-harvest. We predicted that sites harvested and left to revegetate naturally would have the lowest SOC stocks after 20 years, as sites that were planted and managed for competing vegetation would recover faster and contribute to a larger nutrient pool, and that the sand-dominated site would have the largest SOC losses following harvest due to the inherently lower ability of sand soils to chemically and/or physically protect SOC from decomposition following harvest. Over a 20-year period, both forest management treatments generally resulted in reduced total (litter, F/H, and mineral horizon) SOC stocks compared with the control: the Harvest Only treatment reduced overall SOC stocks by 15% at the silt-dominated site and 31% at the clay-dominated site but increased overall SOC stocks by 4% at the sand-dominated site, whereas the Harvest Plus treatment reduced overall SOC stocks by 32% at the sand- and silt-dominated sites and 5% at the clay-dominated site. This suggests that harvesting and leaving plots to revegetate naturally on sand-dominated sites and harvesting followed by post-harvest silviculture on clay-dominated sites may minimize total SOC losses at similar sites, though a full replicated field experiment is needed to test this hypothesis. Most treatment effects in this study were observed only in the second decade post-harvest (14 and 20 years post-harvest), highlighting the importance of long-term field experiments on the effects of forest harvesting and post-harvest silviculture. This research improves our understanding of the relationship between C dynamics, forest management, and soil texture, which is integral for developing sustainable management strategies that optimize C sequestration and contribute to the resilience of boreal forest ecosystems in the face of climate change. Full article

Farmland ecosystems, as the most active carbon pool, are integral to global climate change and carbon cycling. Therefore, systematically studying the roles of carbon sources and sinks in farmland ecosystems is essential to deepening our understanding of the carbon cycle and meeting the goals of “peak carbon emissions” and “carbon neutrality” in agriculture. Using the Web of Science database, this study reviewed 1411 articles (2002–2023) via bibliometric analysis to identify key research themes, trends, future priorities and address suggestions for future directions in farmland ecosystem carbon sources and sinks. The main results include the following: (1) Over the past 22 years, global research in this field has shown a consistent growth trend, with remarkably rapid expansion in the past three years. China, the United States, and Germany are the most influential countries. As the research scope has expanded, the field has evolved into an interdisciplinary domain. (2) The diversity of this research area has become enriched, and the research content is becoming more refined and systematic. The main research topics focus on carbon sequestration, soil organic carbon (SOC), farmland management, greenhouse gas (GHG) emissions, carbon stocks, ecosystem services, land use changes, climate change, and spatiotemporal heterogeneity. (3) Current research hotspots primarily focus on studying soil microbial carbon sequestration mechanisms, the application of remote sensing technologies, and reducing GHG emissions to achieve “carbon neutrality”. While existing studies have systematically elucidated carbon sequestration mechanisms mediated by soil aggregates, microorganisms, and minerals, critical knowledge gaps persist. Regional disparities in the relative contributions of these mechanisms remain unresolved, compounded by methodological inconsistencies in carbon assessment that introduce substantial uncertainties. Although farmland management practices are identified as pivotal drivers of carbon flux variation, the interactive effects of anthropogenic interventions and natural factors on ecosystem-scale carbon balance require further mechanistic exploration. This review provides a comprehensive reference for further study on carbon sources and sinks of farmland ecosystems and devising effective emission reduction strategies. Full article

Understanding the mechanisms of converting plant residue carbon (C) into soil C is important for managing the soil C pool and improving soil fertility. However, little is known yet about how the heterogeneous C from the plant residues, e.g., from the various plant parts, is bound in the aggregates of soil with different initial fertility. To address this, an incubating experiment was carried out through the addition of the ¹³C-labelled aboveground (stems and leaves) and belowground (roots) residue of maize into Mollisols with high and low fertility. Soil aggregates (> 250 μm and < 250 μm) were sieved, and their δ¹³C of soil organic carbon (SOC) was quantified. The amino sugar content (calculating for microbial residue C, MRC) and the contribution of MRC to the SOC pool (MRC/SOC) were calculated. The results showed that the SOC and maize residue-derived carbon (MDC) concentrations decreased quickly at the beginning, and then, the decrease slowed down until reaching a relatively constant level, and the two stages corresponded to two main microbial anabolism processes, which were entailing synthesizing living microbial biomass and producing microbial residues, respectively. During the beginning period, limited priming effects were observed, but this priming effect is stronger in the macroaggregates of high-fertility soil. The study further proved the existing conclusion that soil fertility and maize residue quality both influenced the C sequestration in the short term but not in the long term in macroaggregates. In the microaggregates, however, only maize residue quality influenced the C sequestration in the long term. In addition, the microaggregates exhibited higher MDC and SOC concentration, and reached a steady state for the MRC/SOC dynamics later than the macroaggregates. These indicated that the microaggregates had a larger C sequestrating capacity than the macroaggregates. The results suggest that soil aggregates are a major factor influencing exogenous C sequestration, even regulating the effective duration of soil fertility and plant quality. Full article

Peat swamp wetlands, crucial carbon pools in terrestrial ecosystems, significantly impact regional carbon cycling and climate change. In this study, the peat swamp wetland in the Altay Mountains was selected as the research object. In July 2023, soil samples were collected in situ from a depth of 0–80 cm of the peat swamp wetland. Subsequently, the contents of soil organic carbon (SOC), dissolved organic carbon (DOC), particulate organic carbon (POC), and the physicochemical properties of the soil samples were determined. The distribution characteristics of soil organic carbon and its active carbon fractions at different soil depths and their influencing factors were investigated. The results demonstrate that (1) SOC, POC, and DOC concentrations were significantly higher in subsurface layers (20–80 cm) than in those of surface layers (0–20 cm), with SOC and POC peaking at 20–40 cm and DOC predominantly accumulating at 40–80 cm. (2) The concentrations of SOC, POC, and DOC reached minima at 0–10 cm, accounting for 17.25%, 16.91%, and 6.46% of the total 0–80 cm profile, respectively. POC represented 76.46% of SOC throughout the profile. (3) Available phosphorus (AP), total nitrogen (TN), ammonium nitrogen (NH₄⁺N), and soil moisture (SM) accounted for an average of 68.94% of the variation in soil organic carbon and active carbon fractions at a depth of 0–80 cm. Higher levels of soil moisture and total nitrogen content emerged as the primary factors responsible for the reduction in soil organic carbon and active carbon fractions. In shallow soils (0–20 cm), an increase in the content of available phosphorus and ammonium nitrogen contributed to a decline in the soil’s active carbon fraction. Conversely, the situation was reversed in deeper soils. This study thus offers scientific insights into alpine peat bog wetland soil carbon dynamics and environmental responses. Full article

The distribution of the soil aggregate structure and its associated organic carbon along the elevation gradient remains unclear, but it may be crucial for the stabilization of soil carbon pools in mountainous forests. In this study, we first assessed the changes in aggregate-associated organic carbon and the aggregate structure in the 0–20 cm soil layers of an alpine forest in the Sygera Mountains along an elevation gradient (3000–4200 m). We then conducted an incubation experiment to explore the relationship between aggregates and soil organic carbon mineralization, using the Pearson correlation analysis and RDA. The results indicated that macroaggregates and microaggregates were the predominant forms of aggregates in the Sygera Mountains, contributing significantly to organic carbon (33.57% and 38.29%, respectively). As the elevation increased, the stability of aggregates in mid and high elevations (3600–4200 m) was significantly higher than that in low elevations (3000–3300 m). Aggregate stability and macroaggregate-associated organic carbon were positively correlated with the total soil organic carbon, suggesting that organic carbon is essential for promoting soil aggregation in forest soils. With the rising temperatures, the rate of soil mineralization at different elevation sites significantly increased, and the Q₁₀ values were greater at low elevations than at mid and high elevations. This implied that soil carbon pools at low elevations were more sensitive to climate warming. The significant negative correlation between microaggregate-associated organic carbon and soil mineralization suggested that microaggregates contribute to the stabilization of soil carbon pools. Given that the link between aggregates and soil mineralization strengthened with increasing temperatures, the role of aggregates in the stabilization of forest soil carbon pools should be emphasized under a warming trend. Full article

Microbial residual carbon (MRC) is a key component of soil organic carbon (SOC) and crucial for SOC stabilization, contributing to the formation of a stable soil carbon pool. However, the accumulation patterns of MRC in different plantation forest types remain unclear. In this study, based on the principle of site condition similarity and supported by field investigations, soils from Populus alba, Salix matsudana Koidz, and Pinus tabuliformis in Beijing were selected as the research objects. The physical and chemical properties of the soils, as well as the microbial residual carbon content, were measured. Correlation analysis and redundancy analysis (RDA) were then conducted to explore the accumulation patterns of microbial residual carbon across different plantation forest types and to identify the factors influencing these patterns. Results showed that fungal residue carbon, bacterial residue carbon, and total MRC were highest in Populus alba, followed by Salix matsudana Koidz and Pinus tabuliformis. The contributions of fungal, bacterial, and total MRC to SOC were greatest in Populus alba, followed by Pinus tabuliformis and Salix matsudana Koidz. In this study, Populus alba were found to be more effective in sequestering microbial residue carbon. Fungal residue carbon content and its contribution to SOC were greater than bacterial residue carbon in all plantation types. Soil organic carbon, nitrate nitrogen, and available potassium were significantly correlated with both MRC content and its contribution to SOC. These findings deepen our understanding of microbial-driven soil carbon accumulation and provide a foundation for enhancing the carbon sequestration potential of plantation forests. Full article