Aims This study examines the growth responses of major afforestation tree species in Northeast China, specifically Fraxinus mandshurica (a broadleaf species associated with arbuscular mycorrhizae) and Larix gmelinii (a coniferous species associated with ectomycorrhizae), to varying levels of dry and wet reduced nitrogen deposition. By investigating the impact of increased reduced nitrogen on these seedlings, this research aims to enhance our understanding of the relationship between different seedling growth patterns and atmospheric nitrogen deposition forms, thereby providing a theoretical foundation for precise seedling cultivation. Methods The research utilized Fraxinus mandshurica with arbuscular mycorrhizal (AM) seedlings and Larix gmelinii with ectomycorrhizal (ECM) seedlings as test subjects to simulate varying concentrations of dry and wet reduced nitrogen deposition: 0 (CK), 35 (ND-35), 70 (ND-70), 35 (NW-35), and 70 kg N ha-1 yr-1 (NW-70). We assessed changes in seedling growth, photosynthetic capacity, root development, and mycorrhizal infection rates of two types of seedlings. Important findings Under conditions of atmospheric dry and wet nitrogen deposition, seedlings of both mycorrhizal types gradually reduce their dependence on mycorrhizal fungi. The primary response forms are the enhancement of their own photosynthetic performance and an increase in root absorption capacity. (1) During dry sedimentation of Fraxinus mandshurica with arbuscular mycorrhizal, a significant enhancement in leaf accumulation and total biomass was observed, attributed to changes in photosynthetic capacity. Under the ND-70 treatment, the net photosynthetic rate, total chlorophyll, and leaf biomass increased by 49.61% compared to the control, with additional increases of 76.29% and 53.84%, respectively. In contrast, during wet deposition, nitrogen use efficiency improved primarily due to an increased contact area between absorbing roots and soil. Under the NW-35 and NW-70 treatments, the surface area of absorbing roots increased by 14.96% and 16.17%, respectively, compared to the control. (2) Larix gmelinii, characterized by ectomycorrhizal roots, exhibited a more pronounced response to wet sedimentation, primarily enhancing the absorptive capacity of the root system through the elongation and thinning of the absorptive roots. Under the NW-70 treatment, the absorptive root length increased by 20.70% compared to the control, while the average absorptive root diameter and cortical thickness decreased by 10.14% and 27.25%, respectively. This research provides an in-depth analysis of the relationship between mycorrhizal types and atmospheric reduced deposition, serving as a reference for the precise nutrient management of seedlings with varying mycorrhizal types.

Abstract Aims Phosphorus (P) is an essential nutrient for plant growth and a critical factor of determining forest productivity. Most terrestrial plants can form symbiotic associations with either arbuscular mycorrhizal (AM) or ectomycorrhizal (ECM) fungi to enhance their phosphorus uptake. AM mycorrhiza and ECM mycorrhiza vary significantly in their P-absorption strategies, which impacts the P cycling in ecosystems. Understanding how soil P availability varies across the forests dominated by AM trees and ECM trees can be conductive to elucidating the mechanisms of productivity maintenance in subtropical forests and guiding forest nutrient management. Methods We established 35 forest plots across a natural gradient of ECM tree dominance in the Badagongshan Nature Reserve, Hunan Province. We measured the contents of four forms of soil bioavailable P (CaCl2-P, Enzyme-P, Citrate-P, HCl-P), and analyzed their relationships with ECM tree dominance. Correlation analyses were further employed to identify the key factors influencing soil bioavailable P contents. Important findings The results revealed that Enzyme-P content increased significantly with ECM tree dominance, while CaCl2-P, Citrate-P and HCl-P contents showed no significant correlations with ECM tree dominance. CaCl2-P content was positively correlated with leaf litter P content. Citrate-P and HCl-P contents were positively correlated with the contents of soil organic carbon, total nitrogen, and microbial biomass carbon. Enzyme-P content was positively correlated with the contents of soil organic carbon and dissolved organic carbon, and negatively correlated with soil pH. Additionally, soil acid phosphatase activity increased significantly with ECM tree dominance. In conclusion, ECM-dominated forests exhibit higher levels of enzyme-hydrolysable P and acid phosphatase activity, which can facilitate P solubilization through organic P mineralization, thereby promoting the rapid growth of ECM trees in subtropical forests.

Drought is one of the major stresses that forest ecosystems are facing globally, directly affecting plant growth and soil microorganism activities and indirectly altering soil organic carbon cycling. Temperate forests play an important role in global carbon storage and climate regulation, but the mechanism of soil carbon dynamics in response to drought stress remains less understood, particularly mycorrhiza-mediated soil organic carbon process. In this study, in a warm temperate oak forest (dominated by Quercus aliena var. acuteserrat) that received long term manipulative drought, we investigated the respective effect of fine roots, mycorrhizal fungi and free-living microorganisms on soil enzyme activities and organic carbon physical fractions, i.e., particulate organic carbon (POC) and mineral associated organic carbon (MAOC), using in-situ incubation of mesocosms with different mesh sizes (0.001 mm, 0.053 mm, 1.45 mm). The results showed that plants cope with water stress by increasing underground carbon allocation, fine roots and mycorrhizal fungal exudates provided key carbon sources to support the enhanced activity of hydrolytic enzymes. In contrast, oxidative enzyme activity was primarily regulated by water availability and soil pH. Peroxidase (PER) activity significantly decreased under drought treatment, which promoted the accumulation of POC in the 0.001 mm and 0.053 mm microcosms by inhibiting the decomposition of complex compounds. Furthermore, carbon inputs from fine roots and mycorrhizal fungi also played a significant role in the formation of POC. Compared to the effects of biological components, the accumulation of MAOC was more influenced by microbial metabolic activity and changes in the soil environment under drought conditions. In this study, we elucidated for the first time the functional differentiation of fine roots, mycorrhizal fungi and non-symbiotic microorganisms and their synergistic roles under drought stress in a warm-temperate oak forest. The results indicate that drought significantly affects the stability of soil carbon pools by modifying the interaction mechanisms among biological components and regulating the dynamics of enzyme activities and carbon fractions. These findings provide a new theoretical basis for the prediction of forest soil carbon cycle under climate change, as well as scientific support for soil management and carbon pool optimization.

Aims Plant invasion often leads to the loss of local species diversity and causes significant economic losses. The Enhanced Mutualisms Hypothesis used to explain that some alien species have shown a remarkable ability to capitalize on novel but strong soil mutualists, which enhance their invasion success. In this study, the contributions of arbuscular mycorrhizal fungi (AMF) and litter to the growth of invasive plant under different nutrient conditions was investigated. Methods We inoculated AMF, Glomus etunicatum and leaf litter to explore the roles of AMF-litter interactions in the responses of notorious invasive Solidago canadensis to low nutrient stress. Important findings The results showed that litter addition significantly increased the mycorrhizal colonization rate and ratio of abundance class in S. canadensis. Under low-nutrient conditions, both AMF and litter promoted the stem length, leaf area and above-ground biomass, respectively, but significantly decreased the root-shoot ratio, and with the most pronounced synergistic enhancement observed in AMF-litter interactions. Under normal nutrient conditions, only AMF-litter interactions significantly inhibited the development of root system but increased the above-ground biomass in S. canadensis. Relative Interaction Intensity (RII) analysis revealed that AMF and litter significantly stimulated above-ground growth, with stronger effects under low-nutrient conditions compared to normal nutrient levels. These findings suggest that S. canadensis could adjust the allocation strategies for aboveground-belowground resource by AMF-litter interactions to respond low-nutrient stress. This study provides novel insights into how invasive plant utilize symbiotic AMF and litter interactions to mediate resource allocation under nutrient heterogeneity, advancing our understanding of the mechanism of successful invasion of alien plants.

Phosphorus (P), an essential macronutrient for plant growth and development, and its bioavailability has a profound impact on the structure and function of ecosystems. Most plants form symbiotic associations with either arbuscular mycorrhizal (AM) fungi or ectomycorrhizal (ECM) fungi, which can significantly enhances their ability to acquire and utilize P. Although numerous studies have explored the differences in P acquisition and utilization strategies between AM and ECM plants, few studies have systematically synthesized these strategies. In this paper, we comprehensively review the P acquisition and utilization strategies from four perspectives: root morphology and architecture, root physiological traits, root-microbe interactions, and P resorption efficiency. It is concluded here that there exist significant differences in P acquisition and utilization strategies between AM and ECM plants. Specifically, AM plants usually form a mutually beneficial relationship with microorganisms that rapidly mineralize organic matter, have a limited extracellular enzyme secretion capacity, and prefer to absorb inorganic P, therefore adopting an “acquisition strategy” for P acquisition and utilization strategy. In contrast, ECM plants have a strong ability to secrete extracellular enzymes and other secretions, and are able to utilize organic P, and therefore adopt a “conservation strategy” for P acquisition and utilization strategy. Finally, this review proposes six research directions that need to be addressed in future research to overcome current limitations. Overall, this review not only deepens our theoretical understanding of mycorrhizal-mediated phosphorus cycling processes, species coexistence, and productivity maintenance mechanisms, but also provides theoretical guidance for species selection, species configuration, and nutrient management in agricultural and forestry production and ecological restoration practices.

Aims The symbiosis between plants and arbuscular mycorrhizal fungi (AMF) constitutes a critical nutrient transfer network in terrestrial ecosystems, playing an essential role in sustaining ecosystem functions. However, AMF community composition and its ecological mechanism underlying their functional responses to global change remains poorly understood. Methods By integrating a multi-year precipitation increase field experiment in a semi-arid grassland on the Loess Plateau with MiSeq sequencing, we measured plant biomass, root traits, and AMF community composition, and explored the effect of precipitation increase on plant resource acquisition strategies. Important findings Our results showed that precipitation increase altered plant community composition, favoring subshrubs and forbs over grasses. Compared to grass, subshrub and forb often have thicker and shorter roots, which may enhance the colonization potential of AMF. MiSeq sequencing revealed that precipitation increase significantly altered the AMF community composition, increasing the relative abundance of Gigasporaceae and Paraglomeraceae, while reducing the relative abundance of Glomeraceae. Furthermore, precipitation increase enhanced the complexity of AMF community network. In conclusion, our findings demonstrate that precipitation increase regulates plant water and nutrient acquisition pathway via altering plant functional group growth, root traits, and AMF community composition. These results indicate that precipitation increase may have profound effects on nutrient cycling in grassland ecosystems via regulating the plant and AMF interaction network.

Aims The symbiotic relationship between arbuscular mycorrhizal fungi (AMF) and plant roots enhances nutrient acquisition in plant communities and plays a vital role in sustaining key functions and ecological processes in grassland ecosystems. However, the response patterns of soil AMF communities to varying grazing intensities remain under debate, and the mechanisms by which these communities influence soil multifunctionality (SMF) under grazing disturbance are not yet fully understood. Methods To address these knowledge gaps, this study investigated mountain meadow steppes on the northern slope of the Tianshan Mountains in Xinjiang under three grazing intensities: ungrazed, lightly grazed, and heavily grazed. High-throughput sequencing was used to characterize the composition of soil AMF communities and to construct their co-occurrence networks. A weighted average method, based on cluster analysis, was applied to comprehensively evaluate SMF and to analyze how AMF community characteristics vary with grazing intensities and how these variations influence SMF. Important findings The results indicated that the dominant AMF genera in the three grazing treatments were Glomus and Diversispora. As grazing intensity increased, AMF community diversity, as along with network stability, complexity, cohesion, and SMF, exhibited a unimodal pattern—increasing initially and then declining at higher grazing levels. Linear regression and structural equation modeling indicated that grazing influences SMF mainly by modulating AMF community diversity and altering the complexity and stability of AMF networks. The effect of AMF community diversity on SMF was largely indirect, mediated through its effects on network structure, while its direct impact was relatively weak. Overall, this study highlights that the complexity and stability of AMF co-occurrence networks enhance the role of community diversity in shaping SMF and strengthen the interdependent relationship between biodiversity and ecosystem functioning. These findings offer valuable theoretical insights for the restoration and sustainable management of degraded grassland ecosystems.

As a category of emerging contaminants with global distribution, microplastics occur frequently in terrestrial ecosystems, including agricultural soils. Available evidence indicates that microplastics can alter soil physicochemical properties, and affect soil biota, plant performance, and ecosystem functions. As the most ubiquitous plant symbiotic fungi in soils, arbuscular mycorrhizal (AM) fungi can enhance host plant stress resistance through multiple mechanisms and play a critical role in maintaining ecosystem stability. This review synthesizes current research advances in the interactions between microplastics and AM fungi. Microplastics in soil can directly affect AM fungi through adsorption and absorption, or by releasing co-contaminants, and indirectly influence fungal colonization and community structure by altering soil properties (e.g., pH, nutrient availability), pollutant speciation and toxicity, microbial community composition and activity, and plant performance. On the other side, AM fungi exhibit strong tolerance and resilience to microplastics, and may alleviate negative impacts of microplastic contamination on plant and soil environment through multiple pathways, such as improving soil structure，mitigating plant nutrient limitations caused by microplastics, immobilizing microplastics via fungal structures (e.g., extraradical hyphae) to reduce their uptake and translocation by plants. Overall, the interactions between microplastics and AM fungi vary with microplastic characteristics (e.g., type, dose, size, and shape), plant species, soil properties, and exposure conditions, as a result it is still difficult to reach general conclusions. Finally, based on identification of current knowledge gaps, future research priorities are proposed to establish reliable quantitative method for microplastics in the soil plant systems, to assess the ecotoxicological effects of microplastic metabolites and composite pollution on AM fungi, and to reveal the influences of AM fungi on environmental behavior of soil microplastic and its ecological impacts, which will provide theoretical and technical support for the application of mycorrhizal technology to tackle soil microplastic pollution problems.

Aims Saline alkali land is an important reality and potential agricultural resource to solve the shortage of arable land in China. Efficient utilization of saline alkali land resources to develop peanut planting in such environments and achieve high and stable yield has become an urgent demand for ensuring peanut production. Under saline alkali stress habitat, arbuscular mycorrhizal fungi (AMF) can effectively develop potential productivity of host plants and improve their salt resistance and tolerance. Although it has been demonstrated that AMF enhanced peanut salt tolerance under salt stress, however, there have been limited reports on the effects of AMF on the growth and development of salt-tolerant and salt-sensitive peanut. This study was guided by the significant demand for soil improvement in saline alkali land by investigating the response mechanisms of peanut growth and rhizosphere soil environment to AMF under saline-alkali conditions, aiming to provide theoretical basis and technical support for AMF application in peanut production in saline alkali soils. Methods The experiment used salt-tolerant cultivar HY25 and salt-sensitive cultivar HY22 as experimental materials, with AMF seed coating treatment applied under saline alkali and normal soil conditions. Important findings Under two soil conditions, salt-tolerant and salt-sensitive peanut cultivars demonstrated differential response mechanisms to AMF inoculation. Under both soil environments, AMF improved the agronomic characteristics in HY25, optimized photosynthetic parameters, and significantly increased pod yield and its component components. While AMF exhibited partial inhibitory effects on agronomic traits in HY22 in normal soil, it notably improved leaf photosynthetic performance and elevated both pod yield and quality. Significant differences were found in the response of root growth of two cultivars to AMF including: 1) In normal soil, the promoting effect of AMF on the growth of HY25 root system initiated during the flowering-pegging stage and continued to until maturation stage. Under saline-alkaline soil, AMF significantly increased total root length, root surface area, and root volume in HY25 at pod-setting stage. 2) Salt-sensitive cultivar HY22 exhibited greater sensitive to AMF inoculation. Under both normal and saline-alkali soils, AMF demonstrated inhibitory effects on root growth in HY22 during flowering-pegging and/or pod-setting stages, with significantly stronger inhibition observed under saline-alkali soil than normal soil. Moreover, AMF effects on rhizosphere soil properties included: 1) significant elevation in available phosphorus in both cultivars under two soil conditions; 2) increased soil CAT, phosphatase, and intertase activities in both cultivars in saline alkali soil; whereas 3) significant inhibition of soil enzymatic activities in HY22 under normal soil. These results indicated that compared to salt-sensitive cultivar, salt-tolerant cultivar might serve as more efficient symbiotic partner for AMF. AMF might demonstrate superior growth promotion in salt-tolerant cultivar, effectively exerting the synergistic effect of microbial regulation under saline-alkali soil.

Mycorrhizal fungi are crucial components of plant microbiota and key players in terrestrial biogeochemical cycles. Arbuscular mycorrhizal (AM) fungi can form symbiotic relationships with more than 70% of plants and their origin can be traced back to the Devonian period 460 million years ago. They play an important role in the transition of plants from aquatic to terrestrial and profoundly affect the growth performance of plants and ecosystem functions. In the peri-arbuscular space of AM symbiosis, plants provide carbon fixed by photosynthesis in exchange for minerals, especially phosphorus and nitrogen. In the hyphosphere, many bacteria are involved in AM symbiosis. They obtain carbon from extraradical hyphal exudates and compensate for the limited saprophytic capacity of AM fungi by mineralizing organic compounds to enhance fungal mineral availability. Therefore, plants, AM fungi and hyphospheric bacteria form a continuum and are accompanied by top-down carbon flows and bottom-up nutrient flows. In this review, we first introduce the latest research progress on how plants, AM fungi and their related hyphospheric bacteria exchange carbon from host plants and minerals from the soil. These exchanges provide energy for microbial partners and deliver nutrients for plants that are necessary for growth and development. Secondly, we analyze in detail the mechanism by which the plant-AM fungi-bacterial continuum maintains cross-kingdom cooperation, which is conducive to a better understanding of the complex ecological relationships among plants, AM fungi and soil bacteria and their evolutionary significance.

Mycorrhizal fungi represent a widespread group of fungi in nature that form symbiotic associations with most terrestrial plants, playing a crucial role in plant physiological processes and terrestrial ecosystem functioning. In these symbiotic relationships, mycorrhizal fungi receive photosynthesis-derived carbon from their host plants and, in turn, facilitate the host plants with regard to nutrient acquisition and stress tolerance. Recently, the rapid development of molecular biology and bioinformatics has significantly advanced our understanding of mycorrhizal physiology and ecology. To summarise the important progress in these fields, we reviewed the differences in the evolutionary history of arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) fungi, as well as their impacts on the physiological and ecological functions of host plants. We further discussed how these differences affect the nutrient cycling of global terrestrial ecosystems and the structure and function of plant communities. We showed that the origin and evolution of AM and EcM fungi is a process of long-term mutual adaptation and selection with terrestrial plants. During the evolution, mycorrhizal fungi have gradually refined their plant-dependent nutrient acquisition mechanisms, while plants have developed diverse growth strategies to optimize symbiosis with mycorrhizal fungi. In these mutually beneficial interactions, mycorrhizal fungi not only enhance the nutrient uptake and utilization in host plants and improve their tolerance to biotic and abiotic stresses, but also participate in global biogeochemical cycles. Thus, mycorrhizal fungi play a vital role in maintaining the balance and stability of biodiversity and terrestrial ecosystems. Finally, we proposed future research directions, including the response of mycorrhizal fungi to global change, their roles in multi-trophic associations and urban ecosystems, as well as their applications in production practices and diversity conservation, aiming to provide novel insights and approaches to address various ecological and social challenges.

Arbuscular mycorrhizal fungi (AMF), ubiquitously distributed in terrestrial ecosystems, form symbiotic associations with most terrestrial plants. Their extraradical hyphal networks mediate plant-soil interactions, playing indispensable roles in enhancing ecosystem productivity, sustaining biodiversity, and maintaining soil health. While the roles of AMF in enhancing plant nutrient acquisition and stress tolerance are well documented, comprehensive assessments of their ecosystem-scale functions remain scarce. More importantly, methodologies for the targeted manipulation of AMF communities and their ecological functions are still underdeveloped. This review systematically summarizes the ecological functions of AMF from four perspectives: ecosystem productivity, biodiversity-ecosystem stability relationships, biogeochemical cycling, and soil health. To address current technical bottlenecks in AMF community regulation, we propose a triadic ecological regulation framework for the application of AMF in improvement of ecosystem functions, including the activation of indigenous fungal consortia, the synergistic application of exogenous inoculants, and optimizing context-specific management practices. This framework provides a robust, AMF-centered soil ecological regulation paradigm designed to facilitate the development of mycorrhizal technologies. Future studies should prioritize the multidimensional interactions among AMF, host plants, and environmental factors, to address the multiple challenges associated with the targeted regulation of AMF communities. This includes advancing microbial regulation strategies, developing multifunctional consortia, and optimizing long-term field management practices. Ultimately, these efforts aim to promote the widespread application of mycorrhizal technologies in ecological restoration and sustainable agriculture.

Forest as the dominant component of terrestrial ecosystems, hinge on internal nutrient cycling mechanisms to support individual plant development and the maintenance of ecosystem functions. Arbuscular mycorrhizae (AM) and ectomycorrhizae (ECM), the two most widespread mycorrhizal symbioses in forest ecosystems, playing pivotal roles in regulating nutrient cycling and sustaining functional stability along the “soil-plant-litter continuum”. Although numerous efforts have explored the effects of mycorrhizal types on key nutrient cycling processes in forests, these studies focus more on isolated process, with limited attention to the holistic nutrient cycling mediated by mycorrhizal interactions. This review synthesizes research from the past three decades to systematically examine the roles and underlying mechanisms through which AM and ECM-associated plants influence key processes across the internal nutrient cycling, including nutrient mineralization and mobilization, nutrient uptake by mycorrhizal-root systems, nutrient resorption from senescent organs, and nutrient return through litter decomposition. It further elucidates the self-sustaining nutrient dynamics of forest ecosystems dominated by different mycorrhizal types, aiming to provide insights into how nutrient cycling strategies shaped by mycorrhizal symbioses respond and adapt to forest management and global environmental change. Finally, we propose future research directions: (1) investigating the role of Common Mycorrhizal Networks (CMNs) in nutrient internal cycling under AM- versus ECM-dominated stands, while focusing on less-studied mycorrhizal types (e.g., dual-mycorrhizal plants, legumes with rhizobia-AM/ECM symbiosis) and Ericoid Mycorrhiza (ERM); (2) developing “mycorrhiza-site” matching models and mycorrhizal trait databases based on AM and ECM strategic differentiation, to optimize tree species selection in reforestation and afforestation across different site conditions; (3) assessing the buffering capacity of shifts in AM and ECM distributions on nutrient cycling under global change and (4) integrating long-term and multidimensional monitoring to unravel the co-evolutionary dynamics among mycorrhizal types, soil environments, and microbial communities driving nutrient cycling.

Aims Arbuscular mycorrhizal fungi (AMF) can enhance the competitive ability of invasvie plant against native species, which is likely influenced by soil nitrogen forms. Against the backdrop of increasing nitrogen deposition, exploring the effects of AMF on the growth and competitiveness of invasive plants under different forms of nitrogen addition can enhance our understanding of how invader adapts to soil nitrogen patterns shaped by nitrogen deposition. Methods A common garden experiment was conducted using the invasive plant Bidens alba and the native species Emilia sonchifolia. The experimental design included two planting regimes (monoculture and mixture), three nitrogen treatments (ammonium [NH₄⁺], nitrate [NO₃⁻], and no nitrogen addition), and two microbial treatments (with or without AMF). Important findings Under all nitrogen treatments, AMF significantly increased the biomass of the native plant E. sonchifolia. Specifically, when grown in monoculture with NO3- addition, AMF exhibited the greatest promotiing effect on its biomass, indicating high mycorrhizal dependence in the native species, which is also influenced by soil nitrogen forms. AMF did not show a significant impact on the invasive plant B. alba under either monoculture or mixed planting. The greatest enhancement of the competitive response of B. alba by AMF occurred under no nitrogen addition, but no evidence was found that AMF could help the invasive plant adapt to different forms of nitrogen to maintain its competitiveness. This may be related to its strong mycorrhizal autoregulation. ability. The results suggest that the invasive plant B. alba thrive under high nitrogen deposition conditions through direct nutrient uptake pathways and its mycorrhizal autoregulation ability. This study demonstrates that plant-AMF symbiosis is influenced by nitrogen addition and nitrogen forms, highlighting the importance of nitrogen forms in shaping the mycorrhizal responses of invasive plants and deepening the understanding the role of AMF in growth and competitive response of invasive plants under nitrogen deposition.

Aims Soil organic carbon (SOC) is a crucial component for maintaining soil health and fertility in tea plantations, and its fixation process is closely associated with arbuscular mycorrhizal fungi (AMF). However, the response mechanisms of AMF community composition and SOC accumulation to magnesium fertilization in tea plantations remain poorly understood. Methods This study utilizes a 7-year long-term experimental site in Anxi County, Fujian Province, focused on Tieguanyin tea plantations with continuous Mg fertilization. Four gradient treatments of magnesium sulfate heptahydrate (MgSO4·7H2O) application were implemented: Mg0 (0 kg ha-1, control), Mg50 (17.5 kg ha-1), Mg100 (35 kg ha-1), and Mg200 (70 kg ha-1). The research aims to elucidate the responses of both AMF communities and soil organic carbon to Mg fertilization in the tea plantation ecosystem. Important findings Compared to Mg0, Mg50, Mg100, and Mg200 significantly increased soil SOC content (by 7.8%, 11.7%, and 14.8%), exchangeable Mg2+ content (by 1370%, 2351%, and 2746%), soil pH (by 2.3%, 2.8%, and 4.2%), dissolved organic carbon content (by 3.5%, 3.3%, and 4.0%), pruning litter yield (by 6.1%, 13.9%, and 20.2%), and the relative abundance of the genus Glomus (by 59.5%, 75.4%, and 37.3%). Structural equation modeling revealed that magnesium fertilization promotes SOC sequestration synergistically through two main pathways: firstly, by improving soil physicochemical properties and stimulating plant growth to enhance carbon input; and secondly, by optimizing the AMF community structure and strengthening the functional contribution of Glomus. This study elucidates the dual-pathway mechanism through which magnesium fertilization enhances carbon sequestration in tea plantations by regulating the soil microenvironment and AMF communities, providing a theoretical foundation and practical strategies for achieving carbon neutrality in tea garden ecosystems.