Aims  Pinus sylvestris var. mongolica, an evergreen coniferous tree species, plays a pivotal role in ecological restoration efforts in the deserts of northern China. This study aimed to elucidate the community assembly of belowground fungi and the intricate relationships between P. sylvestris var. mongolica and fungi in P. sylvestris var. mongolica plantations. The findings would provide the novel microbial perspectives for sustainable management strategies of P. sylvestris var. mongolica plantations.

Methods  Pinus sylvestris var. mongolica plantations of different stand ages (26 a, 37 a, and 46 a) in the Hulun Buir Sandy Land were selected to examine the diversity, composition and assembly pattern of root-associated fungi (RAF), rhizosphere soil fungi (RhSF) and non-rhizosphere soil fungi (NRhSF).

Important findings  (1) Stand ages and niches significantly influenced fungal diversity. The fungal community richness and diversity indices ranked as follows: 46 a > 26 a > 37 a, and the dissimilarity gradually increased with the increase of the stand age. Among the different niches, the richness, diversity indexes, and dissimilarity were the highest in NRhSF, the middle in RhSF and the lowest in RAF. (2) The belowground fungi were assigned to 14 phyla and 592 genera. The belowground fungal communities of 26 a, 37 a, and 46 a plantations had 3, 1, and 5 abundant genera respectively, and they had symbiotic capability of endophytic or ectomycorrhizal fungi. RAF, RhSF, and NRhSF had 3, 8, and 5 abundant genera, respectively, and the proportions of Mortierellomycota and saprotrophic fungi increased from root to soil. (3) The primary assembly processes of belowground fungal communities were the dispersal limitation (63.54%), drift (22.06%) and homogeneous selection (12.90%). Stand age significantly correlated with structure of belowground fungi. Soil total nitrogen content, soil total nitrogen and phosphorus content, and soil organic matter content were the main factors influencing RAF, RhSF, and NRhSF, respectively. This study highlights temporal and spatial heterogeneity of fungal community diversity and composition in P. sylvestris var. mongolica plantations. Stochastic processes mainly were dispersal limitations, shaping these communities, while the deterministic processes were influenced by host selection and environmental filtering.

Aims: Drought effects on the carbon balance are considered as the major factor of tree mortality and are as-sumed to be regulated by soil nutrient (e.g., nitrogen) availability. However, the effects of nitrogen addition on trees carbon and nitrogen utilization between aboveground and belowground and on coupling relationship of carbon and nitrogen in various organs in response to drought are still unclear in trees. Methods: A two-year full factorial microcosm experiment was set up with sessile oak (Quercus petraea). Nitrogen addition was performed in the first year, and drought was conducted in the second year. The isotope 15N labeling and 13C labeling were carried out before drought and during drought, respectively. Three consecutive samplings were conducted after dual labeling of 13C and 15N labelling in the second year, and the effects of ni-trogen addition on carbon and nitrogen allocation dynamics during progressive drought were tested. Important findings: Our results showed that previous nitrogen addition promoted aboveground photosyn-thetic carbon fixation and nitrogen allocation, increased root nitrogen uptake, reduced the non-structural carbo-hydrates (NSC) contents in all organs and changed the relationships of carbon and nitrogen in aboveground and belowground organs in sessile oak. However, drought had minor effects on nitrogen and carbon allocation be-tween aboveground and belowground, and had minor effects on the relationship of carbon with nitrogen in all organs (represented by the ratio of 13C to 15N in all organs). Drought only significantly reduced the content of NSC in sessile oak. During drought (from day 40 to 73), previous nitrogen addition led sessile oak to prioritize belowground carbon and nitrogen allocation. Our results indicate that sessile oak can change its carbon and ni-trogen allocation strategies to adapt to drought well, while previous nitrogen addition may increase its drought sensitivity.

Aims As a key component of terrestrial ecosystem carbon pools, soil carbon storage in grasslands, encompassing both soil organic carbon (SOC) and inorganic carbon (SIC) pools, plays a crucial role in terrestrial carbon cycling and climate feedback. However, there is relatively limited systematic understanding on driving mechanisms inte-grating both SIC and SOC fractions, compared to the extensive focus on SOC. The comprehensive understanding of soil carbon storage between different grassland types remains unclear. Methods Here, we conducted a field survey in temperate grasslands of Inner Mongolia, selecting two grassland types: typical steppe and meadow steppe. We measured soil physicochemical properties, plant biomass and chemical traits, as well as microbial biomass carbon and community composition. In addition, we acquired a suite of explan-atory factors including climatic, edaphic, vegetational, and microbial variables. Boosted regression trees analyses and structural equation modeling were then used to investigate the relative importance of the four factors and poten-tial mechanisms in affecting total soil carbon storage and its organic and inorganic components. Important findings The results indicated that the SIC stock in the 0 - 60 cm soil layer of typical steppe (2.75 ± 0.15 kg C m-2) was significantly higher than that in meadow (0.45 ± 0.03 kg C m-2), whereas SOC stocks showed no significant difference (8.61 ± 0.19 kg C m-2 for typical steppe and 8.32 ± 0.17 kg C m-2 for meadow). Conse-quently, the total soil carbon stock in typical steppe being significantly higher than that in meadow. The SOC con-tent of both grassland types decreased with soil depth. The SIC content in typical steppe exhibited pronounced ac-cumulation in deeper soil layers, a pattern that was absent in meadow. Biotic and abiotic factors, including plant, climate, and soil, jointly influenced total soil carbon and its SOC and SIC components, with distinct regulatory mechanisms between grassland types. In typical steppe with strong water limitations, soil carbon storage was pri-marily regulated by climate factors, whereas in meadow steppe with relatively higher moisture availability, soil fac-tors played a more prominent role. These findings provide a scientific basis for accurately assessing the soil carbon storage in temperate grasslands and enhance our understanding of the distribution mechanisms of soil carbon under multi-factor interactions.

Aims The community assembly process based on the ecological niche theory and neutral theory is crucial to the biodiversity maintenance mechanism, which was one of the hotspots in forest ecology research. Mountainous areas were rich in biodiversity, but there were relatively few studies on the functional diversity and pattern of changes in the community assembly of mycorrhizal plant along the altitudinal gradient. Methods In this study, based on eight 1 hm2 dynamic monitoring plots established at an altitude of 600-2100 m in Fanjing mountain national nature reserve, we divided 261 woody plants with diameter at breast height (DBH) of ≥ 1 cm into three functional groups: arbuscular mycorrhizal (AM) plants, Ectomycorrhizal (EcM) plants, and Ericoid mycorrhizal (ErM) plants. The change patterns of their community assembly process and functional diversity along the altitude gradient was analyzed, and the potential role of the assembly process in maintaining functional diversity was revealed. Important findings The study showed that the functional diversity of the different mycorrhizal plants varied significantly with altitude, among which, the functional richness and functional dispersion of AM and EcM plants showed a significant decreasing trend with altitude, the community weighted means of leaf area and specific leaf area of AM and EcM plants showed a decreasing trend with altitude. The leaf dry matter content, leaf nitrogen and phosphorus content of EcM plants showed an increasing trend with altitude, while the leaf area, leaf nitrogen and phosphorus content of ErM plants showed an increasing trend with altitude. The community assembly of three mycorrhizal plants were dominated by stochastic processes, in which the drift of ErM plants contributed more to community assembly than AM and EcM. The βNTI (Beta Nearest Taxon Index) of AM plants had no significant effect on the functional diversity, whereas it had a significant effect on the community weighted mean of functional traits of EcM and ErM plants. The βNTI had a significant positive effect on functional diversity of EcM and ErM plants, which maintained their functional diversity. In addition, soil nutrients (soil organic carbon, total nitrogen and hydrolysable nitrogen) had a significant positive effect on the functional diversity of AM and EcM plants, but had a significant negative effect on the functional diversity of ErM plants. Altitude had a significant negative effect on AM and ErM plants, and a significant negative effect on EcM plants. The results of the study provide scientific basis for revealing the mechanism of biodiversity maintenance in the southwestern mountains, which is of great significance for the protection and restoration of natural forests in the central subtropics.

Aims Plant growth is influenced by a combination of their own characteristics and soil microbial communities. However, it remains unclear how plant resource acquisition strategies affect their own biomass through the diversity of rhizosphere soil fungi in natural communities. Methods In this study, we selected 12 dominant and common plant species from the meadow steppe of Saihanba in Hebei Province, and performed high-throughput sequencing on their rhizosphere soil fungi, and simultaneously measured the functional traits of these plants’ leaves and roots, as well as aboveground biomass. The aim was to delve into the relationship between rhizosphere soil fungal diversity and above-ground biomass under different resource acquisition strategies. Important findings The study found that: 1) in terms of resources acquisition strategies, leguminous plants belonged to the “fast-growing” strategy species, while Cyperaceae and Poaceae plants belonged to “slow-growing” strategy species. Cyperaceae plants exhibited a “do-it-yourself” strategy, and most non-leguminous forbs tended to be “outsourcing” strategy. 2) Plants with “slow-growing” and “do-it-yourself” strategies increased the overall rhizosphere fungal and saprotrophic fungal diversity, and the above-ground biomass of plants with these strategies dominated the community. 3) Rhizosphere soil fungal diversity was positively correlated with plant above-ground biomass, with the diversity of saprotrophic and pathogenic fungi playing particularly crucial roles. 4) The differences in above-ground biomass within the community were mainly directly influenced by the “fast-slow” economic spectrum of plants. These findings not only reveal the regulatory effect of plant resource acquisition strategies on rhizosphere soil fungal communities, but also highlight the key role of the “fast-slow” economic spectrum and rhizosphere soil fungal diversity in driving above-ground biomass accumulation. This study provides a theoretical basis for understanding the impact of plant-microbe interactions on the functions of grassland ecosystems.

Aims Grassland plant roots and mycorrhizal fungi are the main sources of soil organic carbon, which play an important role in the formation and turnover of soil organic carbon and its components, and they also affect the soil nitrogen pool. Under the scenario of climate change, global drought events are frequent. How drought regulates the effects of roots and mycorrhizal fungi on soil carbon and nitrogen pools of different components is still unclear. Methods In this study, Cleistogenes squarrosa was planted in indoor pots and subjected to control and drought treatments. Root bags and mycorrhizal bags were set up to distinguish the effects of plant roots and mycorrhizal fungi on the carbon and nitrogen content of soil organic matter and its components during plant growth. After 64 days of plant growth, the plants were harvested. The soil inorganic nitrogen content, plant biomass, plant leaf carbon and nitrogen content, carbon and nitrogen content of soil organic matter and its components in root bags and mycorrhizal bags, and microbial community composition were measured. Important findings The results showed that compared with mycorrhizal bags without root participation, the soil organic carbon and particulate organic carbon content in the root bags enhanced by 17.5% and 55.8%, and the mineral-bound organic nitrogen content increased by 10.1%. Drought treatment increased soil inorganic nitrogen content, reduced plant biomass, had no significant effect on the carbon and nitrogen content of soil organic matter and its components in the root bag, but significantly reduced the content of particulate organic carbon in the mycorrhizal bag. Drought treatment did not significantly change the microbial biomass in the root bag, but increased the microbial biomass in the mycorrhizal bag. The particulate organic carbon content in the mycorrhizal bags was negatively correlated with the amount of mycorrhizal fungi and the total microbial biomass. The results showed that during plant growth, the roots mainly affected the content of particulate organic carbon in the soil, and mycorrhizal fungi mainly affected the content of mineral-bound organic nitrogen. Short-term drought would reduce the content of particulate organic carbon in the soil in which mycorrhizal fungi participated. Future research should pay more attention to how global change affects the relative contribution of grassland plant roots and mycorrhizal fungi to soil organic matter and its components and their soil organic carbon and nitrogen potential on a long-term scale.

Aims Phragmites australis, a typical perennial rhizomatic wetland plant, is an important species in marsh wetland ecosystems. However, with the global climate change and the gradual drying of wetlands, the growth of P. australis is often limited by soil moisture. Understanding the response of P. australis to changes in soil moisture can provide a theoretical basis for the protection and dynamic prediction of its community, as well as for research on the response mechanisms of wetland plants in heterogeneous habitats. Methods In this study, P. australis communities in three typical marsh wetlands in northern China, i.e., Daihai Wetland, Horqin Wetland and Qingtongxia Reservoir, were studied, and the effects of low and high soil moisture, and other environmental factors on the aboveground traits, belowground traits and their relationships of P. australis were analyzed. Important findings Compared with low soil moisture, high soil moisture significantly increased the aboveground biomass and specific leaf area, and significantly reduced the root to shoot ratio of P. australis. High soil moisture significantly reduced the contents of non-structural carbohydrates in leaves, and nitrogen and phosphorus in stems. High soil moisture significantly increased the root biomass, root surface area and root volume, and significantly decreased the root diameter of P. australis. Soil moisture did not affect the positive correlation between root biomass and stem non-structural carbohydrates content. However, the decrease in soil moisture reversed the negative correlation between root diameter and leaf nitrogen content under high soil moisture, as well as the positive correlations between root diameter and leaf non-structural carbohydrates content, and between root diameter and stem non-structural carbohydrates content. In high soil moisture areas, total soil nitrogen and total soil phosphorus were important factors that affected the aboveground and belowground traits of P. australis; in low soil moisture areas, temperature and precipitation were also important factors. Our results indicate that soil moisture may indirectly affect total soil nitrogen and total soil phosphorus and temperature to change the correlations between some aboveground and belowground traits. In summary, high soil moisture was beneficial to the growth of aerial parts and roots of P. australis, but it reduced the contents of nitrogen and phosphorus in stems and the content of non-structural carbohydrates in leaves. soil moisture influences the aboveground and belowground traits and their relationships in P. australis, by indirectly affecting soil nitrogen and phosphorus contents, as well as temperature.

Aims Alpine grassland ecosystems store vast amounts of organic carbon while are fragile. Understanding the responses of the ecosystem carbon storage to the synchronous atmospheric nitrogen deposition and changing precipitation regimes is critical to project the fate of ecosystem carbon budgets under the context of global change. Methods Based on a manipulation field experiment of nitrogen addition (10 g?m–2?a–1) and precipitation change (precipitation reduction by 50% and increase by 50%) in an alpine meadow on the northeastern Qinghai-Xizang Plateau in 2017, the plant biomass, soil organic carbon content (SOCC) and its fractions were observed from 2022 to 2023, in order to explore the response of ecosystem carbon storage to the changes in nitrogen and precipitation. Important findings The results showed that there were little interaction effects of nitrogen addition and precipitation change. The response of vegetation aboveground biomass to the changes in nitrogen and precipitation was functional group-dependent. Nitrogen addition treatment increased the AGB of graminoid and sedge. Decreased precipitation treatment reduced AGB by 27% while increased precipitation treatment impacted AGB insignificantly. Except for sedge, the proportion of functional group AGB against community AGB changed undetectably. The responses of 0–40 cm belowground biomass (BGB) and SOCC to the changes in nitrogen and precipitation were weak and depth- and year-dependent. The root/shoot ratio reduced by 31% in nitrogen addition treatment and increased by 83% in decreased precipitation treatment, respectively. Nitrogen addition treatment increased surface (0–10 cm) mineral-associated organic carbon by 31%. The response ratio (RR) of vegetation AGB was positively related to graminoid. The RR of 0–40 cm BGB was determined by surface and deep (20–40 cm) BGB positively. The RR of 0–40 cm SOCC was equivalently regulated by each layer SOCC. Surface BGB directly impacted the surface POC positively and indirectly impacted the surface MAOC via POC negatively. The vegetation AGB affected the deep MAOC positively and the deep POC negatively. The main effects, rather than the interaction effects of the changes in nitrogen and precipitation, affect AGB significantly while BGB and SOCC undetectably. The differential effects of plant biomass on soil organic carbon fractions are depth-dependent.

Aims: As an important part of the global ecosystem, alpine grasslands are especially sensitive to climate change and human activities. The carbon and nitrogen pools of plants and microorganisms are significant components of the carbon and nitrogen pools in grassland ecosystems. Grazing, as one of the main utilization ways of alpine grasslands, directly determines the distribution, storage and utilization of carbon and nitrogen resources by plants and soil microorganisms. Methods By setting up experiments with different grazing methods in Xihai Town, Haibei Prefecture, Qinghai Province, i.e., Yak grazing alone (YG), Tibetan sheep grazing alone (SG), Yak-Tibetan sheep 1:2 mixed grazing (MG1:2), Yak-Tibetan sheep 1:4 mixed grazing (MG1:4), Yak-Tibetan sheep 1:6 mixed grazing (MG1:6), and no-grazing treatment (CK). Important findings In terms of carbon pools, separate grazing by yaks and Tibetan sheep significantly reduced the carbon pool of the plant community, but did not affect the microbial biomass carbon pool. Mixed grazing also reduced the carbon pool of the plant community, yet significantly increased the microbial biomass carbon pool. Regarding nitrogen pools, when grazing separately, the nitrogen pool of the plant community remained unchanged, while the microbial biomass nitrogen pool increased significantly. Under mixed grazing conditions, the nitrogen pool of the plant community was significantly reduced, and the microbial biomass nitrogen pool was not affected. Studies on the trade-offs between plant and microbial carbon and nitrogen pools found that in the situations of no grazing and separate grazing by yaks and Tibetan sheep, the trade-off of carbon and nitrogen pools favored the plant community. Under mixed grazing conditions, the trade-offs of MG1:2 and MG1:4 were inclined to the microbial biomass carbon pool, and that of MG1:6 was inclined to the microbial nitrogen pool. The above results indicate that grazing may regulate the carbon content in plants by consuming the above-ground parts of plants. This change further affects the trade-off state between the carbon pool of the plant community and the microbial biomass carbon pool. Meanwhile, grazing promotes plant regeneration through consumption, increases the nitrogen content of the plant community, and changes the trade-off relationship between the nitrogen pool of the plant community and the microbial biomass nitrogen pool.

Aims Ecological stoichiometry has been recognized as a useful indicator of nutrient status and process regulation in ecosystems. Quantifying the effects of stand age on carbon (C) : nitrogen (N) : phosphorus (P) stoichiometric characteristics and ecosystem C storage allocation patterns is critical for understanding the mechanisms of biogeochemical cycles and ecological functions in plantation ecosystems. Methods This study compared the C:N:P stoichiometry and the C storage partitioning patterns along a chronosequence of walnut (Juglans regia) plantations in the eastern Taihang Mountains, North China. Plant and soil samples from four stand ages (4-, 8-, 12-, and 16-year-old) were collected and analyzed. Important findings 1) Mean C content in organs (root, stem, branch, and leaf) was 437.17, 449.87, 448.16, and 441.39 g·kg-1, respectively, showing a nog-significant increasing trend with stand age. N and P contents of different organs were 4.15-26.68 g·kg-1 and 0.99-1.95 g·kg-1, respectively, decreasing significantly with stand age. C:N and C:P ratios increased significantly, while N:P remained stable. 2) Under anthropogenic management, soil C, N, and P contents exhibited an initial decline followed by an increase with stand age, with significant variations among age classes. Trends in C:N, C:P and N:P ratios aligned with nutrient content changes. 3) Correlation analysis showed that soil C was positively correlated with soil N (P < 0.001). Leaf C showed a negatively correlation with leaf N (P < 0.05), while leaf N demonstrated a significantly positive correlation with leaf P (P < 0.01). Soil P was positively liked to leaf N, branch P, stem P and N (P < 0.01). 4) Total ecosystem C storage for 4-, 8-, 12-, and 16-year-old plantations was 167.59, 123.69, 136.03, and 202.37 Mg·ha-1, respectively. The soil layer constituted the primary C pool, contributing 88.2%-99.7% of total ecosystem C storage. This study provides a scientific basis for systematically understanding nutrient cycling mechanisms and C sequestration functions in mountain economic plantation ecosystems.

AimsShrublands is an indispensable part of estimating carbon density in terrestrial ecosystems, and the expansion of shrublands is considered as one of the key reasons leading to the increase of carbon density in terrestrial ecosystems in China, and yet there are great uncertainties in the carbon sink capacities of shrublands. Our objectives were to estimate the carbon density and distribution characteristics of common shrublands in North China. Methods The carbon density and distribution characteristics of two typical shrublands (Caragana jubata and Carpinus turczaninowii) in Dongling Mountain, Beijing, were measured based on the field investigation data and by employing allometric approaches. Important findings The results showed that the carbon density (427.59 t?hm-2) of C. jubatashrubland was significantly higher than that (178.19 t?hm-2) of the C. turczaninowii shrubland, in which the carbon storage of soil layer was the most (98.53%and 81.31%), and the carbon storage were 421.29 t?hm-2 and 144.89 t?hm-2, respectively. Soil organic carbon was enriched in the 0–50 cm soil layer, and showed a decreasing trend with increasing soil depth. The organic carbon density in different soil layers of the C. jubata shrubland is higher than that of the C. turczaninowii shrubland, mainly due to the lower temperature and smaller slope in the distribution area of the former, which is conducive to the accumulation of organic matter. The contribution of the shrub layer and the arbor-shrub layer to the carbon density of the entire ecosystem were relatively small (1.27% and 17.77%), with values of 5.44 and 31.69 t?hm-2, respectively. The carbon density of different organs in the arbor layer was in the order of trunk > root > branch > leaf, while the order of carbon density in the shrub layer was branch > root > leaf in both shrublands. Moreover, the carbon density of each organ in the shrub layer of C. jubata shrubland was significantly lower than that in the C. turczaninowii shrubland.The herbaceous layer and litter layer contributed the least to the total carbon density of C. jubata and C. turczaninowii shrublands (0.20% and 0.91%), with values of 0.86 and 1.62t?hm-2, respectively. The carbon density of the herbaceous layer(0.55 t?hm-2) in C. jubata shrubland was significantly higher than that (0.35 t?hm-2) in C. turczaninowii shrublands. Moreover, carbon density of the aboveground and underground parts of the herbaceous layer in C. jubata shrubland was similar, while in C. turczaninowii shrubland, the aboveground carbon density was significantly lower than that of the underground part. The carbon density of the litter layer (1.27 t?hm-2) in C. turczaninowii shrubland was significantly higher than that (0.31 t?hm-2) in C. jubata shrubland.

Aims By investigating aboveground and belowground nutrient allocation strategies of dominant tree species, Juniperus saltuaria and Rhododendron nivale, under different interaction intensities at the alpine treeline of the Sygera Mountains, this study aims to provide theoretical basis and support for ecological protection and restoration for alpine zone. Methods This study focuses on the J. saltuaria community(Cover:60%), the J. saltuaria dominated community(Cover:20%), the R. nivale dominated community(Cover:56%), and the R. nivale community(Cover:75%) at the alpine treeline of the Sygera Mountains. In August 2022, leaves, roots, and soil within the canopy range of dominant species in these four plant communities were collected. The nutrient element content of the samples was measured, and the aboveground and belowground nutrient and stoichiometric characteristics of J. saltuaria and R. nivale under different interaction intensities were analyzed using ecological stoichiometry and Partial Least Squares Path Model (PLS-PM). It aims to clarify the differences in nutrient strategies of the two dominant tree and shrub species under varying interaction intensities at the alpine treeline of the Sygera Mountains. Important findings The results showed that (1) leaf C content in the J. saltuaria community was higher than that in the J. saltuaria dominated community, while N, P, and K contents were the opposite; root C content in the J. saltuaria community was lower than that in the J. saltuaria dominated community, while N, P, and K contents were higher. In the R. nivale dominated community, leaf C and K contents were higher than those in the R. nivale community, whereas N and P contents were lower; root C and N contents were higher in the R. nivale dominated community, while P and K contents were lower. In all four plant communities, leaf C, N, P, and K contents were significantly higher than in roots, as nutrients are transported to leaves from other plant organs to sustain normal physiological activities. (2) Compared to the J. saltuaria community, the J. saltuaria dominated community preferred to allocate more nutrients to leaves, representing an aggressive nutrient strategy. In contrast, the R. nivale dominated community transported more nutrients to roots compared to the R. nivale community, reflecting a more conservative nutrient strategy. Additionally, a positive feedback mechanism exists between plant communities and soil nutrients in the study area.

Aims Dendrobium huoshanense is a national category I Protected Endangered Wild Plant of the Orchidaceae family and the genus Dendrobium. It is also a traditional Chinese medicinal resource plant that can be used both as medicine and food. Currently, facility cultivation and underforest cultivation have become the primary methods for the cultivation of D. huoshanense. However, the correlation characteristics between the aboveground biomass, quality of D. huoshanense and the microbial community in the substrate/soil under these two cultivation modes remain unclear. This limitation hinders the understanding of the aboveground-belowground processes and mechanisms of D. huoshanense. Methods In light of this, a field experiment and sampling were conducted at the D. huoshanense cultivation base in the Dabie Mountains, Anhui, with the aim to investigate the regulatory relationship between nutrients and plant-microbe interactions in the facility and underforest cultivation modes of D. huoshanense. Important findings Underforest cultivation of D. huoshanense significantly altered the microbial community in the soil, whereas facility cultivation did not change the microbial community in the substrate. Significant differences in microbial biomass, community structure, and diversity were observed between the facility and underforest cultivation modes. Specifically, compared to the underforest soil, the substrate showed higher microbial biomass carbon (MBC) and nitrogen (MBN) contents, as well as a higher abundance of phylum Glomeromycota fungi and bacterial diversity. The fresh weight of D. huoshanense in the substrate was significantly higher than that in the underforest soil. Structural equation modeling (SEM) results indicated the regulatory relationships between nutrients-microbes in the substrate/soil and the fresh weight of D. huoshanense in the two cultivation modes. In detail, the eutrophic conditions in the facility cultivation shaped a higher bacterial diversity, which promoted the aboveground biomass of the plants. In contrast, under the oligotrophic conditions of the underforest, an increase in pathogen abundance reduced the aboveground biomass, while potentially prompting an increase in the resistance of secondary metabolites (such as flavonoids) in D. huoshanense. This study clarifies the associations between plant biomass and microbial communities in the facility and underforest cultivation modes of D. huoshanense, providing a scientific basis for the development of functional microbial inoculants to promote plant growth and quality regulation in the artificial cultivation process of D. huoshanense, as well as the conservation of rare and endangered plant resources.

Abstract Aims This research provides theoretical support for exploring the multidimensional characteristics of plant biomass and root structure, as well as for developing urban greening strategies. Methods Two widely used vining plants in landscape applications in eastern China, the cascading Vinca major ‘Variegata’ and the climbing Trachelospermum jasminoides ‘Variegatum’, were selected as experimental subjects. The study compared their three-year growth dynamics, root architecture, and biomass changes in different substrates and predicted their longevity under these conditions. Important findings (1) Plant biomass and root architecture followed a single-peak growth curve, characterized by rapid increase followed by decline in the traditional mixed substrate, whereas in the novel medium, they exhibited a linear and gradual growth trend. (2) Correlation and principal component analyses of plant biomass and root architecture in different substrate types revealed significant variations in root length, root tips, root forks, root surface area, and root volume. These parameters were identified as key indicators for modeling plant longevity, with differing indicator functions: root surface area and root volume were stable, systematic assessment parameters, while root length and root tips were highly sensitive evaluation parameters. (3) Growth curves of the plants in the novel container medium predicted peak growth periods of 6.99 and 10.77 years, respectively, far exceeding the 2-3 years observed in the traditional mixed substrate. The optimal compaction and nutrient content of the novel medium enhanced root vitality and turnover, thereby extending plant lifespan and the duration of ecological services. By revealing and quantifying the complex structure and function of the root system of urban greening vines, this study helps to build a more stable and efficient plant community, which can improve the level of urban biodiversity, and at the same time provide experimental theoretical support for iterative greening camping techniques for special habitats such as green roofs and vertical green walls.