Tree growth rates generally increase with individual size, but how nutrient enrichment alters the size-growth relationship remains poorly understood. In this study, we asked whether a decade of nitrogen (N) addition altered the size-growth relationship of trees, and explored the potential mechanisms underlying such changes. We found a nonlinear shift in the size-growth relationship along the N addition gradient. The near size-symmetric growth observed in control plots shifted to a pattern favoring smaller individuals under low-level N addition (20 kg N ha(-1) yr(-1)). This occurred because small trees had higher leaf N resorption efficiency in controls, reflecting stronger N conservation and allowing a stronger growth response to moderate N inputs. With further increases in N addition (> 50 kg N ha(-1) yr(-1)), the relationship reversed toward size symmetry. This reversal was associated with N-induced changes in nutrient stoichiometry, as smaller trees showed greater phosphorus and potassium resorption efficiencies, suggesting they experienced stronger secondary limitation by these nutrients and consequently lost their growth advantage relative to larger trees. Our findings provide novel insights into how N addition rate reshapes the size-growth relationship of trees, highlighting multiple nutrient limitation as a potential driver of stand development. These results suggest that size-dependent growth responses should be incorporated into forest management and projections of long-term biomass accumulation under increasing N deposition.

Plant biomass and its allocation are fundamental for understanding biospheric matter production. However, the impacts of atmospheric phosphorus (P) deposition on species-specific biomass and its allocation in global terrestrial plants remain unclear. By synthesizing 5548 observations of plant biomass and its allocation related to P addition worldwide, we find that P addition increases plant biomass by an average of 35% globally. This increase varies across plant functional groups, with stronger responses in deciduous (45%), C3 (36%), and N2-fixing plants (54%) than in evergreen (28%), C4 (19%), and non-N2-fixing plants (31%), respectively. Plants possessing traits indicative of an acquisitive strategy, such as higher nutrient concentrations and specific leaf area, faster photosynthetic rates and shorter leaf lifespan, are particularly responsive to P addition. Furthermore, P addition promotes a greater allocation of biomass to aboveground than belowground organs, resulting in a 5% decrease in root-to-shoot ratio. Our findings provide global-scale quantifications of how P addition regulates biomass accumulation and allocation strategies in terrestrial plants, offering critical insights for predicting the response of terrestrial carbon storage to rising atmospheric P deposition.

Nitrogen (N) in the litter and soil inorganic N can have contrasting effects on litter decomposition, such that the positive effects of litter N on the rate of decomposition will likely decrease with increased soil inorganic N due to possible suppression of lignin oxidase. To test this, we reciprocally buried litter collected from multiple treatments in an N addition experiment (0, 20, 50, and 100 kg N ha-1 yr-1). With increasing N addition, we found that the concentration of N in the litter and the availability of inorganic N in the soil increased linearly. Contrary to our expectations, the litter N effects on decomposition changed nonlinearly with the N addition, first decreasing with the N addition rates but then reversed at the highest N addition treatment. This reversal at higher N rates is mainly due to a change in soil decomposing microbes with N addition. We examined the activity of extracellular enzymes in soil and found that phenol oxidase activity was not affected by N addition, but cellulase activity increased linearly with N addition rates. We further found that the relative abundance of bacterial functional genes involved in cellulose and the abundance of soft-rot fungi that decay cellulose increased with N addition. Our study contrasts the assumption that increased soil inorganic N suppresses lignin oxidation and instead reveals an increase in cellulolytic groups and activity of cellulase; this shift in decomposing microbes mediates the litter N effects on decomposition and suggests that more slowly decomposing fractions might be less affected.

The sensitivity of soil respiration (Rs) to temperature (Q10) is a key parameter for benchmarking the carbon (C) cycle and climate feedbacks in the context of global warming. However, previous studies on the factors that drive forest soil Q10 have focused mostly on abiotic factors, such as climate and soil, while the role of biotic factors has been less examined. Here, we compiled a global dataset of 766 soil Q10 values and 17 matched biotic and abiotic factors to explore the factors that drive the variability of global forest soil Q10 using a random forest (RF) model. Our findings showed that soil Q10 increased with microbial biomass carbon (MBC), which was the most important predictor. Additionally, soil Q10 was positively correlated with leaf phosphorus content (LPC) but was negatively correlated with leaf N:P, indicating that plant ecological stoichiometry might be a factor that explained soil Q10 variability. All abiotic factors, including climate, soil properties, and elevation, had great predictive power and were significantly related to soil Q10. By comparing the soil Q10 in multispecies forests and monocultures, we found that Q10 in the mixed needle-leaved and broad-leaved forests (NF & BF) was lower than in monocultures. Our study revealed that, in addition to abiotic factors, biotic factors were also strong predictors of forest soil Q10, which can deepen our understanding of soil respiration in response to global warming and provide insights for improving carbon cycle models.

Understanding the distinct drivers of nitrogen dioxide (NO2) and ammonia (NH3) is essential for effective air-quality management. This study characterizes their nationwide dynamics across China from 2015 to 2023 using an interpretable machine-learning framework that integrates satellite observations with Random Forest modeling and SHapley Additive exPlanations (SHAP). Nationally, NO2 concentrations declined markedly from 6.20 to 4.90 Nμg/m3, whereas NH3 levels remained broadly stable. Spatial patterns show NO2 hotspots concentrated in urban-industrial corridors and NH3 enhancements over agricultural regions. SHAP-based attribution indicates that meteorology is a shared primary driver, yet secondary controls diverge: NO2 is predominantly source-driven, strongly linked to anthropogenic variables such as population density and urban extent (35.1% of explained importance), while NH3 is process-driven, governed by ecological and agricultural factors - including vegetation, soil properties, and fertilizer application (30.9%) - with these effects most pronounced in cropland and vegetated areas. The contrasting regimes of the two pollutants underscore the differing efficacy of control approaches. Direct emission policies have successfully reduced NO2, but the persistence of NH3 highlights the need for integrated, process-oriented management that couples agricultural best practices with climate and ecosystem adaptation. This differentiated understanding provides a scientific basis for regionally tailored nitrogen-mitigation strategies in China.

Nitrogen (N) addition can stimulate tree growth; however, the strength of this growth effect usually changes over time and the factors underlying these responses are not fully understood. Based on a decade-long N addition experiment (by adding 0, 20, 50, and 100 kg N ha-1 yr-1) in a boreal forest, we studied responses of tree growth to N addition over time and explored the potential role of temporal precipitation variation and plant stoichiometric changes in mediating this. We found positive growth responses to N addition but this effect changed nonlinearly over time. Annual precipitation was positively related to growth under high-level N addition; hence, a hump-shape temporal pattern in precipitation contributed to the nonlinear tree growth responses. After precipitation effects were accounted for, the positive growth responses to N addition peaked in the seventh year and then declined for all levels of N. Later reductions in growth responses could partly be attributed to increased leaf N:phosphorus (P) ratio over time, especially at higher N addition rates. We also found an increase in soil acid phosphatase, the ratio of labile to occluded soil P fraction, and a decreased ratio in leaf N to P resorption efficiency with increasing N addition rates during the late stage of this experiment, suggesting increased P demand. Collectively, our results imply that changes in plant nutrient stoichiometry with cumulative N input may limit the N stimulation on tree growth over time, while temporal precipitation variation appears unlikely to modulate this effect under the atmospheric N deposition. Tree growth can be limited by the availability of nitrogen (N), while the stimulation effects of increased N input on growth can change over time due to constraints by the availability of either water or other nutrients such as phosphorus (P). We investigated the temporal dynamics of tree growth to decade-long N addition in a boreal forest and assessed how growth was mediated by temporal precipitation variation and plant tissue N:P. The rate of tree growth was enhanced by N addition, but the positive effect first increased but then decreased over time. Annual precipitation variation mediated the growth response to the highest N addition (100 kg N ha-1 yr-1) only, whereas an increase in leaf N:P ratio over time under N addition explained the changes in tree growth response to N addition. We also found evidence for the acceleration of ecosystem P cycling. Our findings suggest that the relative P limitation may constrain tree growth responses to increased N availability over time, and these should be considered in predicting forest carbon sequestration with N deposition. Effects of N addition on tree growth changed nonlinearly over time Interannual precipitation enhanced the stimulation effect of N addition on tree growth under the highest N level only The increase in leaf N:P ratio over time mediated the temporal dynamics of tree growth responses to N addition

Increased nitrogen (N) input can potentially lead to secondary phosphorus (P) limitation; however, it remains unclear whether differences in the plant's ability to cope with this P deficiency are related to their growth responses. Using a long-term experiment of N addition in a boreal forest, we explored the potential role of plant nutrient resorption efficiency and its stoichiometry in mediating plant growth responses to increased N input. We recorded the cover and measured the concentration and resorption efficiency of leaf N and P as well as the photosynthesis of a grass Deyeuxia angustifolia and a shrub Vaccinium vitis-idaea. The cover of the grass D. angustifolia increased with increasing N addition, while that of the shrub V. vitis-idaea decreased with N addition rate and almost disappeared from the high-level N addition over time. P resorption efficiency (PRE) increased in D. angustifolia but decreased in V. vitis-idaea with increasing leaf N:P which was increased by N addition for both species. In addition, photosynthesis increased linearly with N resorption efficiency (NRE) and PRE but was better explained by NRE:PRE, changing nonlinearly with the ratio in a hump-shaped trend. Furthermore, the variance (CV) of NRE:PRE for V. vitis-idaea (123%) was considerably higher than that for D. angustifolia (29%), indicating a more stable nutrient resorption stoichiometry of the grass. Taken together, these results highlight that efficient P acquisition and use strategy through nutrient resorption processes could be a pivotal underlying mechanism driving plant growth and community composition shifts under N enrichment.

Leaf dark respiration (Rdark), an important yet rarely quantified component of carbon cycling in forest ecosystems, is often simulated from leaf traits such as the maximum carboxylation capacity (Vcmax), leaf mass per area (LMA), nitrogen (N) and phosphorus (P) concentrations, in terrestrial biosphere models. However, the validity of these relationships across forest types remains to be thoroughly assessed. Here, we analyzed Rdark variability and its associations with Vcmax and other leaf traits across three temperate, subtropical and tropical forests in China, evaluating the effectiveness of leaf spectroscopy as a superior monitoring alternative. We found that leaf magnesium and calcium concentrations were more significant in explaining cross-site Rdark than commonly used traits like LMA, N and P concentrations, but univariate trait-Rdark relationships were always weak (r2 <= 0.15) and forest-specific. Although multivariate relationships of leaf traits improved the model performance, leaf spectroscopy outperformed trait-Rdark relationships, accurately predicted cross-site Rdark (r2 = 0.65) and pinpointed the factors contributing to Rdark variability. Our findings reveal a few novel traits with greater cross-site scalability regarding Rdark, challenging the use of empirical trait-Rdark relationships in process models and emphasize the potential of leaf spectroscopy as a promising alternative for estimating Rdark, which could ultimately improve process modeling of terrestrial plant respiration.

Nitrogen (N) deposition has changed plants and soil microbes remarkably, which deeply alters the structures and functions of terrestrial ecosystems. However, how forest fungal diversity, community compositions, and their potential functions respond to N deposition is still lacking in exploration at a large scale. In this study, we conducted a short-term (4–5 years) experiment of artificial N addition to simulated N deposition in five typical forest ecosystems across eastern China, which includes tropical montane rainforest, subtropical evergreen broadleaved forest, temperate deciduous broadleaved forest, temperate broadleaved and conifer mixed forest, and boreal forest along a latitudinal gradient from tropical to cold temperature zones. Fungal compositions were identified using high-throughput sequencing at the topsoil layer. The results showed that fungal diversity and fungal community compositions among forests varied apparently for both unfertilized and fertilized soils. Generally, soil fungal diversity, communities, and their potential functions responded sluggishly to short-term N addition, whereas the fungal Shannon index was increased in the tropical forest. In addition, environmental heterogeneity explained most of the variation among fungal communities along the latitudinal gradient. Specifically, soil C: N ratio and soil water content were the most important factors driving fungal diversity, whereas mean annual temperature and microbial nutrient limitation mainly shaped fungal community structure and functional compositions. Topsoil fungal communities in eastern forest ecosystems in China were more sensitive to environmental heterogeneity rather than short-term N addition. Our study further emphasized the importance of simultaneously evaluating soil fungal communities in different forest types in response to atmospheric N deposition.

Evergreen broad-leaved forest (EBLF) is climax vegetation in East China, and Jiangxi Province is located at the center of EBLF. Although many phytosociological studies have provided detailed descriptions on this forest at local and regional scales, knowledge on the high-level classification of EBLF and factors controlling their tree species composition and distribution are still lacking. We aim at providing a high-level classification framework for EBLF in Jiangxi and exploring the roles of topographic and climatic factors in driving their distributions. We investigated 205 EBLF plots covering the main alliances across Jiangxi Province. Two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) were used to distinguish the EBLF types. Diagnostic and indicator species were detected. The nonparametric Kruskal-Wallis test was used to compare the differences between the groups of EBLFs. We also used redundancy analysis and variation partitioning to estimate the effects of climatic, geographical and topographical factors on the distribution of EBLFs in Jiangxi. The EBLFs in Jiangxi were classified into four types based on the diagnostic taxa and verified by TWINSPAN, i.e. lowland, ravine monsoon, montane typical and dwarf cloud EBLF types. These four EBLF types are associated with climatic and topographic conditions, and their distribution pattern reflects biogeographic differences. Our study provides an important basis for the syntaxonomic classification of EBLFs and further in-depth studies on humid EBLFs in East China. We also emphasize the importance of conservation practices to protect these forests as diversified Tertiary relict plants.

Increased nitrogen (N) deposition has a great impact on soil greenhouse gas (GHG) emissions, and numerous studies have revealed the individual effects of N addition on three major GHGs (CO2, CH4, and N2O). Nevertheless, quantitative evaluation of the effects of N addition on the global warming potential (GWP) of GHGs based on simultaneous measurements is needed not only to better understand the comprehensive effect of N deposition on GHGs but also for precise estimation of ecosystem GHG fluxes in response to N deposition. Here, we conducted a meta-analysis using a dataset with 124 simultaneous measurements of the three major GHGs from 54 studies to assess the effects of N addition on the combined global warming potential (CGWP) of these soil GHGs. The results showed that the relative sensitivity of the CGWP to N addition was 0.43%/kg N ha-1 yr-1, indicating an increase in the CGWP. Among the ecosystems studied, wetlands are considerable GHG sources with the highest relative sensitivity to N addition. Overall, CO2 contributed the most to the N addition-induced CGWP change (72.61%), followed by N2O (27.02%) and CH4 (0.37%), but the contributions of the three GHGs varied across ecosystems. Moreover, the effect size of the CGWP had a positive relationship with N addition rate and mean annual temperature and a negative relationship with mean annual precipitation. Our findings suggest that N deposition may influence global warming from the perspective of the CGWP of CO2, CH4, and N2O. Our results also provide reference values that may reduce uncertainties in future projections of the effects of N deposition on GHGs.

Understory plants in forest ecosystems play key roles in carbon (C) cycling and have generally shown negative responses in their diversity and plant cover to increased nitrogen (N) deposition, yet the potential consequences of these responses on the soil C cycle are poorly understood. Here we aim to explore the effects of N addition on understory plants and its consequences on soil respiration (Rs). We conducted a N addition experiment with four N levels (0, 20, 50, and 100 kg N ha−1 yr−1) in a boreal forest and monitored the understory plant cover, plant species richness and Rs after 9 years. We found that N addition decreased the species richness and plant cover of the understory plants. Rs showed a unimodal pattern during the growing season driven mainly by soil temperature, and N addition inhibited Rs when the soil temperature effect was accounted for. A structural equation model revealed that the reduction in Rs with N addition was a result of the reduction in fine root biomass linked with the decline in understory plant cover but was unrelated to the loss of species richness. Our findings suggested that the negative effects of increased N deposition on the understory plant community in forest ecosystems would alter soil C storage with potential climate consequences.

Precipitation changes exert a fundamental effect on the nitrogen (N) cycle in water-limited grasslands. Soil microbes are essential drivers of N cycle, and the rates and their stabilities of interrelated N-cycling processes are reflected by the abundance and diversity of N-cycling genes. Yet, little is known about how altered precipitation affects the genes involved in the entire N-cycling pathways.By combining a 6-year precipitation manipulation experiment (-30%, ambient, +30%, +50%) with metagenomic sequencing, we investigated the responses of N-cycling gene abundance and diversity to altered precipitation at two soil depths (0-10 and 30-50 cm).We found that increased precipitation enhanced the abundance of numerous key genes, leading to an acceleration of N turnover, but decreased the diversity of ammonium assimilation genes. Decreased precipitation did not reduce abundance or diversity of N-cycling genes. Most N-cycling genes showed generally consistent responses to altered precipitation in the topsoil (0-10 cm) and subsoil (30-50 cm), albeit with clear distinctions in both abundance and diversity by soil depth. These precipitation-specific responses and depth-dependent variabilities of functional genes were attributed to the distinct taxonomic composition of each N-cycling gene. Furthermore, we quantified gross N transformation rates and found that they were well predicted by the abundance of most N-cycling genes (e.g. genes involved in ammonium assimilation and nitrification).Our study sheds new light on the soil N cycle under precipitation alterations from the perspective of individual gene abundance and diversity and shows that future increases in precipitation could accelerate soil N turnover in arid and semi-arid lands.Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog.image

Silage maize (Zea mays L.) is one of the most important forages in the world, and its yield and quality properties are critical parameters for livestock production and assessment of forage values. However, relationships between its yield and quality properties and the controlling factors are not well documented. In this study, we collected 5,663 observations from 196 publications across the country to identify the relationships between yield and quality properties of silage maize and to assess the impact of management practices and climatic factors on its yield and quality in China. The average dry matter yield of silage maize was (19.98±6.93) Mg ha−1, and the average value of crude protein, ether extract, crude ash, crude fiber, acid detergent fiber, neutral detergent fiber, nitrogen-free extract, and relative feed value was 7.86%±1.71%, 2.53%±1.01%, 5.05%±1.66%, 23.97%±6.34%, 27.62%±7.12%, 51.60%±9.85%, 59.68%±7.72%, and 131.17±31.49, respectively. In general, its nutritive value decreased as its yield increased. Increasing planting density could increase the yield but inhibit the nutritive values, while increasing fertilization could benefit the nutritive values. Geographically, the yield increased and the nutritive value decreased from warm (south) to cold (north) regions. The length of growth duration was a major controlling factor for the patterns of these properties. Our findings provide insights for police-makers to make strategy for achieving high yield and good quality of silage maize and help local people to implement better management practices.

Aboveground-belowground interactions are important drivers of terrestrial ecosystem structure and function. However, changes in soil microbial diversity caused by shifts in the plant community composition in the context of nitrogen (N) deposition remain poorly understood in boreal forests. Based on a long-term experiment of N addition at rates of 0, 20, 50, and 100 kg N ha−1 year−1 in a boreal forest in northeastern China, we found that N addition resulted in an increasing dissimilarity in understory plant community composition along the elevated N addition rates. N addition had no effects on the soil microbial alpha diversity but did alter the soil microbial beta diversity. The shifts in the soil bacterial beta diversity following N addition were correlated with soil pH, whereas the changes in the soil fungal beta diversity were explained by changes in the understory plant composition. Since soil fungi play an irreplaceable role in boreal forests, our findings imply that N deposition-induced changes in understory plant community structures might be associated with changes in soil fungal community composition, with potential profound consequences on soil nutrient dynamics and soil carbon cycling.

Soil microbes regulate key functions of terrestrial ecosystems, but the effects and underlying mechanisms of elevated nutrient inputs on soil microbial diversity in tropical forests remain unclear. We evaluated the effects of seven-year nitrogen (N) and phosphorus (P) additions on soil microbial diversity in two tropical montane rainforests (P-limited primary forest and N-limited secondary forest). The results showed that soil bacterial richness was not sensitive to N or P addition, whereas soil fungal richness decreased under P and combined N and P additions. Furthermore, P inputs shifted soil fungal community composition: the relative abundance of mutualistic fungi increased and that of saprotrophic fungi decreased. The underlying mechanisms of these effects differed in the two forests. In the P-limited primary forest, the reduction in soil fungal richness was mainly related to a negative microbial interaction between microbial species and a stimulation in plant productivity. In the N-limited secondary forest, P inputs increased soil N and P imbalance, which caused a decline in the fungal richness. Overall, anthropogenic P enrichment could reduce soil fungal richness and alter fungal functional guilds in tropical forests, which will have divergent consequences on plant productivity and microbial functioning.

Alfalfa (Medicago sativa L.) is the most valuable perennial forage crop, and assessing its yield and quality properties is essential to evaluate forage value of livestock production. However, regional patterns and con-trolling factors of the yield and quality of alfalfa have not been well documented. In this study, using a dataset of 7166 observations from 301 sites across the country collected from 334 publications, we explored the re-lationships between the yield and quality properties of alfalfa in China and the effects of environmental factors and management practices on them. The average dry matter yield of alfalfa was 11.18 ?? 6.69 Mg ha-1, with average crude protein, ether extract, crude fiber, acid detergent fiber, neutral detergent fiber, crude ash, nitrogen-free extract, calcium, phosphorus and relative feed values of 19.05 ?? 2.87%, 2.62 ?? 0.97%, 27.16 ?? 5.21%, 31.29 ?? 5.58%, 40.48 ?? 6.34%, 9.49 ?? 1.59%, 38.67 ?? 7.49%, 1.68 ?? 0.55%, 0.25 ?? 0.12%, and 151 ?? 31.94, respectively. Alfalfa quality decreased with increasing yield. Geographically, alfalfa had higher yield and crude protein content in South China than in other regions. Quality was positively correlated with both precipitation and temperature, while yield showed a positive relationship with temperature but no significant relationship with precipitation. High soil nutrient availability (e. g., soil available nitrogen, SAN; soil available phosphorus, SAP; soil available potassium, SAK) improved the yield, while high SAN and SAP contents increased the crude protein content. The alfalfa yield increased and the quality decreased with advancing maturity and age, whereas increasing the number of harvests may benefit the quality. This study documents comprehensive in-formation on the yield and quality of alfalfa and provides insights for policy makers for the effective management and sustainable development of alfalfa production.

Increased nitrogen (N) inputs are widely recognised to reduce soil respiration (Rs), but how N deposition affects the temporal dynamics of Rs remains unclear. Using a decade-long fertilisation experiment in a boreal larch forest (Larix gmelini) in northeast China, we found that the effects of N additions on Rs showed a temporal shift from a positive effect in the short-term (increased by 8% on average in the first year) to a negative effect over the longer term (decreased by 21% on average in the 11th year). The rates of decrease in Rs for the higher N levels were almost twice as high as those of the low N level. Our results suggest that the reduction in Rs in response to increased N input is accelerated by high-level N additions, and experimental high N applications are likely to overestimate the contribution of N deposition to soil carbon sequestration in a boreal forest.

Nitrogen (N) deposition is known to increase carbon (C) sequestration in N-limited boreal forests. However, the long-term effects of N deposition on ecosystem carbon fluxes have been rarely investigated in old-growth boreal forests. Here we show that decade-long experimental N additions significantly stimulated net primary production (NPP) but the effect decreased with increasing N loads. The effect on soil heterotrophic respiration (Rh) shifted from a stimulation at low-level N additions to an inhibition at higher levels of N additions. Consequently, low-level N additions resulted in a neutral effect on net ecosystem productivity (NEP), due to a comparable stimulating effect on NPP and Rh, while NEP was increased by high-level N additions. Moreover, we found nonlinear temporal responses of NPP, Rh and NEP to low-level N additions. Our findings imply that actual N deposition in boreal forests likely exerts a minor contribution to their soil C storage.

. Boreal forests have been evidenced to be highly sensitive to enhanced nitrogen (N) deposition due to prevailing N limitations, and external N inputs from atmospheric deposition are expected to alter plant nutrient stoichiometry. Previous studies have mostly focused on the dominant tree species while neglecting understory plants that often play important role in the nutrient cycles in forest ecosystems. By conducting a six-year N-addition experiment with four treatments of 0 (control), 20 (low N), 50 (medium N), and 100 (high N) kg N (cid:1) ha − 1 (cid:1) yr − 1 in a boreal forest in Northeast China, we assessed the responses of leaf nutrient stoichiometry (N, phosphorus [P], potassium [K], calcium [Ca], and magnesium [Mg]) for tree, shrubs, and grass. Although the responses of different species to N addition varied, six-year N addition, especially the medium and high N treatments, generally increased the leaf N concentration and decreased the leaf P and Ca concentrations. As a result, the foliar N:P, N:K, N:Ca, and N:Mg ratios increased consistently across plant functional groups under the high N addition compared with the control, and the grass Deyeuxia angustifolia showed a larger increase in its foliar N:P, N:Ca, and N:Mg than the shrubs. The leaf N concentration increased consistently with soil inorganic N in a nonlinear saturating form, while the other leaf nutrients either decreased (P, Ca) or were not affected (Mg, K) by the soil N availability. Consequently, the foliar N:P, N:K, N:Ca, and N:Mg ratios increased linearly with increasing soil N availability. In spite of this alteration of the leaf nutrient stoichiometry with increasing soil N availability, foliar nutrients and their stoichiometry were less affected under the low N treatment in both trees and understory plants, suggesting minor effects of current N deposition rates on the foliar nutrient balance in boreal forests. ANOVA results showing the effects of plant functional group, and their interaction on foliar nutrient.