Abstract Fine-root decomposition is a key process in soil carbon (C) and nutrient cycling, but it remains unclear whether nitrogen (N) influences decomposition mainly by altering root traits before decomposition begins or by directly affecting roots during decomposition. We addressed this question in a 3-year field experiment in poplar plantations by separating two pathways of N influence: an indirect pathway reflecting pre-decomposition substrate history (roots from long-term N-addition plots were incubated in a common control soil), and a direct pathway reflecting N exposure during decomposition (control roots incubated across an N-addition gradient). Roots with a long-term N-addition history decomposed more slowly and retained more mass, whereas control roots exposed to elevated N during decomposition showed no significant change in decomposition rate, indicating that indirect effects of N mediated through initial substrate traits were more pronounced than direct soil N effects. Across both pathways, decomposition rate was negatively related to root N content and positively related to C:N and lignin:N, suggesting that trait variation in the initial substrate, rather than contemporaneous soil N conditions, played a dominant role over fine-root decay. These results support the N-inhibition hypothesis and suggest that N enrichment can suppress decomposition through its legacy effects on root functional traits. Our study highlights the need to incorporate pre-decomposition trait states into trait-based frameworks for understanding and predicting belowground decomposition responses to N deposition.

Organo–mineral associations are central to the persistence of soil organic carbon (SOC) in forest mineral soils, yet how nitrogen (N) enrichment affects mineral-associated stabilization across contrasting soil chemistries remains unclear. Using 1,274 paired observations from field N addition experiments spanning a broad soil pH gradient, we found that forest SOC responses to N addition were strongly pH dependent and followed a distinct non-linear (U-shaped) pattern. Nitrogen addition increased SOC in strongly acidic (pH < 4.5) and alkaline (pH > 7.5) soils, but had little effect at intermediate pH (4.5–7.5). Where SOC fractions were available, these contrasting responses were driven primarily by changes in mineral-associated organic carbon (MAOC), whereas particulate organic carbon showed a weaker contribution. Patterns of exchangeable cations supported mineral-mediated stabilization mechanisms, with greater MAOC accumulation associated with increased aluminium availability in acidic soils and increased base cation availability in alkaline soils. Model-based upscaling further suggested that spatial variation in soil pH may explain regional heterogeneity in SOC responses to contemporary N deposition, with stronger positive responses predicted for many tropical forests than for temperate and boreal forests. Together, these results identify soil pH as a key control over forest SOC responses to N enrichment through mineral-associated stabilization, and provide a process-based framework for predicting how anthropogenic N inputs may alter soil C persistence.

Soil microbial carbon use efficiency (CUE) plays a critical role in carbon (C) cycling and ecosystem functioning, yet its response to nitrogen (N) deposition remains poorly understood, particularly in planted forests. This study investigates how N addition affects microbial CUE and its underlying mechanisms in Populus deltoides plantations in coastal eastern China. Using a long-term field experiment with five levels of N addition (0–30 g N·m−2·yr−1), we measured microbial CUE, soil chemical properties, enzyme activities, and microbial community composition from 2018 to 2020. We found that N addition significantly reduced microbial CUE, primarily through N-induced stoichiometric imbalances and soil acidification. Excess N increased available N and decreased the DOC:AN ratio, driving microbial carbon limitation and reducing metabolic efficiency. Furthermore, N addition suppressed bacterial diversity and shifted microbial communities toward taxa with lower CUE. Model selection identified soil pH, available N, and DOC:AN as key predictors of microbial CUE. These findings highlight the dominant role of soil environmental factors—particularly nutrient stoichiometry and pH—in regulating microbial CUE. Our results suggest that excessive N deposition may compromise soil C sequestration in poplar plantations by altering microbial resource allocation and reducing microbial metabolic efficiency. Managing nutrient balance and maintaining microbial diversity are thus critical for sustaining soil health and carbon storage in forest ecosystems under increasing N deposition.

Fine root dynamics are crucial for terrestrial ecosystem productivity and nutrient cycling. However, the effects of nitrogen (N) deposition on fine root dynamics in temperate ecosystems remain poorly understood. In this study, we used a meta-analysis to explore the general patterns and key drivers of fine root biomass and turnover in temperate forests and grasslands in response to N application. We found that N application significantly reduced fine root biomass compared to the control group (no N application), with notable differences across N forms. However, the impact of N application on fine root biomass remained consistent across ecosystem types, soil depths and root diameters. In terms of fine root turnover rate, N application had no significant overall effect, and the response did not vary across N forms, ecosystem types, soil depths or root diameters. However, significant differences were observed across methods for estimating fine root turnover rate. Multiple regression analysis showed that mean annual temperature (MAT) and experimental factors (including duration and N application rates) were the primary determinants of fine root biomass response to N application. In contrast, fine root turnover was not significantly influenced by any of the factors analyzed. Overall, our findings highlight the negative impact of N application on fine root biomass and the neutral effect on fine root turnover, and also suggest that find root dynamics are closely associated with experimental factors, including experiment duration and N application rate. This study provides an important advancement in understanding the feedback between root dynamics and global change, offering insights for developing management strategies to address belowground ecological processes under global change scenarios.

Soil organic carbon (SOC) decomposition is a key process in regulating carbon (C) sequestration in plantation ecosystems, and its sensitivity of temperature (Q10) is essential for predicting C-climate feedback. However, plantations exhibit heightened vulnerability to plant invasion due to resource fluctuations and frequent disturbances, which may significantly affect SOC decomposition. The mechanisms by which plant invasion influences SOC decomposition rate and its Q10 in plantations remain poorly understood, particularly in subsoil layers. To fill the knowledge gap, we sampled topsoil and subsoil in poplar plantations, both with and without Solidago canadensis invasion, and conducted a 28-day incubation experiment. The results indicated that S. canadensis invasion increased SOC decomposition rate and its Q10 in both soil layers. Notably, the primary drivers of SOC decomposition rate and its Q10 vary with soil depth. In the topsoil, increased enzyme activities were the dominant factors driving SOC decomposition rate and Q10. In contrast, in the subsoil, increased substrate availability played a more significant role. These findings challenge the assumption that plant effects are limited to surface soils and demonstrate that SOC dynamics in subsoil are as sensitive to plant invasion as those in topsoil, due to increased substrate availability. This emphasizes the importance of considering subsoil processes when evaluating the impacts of plant invasions. Additionally, the results suggest that we should pay attention to plantation understory vegetation management to prevent the harmful effects of plant invasions on SOC dynamics under future climate warming scenarios, effects that enhance carbon dioxide (CO2) emissions and exacerbate regional C-climate feedbacks.

Anthropogenic nitrogen (N) deposition can alleviate N limitation and stimulate plant growth in many terrestrial ecosystems. While theoretical models often emphasize phosphorus limitations as a constraint on this positive N effect, the impact of N-induced magnesium (Mg) and calcium (Ca) deficits due to soil acidification has been largely overlooked. Here, we synthesized data from 243 experiments across diverse terrestrial ecosystems to investigate the role of Mg and Ca in plant biomass responses to N addition. We found that the effect of N addition on aboveground biomass (AGB) shifted from neutral in low pH (≤ 4.5) to positive in medium (4.5-7.5) and high pH (> 7.5) soils. By contrast, belowground biomass (BGB) responses to N addition were independent of soil pH, leading to asymmetric increases in AGB and BGB. These variations in biomass accumulation across pH levels were primarily explained by changes in foliar Mg and Ca concentrations, which were negatively affected by N addition in low-pH soils but remained stable in medium and high-pH soils. Our findings underscore the critical role of Mg and Ca in modulating plant responses to N fertilization, providing new insights for improving Earth system models and better predicting climate-biosphere feedback.

Soil organic carbon (SOC) plays a vital role in mitigating climate change. While fertilization can substantially influence SOC, its impact on SOC storage in arbuscular mycorrhizal (AM)-dominated forests remains uncertain. To address this knowledge gap, we conducted a meta-analysis of 631 observations from 28 published studies to examine SOC responses to fertilization in bamboo forests dominated by AM fungi. Contrary to numerous previous meta-analyses, our results revealed that fertilization significantly decreased SOC by 4.46%. Specifically, inorganic nitrogen (N) fertilizers negatively affected SOC by disrupting the soil N:P:K stoichiometric balance, which can contribute to soil degradation and potentially impair the role of AM fungi in regulating soil carbon dynamics. In contrast, organic and compound N fertilizers showed no significant effect on SOC due to external nutrient inputs and additional C offsetting these negative impacts. The effects of fertilization on SOC varied depending on the level and duration of fertilization, as well as soil depth. Low-level and long-term fertilization resulted in significant SOC losses, particularly in the subsoil. Furthermore, our correlation analysis indicated that MAP, soil pH, MBC, NH4+-N, and AK were key drivers of SOC responses to fertilization. Our findings offer a new perspective that contrasts with previous studies, showing that N fertilization significantly reduces SOC in bamboo forests. This underscores the need for future investigation into the mechanisms by which AM fungi regulate SOC dynamics. Consequently, we recommend using organic or compound N fertilizers to maintain SOC storage and contribute to climate change mitigation efforts.

Soil microorganisms are crucial in terrestrial ecosystems, influencing carbon (C) sequestration, yet their metabolic activities are often constrained by nitrogen (N) and phosphorus (P) availability. Despite this, a global understanding of microbial nutrient limitation remains elusive. We synthesised 1245 observations from 225 articles to elucidate patterns and factors of microbial nutrient limitation. Contrary to convention, soil microbial P limitation is widespread (83.78% of observations), with N limitation mainly in temperate zones and pronounced P limitation in tropical and cold zones. Soil microbial P limitation correlates positively with mean annual precipitation and clay content, while N limitation correlates negatively with soil pH. Importantly, microbial nutrient limitation directly affects C cycling, as microbial C limitation increases with decreasing N or P limitation. This underscores the significance of microbial nutrient limitation in terrestrial C cycling and the need to incorporate it into Earth system models for accurate predictions under changing conditions.

Diversity-biomass relationships (DBRs) in terrestrial ecosystems tend to vary across spatial scales, but, particularly in hyperdiverse forests, the mechanisms driving these trends remain uncertain. Until now, few have simultaneously investigated the connections between tree species diversity, stand structural diversity, mycorrhizal associations, and ecosystem functioning. In addition, DBRs have only been studied at limited spatial scales, with limited focus on the direct and indirect effects of environmental factors. We addressed these research gaps using a 30-ha forest dynamics plot located in Pu’er City, Southwest China. Through piecewise structural equation models, we quantified the direct effects of tree species diversity (α, β, γ), stand structural diversity, mycorrhizal associations (AM, EcM), and the environmental factors (soil fertility and topography), as well as the indirect effects of the environmental factors on aboveground tree biomass across spatial scales ranging from 400 to 230,400 m2. We hypothesized that complex interactions among these factors underpin the variation in DBRs in natural ecosystems across spatial scales. Our results showed that environmental conditions indirectly affected the tree biomass via changes in tree species diversity, and these effects became stronger as the spatial scale increased. At small to moderate spatial scales, environmental factors were more predictive of tree biomass than tree species diversity (or its components); the effects of stand structural diversity on biomass also gradually increased with spatial scale. Conversely, from the intermediate to the largest spatial scales, mycorrhizal associations gradually became the best predictors of DBR dynamics. Our research offers novel empirical evidence demonstrating the importance of environmental conditions, structural diversity, and mycorrhizal associations in shaping cross-scale DBRs. Future comprehensive studies should consider these factors to assess the mechanisms shaping scale-dependent DBRs in complex natural ecosystems.

Plants and soil bacteria exert a vital function in mediating soil ecosystem multifunctionality (EMF). Nevertheless, plant and soil bacteria interaction during forest secondary succession is poorly understood, and their roles in soil EMF remain largely unexplored. The dynamics of soil physicochemical properties and bacterial diversity was studied in southwest China during forest succession from coniferous to monsoon broadleaf evergreen. Interdomain ecological networks (IDEN) were adopted for investigating plant-bacteria associations. With the purpose of assessing how soil factors, bacterial community and plant diversity influenced soil EMF, the structural equation model (SEM) was used. It was discovered that both soil bacterial diversity and soil EMF gradually increased with the succession. IDEN analysis revealed that plant-bacteria ecological networks differed significantly across successional stages. Keystone plant species richness (KSR) increased with succession, which benefited soil bacteria diversity (path coefficient = 0.802, p < 0.001) while having a direct negative impact on pH (path coefficient = -0.602, p < 0.05) and C:N (path coefficient = -0.759, p < 0.001). Soil pH and C:N ratio declines were observed during forest secondary succession and were found to be inversely related to soil EMF. Furthermore, soil pH was found to be inversely related to bacterial diversity. The SEM analysis explained 88.2% of the variation in soil multifunctionality. The findings suggested that keystone plant species played a key function in regulating the variations of soil bacterial community and EMF (total effect = 0.813). Our study clarified the critical functions of keystone species in driving soil bacterial diversity and multifunctionality during forest succession and provided a new perspective on the relationship between above- and below-ground.

Although patterns in the vertical distribution of soil organic carbon (SOC) are key to assessing soil C sequestration potential, they remain poorly understood. We sampled 18 soil profiles at one meter depth at the Dongtai Forest Farm to investigate the vertical distribution of SOC, the stoichiometric relationship between SOC and total nitrogen (TN) and the controlling factors of SOC at different soil depths. We found that SOC content decreased significantly with increasing soil depth. Approximately 67% of SOC was stored in the top 30 cm. The N-C scaling slope (i.e., the slope of the relationship between log-transformed N and C not significantly different from 1.0) revealed significant differences between top- and subsoil with N and C scaled isometrically in topsoil (0–30 cm), but not in subsoil (30–100 cm). SOC content was co-regulated by soil physiochemical and microbial properties at the site level with soil chemical and microbial properties dominant in the top- and subsoil, respectively. Topsoil SOC increased with soil TN, available phosphorus (AP) and fungal abundance. Subsoil SOC increased with the fungal-to-bacterial ratio, fungal abundance and soil dissoluble organic carbon (DOC). Our study highlights the dominance of microbial community in regulating SOC in the subsoil and advances our understanding of the variation in mechanisms regulating SOC along the soil profile.

Introduction Scale dependencies play a vital role in defining the biodiversity-ecosystem functioning relationship in forest ecosystems, which varies based on the magnitude of multiple plant diversity attributes, soil properties, and aboveground biomass in forest ecosystems. However, the effects of plant diversity and big-sized trees on the relationship between plant diversity and aboveground biomass across different scales remain unclear in forest ecosystems. Methods Based on a 30-ha tropical montane evergreen broad-leaved forest dynamics plot in Yunnan province, China, we comparatively analyzed the importance of scale-dependent effects of multiple plant diversity attributes, soil properties, neighborhood competition intensity and aboveground biomass of big-sized trees, as well as stand structural complexity on aboveground biomass of all woody individuals. The aim is therefore to identify the main predictors for sustaining aboveground biomass of all woody individuals, considering multiple biotic and abiotic factors jointly, as well as underlying mechanisms. Results Our results suggest that indicators such as species richness and phylogenetic diversity did not strongly contribute to aboveground biomass of all woody individuals with increasing spatial scales, while aboveground biomass of big-sized trees exhibited the greatest contribution to aboveground biomass of all woody individuals. Stand structural complexity, characterized by variances in woody plant diameter at breast height, also contributed more to aboveground biomass of all woody individuals indirectly via neighborhood competition intensity and aboveground biomass of big-sized trees. Contributions of functional dispersion and community-weighted mean of leaf phosphorus concentration to aboveground biomass of all woody individuals became stronger with increasing spatial scales. Neighborhood competition intensity exhibited a negative linear relationship with aboveground biomass of all woody individuals at the smallest scale, but it affected positively aboveground biomass of all woody individuals across spatial scales, likely due to indirect effects via aboveground biomass of big-sized trees. Discussion Big-sized trees will likely become more important in biodiversity maintenance and ecosystem function management as deforestation and forest degradation.

AimSoil fauna, a functionally important group of soil organisms, are greatly affected by fertilization. However, it is still debated whether and how fertilization affects the soil faunal community. Here, we aimed to synthesize the global patterns of soil fauna communities in response to fertilization in terrestrial ecosystems. LocationGlobal. Time period1997-2021. Major taxa studiedSoil fauna. MethodsWe examined the effects of fertilization on the abundance, number of groups and Shannon diversity of soil fauna by synthesizing 1218 observations based on 39 published studies. We also explored the associations between fertilization-induced changes in the soil faunal community and changes in soil and microbial properties. ResultsFertilization increased the abundance of soil fauna by 56.3%, without significantly affecting the number of groups and the Shannon index. The type of fertilizer affected the responses of soil faunal abundance, and the effects of fertilizer type were altered by climate zones, ecosystem types and soil depths. Both organic and organic-mineral fertilizer treatments significantly increased the abundance of soil fauna in most climate zones, ecosystem types and soil depths, whereas mineral fertilizer treatment had no such effect. Additionally, we found inconsistent responses of soil fauna to fertilization among different taxonomic groups, not only at the order level but also at the class level, providing evidence for the idiosyncratic nature of the effects of fertilization on soil fauna. Furthermore, our regression analysis showed that changes in food resources, including soil nutrients and microbes, were crucial controls for the response of soil faunal abundance to fertilization. Main conclusionsFertilization generally increased soil faunal abundance at the global scale by affecting food resources, and the effects of fertilization were dependent on the specific soil fauna and type of fertilizer. We suggest the use of organic or organic-mineral fertilizers, rather than mineral fertilizers, to increase the benefits on specific soil fauna.

记录了云南思茅太阳河自然保护区2个红头咬鹃巢的繁殖.红头咬鹃的巢位于枯树干侧面的洞中,窝卵数2～3枚.红外相机监测记录显示,雌、雄亲鸟均参与孵卵,雄鸟白天孵卵,时间较短,雌鸟从傍晚至次日上午孵卵,时间较长.雏鸟孵出后,主要由雌鸟在巢中暖雏,雄鸟送回食物.2个巢均未繁殖成功.

Aim Tropical ecosystems have grown increasingly prone to fire over the last century. However, no consensus has yet emerged regarding the effects of fire disturbances on tropical biogeochemical cycles. Location Tropics. Time period 1960-2018. Major taxa studied Tropical ecosystems: Above- and below-ground carbon (C) and nitrogen (N) dynamics. Methods We analysed the impacts of fire on C and N dynamics in tropical ecosystems through a meta-analysis of 1,420 observations from 87 studies. Results Fire reduced both above- and below-ground C and N pools, with greater reductions above- than below-ground. Fire decreased soil total carbon (TC), total nitrogen (TN) and nitrate nitrogen (NO3-) and increased ammonium nitrogen (NH4+) in surface mineral soil layers but did not affect those in deep layers. Fire decreased TC and TN in savanna but did not affect those in tropical dry and moist forests. Fire did not affect NH4+ and NO3- in savanna because of non-significant responses of N mineralization rate (N-min) to fire. Conversely, fire increased NH4+ and decreased NO3- in tropical dry forest, but did not affect NH4+ and increased NO3- in tropical moist forest owing to thermal decomposition of soil organic N and increased soil nitrification, respectively. Moreover, NH4+ declined and NO3- increased initially and then decreased with time after fire. Above- and below-ground response variables to prescribed fire were mediated largely by fire frequency and experimental duration, respectively. Main conclusions Our results suggest a high vulnerability of the above-ground C and N pools to fire, whereas the biogeochemical cycles below-ground are of high complexity. Fire effects on below-ground C and N pools, which are highly uncertain and vegetation specific, should be investigated further.

A key aspect of global forest management, woodland use intensity (WUI) greatly affects the composition and diversity of soil microbial communities, thereby affecting multiple ecosystem functions and services. However, the effects of WUI on soil microbial community composition and enzymatic activities remains unclear. The effects of anthropomorphic alterations to a natural monsoon evergreen broad-leaved forest in terms of the composition and diversity of soil fungal and bacterial communities, was investigated at a site in Yunnan Province, Southwest China. Soil microbial communities were assessed under four levels of disturbance with increasing levels of WUI: (i) none, undisturbed forest (control), (ii) light, naturally-regenerated Pinus kesiya Royle ex Gordon forest, (iii) intermediate, shrub and grassland communities formed through grazing, and (iv) severe, continuously managed coffee (Coffea arabica L.) plantations. With increasing WUI, the diversity of soil fungal and bacterial communities increased, while similarities in community composition decreased for fungi but increased for bacteria. Among fungal functional guilds, ectomycorrhizal fungi decreased significantly with increasing WUI, whereas saprotrophic fungi (undefined, wood, and soil saprotrophs) increased significantly. The species richness of woody plants remarkably affected fungal functional guilds. Ectomycorrhizal fungi interacted in a synergistic manner with the fungal network structure. Significantly affecting microorganismal network structure, WUI increases led to more homogeneous networks with less integration within modules within the microbial community. The WUI strongly altered hub identity and module composition in the microbial community. According to structural equation models, WUI had direct positive effects on soil fungal community composition via its effects on plant species richness. The diversity of bacterial and fungal communities and composition of bacterial communities were jointly regulated by the indirect effects of plant species richness and soil nutrients (including enzyme activity). Deterministic processes largely determined the composition of soil fungal and bacterial communities. This study highlights the importance of maintaining the diversity of soil fungal and bacterial communities despite changes in woodland use to sustain ecosystem functions. These results can be used to develop management practices in subtropical forests and help sustain plant and soil microbial diversity at levels sufficient to maintain long-term ecosystem function and services.

Fine root decomposition plays an essential role in the nutrient cycle and energy transfer in terrestrial ecosystems, and changes in decomposition induced by nitrogen (N) deposition have become a global concern. However, patterns of fine root decomposition with N application are still scattered, and the dominant factors regulating decomposition are still controversial. Here, we aimed to explore general patterns and key drivers of decomposition in temperate forests with N application. From 20 studies, we synthesized 123 records of fine root decomposition in temperate forests where N was applied. We explored the overall effect of decomposition with N application and the variation in decomposition among N application rates, N forms, fertilization condition of root growth and decomposition (FF, from fertilized to fertilized conditions, and UFF, from unfertilized to fertilized conditions), tree functional types and soil depth. The dominant factors of decomposition were identified using regression. Our results showed that N application decreased fine root decomposition. Specifically, decomposition decreased at the application rate of 100–150 kg N ha‒1 yr‒1, under NH4NO3 application, in broadleaf trees and in deep layers, attributable to the inhibited microbial enzyme activity. Decomposition decreased in FF, likely resulting from home-field advantage (HFA) effects. Multiple regressions showed that initial lignin content was the most important factor determining decomposition. Our results suggested that inhibited microbial enzymes were associated with decreased decomposition under N application in temperate forests. Additionally, our results confirmed the importance of initial root traits, such as lignin, in regulating decomposition.

Soil organic carbon (SOC) is the largest carbon sink in terrestrial ecosystems and plays a critical role in mitigating climate change. Increasing reactive nitrogen (N) in ecosystems caused by anthropogenic N input substantially affects SOC dynamics. However, uncertainties remain concerning the effects of N addition on SOC in both organic and mineral soil layers over time at the global scale. Here, we analysed a large empirical data set spanning 60 years across 369 sites worldwide to explore the temporal dynamics of SOC to N addition. We found that N addition significantly increased SOC across the globe by 4.2% (2.7%–5.8%). SOC increases were amplified from short‐ to long‐term N addition durations in both organic and mineral soil layers. The positive effects of N addition on SOC were independent of ecosystem types, mean annual temperature and precipitation. Our findings suggest that SOC increases largely resulted from the enhanced plant C input to soils coupled with reduced C loss from decomposition and amplification was associated with reduced microbial biomass and respiration under long‐term N addition. Our study suggests that N addition will enhance SOC sequestration over time and contribute to future climate change mitigation.

Aims Leaf nutrient resorption is sensitive to changes in soil nutrients. However, the effects of N deposition on nutrient resorption efficiency (NuRE) in plant macro-nutrients remain unclear. Poplar (Populus deltoids) is one of the most extensively cultivated hardwood species worldwide. We explored general patterns and dominant drivers of NuRE and stoichiometry of poplar plantations in response to N addition. Methods We conducted a 4-year N-addition experiment to explore NuRE and stoichiometric responses to N addition in two poplar (P. deltoids) plantations (8- and 12-year-old stands) in a coastal region of eastern China. We measured soil and foliar (green and senesced leaves) concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) for a series of N addition treatments including N-0 (0 kg N ha(-1) yr(-1)), N-1 (50 kg N ha(-1) yr(-1)), N-2 (100 kg N ha(-1) yr(-1)), N-3 (150 kg N ha(-1) yr(-1)) and N-4 (300 kg N ha(-1) yr(-1)). Important Findings Consistent for (both) 8- and 12-year-old stands, N addition did not affect the NuRE and stoichiometry with the exception of CaRE and CaRE:MgRE ratio). N resorption efficiency-P resorption efficiency (NRE-PRE) scaling slopes were consistently less than 1.0 under N addition. These results suggest that NRE generally decouples from PRE within each N treatment. Moreover, these results point to robust control of green leaf nutritional status on nutrient resorption processes as indicated by the positive relationships between NuRE and green leaf nutrient concentrations. Our findings provided a direct evidence that growth in 12-year-old poplar plantations was N-limited in the coastal region of eastern China.