Effectiveness of forest restoration efforts depends on the methods employed. Here, we compared tree species composition, niche characteristics, and mammal habitat use in primary, secondary, and artificial forests in Wanglang Nature Reserve. Results showed that primary forests were mainly indicated by Abies fargesii var. faxoniana (Af), Picea purpurea (Pp), and Juniperus saltuaria (Js); secondary forests were mainly indicated by Af and Betula albosinensis (Ba); and artificial forests were mainly indicated by Picea asperata (Pa) and Acer caesium (Ac). Af had the broadest niche breadth in natural forests, and Pa had the broadest niche breadth in artificial forests. Low niche overlap among common species was observed in natural forests, whereas high niche overlap between Pa and Ba occurred in artificial forests. Interspecific correlations showed that Af was negatively correlated with Pp in primary forests and Populus szechuanica (Ps) in secondary forests. In artificial forests, Af and Ac were positively correlated. Furthermore, no traces of the three National Class I protected species were found in artificial forests, while traces of two representative mammals were associated with Af. These findings highlight the differences among the three types of forests.

IntroductionPlant stoichiometric traits can indicate nutrient allocation and resource-use strategies, but their interpretation depends on organ identity and developmental stage. Fargesia denudata is a staple bamboo for giant pandas and an important clonal understory plant in subalpine forests. We examined how C, N, and P concentrations and their ratios are coordinated across aboveground organs and ontogeny, and how stage-specific stoichiometric economics is associated with environmental and community variables.MethodsAcross 52 plots in Wanglang National Nature Reserve, including 37 plots with F. denudata, we measured stoichiometric traits in shoot culms and in mature culms, leaves, and twigs, together with topographic, soil, and community variables.ResultsStoichiometric coordination was modular and stage-specific, with limited independent within-organ coordination retained only in shoot culms and mature twigs, and cross-organ links suggesting that mature twigs acted as the main bridge between culms and leaves. PC1 axes generally separated N- and P-enriched stoichiometry from ratio-enriched stoichiometry, indicating comparable but developmentally reorganized stoichiometric-economic axes. Shoot culms occupied the nutrient-enriched, relatively acquisitive end of the axis, whereas mature culms shifted toward the ratio-enriched, more conservative end. Shoot-culm PC1 did not scale significantly into mature organ-level or integrated mature aboveground PC1, indicating developmental reorganization rather than direct continuity. In mature bamboo, aboveground stoichiometric economics was assembled through organ-specific contributions, with twigs forming the main link between culms and leaves. Plots with F. denudata occurred on steeper slopes and had higher soil C concentration than plots without F. denudata. Environmental and community associations were stage-dependent and were concentrated mainly in shoot culms. Elevation showed a significant positive total effect on shoot-culm PC1, corresponding to a shift toward a more conservative stoichiometric strategy along the elevational gradient. Mature aboveground PC1 showed a more limited pattern, with only a single correlation with soil pH.DiscussionThese results suggest that stoichiometric strategies in F. denudata are shaped by organ-specific coordination, ontogenetic reorganization, and stage-dependent links with environmental and community conditions. Organ- and stage-specific stoichiometric indicators may inform bamboo resource assessment and giant panda habitat evaluation.

Planted forests serve as critical carbon sinks in climate mitigation strategies, yet balancing individual growth with stand-level carbon storage through age-specific density regulation remains a key knowledge gap. By integrating dendrochronological analysis (1003 increment cores from 532 trees) with longitudinal stand development data (50 permanent plots), we quantify moisture-mediated thresholds governing carbon dynamics in Larix principis-rupprechtii plantations. Our results showed that tree biomass dominated ecosystem carbon storage, accounting for over 95

As rising temperatures and increasing drought pose serious risks to forest ecosystems, understanding the spatial patterns of tree growth-climate responses is crucial for predicting and mitigating the impacts of climate change. In this study, we employ an integrative analysis approach to establish a comprehensive database of 190 tree ring growth-climate relationships for Pinus tabuliformis. Findings indicate that increased precipitation during the previous summer and the current spring generally promotes tree growth, and higher temperatures from July to September of the previous year and May to July of the current year inhibit growth. Notably, P. tabuliformis populations in high-latitude or high-elevation regions are not exempt from the negative impacts of future warming. In addition, the growth-climate sensitivity of P. tabuliformis varies along temperature and precipitation gradients. As regional climates shift from warm and wet to cold and dry, the growth-limiting effect of the previous year's summer precipitation and the current year's growing-season precipitation intensifies, and the inhibitory impact of rising temperatures also increases. Importantly, the precipitation isohyet of 600 mm and the temperature isotherm of 10 degrees C seem to represent critical climatic thresholds for the radial growth response of P. tabuliformis to monthly climate changes. Our results suggest that, if current climate trends persist, the radial growth of P. tabuliformis in its western and northwestern distribution areas is expected to continue declining.

Understanding the ecological processes that shape spatial patterns across different growth stages is crucial for revealing the mechanisms of species coexistence and community dynamics. This study investigates the spatial patterns and associations between the regeneration layer and the overstory layer in Quercus variabilis forests in northern China. Using spatial point pattern analysis, we analyzed the distribution of 2761 seedlings and 449 adult trees across twelve 20 x 20 m plots. Our results revealed a consistent pattern where seedlings exhibited significant spatial aggregation, best fitted by a simple Thomas process with an average cluster radius of 3.89 m calculated across all plots, while adult trees displayed a complete spatial random distribution. A marked reduction in local density from seedlings to adults, indicated by a self-thinning index greater than 1 in most plots, provided evidence for density-dependent mortality during stand development. However, bivariate analysis detected no significant spatial association or mark correlation between adult trees and seedlings in most plots, suggesting limited interaction between these layers after initial seedling establishment. These findings demonstrate a clear transition from clustered regeneration to randomly distributed adults, which is consistent with the potential roles of dispersal limitation, habitat filtering and competition processes, with implications for the management and conservation of temperate Quercus forest ecosystems.

Promoting the formation and accumulation of soil carbon (C) is one of the natural solutions to address climate change, but frequent wildfires increase its uncertainty and challenge. This two-year study deciphered the driving pathways of seasonal and vertical patterns in a soil C pool following a wildfire from a microbial perspective. Results showed that total organic C concentration and stock postfire decreased by 29.9 and 17.5% on average compared with the unburned control, respectively, whereas the allocations of labile C increased by 25.1-45.7%. Fire-induced alterations in labile C fractions were complicated due to their significant seasonality and respective sensitivities. Nonetheless, we emphasized that microbial life-history traits were the decisive mediators of variations and that significant positive linkages existed between labile C and microbial r-selected communities. Fire stimulated lower bacterial and fungal copiotroph/oligotroph ratios and higher ribosomal ribonucleic acid operon copy number, shifting microbes from K- to r-strategists. From integrated soil C pool management indices, fire can be concluded to reduce C stability and accelerate C cycling, but whether the recaptured prevalence of K-strategist over time will modify C processes remains unknown. This study provided a stepping stone for future efforts in accurate C predictions and reasonable C management.

A deeper understanding of growth-climate relationships in natural forests (NFs) and planted forests (PFs) is crucial for the prediction of climate change impacts on forest productivity. Yet, the mechanisms and divergences in climatic responses between these forest types remain debated. This study investigated P. tabulaeformis NFs and PFs in China using tree-ring chronologies to analyze their radial growth responses to climatic factors and associated temporal-spatial dynamics. The results reveal significant negative correlations between radial growth and mean temperatures (Tmean) in August of the previous year and June of the current year, and positive correlations were observed with the September standardized precipitation evapotranspiration index (SPEI) of the previous year and May precipitation (PPT) and SPEI of the current year. Compared with NFs, PFs exhibited a heightened climatic sensitivity, with stronger inhibitory effects from prior- and current-year growing-season temperatures and greater SPEI influences during the growing season. Moving window analysis demonstrated higher temporal variability and more frequent short-term correlation shifts in PF growth-climate relationships. Spatially, NFs displayed latitudinal divergence, autumn Tmean shifted from growth-suppressive in southern regions to growth-promotive in the north, and winter SPEI transitioned from positive to negative correlations along the same gradient. However, PFs showed no significant spatial patterns. Relative importance analysis highlighted water availability (PPT and SPEI) as the dominant driver of NF growth, whereas temperature, moisture, and solar radiation co-regulated PF growth. These findings provide critical insights into climate-driven growth divergences between forest types and offer scientific support for the optimization of NF conservation and PF management under accelerating climate change.

Understanding the mechanisms governing forest community assembly across different growth stages is essential for revealing succession dynamics and guiding forest restoration. While much attention has been given to overstory trees, the understory regeneration layer, critical for forest succession, remains less explored, particularly regarding its stage-specific survival strategies and assembly processes. This study investigates the natural regeneration of Quercus variabilis forests in northern China, focusing on the transition from early to later growth stages. Our objectives were to (1) identify the phylogenetic and functional structures of regeneration communities at early and later stages, (2) explore their responses to environmental gradients, and (3) assess the roles of deterministic and stochastic processes in shaping community assembly. We integrated phylogenetic structure, functional traits, and environmental gradients to examine natural regeneration communities. The results revealed clear stage-dependent patterns: communities exhibited random phylogenetic and functional structures in the early growth stage, suggesting a dominant role of stochastic processes during early recruitment. In contrast, communities showed phylogenetic clustering and functional overdispersion in later growth stages, indicating the increasing influence of environmental filtering and interspecific competition as individuals developed. Generalized Dissimilarity Modeling (GDM) further revealed that dispersal limitation and pH were key predictors of phylogenetic β-diversity in the later growth stage, while total phosphorus drove functional β-diversity in the later growth stage. No significant predictors were found for β-diversity in the early stage. These findings highlight the shift from stochastic to deterministic processes during forest regeneration, emphasizing the stage-dependent nature of assembly mechanisms. Our study elucidates the stage-specific assembly rules of Q. variabilis forests and offers theoretical guidance for stage-targeted interventions in forest management to promote positive succession.

Post-fire recruitment plays a crucial role in enhancing forest resilience. While previous research highlights the importance of early post-fire forest recovery in determining future forest structure, little has breen reported on whether this relationship exists in the boreal coniferous forests of Eastern Siberia. Additionally, there is a lack of research on whether there are differences in the driving mechanisms that affect juvenile recruitment across different timescales. This study compared key biophysical factors affecting recruitment across short-term and long-term timescales. Leveraging field data and dendrochronological techniques, we determined the germination years of saplings and seedlings in 73 plots across eight fire times. We quantified annual recruitment and cumulative recruitment rates post-fire for each plot, examining the correlation between the time to achieve 75% cumulative recruitment post-fire and the number of recruits, thereby assessing the importance of initial recruitment. Utilizing spatial Generalized Linear Mixed Models (GLMMs), we inferred the impact of biophysical factors on recruitment across short- and long-term timescales. Subsequently, we visualized the relationship patterns between predictor variables and recruitment. The findings revealed that plots with a faster post-fire recruitment pace exhibited a greater quantity of recruitment. On long-term timescales, growing-season mean temperature (GSMT) exhibited a positive correlation with Larix gmelinii recruitment. Basal area demonstrated a robust positive effect on Larix gmelinii recruitment, displaying significance at long-term timescales. The stand age between 60 to 150 years, representing the middle-mature stage of Larix gmelinii, is conducive to post-fire recruitment. Downed dead wood (DDW) exhibited a highly significant boost to recruitment at both timescales, albeit with a relatively weaker effect observed at the long-term scale. Our findings provide some confirmation of the critical role of immediate post-fire recruitment in forest resilience, while also unveiling timescale effects that influence the mechanisms of post-fire recruitment. The findings furnish timely new perspectives on integrating temporal scales into model predictions of the recovery process and adaptive forest management strategies.

With gradual global warming and drying up,forest fires not only drive changes in the structure and function of forest ecosystems,but also affect the physiology and growth of trees.The thermal damage caused by forest fires can trigger a series of complicated physiological responses in trees.Revealing the response mechanisms of postfire tree physiology can guide the further understanding of the carbon-water relationship and how it influences the postfire growth recovery limitations of trees.Furthermore,the accuracy of tree mortality prediction after fires must be improved.Starting with a description of the pathways in which forest fires affect trees,this review elaborates on the damage caused by different forms of forest fires(canopy,surface,and ground fires)on various parts(crowns,trunks,and roots)of trees.In particular,this review discusses the direct and indirect effects of forest fires on tree physiology and the tree physiology-abiotic/biotic interactions after fires.Cambium and phloem necrosis and xylem hydraulic dysfunction are the main response mechanisms of postfire tree physiology.The two physiological functional limitations—carbon starvation and hydraulic failure—caused by the two aforementioned mechanisms seriously affect the carbon-water relationship of trees,further influencing the growth recovery of trees or their delayed death after fires.The physiological mechanisms of trees after fires are also closely related to drought,insect attack,microbial invasion,and other factors.The quantitative analyses of forest fire intensity and the accurate judgment of the plant tissue death threshold are urgent tasks,and the interaction of tree physiology with the functional traits of trees and other factors after fires must be explored.Accurately evaluating the relationship between tree physiological mechanisms is crucial in fully understanding how forest fires affect the tree functional integrity of trees and contributes to the improvement of forest fire risk assessments and mortality model predictions.In the context of high-frequency and high-intensity forest fires driven by future climate warming and drying,a profound understanding of tree physiological responses can also enhance the study of the dynamics of postfire ecosystems and their interrelationships with climate factors.

Bark is vital for woody plants, providing protection, transporting nutrients and water, and storing essential resources. For fire-prone ecosystems, bark thickness is a key adaptive trait conferring fire resistance. Few studies have been conducted on the drivers of variation in bark thickness of the widely distributed Larix gmelinii (Rupr.) Kuzen in the Great Xing'an Mountains region, on the southern edge of East Siberia, where surface fire disturbances are frequent. To elucidate the relationships between variation in bark thickness (inner vs. outer bark) of L. gmelinii and plant size, environmental factors, and co-variation with other fire-tolerance traits, we selected 26 sites to set up plots and carried out a survey and bark sampling. Results showed that stem diameter primarily determines variation in bark thickness, especially outer bark. The proportion of outer bark to total bark increased accordingly as the tree increased in size. We also observed stronger correlated variation in outer bark thickness, tree height, and self-pruning capacity, implying that larger trees have thicker protective outer bark and taller heights with greater self-pruning, mitigating crown fire risks. Environmental factors appear to have a relatively limited effect on changes in bark thickness in L. gmelinii. Mean air temperature, annual precipitation, and total soil nitrogen content had some effect on outer bark thickness, and mean air temperature had some effect on inner bark thickness.

Context Afforestation has been widely implemented to deliver climate change mitigation and restore ecosystem benefits. However, the efficacy of afforestation has been deputed. The regeneration ability of most plantations in Northern China has been suggested to fail to reach their optimal. Objectives Here, we compared the regeneration ability of plantations and natural forests in Northern China and explored how the climate factors and site features can determine the regeneration ability. We hypothesize that the deficient regeneration ability of plantations is mainly due to the single tree age and high stand density. Furthermore, the effects of climate factors cannot be ignored. Methods We investigated the climate factor, stand features, tree radial growth, and regeneration ability (the number of cones and seedlings) of two dominant conifers, Larix principis-rupprechtii and Pinus sylvestris var. mongolica in natural forests and plantations in northern China. Results Our analysis shows a significant difference in the number of both cones and regenerated seedlings produced by plantations and natural forests within the same site ( P < 0.05). The stand density of plantations had a significant negative effect on the generation of seedlings ( P < 0.05). Additionally, climatic factors, such as mean annual temperature and mean precipitation play a major role in regulating the heat and water availability for forest regeneration. Finally, we found that the inter-annual fluctuations in the radial growth of trees are also related to the number of seedlings produced, which is likely due to higher growth fluctuations indicating poorer drought adaptation of trees. Conclusions Our study suggests that no single factor can explain the regeneration failure of plantations in semi-humid and semiarid regions of China. Both site features and climatic factors affect the production of seedlings. Future afforestation should follow low-density afforestation in areas with favorable climatic conditions for tree growth.

Global climate warming is propelling an increase in forest wildfires and relevant ecosystem degradation. How the legacy effect of wildfires will act on soil multifunctions and whether litterfall, especially prominent in terms of biotically induced functions, will contribute most to the recovery patterns after wildfires remain largely unexplored. To fill these gaps in knowledge, comprehensive soil function assessments were conducted using 38 soil indicators, covering five functional groups, namely, soil buffering and filtration, water conservation, carbon storage, nutrient cycling and microbial habitat. We tracked their shifts and the overall soil multifunctionality in paired burned and unburned sites during the mid-growing season from 2019 to 2021 (i.e., the first three years following high-severity wildfires) over the Pinus tabuliformis plantation of North China. The responses of the trade-offs and synergies between soil functions to wildfires, year and their interaction were illuminated. We further determined 18 biotic (i.e., understory plant and litterfall) and abiotic (i.e., soil temperature) variables to explain the mechanism of variations in soil multifunction. Results showed that soil multifunctionality and most single functions of the burned site were coherently less than those of the unburned site, whereas the opposite pattern was found for the soil microbial habitat, which is particularly significant in the first post-wildfire growing season. Although mutual benefit and win–win results were the melody of soil multifunction, trade-offs/synergies among functions in the burned site were dampened over time. Plant attributions explained 60.6% of the variation in soil water conservation, whereas they and litterfall properties played as the main direct pathways to wildfire impacts on soil buffering and filtration. We highlighted the tremendous effect of litterfall mass on soil multifunctionality as well as carbon storage and nutrient cycling independent function, largely overpassing those of plant attributions and soil temperature. These findings unfold the potential of litterfall input as a suitable early intervention for facilitating soil functioning after wildfires. Moreover, the strong interactions of wildfires and time shed lights on the requirement for long-term frameworks concurrently considering biotic and abiotic factors to understand the overall situation of wildfire influences on ecological processes.

Betula platyphylla is a pioneer tree species after fire disturbance in forest communities in the Daxing'an Mountains of China. Bark, as an external structure of vascular cambium, plays an important role in protection and transport. To understand the survival strategy of B. platyphylla under fire disturbance, we analyzed the functional traits of inner and outer bark of B. platyphylla at different heights (0.3, 0.8 and 1.3 m) in natural secondary forest of the Daxing'an Mountains. We further quantified the explanation of three environmental factors (stand, topography and soil) and identified the key factors driving the changes in those traits. The results showed that the relative inner bark thickness of B. platyphylla in burned plot followed an order of 0.3 m (4.7%) > 0.8 m (3.8%) > 1.3 m (3.3%), which was 28.6%, 14.4% and 3.1% higher than that in the unburned plot (30-35 years without fire disturbance), respectively. The relative outer bark thickness and the relative total bark thickness showed similar pattern with tree height. Fire had different effects on other bark functional traits of B. platyphylla. The inner bark density of B. platyphylla in burned plot was significantly decreased by 3.8%-5.6% and water content was significantly increased by 11.0%-12.2%, compared with that in unburned plot across the three heights. However, the contents of carbon, nitrogen, and phosphorus in inner (or outer) bark were not significantly affected by fire. Further, the mean inner bark nitrogen content at 0.3 m in burned plot (5.24 g·kg-1) was significantly higher than that at the other two heights (4.56-4.76 g·kg-1). Environmental factors explained 49.6% and 28.1% of the total variation in inner and outer bark functional traits, respectively, with the highest single explanation (18.9% or 9.9%) of soil factors. Diameter at breast height was the most important factor affecting the growth of inner and outer barks. In summary, fire affected survival strategies of B. platyphylla (e.g., increased the resource allocation to the base bark) via changing the environment factors, which would help improve their defense ability under fire disturbance.

The population dynamics and individual growth dynamics of dominant tree species in boreal forests are associated with fire regimes. Fire regimes in the boreal forests of eastern Siberia are dominated by non-stand replacing (NSR) fire types. Fire drives population demographics by triggering tree mortality and births, and affects the post-fire growth dynamics of surviving individuals. When a non-stand replacing fire occurs, population dynamics fluctuate and individual growth changes occur simultaneously. The Great Xing'an Mountains is located at the southern edge of the eastern Siberia boreal forest and research on fire regimes and stand dynamics in this region are scarce. Understanding the effect of fire on the population structure and individual growth of the dominant species in the stand and the disturbance mechanisms are essential to understand the develop of boreal forests in the context of climate warming. In this study, three Larix gmelinii stands disturbed by NSR fire in the Great Xing'an Mountains were selected and established plots, and control stand plots were established at similar site conditions. We conducted a forest inventory and used dendrochronological methods to reveal the short- and long-term effects of NSR fire disturbance on the population dynamics and individual growth of the dominant species of L. gmelinii. Specifically, the effects of NSR fire on stand structure, the relationship between L. gmelinii demographics and disturbance, and the response of growth dynamics to disturbance were analyzed. Finally, the history of potential disturbance at stand level was reconstructed. The study found that common NSR fire affect the biomass and species composition of L. gmelinii forests. Fire disturbance contributes to the younger age structure of L. gmelinii populations. However, The NSR fire may limit the size of L. gmelinii populations but does not necessarily destroy population resilience depending on stand conditions. Irregular fluctuations in population survival and mortality curves are directly related to historical disturbance events. The NSR fire can inhibit the growth of surviving trees for 1-2 years, resulting in temporary growth asynchrony. The population dynamics fluctuations and temporal patterns of growth release signals can reconstruct historical disturbance events at the stand level. For example, the MH intra-group (Mohe Luogu River Nature Reserve burned stand&Mohe Luogu River Nature Reserve unburned stand) probably experienced a high-severity fire in 1880-1900, the TH intragroup (Tahe Nature Reserve burned stand&Tahe Nature Reserve unburned stand) experienced a high-severity fire around 1930, and THB (Tahe Nature Reserve burned stand) suffered stand-replacing. Overall, irregular fluctuations in population survival and mortality curves have been directly related to historical disturbance events. These findings provide direct evidence of the short- and long-term effects of fire on the survival and growth of L. gmelinii populations.

Fire is an important regulator of ecosystem dynamics in boreal forests, and in particular has a complicated association with growth and physiological processes of fire-tolerant tree species. Stable isotope ratios in tree rings are used extensively in eco-physiological studies for evaluating the impact of past environmental (e.g., drought and air pollution) factors on tree growth and physiological processes. Yet, such studies based on carbon (δ13C) and oxygen (δ18O) isotope ratios in tree rings are rarely conducted on fire effect, and are especially not well explored for fire-tolerant trees. In this study, we investigated variations in basal area increment and isotopes of Larix gmelinii (Rupr.) Rupr. before and after three moderate fires (different fire years) at three sites across the Great Xing'an Mountains, Northeastern China. We found that the radial growth of L. gmelinii trees has significantly declined after the fires across study sites. Following the fires, a simultaneous increase in δ13C and δ18O has strengthened the link between the two isotopes. Further, fires have significantly enhanced the 13C-derived intrinsic water-use efficiency (iWUE) and largely altered the relationships between δ13C, δ18O, iWUE and climate (temperature and precipitation). A dual-isotope conceptual model revealed that an initial co-increase in δ13C and δ18O in the fire year can be mainly attributed to a reduction in stomatal conductance with a constant photosynthetic rate. However, this physiological response would shift to different patterns over post-fire time between sites, which might be partly related to spring temperature. This study is beneficial to better understand, from a physiological perspective, how fire-tolerant tree species adapt to a fire-prone environment. It should also be remembered that the limitation of model assumptions and constraints may challenge model applicability and further inferred physiological response.

Wildfires are natural and ubiquitous disturbances in boreal forests. Assessing their impacts on tree growth and resilience are particularly important to recognize the adaptation strategies of fire-tolerant species and forest succession in fire conditions. To date, the growth resilience of fire-tolerant species in boreal forests remains largely unquantified, and the drivers of resilience are poorly understood. Here, we measured the tree-ring widths of 99 fire-scarred trees from three sites in natural Dahurian larch (Larix gmelinii) forests. Three moderate-severity fire events in years 1987, 1990, and 2000 occurring at three sites were detected from the records of local forestry bureau. Based on tree-ring width data, we calculated resilience components (i.e., resistance, recovery, resilience and relative resilience) to quantify the responses of growth resilience in the larch trees to fires and analyzed their drivers at three sites. Results indicated that fires significantly reduced the tree growth. With the increasing tree age, these reductions were more pronounced. As for resilience components, our study showed a limited resis-tance but high recovery of tree growth against fires, and resistance tended to increase northwards but recovery showed the opposite, suggesting a growth-survival tradeoff was exhibited in Dahurian larch trees. With an increasing tree age, regional resistance and resilience showed a decreasing trend, whereas recovery and relative resilience showed an increasing trend. Resilience components were mainly affected by the climatic factors in spring. An increase in moisture availability enhanced resistance, a reduction in diurnal temperature range enhanced recovery, and an increase in mean temperature enhanced resilience and relative resilience. This study reveals that Dahurian larch could be even less favorable when faced with moderate or severe fire events, but a high capacity of recovery enables this species to adapt to the fire-prone condition. Moreover, this work highlights that the resilience of tree growth should be considered to understand tree behaviors and survival strategies of boreal forests following fires across fire-prone regions under future climate warming.

Wildfire is crucial in the regulation of nutrient allocation during the succession of boreal forests. However, the allocation strategies of carbon (C), nitrogen (N) and phosphorus (P) between leaves and fine roots in response to wildfire severities remain poorly studied. We aimed to explore the allocation strategies of C, N and P between leaves and fine roots among different fire severities. We selected four wildfire severities (unburned, low, moderate and high severity) after 10 years recovery in the Great Xing’an Mountains, northeast China, and compared C, N and P concentrations in leaves and fine roots of all species among fire severities using stoichiometry theory and allometric growth equations. Compared with unburned treatment, C concentrations in leaves and fine roots increased at low severity, and leaf N concentration was the greatest at high severity, but the lowest fine root N concentration occurred at high severity. Plant nutrient utilization tended to be P-limited at high fire severity according to the mean value of N:P ratio > 16. More importantly, C, N and P allocation strategies between fine roots and leaves changed from allometry to isometry with increasing fire severities, which showed more elements allocated to leaves than to fine roots with increasing fire severities. These changes in patterns suggest that the allocation strategies of elements between leaves and fine roots are of imbalance with the wildfire severity. This study deepens our understanding of nutrient dynamics between plant and soil in ecosystem succession.

林火是森林生态系统的主要干扰因子,火后森林恢复过程中物种组成的变化规律是恢复生态学研究的重要内容.本研究以漠河地区中度林火干扰不同恢复时期的天然落叶松火烧迹地为研究对象,采用群落调查的方法对样方进行调查,分析落叶松林群落的物种组成和多样性动态变化特征.结果表明:(1)中度火烧迹地在恢复的过程中,乔木层树种组成变化巨大,虽然优势树种未变,但伴生树种的重要值持续上升,在恢复30 a时,群落伴生树种和落叶松的重要值基本持平.(2)林下灌木层和草本层受乔木层影响,落叶松林群落在恢复19 a时,种间竞争加剧,恢复至30 a时,群落回归较稳定的状态;灌木层多样性由大到小的顺序为:恢复19 a、恢复10 a、恢复30 a、对照;盖度随时间增加而增长,并逐渐趋于稳定;草本层多样性由大到小的顺序为:对照、恢复30 a、恢复19 a、恢复10a;盖度随时间增加而降低,并逐渐趋于稳定.(3)整体来看,经过30a的恢复时间群落回归稳定,但林火干扰改变了群落原有的演替方向,朝着混交方向发展.