Forest Ecosystems最新文献_第3页

Compound heatwave-drought alters eco-hydrological processes in subtropical evergreen and deciduous forests 复合热浪-干旱改变了亚热带常绿和落叶森林的生态水文过程

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-12-11 DOI: 10.1016/j.fecs.2025.100416

Diwen Zheng , Yuyu Lu , Jingjing Xiao , Chaoyang Wu , Zhi Ding , Alexandre Maniçoba da Rosa Ferraz Jardim , Thieres George Freire da Silva , Xuguang Tang

In recent years, extreme climate events have occurred globally with increasing frequency, posing severe challenges to forest water cycles. Particularly during the summer of 2022, an unprecedented compound heatwave-drought (CHD) event swept through southern China, while the potential effect on subtropical forest ecosystems remains unclear. On the basis of three-year continuous eddy covariance (EC)-based water flux and climate observations at the subtropical evergreen and deciduous forests between 2021 and 2023, this study addressed to quantify the process and the degree of influence of such CHD event on the ratio of transpiration (T) to evapotranspiration (ET), T, ET, and cumulative (precipitation (P) − ET), respectively. In contrast to the adjacent years, water contents at different soil depths in the two forest types declined sharply during the summer of 2022. Large differences in the variation ranges of T/ET were revealed between the two forest types, and the evergreen forest (EBF) exhibited relatively mild seasonal fluctuations, whereas the deciduous forest (DBF) showed relatively higher T/ET, T, and ET in summertime. Subsequent analysis revealed that MODIS EVI time-series effectively captured the variability in these eco-hydrological parameters. Furthermore, divergent differences were observed about the CHD-induced stress. For the DBF, both ET and T increased significantly, resulting in a severe water deficit (cumulative (P − ET)) of approximately −116.31 mm in 2022. In contrast, the EBF experienced a substantial reduction in both ET and T, with a water deficit of only −26.34 mm in 2022. All these analyses provide mechanistic evidence of the divergent drought response strategies between subtropical evergreen and deciduous forests, and offer scientific support for optimizing forest water resource management and enhancing climate resilience.

近年来，全球极端气候事件频发，给森林水循环带来严峻挑战。特别是在2022年夏季，一场前所未有的复合热浪干旱（CHD）事件席卷了中国南方，而对亚热带森林生态系统的潜在影响尚不清楚。基于2021 - 2023年3年连续涡动相关变化（EC）的亚热带常绿和落叶森林水通量和气候观测，研究了CHD事件对蒸腾（T) /蒸散发（ET）、T、ET和累积降水(P)−ET）的影响过程和程度。与相邻年份相比，两种森林类型在2022年夏季不同土壤深度的含水量急剧下降。两种森林类型的T/ET变化幅度差异较大，常绿林（EBF）表现出相对温和的季节波动，而落叶林（DBF）在夏季表现出相对较高的T/ET、T和ET。随后的分析表明，MODIS EVI时间序列有效地捕获了这些生态水文参数的变化。此外，冠心病诱导的应激也存在不同程度的差异。对于DBF， ET和T均显著增加，导致2022年严重的水分亏缺（累积（P - ET））约为- 116.31 mm。相比之下，EBF的ET和T均大幅减少，2022年水分亏缺仅为−26.34 mm。这些分析结果为亚热带常绿与落叶森林不同的干旱响应策略提供了机制证据，为优化森林水资源管理和增强气候适应能力提供了科学依据。

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引用次数: 0

Thinning counteracts drought-induced reduction in soil interception capacity during heavy rainfall in a larch plantation 在落叶松人工林中，间伐可以抵消因干旱导致的强降雨期间土壤截留能力的下降

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-12-10 DOI: 10.1016/j.fecs.2025.100415

Jiao Ma , Xiaomei Sun , Chunyan Wu , Dongsheng Chen , Hongxing Wang , Xin Ran , Shougong Zhang

Forest management and climate change critically shape forest ecosystem functions. The efficacy of thinning in mitigating drought impacts on forest soil–water conservation remains uncertain. In this study, hydrogen stable isotopes were used to quantify the contribution of rainfall to soil water (CRSW) under a four-year experiment combining precipitation reduction (−30%), thinning (45% of trees removed), and their interaction in a Larix kaempferi plantation. We found that prolonged precipitation reduction significantly reduced the contribution of heavy rainfall to soil water (CHRSW) by 8.15%–9.88%. However, thinning alone or combined with precipitation reduction significantly increased CHRSW by 11.47%–13.27% and 6.52%–8.77%, respectively. Additionally, the influence of canopy, understory vegetation, and litter on CHRSW declined with soil depth, while soil and root properties persistently affected CHRSW across 0–40 cm depths. Crucially, the positive effects of thinning on these variables consistently outweighed the negative impacts of precipitation reduction, resulting in a net increase in CHRSW. Therefore, thinning effectively mitigates drought-associated declines in soil interception capacity during heavy rainfall, indicating its potential as a climate-adaptive management strategy for sustaining soil–water conservation functions in managed forests.

森林管理和气候变化对森林生态系统功能有着至关重要的影响。疏伐对减轻干旱对森林水土保持影响的效果尚不确定。本研究在日本落叶松人工林进行了为期4年的降水减少（- 30%）、间伐（45%树木被砍伐）及其相互作用试验，利用氢稳定同位素定量分析了降雨对土壤水分的贡献。结果表明，长时间降水减少显著降低了强降雨对土壤水分（CHRSW）的贡献，减少幅度为8.15% ~ 9.88%。单作间伐或联合减降水显著增加了CHRSW，增幅分别为11.47% ~ 13.27%和6.52% ~ 8.77%。此外，冠层、林下植被和凋落物对CHRSW的影响随土壤深度的增加而降低，而土壤和根系特性在0 ~ 40 cm深度范围内持续影响CHRSW。至关重要的是，变薄对这些变量的积极影响始终超过降水减少的负面影响，导致CHRSW的净增加。因此，间伐有效缓解了暴雨期间因干旱导致的土壤截留能力下降，表明其作为一种气候适应性管理战略的潜力，可在管理森林中维持水土保持功能。

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引用次数: 0

The overlooked role of individual variability in autumn xylem phenology and carbon sequestration 个体变异在秋季木质部物候和固碳中被忽视的作用

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-12-04 DOI: 10.1016/j.fecs.2025.100414

Chunsong Wang , Jean-Daniel Sylvain , Roberto Silvestro , Guillaume Drolet , Keyan Fang , Sergio Rossi

Accurate modeling of carbon sequestration by forests requires scaling wood formation processes from trees to the landscape. The quantification of growth and carbon dynamics requires deep knowledge of the variability in xylem phenology among individuals. This study presents a comprehensive assessment of seasonal and individual variability in xylem phenology based on more than 800 balsam firs (Abies balsamea (L.) Mill.) monitored weekly across 33 plots from 2018 to 2022 in Montmorency Forest, Quebec, Canada. Wood microcores were collected from April to October to quantify the timings of cambial activity and xylem development on anatomical sections observed at high magnification under the microscope. The first enlarging cells appeared between late May and early June (day of the year (DOY) 153–167), and cell-wall thickening ended in late August (DOY 223–238), resulting in a growing season of 63–79 days. Xylem production ranged from 27.4 to 47.9 radial cells. While the onset of xylogenesis was well synchronized among individuals, within 2 weeks, the cessation of growth showed a greater variability, reaching up to 3 weeks. This autumnal variability was positively correlated with wood production, as higher cambial activity increases the accumulation of xylem cells to be differentiated. Our findings provide empirical evidence that individual variability in growth cessation reflects the underlying heterogeneity in cambial activity among trees of the same stand. Our results demonstrate the role of xylem phenology, especially during the autumn, in shaping forest growth. The assessment of both seasonal and individual variability in phenology is an essential step to improve the representation of autumn processes in forest carbon models, which can help to reduce the uncertainty in predictions of boreal forest growth under current or future climate scenarios.

森林固碳的精确建模需要按比例计算从树木到景观的木材形成过程。生长和碳动态的量化需要深入了解个体间木质部物候变化。本文以800多株苦瓜冷杉（Abies balsamea (L.)）为研究对象，对木质部物候的季节和个体变异进行了综合评价。Mill.)从2018年到2022年，每周对加拿大魁北克省蒙特莫伦西森林的33个地块进行监测。从4月到10月采集木材微芯，在高倍显微镜下观察解剖切片，量化形成层活性和木质部发育的时间。5月下旬至6月上旬（年初一（DOY） 153 ~ 167）出现第一次细胞增大，细胞壁增厚结束于8月下旬（DOY 223 ~ 238），生长期63 ~ 79 d。木质部产量为27.4 ~ 47.9个径向细胞。虽然个体间木质化的开始是同步的，但在2周内，生长停止表现出更大的变异性，可达3周。这种秋季变异与木材产量呈正相关，因为更高的形成层活性增加了木质部细胞的积累。我们的研究结果提供了经验证据，表明生长停止的个体差异反映了同一林分树木形成层活性的潜在异质性。我们的研究结果证明了木质部物候的作用，特别是在秋季，在塑造森林生长。对物候学的季节和个体变异进行评估是改善森林碳模型中秋季过程表征的必要步骤，这有助于减少在当前或未来气候情景下对北方森林生长预测的不确定性。

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引用次数: 0

Modeling eccentric growth explicitly to investigate intra-annual drivers of xylem cell production using xylogenetic data 利用木质部发生数据建立偏心生长模型，明确研究木质部细胞生产的年内驱动因素

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-12-01 DOI: 10.1016/j.fecs.2025.100413

Lucie Nina Barbier , Marc-André Lemay , Étienne Boucher , Sergio Rossi , Fabio Gennaretti

Xylogenesis, the process through which wood cells are formed, results in the long-term storage of carbon in woody biomass, making it a key component of the global carbon cycle. Understanding how environmental drivers influence xylogenesis during the growing season is therefore of great interest. However, studying short-term drivers of wood production using xylogenetic data is complicated by the usual sampling scheme and the influence of eccentric growth, i.e., heterogeneous growth around the stem. In this study, we improve xylogenesis research by introducing a statistical approach that explicitly considers seasonal phenology, short-term growth rates, and growth eccentricity. To this end, we developed Bayesian models of xylogenesis and compared them with a conventional method based on the use of Gompertz functions. Our results show that eccentricity generated high temporal autocorrelation between successive samples, and that explicitly taking it into account improved both the representativeness of phenology and intra-ring variability. We observed consistent short-term patterns in the model residuals, suggesting the influence of an unaccounted-for environmental variable on cell production. The proposed models offer several advantages over traditional methods, including robust confidence intervals around predictions, consistency with phenology, and reduced sensitivity to extreme observations at the end of the growing season, often linked to eccentric growth. These models also provide a benchmark for mechanistic testing of short-term drivers of wood formation.

木质学是木材细胞形成的过程，导致木质生物质中长期储存碳，使其成为全球碳循环的关键组成部分。因此，了解环境驱动因素如何影响生长季节的木质化是非常有趣的。然而，利用木学数据研究木材生产的短期驱动因素由于通常的采样方案和偏心生长（即茎周围的非均质生长）的影响而变得复杂。在这项研究中，我们通过引入一种统计方法，明确考虑季节性物候、短期生长速率和生长偏心率，来改进木质学的研究。为此，我们建立了木材发生的贝叶斯模型，并将其与基于Gompertz函数的传统方法进行了比较。我们的研究结果表明，离心率在连续样品之间产生了高度的时间自相关性，明确考虑离心率可以提高物候学和环内变异的代表性。我们在模型残差中观察到一致的短期模式，表明未解释的环境变量对细胞生产的影响。与传统方法相比，提出的模型有几个优点，包括预测的可靠置信区间，与物候的一致性，以及对生长季节结束时极端观测的敏感性降低，这些极端观测通常与反常生长有关。这些模型还为木材形成的短期驱动因素的力学测试提供了基准。

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引用次数: 0

Non-native shrub overrides understory assembly rules through ecosystem engineering 非原生灌木通过生态系统工程覆盖了林下植物的组合规则

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-11-28 DOI: 10.1016/j.fecs.2025.100412

Patryk Czortek , Mateusz Rawlik , Marcin Koprowski , Piotr Sewerniak , Radosław Puchałka

Non-native plants are increasingly recognized as ecosystem engineers across a wide range of ecosystems. While their impacts on understory composition have been widely documented, consequences for community assembly remain largely unexplored. We investigated the engineering impacts of Sorbaria sorbifolia, a naturalized Rosaceae shrub, on abiotic conditions and understory community assembly in Central European forests. Across 60 plots spanning coniferous and deciduous stands, we quantified light availability, organic layer C/N ratio and thickness, and understory functional diversity along an invasion gradient. Using ordination and linear regression, we found that increasing S. sorbifolia cover reduced light availability, thickened the organic layer, and altered C/N ratio in contrasting, forest-type-specific ways. In coniferous stands, invasion increased C/N and strongly suppressed understory light, whereas in deciduous stands it reduced C/N with weaker shading effects. These changes translate into consistent declines in functional richness and dispersion, particularly in coniferous forests where invasion led to homogenization of the understory. Trait shifts indicated stronger habitat filtering under invasion, with declines in specific leaf area (SLA) and increases in leaf dry matter content and seed mass, reflecting exclusion of light-demanding species and persistence of stress-tolerant taxa and woody seedlings. Remarkably, once S. sorbifolia exceeded ∼50% cover, positive relationships between habitat properties and understory functional diversity collapsed, replaced by uniform light limitation. This threshold effect highlights S. sorbifolia as an ecosystem engineer, capable of transforming forest structure and regeneration trajectories. Early detection and management are therefore crucial to prevent long-term homogenization and the formation of novel, invasion-driven forest states.

非本地植物越来越被认为是广泛生态系统中的生态系统工程师。虽然它们对林下植被组成的影响已被广泛记录，但对群落聚集的影响在很大程度上仍未被探索。研究了归化蔷薇科灌木Sorbaria sorbifolia对中欧森林非生物条件和林下群落聚集的工程影响。在60个样地，包括针叶林和落叶林，我们沿着入侵梯度量化了光有效性、有机层C/N比和厚度以及林下功能多样性。通过排序和线性回归分析，我们发现增加文冠盖度会降低光效，增加有机层厚度，并以不同林型的方式改变C/N比。在针叶林中，入侵增加了C/N，强烈抑制了林下光照，而在落叶林中，入侵降低了C/N，遮光作用较弱。这些变化转化为功能丰富度和分散度的持续下降，特别是在针叶林中，入侵导致下层植被同质化。性状变化表明，入侵对生境的过滤作用更强，比叶面积（SLA）下降，叶片干物质含量和种子质量增加，反映了需光物种的排除和耐胁迫分类群和木本幼苗的持续存在。值得注意的是，一旦文冠枯盖度超过50%，生境特性和林下功能多样性之间的正相关关系就会消失，取而代之的是均匀光照限制。这种阈值效应凸显了文冠是一个生态系统工程师，能够改变森林结构和更新轨迹。因此，早期发现和管理对于防止长期同质化和形成新的、由入侵驱动的森林状态至关重要。

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引用次数: 0

Old-growth mixed beech-dominated forests continue accumulating carbon with advancing age 以混合山毛榉为主的原始森林随着年龄的增长继续积累碳

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-11-25 DOI: 10.1016/j.fecs.2025.100411

Katarína Markuljaková , Marek Svitok , Martin Mikoláš , Jeňýk Hofmeister , Wiliam S. Keeton , Anders Alhström , Dheeraj Ralhan , Jakob Pavlin , Audrey Rose Salerno , Daniel Kozák , Daniela Dúhová , Pavel Janda , Stjepan Mikac , Tzvetan Zlatanov , Momchil Panayotov , Elvin Toromani , Srdjan Keren , Abdulla Dikku , Cătălin-Constantin Roibu , Krešimir Begović , Miroslav Svoboda

Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks. The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage. To clarify these relationships in Fagus sylvatica, systems, we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries. By employing a dendrochronological approach and integrating key environmental variables, including elevation, slope, temperature, and the presence of large-diameter trees (≥60 cm), we analyzed the complex relationships between tree/stand age within a plot (represented by plot-level mean values, hereafter “stand age”) and aboveground carbon stock across live, standing, and lying deadwood pools. The average stand age was 220 years, with 230 tC·ha⁻¹ of carbon stored in aboveground biomass and necromass. We found a positive correlation between age and carbon storage at both the individual tree and plot levels. Notably, the presence of large-diameter trees was the strongest indicator of carbon stock, with carbon accumulation peaking at about 30% large-tree stems proportion before stabilising, while younger beech trees (below 100 years old) had a smaller contribution to carbon storage. We found no evidence of a decline in carbon stock with advancing stand age across the studied sites. Despite the ecological importance of old-growth forests, many of them remain unprotected and are disappearing across Europe. Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs.

原始森林独特地支持着生物多样性，同时也是地球上最重要的碳储量之一。树木和林分年龄对碳通量动力学的影响仍然存在争议，这是一个迫切的问题，因为气候驱动的干扰可能重塑森林年龄结构和原位碳储量。为了澄清这些关系，我们研究了一个独特的数据集，其中包括来自五个南欧国家保存最完好的原始森林的190个样地的3503个树木年轮系列。通过采用树木年代学方法，结合海拔、坡度、温度和大直径树木（≥60 cm）的存在等关键环境变量，分析了样地内树木/林龄（用样地水平平均值表示，以下简称“林龄”）与活、立、卧枯木池地上碳储量之间的复杂关系。林龄平均为220年，地上生物量和坏死物碳储量为230 tC·ha−1。我们发现树龄与碳储量在单株和样地水平上均呈正相关。值得注意的是，大直径树木的存在是碳储量的最强指标，碳积累在大树干比例约30%时达到峰值，然后趋于稳定，而幼龄山毛榉（100岁以下）对碳储量的贡献较小。我们没有发现碳储量随林龄增长而下降的证据。尽管原生林具有重要的生态意义，但在欧洲，许多原生林仍未受到保护，甚至正在消失。我们的研究结果强调了保护原始森林的重要性，以最大限度地发挥其作为长期生态系统碳库的作用。

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引用次数: 0

Wildfire increased summer low flows in snow-dominated watersheds: A combined approach of hydrometric monitoring and geochemical tracing 野火增加了积雪占主导地位的流域夏季低流量：水文监测和地球化学示踪的结合方法

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-11-21 DOI: 10.1016/j.fecs.2025.100408

Shixuan Lyu , Xiaohua Wei , Ming Qiu , Mackenzie Myers , Zhaozhi Wang , Jinyu Hui , Wenhui Yan , Tongqing Shen , Meirong Sun , Shuhui Wang , Yiping Hou

Forests are experiencing more frequent and intense wildfires in Canada, which pose considerable threats to water quantity and quality, particularly during the summer low-flow period when water demand is high. While the impacts of wildfire on hydrology have been widely assessed at the watershed scale, the underlying mechanisms of the responses of summer low flows remain poorly understood. In this study, we employed an integrated research framework that combines hydrometric monitoring with geochemical tracing to evaluate how the 2021 White Rock Lake Wildfire affected summer low flows, and to identify the underlying mechanisms governing these responses in the Okanagan Valley, British Columbia (BC), Canada. We found that (1) summer low flows, represented by Q₉₀ (flows exceeded at 90% of the time in summer) significantly increased following the wildfire (p < 0.05); (2) summer low flows were primarily regulated by snow water in early summer (July), while dominated by groundwater in late summer (August and September); and (3) enhanced snow water contribution and reduced evapotranspiration (ET) were two primary contributors to the increased summer low flows. Our results provide insights for developing sustainable water management strategies for the region in the context of climate change and increasing forest disturbance. This study also demonstrates that the combination of hydrometric monitoring and geochemical tracing is an effective approach towards uncovering mechanisms that drive low-flow responses.

加拿大的森林正在经历更频繁和强烈的野火，这对水的数量和质量构成相当大的威胁，特别是在夏季低流量期间，因为水的需求很高。虽然野火对水文的影响已经在流域尺度上得到了广泛的评估，但对夏季低流量响应的潜在机制仍然知之甚少。在这项研究中，我们采用了一个综合的研究框架，将水文监测与地球化学示踪相结合，以评估2021年白岩湖野火如何影响加拿大不列颠哥伦比亚省（BC）奥肯那根山谷的夏季低流量，并确定控制这些响应的潜在机制。结果发现：(1)夏季低流量，以Q90（夏季90%时间不超过流量）为代表，在野火后显著增加（p < 0.05）；(2)夏季低流量在初夏（7月）以雪水为主，在夏末（8、9月）以地下水为主；(3)积雪水贡献增加和蒸散发（ET）减少是夏季低流量增加的两个主要原因。我们的研究结果为该地区在气候变化和森林干扰增加的背景下制定可持续的水资源管理战略提供了见解。该研究还表明，水文观测和地球化学示踪剂的结合是揭示驱动低流量响应机制的有效方法。

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引用次数: 0

Temperature determines the biomass of forest floor bryophytes: A cross-regional investigation in 413 sites 温度决定森林地面苔藓植物生物量：413个站点的跨区域调查

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-11-19 DOI: 10.1016/j.fecs.2025.100409

Zhe Wang , Defeng Feng , Yanqiang Jin , Mijun Zou , Beibei Gao , Xin Liu , Weikai Bao

Understory bryophytes play unique and disproportionately important roles in water retention, biogeochemical cycling, and biodiversity conservation, and serve as bioindicators of environmental health in forest ecosystems. However, biogeographical research on the biomass of forest bryophytes is inadequately studied and has been limited to elevational gradients. We conducted a systematic cross-regional survey of bryophyte biomass across 413 forest sites in Sichuan Province, China. We analyzed how each environmental variable, including climatic and atmospheric factors, overstory covers, and soil nutrients, relates to bryophyte biomass and quantified their relative contributions. The results indicate that, largely similar to previous local investigations and experiments, at a large scale, bryophytes are abundant in forests with lower temperature, nitrogen deposition, vapor pressure deficit, and tree and herb covers, as well as higher light availability. Moreover, bryophyte biomass is positively associated with soil carbon and nitrogen content. These environmental variables are closely related and jointly influence bryophyte biomass, with mean annual temperature being the most significant factor (accounting for 83% of the relative contribution). The biogeographical patterns of bryophyte biomass contribute to deepening our understanding of their adaptations to multiple environmental variables and enable us to predict their responses to global climate change. These patterns also provide essential evidence for establishing more accurate terrestrial vegetation ecosystem models.

林下苔藓植物在保水、生物地球化学循环和生物多样性保护等方面发挥着独特而重要的作用，是森林生态系统环境健康的生物指标。然而，关于森林苔藓生物量的生物地理学研究还不够充分，而且仅限于海拔梯度。对四川省413个森林样地的苔藓植物生物量进行了系统的跨区域调查。我们分析了气候和大气因子、植被覆盖度和土壤养分等环境变量与苔藓生物量的关系，并量化了它们的相对贡献。结果表明，与以往的局部调查和实验结果基本相似，在大尺度上，在温度较低、氮沉降较低、蒸汽压亏缺、乔木草本覆盖、光照有效度较高的森林中，苔藓植物丰富。此外，苔藓生物量与土壤碳氮含量呈正相关。这些环境变量密切相关，共同影响苔藓植物生物量，其中年平均温度是最显著的因素（占相对贡献的83%）。苔藓植物生物量的生物地理格局有助于加深我们对其适应多种环境变量的认识，并使我们能够预测其对全球气候变化的响应。这些模式也为建立更精确的陆地植被生态系统模型提供了重要依据。

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引用次数: 0

Canopy and understory nitrogen additions differentially regulate soil organic carbon fractions via litter–microbe–mineral interactions 冠层和林下氮添加量通过凋落物-微生物-矿物相互作用对土壤有机碳组分的调节存在差异

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-11-19 DOI: 10.1016/j.fecs.2025.100410

Youchao Chen , Qinxi Liu , Xinli Chen , Ji Chen , Biao Zhu , Shenglei Fu , Scott X. Chang , Yanjiang Cai

The effects of nitrogen (N) deposition on forest soil organic carbon (SOC) are largely unclear, likely due to the divergent responses of particulate (POC) and mineral-associated carbon (MAOC). Conventional understory inorganic N (UIN) additions neglect canopy processes and the impacts of organic N, potentially misevaluating N deposition effects. This study was conducted in a long-term N addition experiment established in a Moso bamboo forest, which included six treatments combining canopy and understory N additions with organic (urea + glycine) and inorganic (NH₄NO₃) forms at a rate of 50 kg N·ha⁻¹·yr⁻¹. Litterbags were installed for a two-year decomposition experiment and collected at quarterly intervals, together with concurrent soil sampling under litterbags at 0–10 cm depth. We aimed to examine the effects of canopy vs. understory N addition and organic vs. inorganic N form on soil POC and MAOC concentrations. Our results showed that canopy N additions significantly reduced POC (−15.9%) but did not affect MAOC (P > 0.05). Conversely, understory N additions significantly increased POC (+30.9%) and decreased MAOC (−28.9%). Canopy N additions decreased POC by enhancing peroxidase activity and fungal diversity (FuD), while understory N additions promoted POC by inhibiting litter decomposition. Additionally, understory N addition-induced soil acidification decreased soil Ca²⁺ concentration, microbial carbon use efficiency, and bacterial necromass C, as well as the release of litter water-soluble compounds, thereby inhibiting MAOC. Moreover, nitrogen forms (organic vs. inorganic) had no effect on SOC fractions. Our findings underscore that canopy and understory N addition approaches differentially regulate SOC fractions by altering litter decomposition–microbial–mineral interactions, and the understory approach may overestimate soil POC gain and MAOC loss driven by atmospheric N deposition.

氮沉降对森林土壤有机碳（SOC）的影响在很大程度上是不清楚的，可能是由于颗粒（POC）和矿物相关碳（MAOC）的不同响应。传统的林下无机氮（un）添加忽略了林冠过程和有机氮的影响，潜在地错误评估了N沉降效应。本研究在毛梭竹林进行了长期施氮试验，包括6个处理，分别以有机（尿素+甘氨酸）和无机（NH4NO3）形式，以50 kg N·ha−1·yr−1的速率向林下和林下施氮。安装垃圾袋进行为期两年的分解实验，每季度收集一次，同时在垃圾袋下进行0-10 cm深度的土壤采样。研究了林冠和林下N添加量以及有机和无机N形态对土壤POC和MAOC浓度的影响。结果表明，添加冠层氮显著降低了POC(- 15.9%)，但对MAOC没有影响（P > 0.05）。相反，林下N添加显著提高POC(+30.9%)，降低MAOC（- 28.9%）。林冠氮素添加通过提高过氧化物酶活性和真菌多样性（FuD）降低POC，林下氮素添加通过抑制凋落物分解提高POC。此外，林下N添加引起的土壤酸化降低了土壤Ca2+浓度、微生物碳利用效率、细菌坏死质量C以及凋落物水溶性化合物的释放，从而抑制了MAOC。此外，氮形态（有机和无机）对有机碳分数没有影响。研究结果表明，林冠和林下加氮方法通过改变凋落物分解-微生物-矿物相互作用来调节土壤有机碳含量，林下加氮方法可能高估了大气氮沉降驱动的土壤POC增益和MAOC损失。

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引用次数: 0

Height-based biomass models differ for naturally regenerated and planted young trees 基于高度的生物量模型对于自然再生和种植的幼树是不同的

IF 4.4 1区农林科学 Q1 FORESTRY

Forest Ecosystems

Pub Date : 2025-11-13 DOI: 10.1016/j.fecs.2025.100406

Peter Marčiš , Jozef Pajtík , Bohdan Konôpka , Martin Lukac

This study investigated biomass allocation in young stands of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) across 31 forest sites in the Western Carpathians, Slovakia. A total of 541 trees aged 2–10 years, originating from natural regeneration and planting, were destructively sampled to quantify biomass in four components: foliage, branches, stems, and roots. Generalized non-linear least squares (GNLS) models with a weighing variance function outperformed log-transformed seemingly unrelated regression (SUR) models in terms of accuracy and robustness, especially for foliage and branch biomass. When using height as the predictor, SUR models tended to underestimate biomass in planted beech, leading to notable underprediction of aboveground and total biomass. Biomass allocation patterns varied significantly by species and regeneration origin. Using a non-linear system of equations and component ratio modelling, we found out that planted spruce displayed low variability and a consistent dominance of needle biomass, while naturally regenerated beech showed greater variability and a higher proportion of stem biomass, reflecting stronger competition-driven vertical growth. Interspecific differences in total biomass were more pronounced when using tree height, with spruce generally exhibiting greater biomass than beech at equivalent heights. Overall, stem base diameter marginally outperformed tree height as a predictor of biomass. However, tree height-based models showed strong performance and are particularly suitable for integration with remote sensing applications. These findings can directly support forest managers and modellers in comparing regeneration methods and biomass estimation approaches for early-stage stand development, carbon accounting, and remote sensing calibration.

研究了欧洲山毛榉（Fagus sylvatica L.）和挪威云杉（Picea abies (L.)）幼林的生物量分配。喀斯特)横跨斯洛伐克喀尔巴阡山脉西部的31个森林遗址。对541棵2 ~ 10年树龄的自然再生和种植树木进行了破坏性采样，量化了叶、枝、茎和根4个组成部分的生物量。具有加权方差函数的广义非线性最小二乘（GNLS）模型在精度和鲁棒性方面优于对数变换的看似不相关回归（SUR）模型，特别是在叶和枝生物量方面。当使用高度作为预测因子时，SUR模型倾向于低估人工山毛榉的生物量，导致地上生物量和总生物量的显著低估。生物量分配模式因物种和再生来源的不同而有显著差异。利用非线性方程系统和成分比模型，我们发现人工云杉表现出较低的变异性，针叶生物量占主导地位，而自然再生山毛榉表现出较大的变异性和较高的茎生物量比例，反映出更强的竞争驱动的垂直生长。当使用树高时，总生物量的种间差异更为明显，在同等高度下，云杉的生物量普遍大于山毛榉。总体而言，作为生物量的预测因子，茎基部直径略优于树高。然而，基于树高的模型表现出很强的性能，特别适合与遥感应用相结合。这些发现可以直接支持森林管理者和建模者比较早期林分发育的更新方法和生物量估算方法、碳核算和遥感校准。

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引用次数: 0