Agricultural and Forest Meteorology最新文献_第10页

A framework for phenotyping rubber trees under intense wind stress using laser scanning and digital twin technology 利用激光扫描和数字孪生技术对强风胁迫下的橡胶树进行表型分析的框架

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-28 DOI: 10.1016/j.agrformet.2024.110319

Ting Yun , Markus P. Eichhorn , Shichao Jin , Xinyue Yuan , Wenjie Fang , Xin Lu , Xiangjun Wang , Huaiqing Zhang

Rubber trees in coastal habitats are exposed to a high degree of wind stress. An algorithm-hardware synergetic methodology was developed for investigating and predicting rubber tree phenotyping excited by strong winds. The framework includes (1) a custom-designed industrial fan that recreates a variable airflow field at wind speeds of 15, 30 and 45 m/s coupled with a terrestrial laser scanner and bundled motion sensors to acquire point clouds and vibration data; (2) a graphic model that approximates tree canopies based on foliage clumps with phenotypic traits that are derived from point clouds captured while trees are subjected to aerodynamic drag; and (3) the wind characteristic parameters of forest canopies were calculated by a developed forest-specialized k-ε turbulence model combining the constructed tree models and grid-scale subdivision of the wind fluid field. (4) A digital twin model that incorporates detailed tree phenotypic traits and considers plant mechanical characteristics was established, depicting the related wind-induced actions of target trees under various wind influences. The results show that tree crowns with spreading forms are prone to yield larger pendulum amplitudes than compact crowns, but trees directly exposed to wind exhibit greater crown volume reductions than trees in sheltered areas. Within tree canopies, a one-fold increase in inlet wind speed intensified crown compression (approximately 17 % decrease in crown volume), generated 2.1-fold pressure gradients and increased turbulence kinetic energy by approximately 60 %. Moreover, the entire scenario of the adaptation of experimental trees to wind perturbations was visually restored using digital twin techniques, serving as an integral behaviour dataset for further data-driven decision-making. In summary, this paper presents a comprehensive methodology that can decipher the phenotypic manifestations of trees' reactions to wind hazards, with potential applications in phenotyping or envirotyping studies designed to evaluate the wind resistance properties of rubber trees.

沿海栖息地的橡胶树面临着很大的风压。为研究和预测橡胶树在强风作用下的表型，开发了一种算法-硬件协同方法。该框架包括：(1) 一个定制设计的工业风扇，可在 15、30 和 45 米/秒的风速下再现可变气流场，并配有地面激光扫描仪和捆绑式运动传感器，以获取点云和振动数据；(2) 一个图形模型，根据表型特征的叶丛近似树冠，这些表型特征来自树木受到空气阻力时捕获的点云；以及 (3) 森林树冠的风特性参数由开发的森林专用 k-ε 湍流模型计算，该模型结合了构建的树木模型和网格尺度细分的风流体场。(4) 建立了包含详细树木表型特征并考虑植物机械特征的数字孪生模型，描述了目标树木在各种风力影响下的相关风致作用。结果表明，树冠舒展的树木比树冠紧凑的树木容易产生更大的摆幅，但直接暴露在风中的树木比位于遮蔽区域的树木表现出更大的树冠体积缩减。在树冠内，入口风速增加一倍会加剧树冠压缩（树冠体积减少约 17%），产生 2.1 倍的压力梯度，湍流动能增加约 60%。此外，还利用数字孪生技术直观地还原了实验树适应风扰动的整个过程，为进一步的数据驱动决策提供了完整的行为数据集。总之，本文提出的综合方法可以解读树木对风危害反应的表型表现，有望应用于旨在评估橡胶树抗风特性的表型或环境类型研究。

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引用次数: 0

Climate suitability for the moisture-sensitive conifer species may not be universally declining in a warming world 在气候变暖的世界中，对水分敏感的针叶树种的气候适宜性可能不会普遍下降

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-28 DOI: 10.1016/j.agrformet.2024.110328

Bo Wang , Tuo Chen , Guobao Xu , Guoju Wu , Guangxiu Liu

Amid ongoing and escalating climate change, understanding changes in habitat suitability for forest tree species is crucial for anticipating risks to their growth and ecosystem services. Despite advancements in this area, challenges remain, particularly in addressing spatial and temporal discrepancies in suitability change. This study evaluated habitat suitability changes for Qinghai spruce, a moisture-sensitive conifer species, during the warming period from 1960 to 2020, by integrating species distribution modeling with dendrochronological methods. Maxent model outputs revealed a distinct dipole pattern in habitat suitability changes: an increase in the west (56.2%) and a decrease in the east (43.8%). This dipole pattern was corroborated by the spatial pattern of forest population dynamics, highlighting much higher adult-tree mortality frequency, rate, and density decline in regions with decreased suitability, while showing minimal values in most (3 out of 4) regions with increased suitability. Climate factors and their changes explained 80.9% of the variance in suitability changes. Precipitation change, with a significant positive relationship to suitability changes, contributed the most (54.5%) to this explained variance, followed by post-warming temperature, which contributed 34.3% with a significant negative relationship. Thresholds of +20 mm for precipitation change and 0 °C for post-warming temperature distinguished regions with a high probability of increased suitability from those with a high probability of decreased suitability. This study provides nuanced insights into the responses of moisture-sensitive conifer species to climate change, helping inform and enhance conservation strategies for Qinghai spruce.

在持续且不断升级的气候变化中，了解森林树种栖息地适宜性的变化对于预测其生长和生态系统服务面临的风险至关重要。尽管在这一领域取得了进展，但挑战依然存在，尤其是在解决适宜性变化的时空差异方面。本研究通过将物种分布建模与树木年代学方法相结合，评估了青海云杉（一种对水分敏感的针叶树种）在1960年至2020年气候变暖期间的栖息地适宜性变化。Maxent 模型的输出结果显示了栖息地适宜性变化的明显偶极模式：西部增加（56.2%），东部减少（43.8%）。森林种群动态的空间模式也证实了这一偶极模式，在适宜性下降的地区，成树死亡率、死亡率和密度下降率都要高得多，而在适宜性上升的大部分地区（4 个地区中的 3 个），成树死亡率、死亡率和密度下降率的数值都很小。气候因素及其变化解释了适宜性变化中 80.9% 的差异。降水变化与适宜性变化呈显著正相关，对这一解释方差的贡献最大（54.5%），其次是变暖后的温度，占 34.3%，呈显著负相关。降水变化的阈值为 +20 毫米，气候变暖后温度的阈值为 0 °C，这两个阈值将适宜性极有可能增加的地区与适宜性极有可能减少的地区区分开来。这项研究为湿度敏感针叶树种对气候变化的反应提供了细致入微的见解，有助于为青海云杉的保护战略提供信息并加以改进。

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引用次数: 0

Seasonal patterns of CO2 exchange in a tropical intensively managed pasture in Southeastern Brazil 巴西东南部热带集约化管理牧场的二氧化碳交换季节模式

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-28 DOI: 10.1016/j.agrformet.2024.110324

Vitor de J.M. Bianchini, Alex da S. Sechi, Fábio R. Marin

Tropical pastures are one of the main land uses in Brazil, forming the backbone of the country's beef and milk production chain. Adopting sustainable management practices that increase the productivity of pastoral livestock systems is essential to mitigate environmental impacts and ensure food security. However, eddy covariance studies that contribute to understanding the influence of grazing management strategies on the ability of intensively grazed tropical pastures to absorb carbon remain scarce. Therefore, our main objective was to investigate the dynamics of CO₂ and water vapor exchange and biomass production in a tropical C4 grass (Pennisetum purpureum Schum. cv. Cameroon) pasture under intermittent stocking management strategies from March 2021 to June 2023. We found that the pasture acted as a net source of CO₂ to the atmosphere in both years studied. The annual NEE was 34 ± 14 g CO₂-C m⁻² yr⁻¹ in 2021–2022 and 21 ± 12 g CO₂-C m⁻² yr⁻¹ in 2022–2023. Reco, influenced by rising air and soil temperatures, increased rainfall, and higher incoming solar radiation levels, especially during spring and summer, played a crucial role in this result. The pasture absorbed more CO₂, showed higher evapotranspiration, and produced more leaves in the rainy periods when the pasture structure was kept close to the previously established management targets. CO₂ losses to the atmosphere prevailed in the dry periods and in wet periods where the pasture structure was far from the optimal limits for elephant grass.

热带牧场是巴西的主要土地用途之一，是巴西牛肉和牛奶生产链的支柱。采用可持续的管理方法提高牧业畜牧系统的生产力，对于减轻环境影响和确保粮食安全至关重要。然而，有助于了解放牧管理策略对密集放牧的热带牧场吸碳能力的影响的涡度协方差研究仍然很少。因此，我们的主要目标是研究 2021 年 3 月至 2023 年 6 月间歇性放牧管理策略下热带 C4 草（Pennisetum purpureum Schum.我们发现，在研究的两年中，牧场都是大气中二氧化碳的净来源。2021-2022 年的年净排放源为 34 ± 14 g CO2-C m-2 yr-1，2022-2023 年为 21 ± 12 g CO2-C m-2 yr-1。受空气和土壤温度升高、降雨量增加以及太阳辐射入射水平升高（尤其是在春季和夏季）的影响，Reco 对这一结果起到了至关重要的作用。当牧场结构保持在先前设定的管理目标附近时，牧场吸收的二氧化碳更多，蒸散量更大，在雨季产生的叶片也更多。在干旱期和潮湿期，当牧场结构远未达到象草的最佳生长极限时，向大气中排放的二氧化碳会更多。

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引用次数: 0

The vulnerability of winter wheat in Germany to air temperature, precipitation or compound extremes is shaped by soil-climate zones 德国冬小麦易受气温、降水或复合极端气候影响的程度取决于土壤-气候区

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-27 DOI: 10.1016/j.agrformet.2024.110322

Rike Becker , Bernhard Schauberger , Ralf Merz , Stephan Schulz , Christoph Gornott

Whether hydroclimatic extremes cause yield losses or failures not only depends on their intensity but also on local environmental conditions. These conditions shape the capacity to buffer climatic shocks and thus necessitate a regionally specific impact assessment and adaptation planning. However, the degree to which different environmental conditions affect climate impacts on yields and its spatiotemporal variability across Germany is relatively unknown. In this study, we use a regression-based crop-climate modelling approach for 71 regions, classified according to soil and climate characteristics and investigate region-specific vulnerabilities of winter wheat yields to hydroclimatic extremes for the period 1991–2019. We account for the co-occurrence of temperature and moisture impacts (i.e. compound effects) as well as for local soil-climate conditions. On average, our models can explain approx. 67 % of past winter wheat yield variations. Despite the rather homogeneous climate in Germany, the results reveal clear geographic differences across different soil-climate regions. While the north-eastern regions show a clear dominance of drought impacts, southern regions show stress due to moisture excess. Heat impacts can clearly be linked to the warm regions along the western part of the country. Overall, compound dry-hot extremes pose the strongest and most widespread risk for winter wheat yields in Germany, being responsible for approx. 38 % and in some regions for up to 50 % of past yield variations. Based on the identified regional differences in hydroclimate susceptibility, we can define four geographic risk clusters, which exhibit vulnerability to climatic extremes such as summer droughts, winter droughts, summer heat waves, and winter moisture excess. The identified risk clusters of heat and moisture stresses could inform regional-specific adaptation planning.

极端水文气候是否导致减产或歉收，不仅取决于其强度，还取决于当地的环境条件。这些条件决定了缓冲气候冲击的能力，因此有必要进行针对具体地区的影响评估和适应规划。然而，不同环境条件对德国气候对产量的影响程度及其时空变异性还相对未知。在本研究中，我们采用基于回归的作物气候建模方法，根据土壤和气候特征对 71 个地区进行了分类，并调查了 1991-2019 年期间各地区冬小麦产量易受极端水文气候影响的程度。我们考虑了温度和湿度的共同影响（即复合效应）以及当地的土壤气候条件。平均而言，我们的模型可以解释约 67% 的过去冬小麦产量变化。尽管德国的气候比较均匀，但研究结果显示不同土壤气候地区之间存在明显的地理差异。东北部地区明显受到干旱的影响，而南部地区则因水分过多而受到压力。热影响显然与德国西部的温暖地区有关。总体而言，干热复合极端气候对德国冬小麦产量造成的风险最大、范围最广，约占过去产量变化的 38%，在某些地区甚至高达 50%。根据已确定的水文气候易感性的地区差异，我们可以定义四个地理风险群组，它们表现出对极端气候的脆弱性，如夏季干旱、冬季干旱、夏季热浪和冬季水分过多。所确定的热量和湿度压力风险集群可为特定区域的适应规划提供参考。

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引用次数: 0

Land-atmosphere feedback exacerbated the mega heatwave and drought over the Yangtze River Basin of China during summer 2022 陆地-大气反馈加剧了 2022 年夏季中国长江流域的特大热浪和干旱

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-25 DOI: 10.1016/j.agrformet.2024.110321

Xiao Chen , Jialin Wang , Feifei Pan , Yu Song , Ju Liang , Na Huang , Kang Jiang , Riping Gao , Jingyu Men , Pengshuai Bi , Fangxiao Zhang , Zhanrui Huang , Binxiang Huang , Zhihua Pan

In the summer of 2022, a record-breaking heatwave and drought event occurred in the Yangtze River (YR) Basin of China, causing great damage to the society and ecosystem. However, the role of land-atmosphere (LA) interactions in driving and reinforcing this event has not been fully studied. In this study, using air temperature, soil moisture (SM), surface sensible heat fluxes, surface latent heat fluxes and radiation fluxes data from ERA5, we analyze the process of this event and reveal the contribution of the LA feedbacks. The results indicate that during the 2022 YR Basin heatwave and drought event, the regional average maximum air temperature and SM reached unprecedented levels of 2.7 standard deviations (SDs) and −3.5 SDs, respectively, compared to the climatology from 1980 to 2021. In August 2022, SM rapidly declined, pushing the region into a rare "dry" state. The dry soil increased the sensitivity of daily maximum air temperature to SM, intensifying the occurrence of heatwaves in the area. Simultaneously, increased downward solar radiation reached surface and most of that converted to sensible heat fluxes due to low soil moisture limitations leading to elevated air temperatures. While similar events have been reported multiple times in regions like Europe and western North America, their occurrence in the "moist" region of the YR Basin of China is exceptionally rare, which suggests an increasing likelihood of such extreme events in this region. Land-atmosphere interactions play an increasingly crucial role in exacerbating extreme conditions, and therefore, more studies such as this are needed for improving predictability of extreme events on a sub-seasonal time scale.

2022 年夏季，中国长江流域发生了破纪录的热浪和干旱事件，对社会和生态系统造成了巨大破坏。然而，陆地-大气（LA）相互作用在驱动和强化这一事件中的作用尚未得到充分研究。本研究利用ERA5的气温、土壤水分（SM）、地表显热通量、地表潜热通量和辐射通量数据，分析了该事件的发生过程，并揭示了LA反馈的贡献。结果表明，在2022年YR盆地热浪和干旱事件期间，区域平均最高气温和SM达到了前所未有的水平，与1980-2021年的气候资料相比，分别为2.7个标准差和-3.5个标准差。2022 年 8 月，SM 迅速下降，使该地区进入罕见的 "干旱 "状态。干燥的土壤增加了日最高气温对SM的敏感性，加剧了该地区热浪的发生。与此同时，到达地表的向下太阳辐射增加，由于土壤湿度低的限制，大部分太阳辐射转化为显热通量，导致气温升高。虽然类似事件在欧洲和北美西部等地区多次发生，但在中国雅砻江盆地的 "湿润 "地区发生却异常罕见，这表明该地区发生此类极端事件的可能性越来越大。陆地-大气相互作用在加剧极端条件方面发挥着越来越关键的作用，因此，需要开展更多类似的研究，以提高亚季节时间尺度上极端事件的可预测性。

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引用次数: 0

Spatio-temporal dynamics and controls of forest-floor evapotranspiration across a managed boreal forest landscape 受管理的北方森林景观中林地蒸散的时空动态和控制因素

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-24 DOI: 10.1016/j.agrformet.2024.110316

Zifan Guo , Hengshuo Zhang , Eduardo Martínez-García , Xizhi Lv , Hjalmar Laudon , Mats B. Nilsson , Matthias Peichl

Forest-floor evapotranspiration (ET_ff) is a major pathway for water loss in terrestrial ecosystems, often accounting for more than half of ecosystem evapotranspiration. However, our understanding of the environmental and stand structural controls on the spatio-temporal dynamics of ET_ff across the managed boreal forest landscape remains limited. In this study, we conducted chamber-based flux measurements of ET_ff and its components, i.e., soil evaporation (E_s) and forest-floor understory transpiration (T_u), on natural and vegetation removal plots across 50 diverse forest stands (ranging 5–211 years old) in Northern Sweden over two contrasting growing seasons. We found manifold variations in the growing season means of ET_ff, E_s, and T_u, ranging from 0.008 to 0.048 mm h⁻¹, 0.004 to 0.034 mm h⁻¹, and 0.002 to 0.030 mm h⁻¹, respectively, across the 50 forest stands. The contribution of E_s and T_u to ET_ff ranged from 19 to 83 % and 38 to 85 %, respectively, with the average E_s:T_u ratio shifting from 0.84 in 2017 to 0.63 during 2018, the latter experiencing an exceptional summer drought. Seasonal variations in ET_ff and its component fluxes were mainly controlled by below-canopy air temperature, while radiation was the main driver of their spatial variations across the forest stands. At the landscape-level, stand age was the dominant control of ET_ff by modifying overstory tree characteristics such as biomass and leaf area index. In contrast, neither tree species nor soil type had any effect on ET_ff or T_u. However, E_s was higher in sediment compared to till soils. Thus, our results suggest that environmental and stand structural factors jointly control the spatio-temporal dynamics of ET_ff across the managed boreal forest landscape. Our study furthermore highlights the need for an in-depth understanding of ET_ff and its components when assessing the water cycle feedbacks of the boreal forest to changes in forest management and climate.

林地蒸散（ETff）是陆地生态系统失水的主要途径，通常占生态系统蒸散量的一半以上。然而，我们对整个北方森林景观中环境和林分结构对 ETff 时空动态控制的了解仍然有限。在这项研究中，我们在瑞典北部 50 个不同林分（林龄从 5 年到 211 年不等）的自然地块和植被清除地块上，在两个不同的生长季节对 ETff 及其组成部分（即土壤蒸发量（Es）和林底林下蒸腾量（Tu））进行了室内通量测量。我们发现，在这 50 个林分中，ETff、Es 和 Tu 的生长季平均值存在多方面的差异，分别为 0.008 至 0.048 毫米/小时-1、0.004 至 0.034 毫米/小时-1 和 0.002 至 0.030 毫米/小时-1。Es和Tu对ETff的贡献率分别为19%至83%和38%至85%，Es:Tu的平均比率从2017年的0.84降至2018年的0.63，2018年经历了异常的夏季干旱。ETff及其组分通量的季节变化主要受冠层下气温的控制，而辐射则是林分空间变化的主要驱动因素。在景观层面上，林分年龄通过改变上层树木的特征（如生物量和叶面积指数）对 ETff 起着主要的控制作用。相比之下，树种和土壤类型对 ETff 或 Tu 都没有影响。然而，与耕作土壤相比，沉积物中的Es更高。因此，我们的研究结果表明，环境因素和林分结构因素共同控制着整个北方森林景观中 ETff 的时空动态。我们的研究还进一步强调，在评估北方森林对森林管理和气候变化的水循环反馈时，需要深入了解 ETff 及其组成部分。

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引用次数: 0

Spatiotemporal variation in carbon use efficiency derived from eddy-covariance measurement of global terrestrial biomes 全球陆地生物群落涡度协方差测量得出的碳利用效率的时空变化

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-23 DOI: 10.1016/j.agrformet.2024.110318

Chuan Jin , Tianshan Zha , Charles P.-A. Bourque , Zehao Fan , Weirong Zhang , Kai Di , Yue Jiao , Qiaofeng Ma , Dongdan Yuan , Hongxian Zhao , Shaorong Hao , Yifei Lu , Zhongmin Hu

Vegetation carbon use efficiency (CUE), the ratio between net primary productivity (NPP) and gross primary productivity (GPP), provides insight into the ability of ecosystems to transfer large amounts of carbon (C) from the atmosphere to potential C-sinks. Although the patterns and feedback of CUE on climate change have been previously studied, large uncertainties remain due to methodological constraints. To address this problem, we proposed a new method that enables the separation of autotrophic respiration (R_a) from ecosystem respiration (R_e) by assuming that R_a is related to the lower bound of the relationship between R_e and GPP. By applying this method, we analyzed flux data acquired from 195 sites globally in an investigation of spatiotemporal dynamics in CUE. The results revealed a global average CUE of 0.50 ± 0.13, with the greatest values corresponding with croplands and the lowest with mixed forests. Spatially, CUE was greatest for Mediterranean and subtropical regions, and least for tropical regions. Temporally, CUE exhibited seasonal fluctuations across most biomes, with CUE increasing during the early growing season and then decreasing as the season progressed. We also investigated CUE's response to variations in several environmental drivers (e.g., air temperature, soil moisture, and incident solar radiation), with the help of machine learning, specifically extreme gradient boosting (xgboost) and a SHapley Additive exPlanation (SHAP)-value based interpretation of the results. A negative relationship was shown to exist between ambient CO₂ concentrations and CUE, confirming hypotheses that relate translocation and accumulation of nonstructural carbohydrates in plant tissues. These findings highlight the feasibility and value of leveraging flux data through advanced methods in deepening our understanding of CUE dynamics and their regulation at a global scale.

植被碳利用效率（CUE）是净初级生产力（NPP）与总初级生产力（GPP）之间的比率，它有助于深入了解生态系统将大量碳（C）从大气转移到潜在碳汇的能力。虽然以前对 CUE 的模式和对气候变化的反馈进行过研究，但由于方法上的限制，仍然存在很大的不确定性。为了解决这个问题，我们提出了一种新方法，通过假定 Ra 与 Re 和 GPP 之间关系的下限相关，将自养呼吸（Ra）与生态系统呼吸（Re）分离开来。通过应用这种方法，我们分析了从全球 195 个地点获得的通量数据，研究了 CUE 的时空动态。结果显示，全球平均 CUE 为 0.50 ± 0.13，耕地的数值最大，混交林的数值最小。从空间上看，地中海和亚热带地区的 CUE 最大，热带地区最小。从时间上看，大多数生物群落的 CUE 都表现出季节性波动，CUE 在生长季初期增加，然后随着季节的进展而减少。我们还研究了 CUE 对几种环境驱动因素（如气温、土壤湿度和入射太阳辐射）变化的响应，借助机器学习，特别是极端梯度提升（xgboost）和基于 SHAP 值的结果解释。结果表明，环境二氧化碳浓度与 CUE 之间存在负相关关系，证实了非结构碳水化合物在植物组织中的转移和积累相关的假设。这些发现凸显了通过先进方法利用通量数据加深我们对全球范围内 CUE 动态及其调控的理解的可行性和价值。

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引用次数: 0

An increasing delay in vegetation spring phenology over northern snow-covered landmass driven by temperature and snowmelt 在温度和融雪的驱动下，北方积雪陆地植被春季物候日益推迟

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-22 DOI: 10.1016/j.agrformet.2024.110310

Tao Xiong , Shihong Du , Xiuyuan Zhang , Hongyan Zhang , Jianjun Zhao

The start of the growing season (SOS) has received much attention for its key role in the interactions between terrestrial ecosystems and the atmosphere. Recent studies have shown that the warming-induced SOS advancing trend in the Northern Hemisphere has slowed since 2000. This phenomenon is currently attributed mainly to a slowdown of the increase in preseason temperature (PT). However, snow cover dynamics, including the changes in maximum snow water equivalent (SWE_max) and snow cover end date (SCE), also have a significant impact on SOS over the northern snow-covered landmass, but their influence on the slowdown in the SOS advancing trend has not been thoroughly investigated. In this research, we first employed four commonly utilized methods for phenological extraction to extract SOS and its associated trends. We then evaluated the response of SOS to PT, SWE_max and SCE, and determined the relative importance of these three influencing factors. Our results showed that in the northern non-mountainous snowy areas: (1) The slowdown in the overall SOS advancing trend after 2000 can be attributed to the increasing delay in the SOS between 60°N and 70°N. (2) The impact of SWE_max on SOS is negligible in most regions, except for some regions in the northern Chukotka Peninsula and southern Eurasia. In temperate zones, SOS is primarily driven by PT, while in Arctic-boreal zones, it is mainly influenced by both PT and SCE. (3) The expansion of the decreasing trend in PT and the delayed trend in SCE between 60°N and 70°N after 2000 were the primary cause of the increasing delay in SOS. Our study confirms, for the first time, that the delay in SCE is an important but neglected factor contributing to the slowdown of the SOS advancing trend in the Northern Hemisphere after 2000.

生长季节的开始（SOS）在陆地生态系统与大气之间的相互作用中发挥着关键作用，因而备受关注。最近的研究表明，自 2000 年以来，北半球由气候变暖引起的 SOS 提前趋势已经放缓。这一现象目前主要归因于季前温度（PT）上升的减缓。然而，雪盖动力学，包括最大雪水当量（SWEmax）和雪盖结束日期（SCE）的变化，也对北雪盖陆地上的 SOS 有重要影响，但它们对 SOS 推进趋势放缓的影响尚未得到深入研究。在这项研究中，我们首先采用了四种常用的物候提取方法来提取 SOS 及其相关趋势。然后，我们评估了 SOS 对 PT、SWEmax 和 SCE 的响应，并确定了这三个影响因素的相对重要性。结果表明，在北部非山地积雪区：（1）2000 年后，SOS 的总体上升趋势放缓，这可能是由于北纬 60 度至 70 度之间的 SOS 越来越延迟所致。(2）除楚科奇半岛北部和欧亚大陆南部的一些地区外，SWEmax 对大部分地区 SOS 的影响可以忽略不计。在温带地区，SOS 主要受 PT 的驱动，而在北极-寒带地区，SOS 主要受 PT 和 SCE 的影响。(3) 2000 年后，北纬 60 度和 70 度之间 PT 下降趋势的扩大和 SCE 趋势的延迟是 SOS 延迟增加的主要原因。我们的研究首次证实，SCE的延迟是导致2000年后北半球SOS上升趋势减缓的一个重要因素，但却被忽视了。

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引用次数: 0

Feasibility analysis of expanding winter rapeseed northwards in China 中国冬油菜向北扩展的可行性分析

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-22 DOI: 10.1016/j.agrformet.2024.110297

Junqiang Fan , Gang Yang , Junyan Wu , Yuanyuan Pu , Lijun Liu , Li Ma , Tingting Fan , Wangtian Wang , Yahong Zhang , Jianming Lei , Qiang Li , Xianfei Hou , Caixia Zhao , Song Tang , Changbing Chen , Zhe Zhang , Jihong Zhou , Chunqing Miao , Wanpeng Wang , Jing Bai , Wancang Sun

With high elevations, complex topographies, cold winter, diverse ecosystems, and a long history of oilseed Brassica rapa cultivation, Northwest China is rich in winter-hardy B. rapa germplasms. Using these germplasms, a number of ultra-winter-hardy rapeseed cultivars were developed in past three decades, leading to a large-scale northward expansion of winter rapeseed production in China. Based on 19 years of field trial data, this study was to assess the feasibility of growing winter rapeseed in the areas of northern China where conventionally no winter rapeseed had grown prior to availability of the ultra-winter-hardy B. rapa cultivars. The impacts of the major climate factors on overwintering rates and yields were analyzed. Using the boundary line analysis, the suitable growing regions for different cultivars were defined. The ultra winter-hardy cultivars displayed exceptional adaptability in frigid environments, with overwintering rates exceeding 70 % under conditions of extreme winter temperatures as low as -42.35 °C. Suitability analyses indicate that up to 534,000 km² of farmland in northern China are suitable for expanding winter rapeseed cultivation, potentially yielding between 5.61 and 12.34 million tons of winter rapeseed. This expansion could result in an approximately 30 % increase in the total domestic oilseed processing volume, significantly enhancing China's self-sufficiency in vegetable oil production. Our data suggest that these new ultra-winter-hardy rapeseed cultivars have made winter rapeseed production feasible, profitable, environmentally beneficial, and economically important in northern China.

中国西北地区海拔高，地形复杂，冬季寒冷，生态系统多样，油菜种植历史悠久，具有丰富的耐寒油菜种质资源。利用这些种质资源，过去 30 年间培育出了一批超耐寒油菜栽培品种，带动了中国冬油菜生产的大规模北扩。基于 19 年的田间试验数据，本研究旨在评估在超耐寒油菜品种问世之前，在中国北方传统上没有种植过冬油菜的地区种植冬油菜的可行性。分析了主要气候因素对越冬率和产量的影响。通过边界线分析，确定了不同栽培品种的适宜种植区域。超耐寒栽培品种在寒冷环境中表现出了超强的适应性，在冬季极端气温低至-42.35 °C的条件下，其越冬率超过70%。适宜性分析表明，中国北方多达 53.4 万平方公里的农田适合扩大冬油菜种植，冬油菜产量可能在 561 万吨至 1234 万吨之间。扩大种植面积可使国内油籽加工总量增加约 30%，显著提高中国植物油生产的自给率。我们的数据表明，这些新的超耐寒油菜栽培品种使中国北方的冬油菜生产具有可行性、盈利性、环境效益和经济重要性。

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引用次数: 0

Stronger effects of accumulated soil moisture deficit on gross primary productivity and light use efficiency than lagged soil moisture deficit for cropland and forest 在耕地和森林中，累积的土壤水分亏损对总初级生产力和光利用效率的影响比滞后的土壤水分亏损更大

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2024-11-21 DOI: 10.1016/j.agrformet.2024.110317

Zhuoyou Jiang , Yanlian Zhou , Shang Gao , Zhoutong Dong , Yingying Wang , Zheng Duan , Wei He , Yibo Liu , Weimin Ju

Many studies have underscored the impacts of drought on ecosystems, and some researchers reported the effects of accumulated soil moisture deficit (ASMD) on light use efficiency (LUE) in grassland. However, the potential effects of ASMD on gross primary productivity (GPP) and LUE for both cropland and forest ecosystems are still not understood. This study elucidated the effects of accumulated and lagged soil moisture deficit (ASMD and LSMD, respectively) on GPP and LUE in these two ecosystems by using observations from 10 cropland and 25 forest flux sites during drought years. The results showed that the effects of ASMD and LSMD on LUE/GPP for both cropland and forests obviously surpass the concurrent effects (CSMD). For cropland, the mean R² between CSMD/LSMD/ASMD with LUE were 0.22, 0.47, 0.56, respectively, and were 0.29, 0.54, 0.74 with GPP, respectively. For forest, the mean R² between CSMD/LSMD/ASMD with LUE were 0.21, 0.36, 0.46, respectively, and were 0.34, 0.63, and 0.65 with GPP, respectively. Additionally, the effects of ASMD and LSMD on LUE are more pronounced for cropland than for forests, and for both cropland and forest, the effect of ASMD is stronger than that of LSMD. This study underscores the crucial role of ASMD in influencing LUE and GPP for cropland and forests, thereby offering a theoretical foundation for incorporating ASMD into LUE models to enhance the accuracy of GPP simulations, especially during drought periods.

许多研究都强调了干旱对生态系统的影响，一些研究人员还报告了累积土壤水分亏缺（ASMD）对草地光利用效率（LUE）的影响。然而，ASMD 对耕地和森林生态系统的总初级生产力（GPP）和光利用效率的潜在影响仍不清楚。本研究通过对干旱年份的 10 个耕地和 25 个森林通量观测点的观测，阐明了累积和滞后土壤水分亏缺（分别为 ASMD 和 LSMD）对这两个生态系统的 GPP 和 LUE 的影响。结果表明，ASMD 和 LSMD 对耕地和森林 LUE/GPP 的影响明显超过同期效应（CSMD）。在耕地中，CSMD/LSMD/ASMD 对 LUE 的平均 R2 分别为 0.22、0.47、0.56，对 GPP 的平均 R2 分别为 0.29、0.54、0.74。对于森林，CSMD/LSMD/ASMD 与 LUE 之间的平均 R2 分别为 0.21、0.36 和 0.46，与 GPP 之间的平均 R2 分别为 0.34、0.63 和 0.65。此外，ASMD 和 LSMD 对 LUE 的影响在耕地中比在森林中更明显，而且在耕地和森林中，ASMD 的影响比 LSMD 的影响更强。本研究强调了 ASMD 在影响耕地和森林的 LUE 和 GPP 方面的关键作用，从而为将 ASMD 纳入 LUE 模型以提高 GPP 模拟的准确性（尤其是在干旱时期）提供了理论依据。

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引用次数: 0