Agricultural and Forest Meteorology最新文献_第6页

Tidal irrigation-based rice cultivation enhances coastal blue carbon and decreases GHG emissions in brackish mudflats 以潮汐灌溉为基础的水稻种植增加了沿海蓝碳，减少了咸淡泥滩的温室气体排放

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2026-01-02 DOI: 10.1016/j.agrformet.2025.111010

Lang Zhang , Linlin Li , Hualei Yang , Wenbang Tang , Ji Chen , Hongkai Zhou , Ying Huang , Xuechu Chen , Xiuzhen Li , Ming Luo , Xingyun Huang , Faming Wang , Zhenming Ge

Coastal agriculture has been adopted to increase agricultural productivity, whereas its effects on blue carbon ecosystem function and greenhouse gas (GHG) exchange dynamics are unclear. This research examined the impact of tidal saltwater irrigation on agronomic traits, CO₂ uptake, and CH₄ and N₂O emissions within a coastal rice ecosystem (tidal-influenced and saline), and explored the microbial mechanisms responsible for GHGs mitigation. The study was conducted over 2 years on Chongming island, Shanghai, China. Here, the use of 6‰ saltwater for irrigation in sea rice cultivation led to an increase in net ecosystem CO₂ exchange and gross primary productivity, mitigated CH₄ and N₂O emissions through tidal saltwater treatment with a projected decrease in CH₄ emissions during the tillering stage, and was accompanied by a marked upregulation of the AcsB gene associated with CO₂ fixation as well as the PmoA and Nirk2 genes involved in CH₄ and N₂O oxidation. Despite a decrease in plant height, this approach promoted tillering, thereby increasing shoot dry mass and ultimately maintaining rice yields without reduction. The study further revealed the combined CO₂-equivalent emissions of CO₂, CH₄, and N₂O during the tidal saltwater irrigation period, with reductions ranging from 22 % to 39 % for two different sea rice varieties. Therefore, the experimental simulation of tidal saltwater in a coastal rice system demonstrated its ability to sustain yield, increase carbon uptake and mitigate GHG emissions, although the effects were not statistically significant. We suggest that coastal rice cultivation using natural tidal irrigation is an effective approach to strengthen the ecological of coastal tidal mudflats by reducing GHG emissions and enhancing rice yields.

沿海农业已成为提高农业生产力的重要手段，但其对蓝碳生态系统功能和温室气体交换动态的影响尚不清楚。本研究考察了潮汐盐水灌溉对沿海水稻生态系统（潮汐影响和咸水影响）农艺性状、CO2吸收、CH4和N2O排放的影响，并探讨了温室气体缓解的微生物机制。这项研究在中国上海崇明岛进行了两年多的研究。本研究表明，在海稻种植中，使用6‰的盐水灌溉导致生态系统净CO2交换和总初级生产力的增加，通过潮汐盐水处理减轻了CH4和N2O的排放，预计分蘖期CH4排放量将减少，并伴有与CO2固定相关的AcsB基因以及与CH4和N2O氧化相关的PmoA和Nirk2基因的显著上调。尽管降低了株高，但这种方法促进了分蘖，从而增加了茎干质量，最终保持了水稻产量而不减少。该研究进一步揭示了潮汐盐水灌溉期间CO2、CH4和N2O的总CO2当量排放量，两种不同的海稻品种减少了22%至39%。因此，沿海水稻系统中潮汐盐水的实验模拟表明，潮汐盐水具有维持产量、增加碳吸收和减少温室气体排放的能力，尽管这种影响在统计学上并不显著。研究结果表明，利用自然潮汐灌溉进行滨海水稻种植是一种通过减少温室气体排放和提高水稻产量来加强滨海潮滩生态的有效途径。

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引用次数: 0

Rainfall partitioning and interception simulation for typical species in the Taihang Mountains, China 太行山典型物种降雨分配与截留模拟

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2026-01-02 DOI: 10.1016/j.agrformet.2025.111004

Bo Guo , Hui Yang , Chunyu Zhu , Zhibang Yan , Jiansheng Cao , Yanjun Shen

Rainfall partitioning plays a key role in the ecosystem water cycle and watershed water balance, and understanding its processes in the Taihang Mountains is essential for optimizing afforestation strategies and improving water resource management. Various afforestation species have been introduced since the implementation of ecological restoration projects, yet their effects on rainfall partitioning remain unclear. In this study, we used field observations and the Revised Gash model to investigate rainfall partitioning and its influencing factors among typical species in the Taihang Mountains. The results showed that the interception percentage, throughfall percentage, and stemflow percentage of different species at the study site ranged from 8.1% to 28.7%, 69.6% to 90.9%, and 0.9% to 10.5% of total rainfall, respectively. Rainfall amount was the most significant factor affecting rainfall partitioning, while rainfall duration and rainfall intensity had less impact on rainfall partitioning. The Revised Gash model was effectively parameterized for this region, with the relative error of the validation model for simulating typical vegetation interception ranging from -11.9% to 10.2%. The calculation method for the average evaporation rate of the canopy in the Revised Gash model affected the accuracy of interception simulations, with the Penman-Monteith method (

{\overline{E}}_{PM}

) providing better interception loss simulations for P. bungeana, while the mean method (

{\overline{E}}_{TF}

) was recommended for other species. Under extreme heavy rainfall events, interception loss ranged from 6.5% to 27.0% among different species. The Revised Gash model parameterized using the mean method (

{\overline{E}}_{TF}

) achieved relative errors ranging from -26.9% to 7.2% in simulating interception loss under extreme heavy rainfall events across different species. For all species, interception loss during and after rainfall accounted for the largest proportion, comprising 92.83% to 98.40% of interception loss. Compared to native species, economic species exhibited higher interception capacities, suggesting their more significant potential to influence rainfall partitioning and hydrological processes in the Taihang Mountains. In summary, evaluating the rainfall partitioning of typical species in this region has scientific significance for assessing hydrological processes and selecting afforestation species.

降雨分配在生态系统水循环和流域水平衡中起着关键作用，了解降雨分配过程对优化造林策略和改善水资源管理具有重要意义。生态修复工程实施以来，引入了多种造林物种，但其对降雨分配的影响尚不清楚。本文采用野外观测和修正Gash模型对太行山典型物种的降雨分配及其影响因素进行了研究。结果表明：研究点不同树种截流率、穿透率和茎流率分别占总降雨量的8.1% ~ 28.7%、69.6% ~ 90.9%和0.9% ~ 10.5%；降雨量是影响降雨分配最显著的因素，而降雨持续时间和降雨强度对降雨分配的影响较小。修正后的Gash模型参数化效果较好，验证模型模拟典型植被截留的相对误差在-11.9% ~ 10.2%之间。订正Gash模型中树冠平均蒸发速率的计算方法影响了拦截模拟的准确性，其中Penman-Monteith方法（E - PM）为白杨提供了更好的拦截损失模拟，而对于其他物种则推荐采用均值方法（E - TF）。在极端强降雨条件下，不同物种的截留损失在6.5% ~ 27.0%之间。采用均值法（E - TF）参数化的修正Gash模型在模拟不同物种极端强降雨事件下的拦截损失时，实现了-26.9% ~ 7.2%的相对误差。在所有物种中，雨中和雨后截留损失所占比例最大，分别为92.83% ~ 98.40%。与本地物种相比，经济物种表现出更高的截流能力，表明其对太行山降水分配和水文过程的影响潜力更大。综上所述，评价该地区典型物种的降雨分配对水文过程评价和造林树种选择具有重要的科学意义。

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引用次数: 0

Corrigendum to “Global optimization of a water-constrained two-leaf light use efficiency model through multi-biome FLUXNET observations” [Agricultural and Forest Meteorology 375 (2025) 1–18/110845] “基于多生物群群FLUXNET观测的水约束双叶光利用效率模型的全局优化”[农林气象375(2025)1-18/110845]的勘误表

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2026-01-01 DOI: 10.1016/j.agrformet.2025.110997

Sha Zhang , Wenchao Wang , Jinguo Yuan , Yun Bai

引用次数: 0

The impact of nonlinear surface energy partitioning on potential evapotranspiration: A machine learning study based on FLUXNET data 非线性表面能量分配对潜在蒸散的影响：基于FLUXNET数据的机器学习研究

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-31 DOI: 10.1016/j.agrformet.2025.111005

Weiqi Liu , Shaoxiu Ma , Haiyang Xi , Linhao Liang , Kun Feng , Atsushi Tsunekawa

Potential evapotranspiration (PET) is a key variable in drought occurrence and modeling. The no-water-limited Bowen ratio (β_NWL) is widely used to construct energy balance-based PET models by assuming that β_NWL does not vary with climate and vegetation conditions. However, we found that β_NWL varies significantly with climate as well as vegetation conditions based on global-wide observational flux data. Therefore, this study aims to investigate the dominant influence factors of β_NWL and to simulate the nonlinear relationship between β_NWL with environmental factors by leveraging flux observation globally and machine learning models. We then applied the nonlinear β_NWL to develop a PET model (

P E T_{β_{N W L - R F}}

) and evaluated its performance under various conditions, comparing it against commonly used PET models. Our results showed that the gross primary productivity (GPP) had the most significant effect on β_NWL, with a relative importance of 31%. The

P E T_{β_{N W L - R F}}

model significantly improved the accuracy of daily PET estimation (R² ≥ 0.93, TSS ≥ 0.96, RMSE ≤ 0.48 mm/day, -0.04 mm/day ≤ MB ≤ 0.06 mm/day) against observation. Moreover, we also found that the

P E T_{β_{N W L - R F}}

model can effectively reduce the uncertainty (overestimation or underestimation) of PET estimation by commonly used PET models especially under drought conditions and hence significantly enhance the reliability of drought monitoring. This study reveals the influence of nonlinear relationships of surface energy partitioning on PET, which would be insightful for PET estimation as well as drought monitoring.

潜在蒸散发（PET）是干旱发生和模拟的关键变量。无水限波文比（βNWL）被广泛用于构建基于能量平衡的PET模型，假设βNWL不随气候和植被条件变化。然而，基于全球观测通量数据，我们发现βNWL随气候和植被条件变化显著。因此，本研究旨在研究βNWL的主导影响因素，并利用通量全局观测和机器学习模型模拟βNWL与环境因子的非线性关系。然后，我们将非线性βNWL应用于PET模型（PETβNWL−RF），并评估其在各种条件下的性能，并将其与常用的PET模型进行比较。结果表明，总初级生产力（GPP）对βNWL的影响最为显著，相对重要性为31%。PETβ nwl−RF模型较观测值的日PET估计精度显著提高（R2≥0.93,TSS≥0.96,RMSE≤0.48 mm/day, -0.04 mm/day≤MB≤0.06 mm/day）。此外，我们还发现，PETβ nwl−RF模型可以有效降低常用PET模型在干旱条件下对PET估计的不确定性（高估或低估），从而显著提高干旱监测的可靠性。该研究揭示了地表能量分配的非线性关系对PET的影响，对PET估算和干旱监测具有重要意义。

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引用次数: 0

Corrigendum to “New allometric models for Eucalyptus tereticornis using terrestrial laser scanning show increased carbon storage in larger trees” [Agricultural and Forest Meteorology 373 (2025): 110708] “利用陆地激光扫描的新异速生长模型显示较大树木的碳储量增加”[农林气象373(2025):110708]的勘误表

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-30 DOI: 10.1016/j.agrformet.2025.110988

Louise Terryn , David Ellsworth , Belinda E. Medlyn , Matthias Boer , Tom E. Verhelst , Kim Calders

引用次数: 0

Data-driven modelling of methane fluxes across a mire complex based on replicated eddy covariance measurements and spatially-resolved driver information 基于重复涡动相关测量和空间分辨驱动信息的沼泽复合体甲烷通量数据驱动建模

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-30 DOI: 10.1016/j.agrformet.2025.111002

Koffi Dodji Noumonvi , Mats B. Nilsson , Natascha Kljun , Joshua L. Ratcliffe , Mats G. Öquist , Johan E.S. Fransson , Matthias Peichl

Northern mires are significant natural sources of atmospheric methane (CH₄), yet estimating CH₄ emissions remains challenging due to their complex spatio-temporal dynamics. While eddy covariance (EC) measurements provide valuable insights into ecosystem-scale CH₄ fluxes (FCH₄) over mire areas typically < 0.05 km², the predictability of FCH₄ at the mesoscale (∼0.5 – 20 km²) of a mire complex based on single-site EC measurements has not been explored. In this study, we utilized a network of four EC towers and developed a machine learning approach that integrates these EC data with comprehensive spatial information on drivers to predict FCH₄ across a boreal mire complex in Northern Sweden. For this purpose, environmental driver variables were mapped and area-weighted within dynamic EC flux footprints and related to FCH₄ in a spatially-explicit random forest model (‘footprint-based model’). For comparison, we also considered a standard random forest model used for gapfilling of FCH₄ data that is based on environmental measurements from fixed sensor locations (‘biomet model’). For both models, variable importance analysis revealed NDVI as the strongest predictor of temporal FCH₄ patterns, followed by air pressure, soil temperature and water table. Adjusting for site-specific carbon-to-nitrogen (C:N) ratios substantially improved model performance. Both models significantly improved estimates of the mire complex average FCH₄ compared to simple extrapolation of single-site measurements, reducing the uncertainty from ∼22 % in 2022 and 32 % in 2023 to <10 % and <25 % for the footprint-based model, and to <11 % and <30 % for the biomet model, respectively. Overall, our findings suggest that the comprehensive spatially-resolved driver information resulted in only marginally improved model performance at our study site. In comparison, the biomet model offers practical advantages through simpler implementation and wider applicability. However, we encourage testing the footprint-based model approach at other more heterogenous sites where it might become superior due to its ability to account for complex site conditions.

北方矿井是大气甲烷（CH4）的重要天然来源，但由于其复杂的时空动态，估算CH4排放量仍然具有挑战性。虽然涡旋相关方差（EC）测量为典型为0.05 km²的沼泽地区生态系统尺度的CH4通量（FCH4）提供了有价值的见解，但基于单点EC测量的沼泽复发区中尺度（~ 0.5 - 20 km²）的FCH4的可预测性尚未得到探讨。在这项研究中，我们利用了四个EC塔的网络，并开发了一种机器学习方法，将这些EC数据与驾驶员的综合空间信息相结合，以预测瑞典北部北方沼泽复杂地区的FCH4。为此，在一个空间明确的随机森林模型（“基于足迹的模型”）中，对动态EC通量足迹中的环境驱动变量进行了映射和面积加权，并与FCH4相关。为了进行比较，我们还考虑了一个标准的随机森林模型，用于基于固定传感器位置的环境测量的FCH4数据的空白填充（“生物群落模型”）。变量重要性分析表明，NDVI是预测FCH4时间格局的最强因子，其次是气压、土壤温度和地下水位。调整特定地点的碳氮比（C:N）大大提高了模型的性能。与单站点测量的简单外推相比，这两种模式都显著提高了泥沼复杂平均FCH4的估计值，将不确定性从2022年的~ 22%和2023年的32%降低到基于足迹的模式的10%和25%，以及生物群落模式的11%和30%。总的来说，我们的研究结果表明，在我们的研究地点，全面的空间分辨驾驶员信息只会略微提高模型的性能。相比之下，生物元模型实现更简单，适用性更广，具有实际优势。然而，我们鼓励在其他更异质的站点上测试基于足迹的模型方法，因为它能够解释复杂的站点条件，因此它可能会变得更优越。

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引用次数: 0

Heat waves associated with higher methane emissions from dairy manure: A 6-year study 热浪与奶牛粪便中甲烷排放量增加有关：一项为期6年的研究

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-29 DOI: 10.1016/j.agrformet.2025.110980

Andrew VanderZaag , Hambaliou Baldé , Thomas K. Flesch , Chih-Yu Hung , Claudia Wagner-Riddle

Accurate methane (CH₄) emission estimates for dairy manure management require farm-scale studies that capture the effect of changing temperatures under in situ conditions. In Northern climates the sensitivity of methanogenesis to temperature is critically important for annual emission estimates; however, most data on CH₄ emission dynamics come from lab studies at constant temperatures. A related source of uncertainty in emission estimates is the potential for naturally forming surface crusts to enable aerobic methanotrophs to mitigate CH₄ emissions. This study used an inverse-dispersion approach to measure CH₄ emissions for 6 years and NH₃ emissions for 2 years at a dairy manure storage near Edmonton, Alberta, Canada (53°N). Results showed the effect of inter-annual temperature variability: CH₄ emissions were highly sensitive to heat waves that occurred in two out of six years. In those years, annual CH₄ emissions were 2 to 3times higher than other years. Increased CH₄ emissions in years with heat waves indicated that brief exposure to warmer temperature was associated with a sustained increase in emissions. This supports the idea that there is a temperature threshold above which CH₄ production accelerates. Manure surface crusts developed in the warm years but did not reduce CH₄ emissions compared to colder years without crust. This finding does not support the use of lower CH₄ emission factors when surface crusts are present. Ammonia emissions were lower in the warmer year (2021) when a thick, dry crust developed, compared to the cooler year (2019) with less crust. Ammonia emissions represented a modest 6.6 % (2021) and 4.8 % (2019) of the estimated N loading rate into the manure storage. From a climate perspective the results of this study point to a reinforcing feedback loop where warming climate leads to higher CH₄ emissions under business-as-usual management.

对奶牛粪便管理进行准确的甲烷（CH4）排放估算，需要进行农场规模的研究，以捕捉原位条件下温度变化的影响。在北方气候中，产甲烷对温度的敏感性对年排放估算至关重要；然而，大多数关于甲烷排放动力学的数据来自恒温下的实验室研究。排放估算中一个相关的不确定性来源是自然形成表面结壳的可能性，从而使好氧甲烷氧化菌能够减轻CH4排放。本研究采用反分散方法测量了加拿大艾伯塔省埃德蒙顿附近（53°N）一个奶牛粪便储存库6年的CH4排放量和2年的NH3排放量。结果表明，年际温度变化的影响：CH4排放对6年中有2年发生的热浪高度敏感。这些年份的年CH4排放量是其他年份的2 ~ 3倍。在有热浪的年份，甲烷排放量增加表明，短暂暴露于较暖的温度与排放量的持续增加有关。这支持了存在一个温度阈值的观点，超过这个温度阈值，甲烷的生成就会加速。在温暖年份，粪肥表面结壳形成，但与没有结壳的寒冷年份相比，没有减少CH4的排放。这一发现不支持在地表结壳存在时使用较低的CH4排放因子。与地壳较少的较冷年份（2019年）相比，较温暖年份（2021年）的氨排放量较低，当时形成了厚而干燥的地壳。氨排放量在粪便储存的估计氮负荷率中仅占6.6%（2021年）和4.8%（2019年）。从气候角度来看，本研究的结果指出了一个不断强化的反馈循环，即在一切照旧的管理下，气候变暖导致甲烷排放量增加。

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引用次数: 0

Drier year exhibits amplified promoting effects of shrub encroachment on methane uptake in Tibetan alpine meadows 干旱年份灌丛入侵对高寒草甸甲烷吸收的促进作用增强

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-29 DOI: 10.1016/j.agrformet.2025.111007

Lili Nan , Zelong Zhang , Dezhao Gan , Huinan Li , Dongsheng Yu , Zhenrong Lin , Zheng Li , Jian Hu , Hui Wang , Qingping Zhou , Shuli Niu , Jinsong Wang , Ruijun Long , Lei Ma

Shrub encroachment into grasslands notably influences the ecosystem services and the economics provided by these ecosystems. However, the effects of shrub encroachment on the multiyear methane (CH₄) uptake and associated mechanisms in alpine meadows remain unknown. Here, we combined two years of CH₄ flux measurements from paired shrub patches (SPs) and ambient meadow patches (MPs) in a Tibetan alpine meadow with collated annual CH₄ fluxes derived from meta-analysis across alpine meadows and temperate steppes in northern China. We found that the increase in the annual CH₄ uptake under shrub encroachment was greater during a dry year 2023–2024 (a net increase of 0.91 ± 0.40 kg C ha^–1) than during a wet year 2022–2023 (0.52 ± 0.19 kg C ha^–1). Approximately 20–40% of these net increases occurred during the nongrowing season (NGS). Meta-analysis verified that shrub encroachment significantly increased CH₄ uptake in Tibetan alpine grass meadows, in which the significantly decreased topsoil water-filled pore space (WFPS) and increased functional gene (pmoA) abundance levels for soil methanotrophs jointly explained these results. CH₄ uptake during the NGS contributed 22∼28% and 21∼30% to the annual CH₄ uptake in MPs and SPs, respectively. A bell-shaped relationship was observed with the growing season (GS) soil WFPS, with the lowest NGS contribution occurring at intermediate soil WFPS. The annual CH₄ uptake was greater in temperate steppes than in alpine shrub meadows and grass meadows across northern China, which was driven mainly by the significant decrease in soil WFPS. These results provide a basis for understanding the magnitudes of CH₄ uptake in alpine meadows and their responses to shrub encroachment. Initiating long-term CH₄ flux measurements from various encroached shrub species and across different shrub encroachment intensities can increase our understanding of soil CH₄ uptake within the context of increasing shrub encroachment trends.

灌木对草原的侵蚀对草原生态系统的服务功能和经济效益有显著影响。然而，灌丛入侵对高寒草甸多年甲烷（CH4）吸收的影响及其相关机制尚不清楚。在这里，我们结合了西藏高寒草甸灌木斑块（SPs）和环境草甸斑块（MPs）两年的CH4通量测量数据，并整理了中国北方高寒草甸和温带草原的年度CH4通量。研究发现，2023-2024年干旱年（净增加0.91±0.40 kg C ha-1）比2022-2023年湿润年（净增加0.52±0.19 kg C ha-1）增加更多。其中约20-40%的净增长发生在非生长季（NGS）。meta分析证实，灌丛入侵显著增加了青藏高原高寒草甸CH4的吸收，这与土壤甲烷化菌功能基因（pmoA）丰度和表层土壤充水孔空间（WFPS）显著减少有关。NGS期间的CH4吸收量分别占MPs和SPs年CH4吸收量的22 ~ 28%和21 ~ 30%。NGS对土壤水分的贡献与生长季土壤水分的贡献呈钟形关系，中间土壤水分的贡献最小。中国北方温带草原的年CH4吸收率高于高寒灌丛草甸和草甸，这主要是由于土壤WFPS显著降低所致。这些结果为了解高寒草甸CH4吸收的大小及其对灌木入侵的响应提供了基础。启动不同被侵占灌木物种和不同灌木入侵强度的长期CH4通量测量，可以增加我们对灌木入侵增加趋势下土壤CH4吸收的认识。

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引用次数: 0

A tale of two towers: comparing NEON and AmeriFlux data streams at Bartlett Experimental Forest 双塔故事：在巴特利特实验森林比较NEON和AmeriFlux的数据流

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-28 DOI: 10.1016/j.agrformet.2025.110939

Yujie Liu , Paul Stoy , Housen Chu , Dave Y. Hollinger , Scott V. Ollinger , Andrew P. Ouimette , David J. Durden , Cove Sturtevant , Ben Lucas , Andrew D. Richardson

Long-term ecological data are essential for detecting impacts of climate change and other global change factors, and for making informed predictions about future change. However, long-term measurements are rarely replicated at the site level, which raises questions about their representativeness. We used a multiscale approach to evaluate the agreement of parallel observations from AmeriFlux and NEON (National Ecological Observatory Network) towers at Bartlett Experimental Forest, New Hampshire, USA. The two towers are separated by a horizontal distance of 93 m. We focused our analysis on standard meteorological variables; fluxes of CO₂, sensible heat, and latent heat measured by eddy covariance; and phenology derived from PhenoCam imagery. Results suggest excellent agreement between AmeriFlux and NEON in meteorology and phenology, and good agreement in fluxes at the half-hourly scale. However, large disagreements in CO₂ and latent heat fluxes occurred at the annual scale, with implications especially for the forest carbon balance. The AmeriFlux tower measurements indicate a site that is close to carbon-neutral (-8 ± 65 g C m^-2 y^-1, mean ± 1 SD), whereas the NEON tower measurements indicate a forest that is a carbon sink (-137 ± 10 g C m^-2 y^-1). Causes of this disagreement may include measurement height (26 m vs. 35 m), which resulted in different flux footprints being measured by the two towers, and differences in the flux measurement systems. Our results suggest the need for caution when attempting to merge long-term flux data from two different measurement platforms, and when using measurements from any one measurement platform to inform decision-making on issues related to carbon accounting or natural climate solutions.

长期生态数据对于探测气候变化和其他全球变化因素的影响以及对未来变化作出明智的预测至关重要。然而，长期测量很少在现场水平上复制，这就提出了关于它们的代表性的问题。我们使用多尺度方法来评估美国新罕布什尔州巴特利特实验森林AmeriFlux和NEON（国家生态观测站网络）塔平行观测结果的一致性。两座塔之间的水平距离为93米。我们将分析重点放在标准气象变量上；涡动相关测量的CO2通量、感热通量和潜热通量；和物候学来自于PhenoCam图像。结果表明，AmeriFlux和NEON在气象学和物候学上具有很好的一致性，在半小时尺度上的通量也有很好的一致性。然而，CO2和潜热通量在年尺度上存在较大差异，尤其对森林碳平衡有影响。AmeriFlux塔的测量结果表明该地点接近碳中性（-8±65 g C m-2 y-1，平均±1标准差），而NEON塔的测量结果表明森林是碳汇（-137±10 g C m-2 y-1）。造成这种差异的原因可能包括测量高度（26米对35米），这导致两个塔测量的通量足迹不同，以及通量测量系统的差异。我们的研究结果表明，在试图合并来自两个不同测量平台的长期通量数据时，以及在使用任何一个测量平台的测量结果为与碳核算或自然气候解决方案有关的问题的决策提供信息时，需要谨慎。

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引用次数: 0

Beyond optimality: Dryland ecosystems infrequently use water efficiently for carbon gain 超越最佳：旱地生态系统很少有效地利用水来获得碳

IF 5.7 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology

Pub Date : 2025-12-26 DOI: 10.1016/j.agrformet.2025.110996

E.G. Reich , K. Samuels-Crow , J.B. Bradford , M. Litvak , D.R. Schlaepfer , K. Ogle

Optimality theory assumes plants maximize carbon gain per unit water lost and is often implemented to scale leaf-level carbon gain and water use to regional and global scales. Optimality theory is often mathematically represented by assuming plant water-use efficiency (WUE) scales with VPD^k, where k = ½ represents expected optimal behavior. It is unclear, however, if this relationship holds in arid and semi-arid ecosystems that are strongly impacted by soil and atmospheric moisture status. We used data from seven flux tower sites along an aridity gradient in New Mexico to answer: how does the relationship between WUE and VPD compare to expectations based on optimality theory? To address this question, we integrated the Dynamic Evapotranspiration Partitioning Approach for Rapid Timescales with a stochastic antecedent model to estimate ecosystem-level WUE (GPP/T) and the net sensitivity of WUE to VPD, or k^Dynamic, which we compare to the theoretical optimal sensitivity of k = ½. Our results show that optimality theory is not always appropriate, and k^Dynamic often deviates from ½, especially at some of the more arid sites or during periods of low soil moisture. At less arid, higher elevation sites, k^Dynamic is most consistent with optimality theory at moderate VPD levels, but not at high VPD. In general, the sensitivity of WUE to VPD is highly variable such that k^Dynamic exhibits notable daily and seasonal variability, suggesting highly dynamic stomatal behavior. These results emphasize that representing plant water-use strategies as dynamic in time and space is critical to improving large-scale estimates of plant water use.

最优性理论假定植物每单位水分损失的碳增益最大化，并经常用于将叶片水平的碳增益和水分利用扩展到区域和全球尺度。最优性理论通常在数学上通过假设植物水分利用效率（WUE）与VPDk的尺度来表示，其中k = 1 / 2表示预期的最优行为。然而，目前尚不清楚这种关系是否适用于受土壤和大气湿度状况强烈影响的干旱和半干旱生态系统。我们使用了新墨西哥州沿干旱梯度的七个通量塔站点的数据来回答：基于最优性理论，WUE和VPD之间的关系如何与预期相比较？为了解决这个问题，我们将快速时间尺度的动态蒸散发分配方法与随机先行模型相结合，以估计生态系统水平的WUE （GPP/T）和WUE对VPD或kDynamic的净灵敏度，并将其与理论最佳灵敏度k = 1 / 2进行比较。我们的结果表明，最优性理论并不总是合适的，kDynamic经常偏离½，特别是在一些较干旱的地点或在土壤湿度较低的时期。在干旱程度较低、海拔较高的地点，kDynamic在中度VPD水平下最符合最优性理论，而在高VPD水平下则不符合。总的来说，WUE对VPD的敏感性是高度可变的，kDynamic表现出显著的日和季节变化，表明气孔行为是高度动态的。这些结果强调，将植物水分利用策略在时间和空间上表现为动态的，对于提高植物水分利用的大规模估计至关重要。

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