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Quantifying forest structural attributes and aboveground carbon dynamics with terrestrial laser scanning in a temperate deciduous forest 基于陆地激光扫描的温带落叶森林结构属性和地上碳动态定量研究
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-18 DOI: 10.1016/j.agrformet.2025.110995
Shilin Chen , Hans Verbeeck , Louise Terryn , Wout Cherlet , Chang Liu , Mathias Disney , Yadvinder Malhi , Niall Origo , Joanne Nightingale , Kim Calders
Quantifying forest structure and aboveground biomass carbon (AGBC) dynamics over time is crucial for evaluating climate change impact on carbon stocks, and providing key insights into changes in the terrestrial carbon cycle. To date, the use of multi-temporal terrestrial laser scanning (TLS) to detect temporal dynamics of forest structure and AGBC remains largely unexplored. In this study, we demonstrate the use of bi-temporal TLS data to quantify fine-scale dynamics of forest structure and AGBC. A total of 831 live trees were extracted and manually aligned from two leaf-off datasets collected in a 1.4 ha area of temperate woodland (Wytham Woods, UK) in 2016 and 2022. Results indicated that, at the individual tree level, most trees exhibited positive growth in structural attributes between 2016 and 2022, including diameter at breast height (DBH, 60.2 % of trees), tree height (H, 75.8 %), crown projection area (CPA, 64.7 %), crown volume (CV, 60.5 %), and aboveground volume (V, 50.5 %). At the plot level, all structural attributes also increased, including basal area (1.8 m²/ha, 4.8 % growth), H (128.9 m/ha, 1.4 %), CPA (411.9 m²/ha, 3.0 %), DBH (1.5 m/ha, 1.1 %), CV (181.7 m³/ha, 0.3 %), and V (7.9 m³/ha, 1.0 %). The total AGBC of the study area saw a net carbon gain of 0.4 Mg C/ha/year over the six-year period. Notably, trees with DBH greater than 60 cm contributed over 40 % of the total AGBC. Moreover, our results reveal that branch dynamics play a crucial role in AGBC dynamics, underscoring the added value of TLS for tracking AGBC changes over time.
量化森林结构和地上生物量碳(AGBC)随时间的动态对于评估气候变化对碳储量的影响至关重要,并为了解陆地碳循环的变化提供关键见解。迄今为止,利用多时相地面激光扫描(TLS)来探测森林结构和AGBC的时间动态仍然是一个很大的未知领域。在这项研究中,我们展示了使用双时态TLS数据来量化森林结构和AGBC的精细尺度动态。从2016年和2022年在1.4公顷温带林地(英国威瑟姆森林)收集的两个叶片数据集中,共提取并手动对齐了831棵活树。结果表明,在单株水平上,2016 - 2022年,大多数树木的结构属性呈正增长,包括胸径(DBH, 60.2%)、树高(H, 75.8%)、树冠投影面积(CPA, 64.7%)、树冠体积(CV, 60.5%)和地上体积(V, 50.5%)。在样地水平上,所有结构属性也有所增加,包括基底面积(1.8 m²/ha,增长4.8%)、H (128.9 m/ha,增长1.4%)、CPA (411.9 m²/ha,增长3.0%)、胸径(1.5 m/ha,增长1.1%)、CV (181.7 m³/ha,增长0.3%)和V (7.9 m³/ha,增长1.0%)。在6年期间,研究区域的总AGBC的净碳增益为0.4 Mg C/ha/年。值得注意的是,胸径大于60 cm的树木占总AGBC的40%以上。此外,我们的研究结果表明,分支动态在AGBC动态中起着至关重要的作用,强调了TLS在跟踪AGBC随时间变化方面的附加价值。
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引用次数: 0
Improved gap-filling of eddy covariance CO2 fluxes using remote sensing and environmental variables via XGBoost 基于XGBoost的基于遥感和环境变量的涡动相关co2通量补隙改进
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-18 DOI: 10.1016/j.agrformet.2025.110987
Simon De Cannière , Sebastian Wieneke , Thomas Servotte , Adrià Descals , Tim Verdonck , Ivan Janssens
Gap-filling of eddy covariance (EC) CO2 flux data is critical for quantifying ecosystem carbon balances, yet traditional methods like Marginal Distribution Sampling (MDS) do not adequately represent sub-daily carbon fluxes and it fails to leverage vegetation dynamics, which is especially problematic for filling in gaps longer than one week. This study evaluates the potential of eXtreme Gradient Boosting (XGBoost), a machine learning approach, to improve gap-filling of net ecosystem exchange (NEE) and gross primary production (GPP) by integrating remote sensing (RS) data and environmental data, both from in-situ measurements and from the ERA5 reanalysis model over a temperate pine forest (ICOS site BE-Bra). We compare three XGBoost models: (1) in-situ (meteorological, soil moisture, and tower-based sun-induced chlorophyll fluorescence (SIF)), (2) large-scale (ERA5 and Sentinel-2-derived vegetation indices), and (3) hybrid (combining ERA5 and Sentinel-2-derived vegetation indices with in-situ radiation). The results show XGBoost outperforms MDS for NEE gap-filling in all of its scenarios, with minimal performance degradation for gaps up to 56 days. Soil moisture and SIF improved predictions during warm periods (Air Temperature > 25° C), when these data were taken from in-situ sources. SHAP analysis revealed light-related drivers as dominant controls. During heatwaves, typically co-occurring with high-light conditions, soil water content became an important driver. Overall, the hybrid model achieved comparable model performance as the models with in-situ data, demonstrating the viability of satellite RS and reanalysis for operational gap-filling. However, in-situ irradiation turned out notably more useful compared to irradiation from a reanalysis. Our findings advocate for XGBoost as a robust tool to integrate multi-source data, advancing carbon flux quantification beyond traditional methods, espescially when it comes to modeling the sub-daily carbon fluxes, which is important when using EC data for evaluating remote sensing based carbon flux estimations.
涡动相关(EC) CO2通量数据的空白填补对于量化生态系统碳平衡至关重要,但传统的方法,如边际分布采样(MDS)不能充分代表亚日碳通量,也不能充分利用植被动态,这在填补超过一周的空白时尤其成问题。本研究评估了极端梯度提升(XGBoost)的潜力,该方法是一种机器学习方法,通过整合遥感(RS)数据和环境数据,包括现场测量数据和ERA5再分析模型,在温带松林(ICOS站点BE-Bra)上改善净生态系统交换(NEE)和总初级生产(GPP)的缺口填补。我们比较了三种XGBoost模型:(1)原位模型(气象、土壤湿度和基于塔的太阳诱导叶绿素荧光(SIF)),(2)大尺度模型(ERA5和sentinel -2衍生的植被指数),以及(3)混合模型(将ERA5和sentinel -2衍生的植被指数与原位辐射相结合)。结果表明,在所有情况下,XGBoost在NEE缺口填充方面都优于MDS,在长达56天的缺口中,性能下降最小。土壤湿度和SIF改善了在温暖时期(空气温度25°C)的预测,当这些数据来自于原位来源时。SHAP分析显示,与光相关的驱动因素是显性控制因素。在热浪期间,通常与强光条件同时发生,土壤含水量成为重要的驱动因素。总体而言,混合模型的模型性能与具有原位数据的模型相当,证明了卫星遥感和再分析用于业务缺口填补的可行性。然而,原位辐照明显比再分析辐照更有用。我们的研究结果表明,XGBoost是一个强大的工具,可以整合多源数据,超越传统方法推进碳通量量化,特别是在亚日碳通量建模方面,这在使用EC数据评估基于遥感的碳通量估算时非常重要。
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引用次数: 0
Multi-year water and carbon flux contrasts between high-yielding and conventional rice cultivars 高产和常规水稻品种多年水碳通量的对比
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-18 DOI: 10.1016/j.agrformet.2025.110983
Keisuke Ono , Hiroki Ikawa , Akira Miyata
Cultivation of high-yielding indica rice varieties has been spreading in Japan. This trend raises concerns about their potential impacts on water use and the carbon cycle. To this end, eddy covariance flux measurements were conducted from transplanting to harvest over three years for a high-yielding rice variety, Oonari, and compared with a conventional japonica rice variety, Koshihikari, in farmers’ fields under actual management practices. Evapotranspiration (ET) was higher for Oonari in 2018 and 2019, being 9.6 % higher than Koshihikari (2018: Oonari, 549.6 mm; Koshihikari, 501.2 mm; 2019: Oonari, 472.0 mm; Koshihikari, 430.5 mm). In 2020, ET for Oonari was 6.0 % smaller due to a shorter growth period (Oonari, 426.5 mm; Koshihikari, 453.9 mm). Gross primary production (GPP) was significantly higher for Oonari, averaging 24 % more than Koshihikari (Oonari: 1175.2±76.5 g C m–2, Koshihikari: 946.5±32.7 g C m–2). Higher ET and GPP of Oonari were reflected in greater crop coefficients and radiation use efficiency. These characteristics are mainly due to Oonari's higher leaf area index and extended photosynthetic period, highlighting the importance of field-scale evaluations throughout the entire growth period. Although both ET and GPP were greater in Oonari than in Koshihikari, the more pronounced difference in GPP indicates that cultivating Oonari has a greater impact on the carbon cycle than on water use.
在日本,种植高产籼稻品种已经在推广。这一趋势引起了人们对它们对水利用和碳循环的潜在影响的关注。为此,在实际管理实践下,对高产水稻品种Oonari进行了从移栽到收获的三年多的涡旋相关方差通量测量,并与传统粳稻品种Koshihikari在农民田间进行了比较。Oonari在2018年和2019年的蒸散量(ET)较高,比Koshihikari高9.6%(2018年:Oonari, 549.6 mm; Koshihikari, 501.2 mm; 2019年:Oonari, 472.0 mm; Koshihikari, 430.5 mm)。2020年,由于生长期较短,Oonari的ET减少了6.0% (Oonari, 426.5 mm; Koshihikari, 453.9 mm)。初级总产量(GPP) Oonari显著高于Koshihikari (Oonari: 1175.2±76.5 g C - m-2, Koshihikari: 946.5±32.7 g C - m-2),平均高出24%。高的ET和GPP反映在较高的作物系数和辐射利用效率上。这些特征主要是由于黄花楸叶面积指数较高,光合期较长,突出了整个生育期田间尺度评价的重要性。虽然Oonari的ET和GPP都大于Koshihikari,但GPP的差异更明显,表明种植Oonari对碳循环的影响大于对水利用的影响。
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引用次数: 0
Daily global transpiration estimation (2001–2018) by integrating satellite solar-induced fluorescence and spatially heterogeneous slope parameter in a conductance-photosynthesis model 在电导-光合作用模型中整合卫星太阳诱导荧光和空间非均质斜率参数估算每日全球蒸腾(2001-2018
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-17 DOI: 10.1016/j.agrformet.2025.110993
Jiaxin Jin , Linan Dong , Guojing Gan , Xingwang Fan , Ying Wang , Qiuan Zhu , Russell Doughty , Yuanwei Qin , Guishan Yang
Plant transpiration (Tc) is a key element of the water cycle. The conductance-photosynthesis (Gs-A) model, which assumes a linear relationship between stomatal conductance (Gs) and photosynthetic rate (A) under specific environmental conditions, is widely used to estimate Gs for the remote sensing of Tc. Nevertheless, the key parameter of the Gs-A model, the slope parameter, is typically assigned a biome-specific constant value, despite significant spatial heterogeneity observed within individual biomes. Moreover, the Gs-A model may introduce uncertainties into Tc estimation due to the broad-scale GPP simulated by empirical or complex process models. In this study, Gs was estimated using a typical Gs-A model (i.e., Ball-Berry model) enhanced by integrating daily satellite-observed solar-induced chlorophyll fluorescence (SIF), with a corresponding slope parameter (termed msif) that varies spatially with the local leaf area index (LAI) and air temperature (TEMa). Subsequently, a daily global Tc product (named Tsif) at a 0.05° spatial resolution (2001–2018) was generated, utilizing the Penman-Monteith equation combined with the improved Gs-A model. Observation data of 56 flux sites from the FLUXNET2015 were used to assess the performance and uncertainty of Tc across major vegetation types. Results demonstrated that daily-scale Tc estimation using the dynamic parameterization scheme of msif (DYN) outperformed the fixed scheme (FIX), reducing the root mean square error (RMSE) by an average of 10.89 % compared with flux observations. Furthermore, the spatiotemporal variations in Tc from our product showed good agreement with widely used Tc products, such as GLEAM, SiTHv2, and PML_v2. Notably, compared with flux observations, Tsif exhibited superior performance for Evergreen Broadleaf Forest, Deciduous Broadleaf Forest & Woody Savannas (DW), Savannas & Shrubland, and Grass, achieving the lowest RMSE values (0.88, 0.85, 0.55, and 0.74 mm day⁻¹, respectively). The Tsif dataset provides a novel, independent product valuable for analyses of the water cycle and ecohydrology at large scales.
植物蒸腾作用(Tc)是水循环的关键要素。导度-光合作用(Gs- a)模型假定在特定环境条件下气孔导度(Gs)与光合作用速率(a)之间存在线性关系,被广泛用于估算遥感Tc的Gs。然而,Gs-A模型的关键参数坡度参数通常被指定为特定于生物群落的恒定值,尽管在单个生物群落中观察到显著的空间异质性。此外,Gs-A模型由于采用经验模型或复杂过程模型模拟大尺度GPP,可能会给Tc估计带来不确定性。在本研究中,利用一个典型的Gs- a模型(即Ball-Berry模型)进行估算,该模型通过整合每日卫星观测到的太阳诱导叶绿素荧光(SIF),以及相应的斜率参数(称为msif),该参数随当地叶面积指数(LAI)和气温(TEMa)而在空间上变化。随后,利用Penman-Monteith方程结合改进的Gs-A模型,生成了0.05°空间分辨率(2001-2018)的全球每日Tc产品(命名为Tsif)。利用FLUXNET2015中56个通量站点的观测数据,对主要植被类型的Tc性能和不确定性进行了评估。结果表明,采用动态参数化方案的msif (DYN)日尺度Tc估计优于固定方案(FIX),与通量观测值相比,均方根误差(RMSE)平均降低10.89%。与GLEAM、SiTHv2、PML_v2等广泛应用的Tc产品相比,该产品的Tc的时空变化具有较好的一致性。值得注意的是,相比之下,通量观测,为常绿阔叶林Tsif表现出优越的性能,落叶阔叶林,伍迪热带稀树草原(DW),热带稀树草原,灌木地,和草,实现最低的RMSE值(0.88,0.85,0.55,0.74毫米天⁻¹,分别)。Tsif数据集为大尺度的水循环和生态水文分析提供了一种新颖的、独立的产品。
{"title":"Daily global transpiration estimation (2001–2018) by integrating satellite solar-induced fluorescence and spatially heterogeneous slope parameter in a conductance-photosynthesis model","authors":"Jiaxin Jin ,&nbsp;Linan Dong ,&nbsp;Guojing Gan ,&nbsp;Xingwang Fan ,&nbsp;Ying Wang ,&nbsp;Qiuan Zhu ,&nbsp;Russell Doughty ,&nbsp;Yuanwei Qin ,&nbsp;Guishan Yang","doi":"10.1016/j.agrformet.2025.110993","DOIUrl":"10.1016/j.agrformet.2025.110993","url":null,"abstract":"<div><div>Plant transpiration (<em>T<sub>c</sub></em>) is a key element of the water cycle. The conductance-photosynthesis (G<sub>s</sub>-A) model, which assumes a linear relationship between stomatal conductance (<em>G<sub>s</sub></em>) and photosynthetic rate (<em>A</em>) under specific environmental conditions, is widely used to estimate <em>G<sub>s</sub></em> for the remote sensing of <em>T<sub>c</sub></em>. Nevertheless, the key parameter of the G<sub>s</sub>-A model, the slope parameter, is typically assigned a biome-specific constant value, despite significant spatial heterogeneity observed within individual biomes. Moreover, the G<sub>s</sub>-A model may introduce uncertainties into <em>T<sub>c</sub></em> estimation due to the broad-scale GPP simulated by empirical or complex process models. In this study, <em>G<sub>s</sub></em> was estimated using a typical G<sub>s</sub>-A model (i.e., Ball-Berry model) enhanced by integrating daily satellite-observed solar-induced chlorophyll fluorescence (SIF), with a corresponding slope parameter (termed <em>m<sub>sif</sub></em>) that varies spatially with the local leaf area index (<em>LAI</em>) and air temperature (<em>TEM<sub>a</sub></em>). Subsequently, a daily global <em>T<sub>c</sub></em> product (named <strong>T<sub>sif</sub></strong>) at a 0.05<sup>°</sup> spatial resolution (2001–2018) was generated, utilizing the Penman-Monteith equation combined with the improved <em>G<sub>s</sub></em>-<em>A</em> model. Observation data of 56 flux sites from the FLUXNET2015 were used to assess the performance and uncertainty of <em>T<sub>c</sub></em> across major vegetation types. Results demonstrated that daily-scale <em>T<sub>c</sub></em> estimation using the dynamic parameterization scheme of <em>m<sub>sif</sub></em> (DYN) outperformed the fixed scheme (FIX), reducing the root mean square error (RMSE) by an average of 10.89 % compared with flux observations. Furthermore, the spatiotemporal variations in <em>T<sub>c</sub></em> from our product showed good agreement with widely used <em>T<sub>c</sub></em> products, such as GLEAM, SiTHv2, and PML_v2. Notably, compared with flux observations, <strong>T<sub>sif</sub></strong> exhibited superior performance for Evergreen Broadleaf Forest, Deciduous Broadleaf Forest &amp; Woody Savannas (DW), Savannas &amp; Shrubland, and Grass, achieving the lowest RMSE values (0.88, 0.85, 0.55, and 0.74 mm day⁻¹, respectively). The <strong>T<sub>sif</sub></strong> dataset provides a novel, independent product valuable for analyses of the water cycle and ecohydrology at large scales.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"378 ","pages":"Article 110993"},"PeriodicalIF":5.7,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Using point dendrometers to improve forest transpiration estimation accuracy at stand scales 利用点树木计提高林分尺度森林蒸腾估算精度
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-16 DOI: 10.1016/j.agrformet.2025.110986
Ryan M. Bright , Danielle Creek , Holger Lange , Helge Meissner , Morgane Merlin , Junbin Zhao
Forest transpiration is often quantified by scaling up stem sap flow measured on a few trees within a stand. This procedure carries uncertainty related to the (ill)representativeness of the sampled trees for the entire stand, often comprising several thousand transpiring trees. Here, we explored the uncertainty reduction potential afforded by increasing the number of sampled trees within the stand – not by costly sap flow monitoring equipment – but by point dendrometers measuring sub-daily fluctuations in stem radii which partially correlate with xylem water movement (i.e., sap flow). Using measurements collected in a forest dominated by even-aged spruce trees over two growing seasons, we built an empirical model for estimating hourly sap flow from individual trees equipped with point dendrometers, then applied it to estimate the daily transpiration of the stand both with and without trees equipped with point dendrometers. We found that the expanded tree sample size reduced the uncertainty of the stand-level estimate by 31–37 %, suggesting that the benefit afforded by increasing the stand representativeness outweighed the cost of introducing modeling error. Given their relative simplicity and affordability, we encourage additional investigations into the use of point dendrometers for studying tree water relations and water consumption patterns of entire forested stands.
森林蒸腾作用通常是通过在一个林分内的几棵树上按比例测量茎液流来量化的。这一过程具有与整个林分(通常包括数千棵蒸腾树)取样树木的(不良)代表性相关的不确定性。在这里,我们探索了通过增加林分内采样树木的数量来减少不确定性的潜力——不是通过昂贵的液流监测设备——而是通过测量与木质部水分运动(即液流)部分相关的茎半径次日波动的点树木计。利用两个生长季节在均龄云杉为主的森林中采集的数据,我们建立了一个经验模型来估算每小时的树液流量,然后将其应用于估算有树和没有树的林分的日蒸腾。我们发现,扩大的树木样本量将林分水平估算的不确定性降低了31 - 37%,这表明增加林分代表性所带来的好处超过了引入建模误差的成本。鉴于点树木密度计相对简单和可负担,我们鼓励进一步研究点树木密度计的使用,以研究树木的水分关系和整个林分的水消耗模式。
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引用次数: 0
Critical snowpack thresholds and escalating risks for extreme decreases in vegetation productivity across Northern Hemisphere ecosystems 北半球生态系统植被生产力极端下降的关键积雪阈值和不断上升的风险
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-16 DOI: 10.1016/j.agrformet.2025.110992
Hao Liu , Pengfeng Xiao , Xueliang Zhang , Xin Miao , Bo Tang , Yantao Liu , Siyong Chen , Gareth Rees , Weimin Ju
Seasonal snowpack is a key driver of vegetation productivity dynamics, but it is unclear at which levels of snowpack changes cause extreme decreases in vegetation productivity (EDVP), increasing the uncertainty in assessing the terrestrial carbon cycle. Here, we investigate the impact of different levels of snowpack changes on EDVP and identify the roles of different ecological processes of snowpack changes in the Northern Hemisphere (NH). The results show that over 30 % of snowpack decrease events are followed by EDVP events in ∼10 % of NH areas (p < 0.05), which is mainly attributed to snowpack’s moisture effect (via altering soil moisture). On average, the response of EDVP to snowpack changes increases rapidly when snow water equivalent (SWE) is –0.85 standard deviations (σ) below the mean, peaking at –1.33σ. Moreover, vegetation in warm and dry regions, especially grasslands, is more vulnerable to decreased SWE, and its resistance significantly increases with increasing precipitation. The future risk of EDVP occurrence will significantly increase in more regions owing to decreased snowpack, with ∼8 % of NH areas experiencing EDVP annually after ∼2083 under SSP5-8.5 scenario. Our findings underscore the significance of decreased snowpack in regulating EDVP and provide insights for better projecting and mitigating ecological consequences of snowpack changes.
季节性积雪是植被生产力动态的关键驱动因素,但目前尚不清楚积雪变化在何种程度上导致植被生产力(EDVP)的极端下降,这增加了陆地碳循环评估的不确定性。在此基础上,研究了北半球不同程度积雪变化对EDVP的影响,并确定了不同生态过程在积雪变化中的作用。结果表明,在约10%的NH地区,超过30%的积雪减少事件之后是EDVP事件(p < 0.05),这主要归因于积雪的水分效应(通过改变土壤水分)。平均而言,当雪水当量(SWE)低于平均值-0.85标准差(σ)时,EDVP对积雪变化的响应迅速增加,在-1.33σ处达到峰值。温暖干燥地区植被,尤其是草地,更容易受到SWE降低的影响,其抵抗能力随降水量的增加而显著增强。由于积雪减少,未来EDVP发生的风险将在更多地区显著增加,在SSP5-8.5情景下,在~ 2083年后,约8%的NH地区每年都会发生EDVP。我们的研究结果强调了积雪减少对EDVP的调节作用,并为更好地预测和减轻积雪变化的生态后果提供了见解。
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引用次数: 0
Intra-annual density fluctuations in Pinus massoniana across subtropical forests in China: Occurrence patterns and triggering factors 中国亚热带森林马尾松年际密度波动:发生模式及触发因素
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-16 DOI: 10.1016/j.agrformet.2025.110990
Qin He , Paolo Cherubini , J. Julio Camarero , Xiaochun Wang , Yuan Zhang , Danyang Yuan , Shuguang Liu , Liangjun Zhu
Intra-annual density fluctuations (IADFs) are wood cells formed in response to abnormal climatic events during the growing season. They are crucial for evaluating the relationship between extreme climatic events and radial growth, as well as for understanding wood quality. However, most existing research has focused on seasonally dry Mediterranean and semi-arid conifer forests, with limited studies conducted in other regions—particularly subtropical forests, where frequent and severe droughts constrain forest productivity and growth. Here, we investigated the occurrence patterns and triggering factors of IADFs in Pinus massoniana plantations along a climate gradient in southern China. We found that latewood IADFs (IADF-L) are the predominant type formed by P. massoniana, whereas earlywood IADFs (IADF-E) are relatively rare. The frequency of IADFs showed a clear spatial pattern, gradually increasing as climate conditions became warmer and wetter. IADF-L frequency was negatively correlated with elevation but positively correlated with tree-ring width. High precipitation in late summer and early autumn, as well as hot and dry conditions during summer, triggered the formation of IADF-Ls, while spring (May) droughts induced IADF-E. The inferred climatic drivers of IADFs were further confirmed by climate-growth relationships based on seasonal wood data and the VS-Lite tree-ring growth model. Our findings provide a valuable foundation for developing management strategies for drought-prone subtropical pine forests. For example, artificial rainfall or supplemental irrigation during summer-autumn dry spells could stimulate the formation of IADF-Ls, thereby enhancing forest growth and carbon sequestration capacity.
年际密度波动(IADFs)是指在生长季节因异常气候事件而形成的木细胞。它们对于评估极端气候事件与径向生长之间的关系以及了解木材质量至关重要。然而,大多数现有的研究集中在季节性干燥的地中海和半干旱的针叶林,在其他地区进行的研究有限,特别是在频繁和严重干旱限制森林生产力和生长的亚热带森林。本文以马尾松人工林为研究对象,研究了不同气候梯度马尾松人工林IADFs的发生模式和触发因素。我们发现马尾松形成的晚木型IADFs (IADF-L)占主导地位,而早木型IADFs (IADF-E)相对较少。随着气候条件变暖、变湿,iadf频率呈明显的空间格局,逐渐增加。IADF-L频率与海拔高度呈负相关,与树轮宽度呈正相关。夏末秋初的高降水和夏季的干热条件触发了iadf - l的形成,而春季(5月)干旱诱发了IADF-E的形成。基于季节木材数据和VS-Lite树木年轮生长模型的气候生长关系进一步证实了IADFs的气候驱动因素。本研究结果为制定干旱易发的亚热带松林管理策略提供了有价值的基础。例如,在夏秋干旱期,人工降雨或补充灌溉可以刺激iadf - l的形成,从而提高森林生长和固碳能力。
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引用次数: 0
Unveiling spatial and temporal characteristics of cooling effects of rice paddy expansion in Northeast China 揭示东北地区稻田扩张降温效应的时空特征
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-16 DOI: 10.1016/j.agrformet.2025.110967
Tong Yang , Jinwei Dong , Jie Wang , Chao Zhang , Wenqi Liu , Yuting Zhou , Geli Zhang , Guosong Zhao
Rice paddy expansion in Northeast China can affect land surface temperature (LST) through biophysical mechanisms. However, the temporal and spatial heterogeneity of the LST effects, the variations associated with the area proportions of rice paddy, and the underlying biophysical mechanisms remain poorly understood. In this study, we analyze the differences in LST (dLST), albedo (dAlbedo), and evapotranspiration (dET) between rice paddies and adjacent rainfed croplands using a pair-wise comparison approach. Our results show that the expansion of rice paddies potentially reduces daytime LST (−2.02 ± 1.03 °C) and albedo (−1.02 ± 1.07 %) while increases nighttime LST (0.76 ± 0.41 °C) and ET (0.03 ± 1.20 mm/8 days) in Northeast China during the growing season (May to September). The effects are more pronounced in spring than in summer and autumn. Spatially, Sanjiang Plain exhibits a daytime cooling effect in later months and a nighttime warming effect in earlier months than other regions. For every ten percent increase in the area proportion of rice paddies, daytime dLST decreases by 1.60 °C, nighttime dLST increases by 0.64 °C, and dAlbedo decreases by 1.40 %. Using a decomposed temperature metric approach, we confirmed that non-radiative mechanisms dominate the cooling effects during the growing season. These findings emphasize the need to consider spatial heterogeneity and biophysical mechanisms of land cover changes in model simulations, crop planting plans, and regional climate mitigation strategies.
东北地区水稻种植扩展通过生物物理机制影响地表温度。然而,地表温度效应的时空异质性、与稻田面积比例相关的变化及其潜在的生物物理机制尚不清楚。在本研究中,我们采用两两比较的方法分析了稻田和邻近旱作农田的地表温度(dLST)、反照率(dAlbedo)和蒸散量(dET)的差异。结果表明:5 ~ 9月稻田面积的扩大使东北地区白天地表温度(- 2.02±1.03°C)和反照率(- 1.02±1.07%)降低,夜间地表温度(0.76±0.41°C)和ET(0.03±1.20 mm/8 d)升高。这种影响在春季比夏季和秋季更为明显。从空间上看,三江平原较其他地区表现出较晚月份的日间降温效应和较早月份的夜间升温效应。稻田面积比例每增加10%,白天dLST降低1.60°C,夜间dLST增加0.64°C, dAlbedo降低1.40%。利用分解温度度量方法,我们证实了非辐射机制在生长季节的冷却效应中占主导地位。这些发现强调了在模式模拟、作物种植计划和区域气候减缓战略中考虑土地覆盖变化的空间异质性和生物物理机制的必要性。
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引用次数: 0
Carbon fluxes and partitioning in Eucalyptus and Pinus plantations across a climatic gradient in Brazil 巴西不同气候梯度的桉树和松林的碳通量和分配
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-15 DOI: 10.1016/j.agrformet.2025.110977
Fernanda Leite Cunha , Otávio Camargo Campoe , Cléber Rodrigo de Souza , Isaira Leite & Lopes , Yann Nouvellon , Timothy Albaugh , David R. Carter , Rafael Rubilar , Isabel Deliberari , Rachel Cook , Joannès Guillemot , Guerric Le Maire , Jean-Paul Laclau , Jose Luiz Stape , Clayton Alcarde Alvares
Brazilian Eucalyptus and Pinus forests are the most productive forests worldwide. The growth rates of these intensively managed plantations depend strongly on environmental conditions and matching genotypes to local environments. Changing climates underscore the value of understanding the intricacies of how these plantations can fix high amounts of carbon (C) and grow so much wood. We measured the full C budgets of Eucalyptus and Pinus forests across climate gradients in Brazil, focusing on the rates of C uptake, the allocation of C to belowground roots and mycorrhizae, and stem growth. We found that gross primary production (GPP) varied more than sixfold across the climate conditions in Brazil. Maximum temperature was the main climatic driver of productivity, where extreme temperatures reduced fluxes to stem production while increasing fluxes to root production. Net ecosystem production varied with management and age across the sites. The ecophysiological investigation presented in this work is fundamental for understanding C partitioning behavior under extreme temperature conditions. In this way, our results provide tools for forest managers to support their decision-making processes as well as starting points for strategies to be implemented in projects aimed at mitigating the effects of climate change.
巴西的桉树和松林是世界上最多产的森林。这些集约化管理人工林的生长速度在很大程度上取决于环境条件和与当地环境相匹配的基因型。不断变化的气候强调了了解这些种植园如何固定大量碳(C)并种植如此多木材的复杂性的价值。我们测量了巴西不同气候梯度的桉树和松林的全部碳收支,重点关注碳吸收率、碳在地下根和菌根中的分配以及茎的生长。我们发现,巴西的初级生产总值(GPP)在不同的气候条件下变化超过6倍。最高温度是生产力的主要气候驱动因素,其中极端温度减少了茎生产的通量,而增加了根生产的通量。网络生态系统的产生随着不同地点的管理和年龄而变化。这项工作中提出的生态生理学研究是理解极端温度条件下C分配行为的基础。通过这种方式,我们的研究结果为森林管理者提供了支持其决策过程的工具,并为旨在减轻气候变化影响的项目实施战略提供了起点。
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引用次数: 0
Evaluating ecosystem water use efficiency and recovery dynamics during flash droughts: insights from observations and model simulations 评估突发性干旱期间生态系统水分利用效率和恢复动态:来自观测和模式模拟的见解
IF 5.7 1区 农林科学 Q1 AGRONOMY Pub Date : 2025-12-13 DOI: 10.1016/j.agrformet.2025.110982
Yuefeng Hao , Jiafu Mao , Yaoping Wang , Lianhong Gu , Jeffrey Wood , Paul J. Hanson , Melanie A. Mayes , Mingzhou Jin , Peter E. Thornton , Xiaoying Shi , Daniel M. Ricciuto
Flash droughts (FD), rapidly emerging in a warming future, disrupt ecosystems, agriculture, and water security. Ecosystem water use efficiency (WUE), the ratio of gross primary production (GPP) to actual evapotranspiration (AET), balances carbon assimilation and water loss. FD rapidly disrupts this balance, making WUE critical for assessing plant stress and recovery. This study investigates the dynamics of landscape-scale WUE, and the components of GPP and AET under FD utilizing both observed data from the Missouri Ozark AmeriFlux site (US-MOz) and version 2 of the U.S. Department of Energy’s Earth, Energy, Exascale System Model (E3SM) Land Model (ELMv2). Observations and simulations reveal GPP as dominant for WUE during earlier FD events (2005, 2007, 2012), shifting to AET in recent events (2014, 2018). This agreement indicates that the ELM can capture the shifting dynamics of GPP and AET in regulating WUE under FD conditions. However, the ELM systematically underestimates both GPP and AET and does so in a manner that does not preserve their ratio. As a result, WUE is also underestimated, suggesting that GPP is more strongly underestimated than AET. Furthermore, the ELM also underestimates the speed of GPP recovery, producing an artificially prolonged GPP recovery time following FD events. Observed environmental drivers such as vapor pressure deficit (VPD), soil moisture (SM), and predawn leaf water potential (PLWP) effectively predict WUE, but ELM primarily highlights SM, underestimating VPD’s role. This study demonstrates that relying solely on soil moisture fails to capture the rapid hydraulic recovery observed in PLWP, underscoring the necessity of integrating plant hydraulics into land surface models to improve flash drought predictability.
在全球变暖的未来,突发性干旱(FD)会迅速出现,破坏生态系统、农业和水安全。生态系统水分利用效率(WUE),即总初级生产量(GPP)与实际蒸散(AET)之比,平衡了碳同化和水分流失。FD迅速破坏了这种平衡,使水分利用效率成为评估植物胁迫和恢复的关键。本研究利用密苏里Ozark AmeriFlux站点(US-MOz)和美国能源部地球、能源、百亿次系统模型(E3SM)陆地模型(ELMv2)的第2版观测数据,研究了FD下景观尺度WUE的动态变化,以及GPP和AET的组成。观测和模拟显示,在早期FD事件(2005年、2007年、2012年)中,GPP是WUE的主导因素,在最近的事件(2014年、2018年)中转向AET。这表明,在FD条件下,ELM可以捕捉GPP和AET在调节WUE方面的变化动态。然而,ELM系统地低估了GPP和AET,并没有保持它们的比例。因此,WUE也被低估了,说明GPP比AET被严重低估。此外,ELM还低估了GPP的恢复速度,人为地延长了FD事件后的GPP恢复时间。观测到的环境驱动因素如水汽压亏缺(VPD)、土壤湿度(SM)和黎明前叶片水势(PLWP)可以有效预测水分利用效率,但ELM主要强调SM,低估了VPD的作用。该研究表明,仅依靠土壤湿度无法捕捉PLWP观测到的快速水力恢复,强调了将植物水力学纳入陆地表面模型以提高突发性干旱可预测性的必要性。
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引用次数: 0
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Agricultural and Forest Meteorology
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