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The biophysical effects of phenological shifts impact land surface temperature for corn expansion in Northeastern China 物候变化对地表温度的生物物理效应对玉米生长的影响
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-27 DOI: 10.1016/j.agrformet.2024.110373
Yuyang Ma , Jie Li , Jianxi Huang , Anne Gobin , Xuecao Li , Wenqi Liu , Haixiang Guan , Nadezhda N. Voropay , Chuli Hu
In the last two decades, rapid corn expansion has significantly impacted local and regional climates in Northeastern China. However, its climatic effects and underlying biophysical mechanisms have rarely been investigated, particularly in accurately describing the changes in surface physiological structure throughout different phenological stages. This study utilized remote sensing observations and the pair-wise comparison approach to examine land surface temperature (LST) change associated with corn expansion at various phenological stages and whole growth seasons, respectively. We then employed the temperature response model to decompose and quantify the LST changes into radiative processes (albedo) and non-radiative processes (i.e., evapotranspiration and turbulent heat exchange). This study indicated that, except for soybean, the mean LST changes (ΔMean_LST) induced by corn expansion initially decreased and subsequently increased with the phenology shifts. Specifically, the potential warming effect was pronounced during three-leaves (EMV3) to seven-leaves stage (V7) and V7 to jointing date (JD), with the largest warming in Mean_LST occurring when corns were converted into trees (1.24±0.43 K) (mean ± 95 % confidence level) (0.93±0.29 K), followed by grass (0.47±0.37 K) (0.43±0.31 K), rice (0.46±0.23 K) (0.31±0.22 K), wetlands (0.16±0.21 K) (0.15±0.34), respectively. EMV3 to JD dominated the ΔMean_LST for the whole growth season, potentially warming the Mean_LST when trees, grass, rice, and wetlands converted to corn, while cooling the Mean_LST when soybeans converted to corn. Furthermore, The effect of phenological stages on LST varies with latitude. For example, during V7 to JD and Milky date (MID) to Maturity date (MD), the non-radiative warming effect of wetland conversion surpassed that of rice conversion as latitude increased (44°N-47°N). This indicates that the wetland conversion causes intensified warming at high latitudes in these stages. Additionally, non-radiative processes, characterized by varying signs and magnitudes, dominated the LST response to corn expansion. Overall, this study comprehensively investigated the ΔLST of corn expansion at various phenological stages and latitudes through the biophysical mechanism, which could be beneficial in developing adaptive and mitigative agricultural management strategies for climate warming in Northeast China.
在过去的二十年中,玉米的快速扩张对中国东北地区的局地和区域气候产生了重大影响。然而,其气候效应和潜在的生物物理机制很少被研究,特别是在准确描述不同物候阶段地表生理结构的变化方面。本研究利用遥感观测和两两比较的方法,分别研究了玉米不同物候期和整个生长季节的地表温度变化与膨大的关系。然后,我们利用温度响应模型将地表温度变化分解并量化为辐射过程(反照率)和非辐射过程(蒸散发和湍流热交换)。本研究表明,除大豆外,玉米膨化引起的平均地表温度变化(ΔMean_LST)随物候变化先减小后增大。其中,三叶期(EMV3)至七叶期(V7)和V7期至拔节期(JD)的潜在增温效应显著,其中玉米转树期(1.24±0.43 K)(平均±95%置信水平)(0.93±0.29 K)的Mean_LST增温最大,其次是草(0.47±0.37 K)(0.43±0.31 K)、水稻(0.46±0.23 K)(0.31±0.22 K)、湿地(0.16±0.21 K)(0.15±0.34)。EMV3到JD在整个生长季中主导ΔMean_LST,当树木、草、水稻和湿地转化为玉米时,可能使Mean_LST变暖,而当大豆转化为玉米时,可能使Mean_LST变冷。此外,物候阶段对地表温度的影响随纬度的变化而变化。例如,在V7 ~ JD和乳日(MID) ~成熟日(MD)期间,随着纬度的增加(44°N ~ 47°N),湿地转化的非辐射增温效应超过水稻转化。这表明在这两个阶段,湿地的转换导致高纬度地区升温加剧。此外,地表温度对玉米膨大的响应主要由非辐射过程主导,且非辐射过程具有不同的特征和幅度。综上所述,本研究通过生物物理机制全面考察了东北不同物候阶段和纬度玉米膨大的ΔLST,为东北地区制定适应和减缓气候变暖的农业管理策略提供了有益的参考。
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引用次数: 0
Decadal isotopic and functional trait evidence reveals water and nitrogen constrains on productivity of three subtropical conifers 年代际同位素和功能特征证据揭示了水氮对三种亚热带针叶树生产力的制约
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-26 DOI: 10.1016/j.agrformet.2024.110375
Jing Wang , Xuefa Wen
Increasing evidence indicates that plant productivity is constrained by water and nutrient availability under natural conditions of the stimulatory effects of elevated CO2 concentration (eCO2). However, it remains unclear how plant traits related to water and nitrogen acquisition and utilization acclimate to the soil water and nitrogen limitations on productivity. To address this, we investigated isotopic and functional traits and net primary productivity (NPP) of three dominant species of Pinus elliottii, Cunninghamia lanceolata, and Pinus massoniana in a subtropical coniferous plantation from 2011 to 2022 along with environmental parameters. Faced with increasing soil water and nitrogen stress, stomatal conductance (gs, 1/leaf δ18O enrichment) decreased with eCO2 in all species. Stomatal closure enhanced intrinsic water use efficiency (iWUE, derived from leaf δ13C using photosynthetic discrimination model) in P. elliottii and P. massoniana but not in C. lanceolata. Although eCO2 compensate for productivity losses resulting from drought-induced decreases in gs, increased NPP was observed only in P. elliottii, reflecting differences in the species' abilities to acclimate and overcome resource limitations. All species showed increased mycorrhizal dependency (the difference in δ15N between leaves and soil, |△15N|), high leaf nitrogen content, but reduced nitrogen use efficiency, leaf water content and specific leaf area. This suggested that plants increased nitrogen investment through biological adaption to mitigate productivity limitations caused by water and nutrient stress. The increased NPP in P. elliottii was due to high nitrogen uptake and low leaf nitrogen demand, compensating for water limitations. Conversely, reductions in NPP in C. lanceolata and P. massoniana were attributed to the relatively low nitrogen uptake and high leaf nitrogen demand, which failed to offset water limitations. This implies that the magnitude and direction of vegetation productivity responses to eCO2 are determined by species-specific differences in plant adaptations to water and nutrient limitations.
越来越多的证据表明,在二氧化碳浓度升高(eCO2)刺激作用的自然条件下,植物生产力受到水分和养分供应的限制。然而,与水分和氮的获取和利用有关的植物性状如何适应土壤水分和氮对生产力的限制尚不清楚。为了解决这一问题,研究了2011 - 2022年亚热带针叶林中3种优势种湿地松(Pinus elliottii)、杉木(Cunninghamia lanceolata)和马尾松(Pinus massoniana)的同位素、功能特征和净初级生产力(NPP)。随着土壤水氮胁迫的增加,所有物种的气孔导度(gs, 1/叶片δ18O富集)随eCO2的增加而降低。气孔关闭提高了油松和马尾松的内在水分利用效率(iWUE),而杉木则没有。尽管eCO2补偿了干旱导致的gs减少所造成的生产力损失,但仅在elliottii中观察到NPP增加,这反映了物种适应和克服资源限制能力的差异。各树种菌根依赖性增强(叶片与土壤的δ15N差,|△15N|),叶片含氮量增加,但氮利用效率、叶片含水量和比叶面积降低。这表明植物通过生物适应增加氮素投入,以减轻水分和养分胁迫造成的生产力限制。水杨NPP的增加是由于叶片氮吸收量高,氮需要量低,弥补了水分的限制。相反,杉木和马尾松的NPP减少是由于相对较低的氮吸收和较高的叶片氮需求,这未能抵消水分限制。这意味着植被生产力对eCO2响应的大小和方向取决于植物对水分和养分限制的适应的物种特异性差异。
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引用次数: 0
Assessing the impact of extreme climate events on European gross primary production 评估极端气候事件对欧洲初级生产总值的影响
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-26 DOI: 10.1016/j.agrformet.2024.110374
Huihui Zhang , Hugo A Loaiciga , Akpona Okujeni , Ji Liu , Min Tan , Tobias Sauter
Climate warming and the associated intensification of extreme climate events (such as droughts, heavy precipitation, and heatwaves) present challenges to plant growth. Plant growth is influenced by a number of factors such as soil moisture, water demand by plants, temperature sensitivity, growth stage, and by irrigation practices in the case of crops. The response of plant growth to extreme climate events across a range of growing periods, climate regions, and agricultural land types under different irrigation strategies remains unclear. This study utilizes ten extreme climate indices and six drought indices to predict plant growth outcomes, as indicated by the end-of-growing season Gross Primary Production (GPP), across different growing seasons in Europe from 2003 to 2020. This work examines the impact of extreme climate events on plant growth with a novel explainable LightGBM model. This model elucidates the contribution of such events to plant growth, and helps to identify their tipping points. This paper's results demonstrate that early-season soil moisture and extreme absolute temperatures are key predictors in forecasting the end-of-growing season GPP, indicating potential drought memory. Plant growth correlates highly with extreme climate events in arid, cold, and temperate climates. In arid climates the extreme precipitation amounts are the predominant predictor of end-of-growing season GPP. Agricultural drought plays a leading role in the model prediction results in cold climates. Extreme climate events have a more pronounced effect on plant growth yield in rainfed cropland and grasslands compared to irrigated croplands. The implementation of irrigation strategies involving human intervention would help mitigate the impact of extreme climate events on plant growth outcomes.
气候变暖和与之相关的极端气候事件(如干旱、强降水和热浪)的加剧给植物生长带来了挑战。植物生长受到许多因素的影响,如土壤湿度、植物对水的需求、温度敏感性、生长阶段,以及作物的灌溉做法。不同灌溉策略下植物生长对不同生长期、气候区域和农业用地类型的极端气候事件的响应尚不清楚。本研究利用10个极端气候指数和6个干旱指数对2003 - 2020年欧洲不同生长季节的植物生长结果进行预测,并以生长季末的初级生产总值(GPP)为指标。本研究用一种新的可解释的LightGBM模型研究了极端气候事件对植物生长的影响。该模型阐明了这些事件对植物生长的贡献,并有助于确定它们的引爆点。结果表明,季前土壤湿度和极端绝对温度是预测季末GPP的关键预测因子,反映了潜在的干旱记忆。在干旱、寒冷和温带气候中,植物生长与极端气候事件高度相关。在干旱气候条件下,极端降水量是生长季末GPP的主要预测因子。在寒冷气候条件下,农业干旱在模式预测结果中起主导作用。与灌溉农田相比,极端气候事件对雨养农田和草地植物生长产量的影响更为显著。实施涉及人为干预的灌溉战略将有助于减轻极端气候事件对植物生长结果的影响。
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引用次数: 0
Wetter, but not wet enough—Limited greenhouse gas mitigation effects of subsurface irrigation and blocked ditches in an intensively cultivated grassland on fen peat 湿润,但不够湿润:在集约化草地上,地下灌溉和阻塞沟渠对泥炭沼泽的温室气体减排效果有限
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-26 DOI: 10.1016/j.agrformet.2024.110367
Sebastian Heller , Bärbel Tiemeyer , Willi Oehmke , Peter Gatersleben , Ullrich Dettmann
High-intensity grassland farming on peatlands is a profitable land use option in Western and Central Europe. This highly productive land use requires extensive drainage measures and regular grassland renewal. The drainage practice in particular substantially increases peat mineralisation, resulting in high emissions of the greenhouse gases (GHG) carbon dioxide (CO2) and nitrous oxide (N2O). Against this, a controlled raising of the water level (WL) by subsurface irrigation (SI) or ditch blocking (DB) has been proposed as a compromise between reducing the GHG emissions and maintaining grassland use on peatlands. We tested this assumption by measuring the full set of GHGs over four years for three water management systems (SI, DB, ditch drainage as control) in combination with three grassland renewal treatments (direct sowing, shallow ploughing, original sward as control) on an intensively used fen grassland in Northwest Germany.
The mean annual WL was successfully raised by SI to −0.25 m below the soil surface, while the DB unit remained at a similar level (−0.37 m) as the control (−0.38 m). However, CO2 emissions were only marginally reduced by SI due to high variability between sites and years. Partially higher CO2 emissions may have been caused by a higher temperature sensitivity of the heterotrophic respiration at intermediate WLs. Partially lower CO2 emissions may reflect increased carbon uptake by root growth (Juncus effuses) rather than reduced peat mineralisation. The GHG mitigation potential of the SI system remained negligible in this study, as the small CO2 reduction was offset by increased CH4 and N2O emissions. The average emissions of the DB system were similar to those of the control unit. Both renewal treatments increased N2O emissions for approximately two years. Overall, our study results do not support the use of SI as a GHG mitigation measure for intensively used fen grasslands.
在西欧和中欧,泥炭地的高强度草地耕作是一种有利可图的土地利用选择。这种高产的土地利用需要广泛的排水措施和定期的草地更新。特别是排水做法大大增加了泥炭矿化,导致温室气体(GHG)二氧化碳(CO2)和一氧化二氮(N2O)的大量排放。为此,提出了通过地下灌溉(SI)或沟渠阻塞(DB)来控制水位(WL)的方法,作为减少温室气体排放和维持泥炭地草地利用之间的折衷方案。我们在德国西北部一个集约利用的沼泽草原上测量了三种水管理系统(SI、DB、沟渠排水作为对照)以及三种草地更新处理(直接播种、浅耕、原始草地作为对照)四年来的全部温室气体排放量,以此验证了这一假设。SI成功地将年平均WL提高到土壤表面以下- 0.25 m,而DB单元保持在与对照(- 0.38 m)相似的水平(- 0.37 m),但由于站点和年份之间的高变异性,SI仅能轻微减少CO2排放。在一定程度上,较高的CO2排放量可能是由于异养呼吸在中间wl的温度敏感性较高造成的。部分降低的二氧化碳排放可能反映了根系生长增加的碳吸收,而不是减少的泥炭矿化。在本研究中,SI系统的温室气体减缓潜力仍然可以忽略不计,因为少量的CO2减少被增加的CH4和N2O排放所抵消。DB系统的平均排放量与控制单元相似。两种更新处理在大约两年内都增加了N2O排放量。总体而言,我们的研究结果不支持将SI作为集约利用的沼泽草原的温室气体缓解措施。
{"title":"Wetter, but not wet enough—Limited greenhouse gas mitigation effects of subsurface irrigation and blocked ditches in an intensively cultivated grassland on fen peat","authors":"Sebastian Heller ,&nbsp;Bärbel Tiemeyer ,&nbsp;Willi Oehmke ,&nbsp;Peter Gatersleben ,&nbsp;Ullrich Dettmann","doi":"10.1016/j.agrformet.2024.110367","DOIUrl":"10.1016/j.agrformet.2024.110367","url":null,"abstract":"<div><div>High-intensity grassland farming on peatlands is a profitable land use option in Western and Central Europe. This highly productive land use requires extensive drainage measures and regular grassland renewal. The drainage practice in particular substantially increases peat mineralisation, resulting in high emissions of the greenhouse gases (GHG) carbon dioxide (CO<sub>2</sub>) and nitrous oxide (N<sub>2</sub>O). Against this, a controlled raising of the water level (WL) by subsurface irrigation (SI) or ditch blocking (DB) has been proposed as a compromise between reducing the GHG emissions and maintaining grassland use on peatlands. We tested this assumption by measuring the full set of GHGs over four years for three water management systems (SI, DB, ditch drainage as control) in combination with three grassland renewal treatments (direct sowing, shallow ploughing, original sward as control) on an intensively used fen grassland in Northwest Germany.</div><div>The mean annual WL was successfully raised by SI to −0.25 m below the soil surface, while the DB unit remained at a similar level (−0.37 m) as the control (−0.38 m). However, CO<sub>2</sub> emissions were only marginally reduced by SI due to high variability between sites and years. Partially higher CO<sub>2</sub> emissions may have been caused by a higher temperature sensitivity of the heterotrophic respiration at intermediate WLs. Partially lower CO<sub>2</sub> emissions may reflect increased carbon uptake by root growth (<em>Juncus effuses</em>) rather than reduced peat mineralisation. The GHG mitigation potential of the SI system remained negligible in this study, as the small CO<sub>2</sub> reduction was offset by increased CH<sub>4</sub> and N<sub>2</sub>O emissions. The average emissions of the DB system were similar to those of the control unit. Both renewal treatments increased N<sub>2</sub>O emissions for approximately two years. Overall, our study results do not support the use of SI as a GHG mitigation measure for intensively used fen grasslands.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110367"},"PeriodicalIF":5.6,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Species distribution models built with local species data perform better for current time, but suffer from niche truncation 用局部物种数据建立的物种分布模型对当前时间有较好的适应性,但存在生态位截断的问题
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-24 DOI: 10.1016/j.agrformet.2024.110361
Nicolò Anselmetto , Donato Morresi , Simona Barbarino , Nicola Loglisci , Matthew G. Betts , Matteo Garbarino
To cope with climate change-induced alterations, forest ecosystems’ conservation and restoration require models that are both capable to incorporate current local-scale dynamics but also to anticipate future changes. These requirements may be fulfilled by robust assessments of response (i.e., species data such as forest inventories) and predictor (e.g., climate) variables. The aim of this study is to predict current and future probability of occurrence for 22 tree species comparing inventory and climate data at different spatial scales and test for model performance, reliability, and niche truncation.
We built species distribution models (SDMs) for 22 tree species of Piedmont, an Alpine administrative region of north-western Italy. We compared (i) a fine-scale model calibrated with a local forest inventory with a 250-m spatial resolution at the extent of Piedmont and a regional climate model calibrated on the Italian extent versus (ii) coarse-scale model calibrated with a pan-European forest inventory (EU-Forest) at 1-km resolution and a global climate dataset (CHELSA v1.2). Moreover, (iii) we developed a data pooling method by combining the species data and using CHELSA. We evaluated models using spatial-block cross-validation and external validation through several metrics. We predicted the probability of occurrence for current and future under RCP4.5 and RCP8.5 climate scenarios.
Models built with local species data performed better for the future than those incorporating broad species data and their current predictions reflected the realized distribution of species but they suffered from niche truncation while extrapolated to the future. Indeed, models calibrated at the local scale predicted greater magnitude of changes for future scenarios compared to coarse-scale models. Integrating species data at different extents and resolutions is a valid approach when both are available.
为了应对气候变化引起的变化,森林生态系统的保护和恢复需要既能纳入当前局地尺度动态又能预测未来变化的模型。这些要求可以通过对响应(如森林清查等物种数据)和预测变量(如气候)进行强有力的评估来满足。本研究的目的是通过比较不同空间尺度下的库存和气候数据,预测22种树种当前和未来的发生概率,并对模型的性能、可靠性和生态位截断进行检验。本文对意大利西北部阿尔卑斯行政区域皮埃蒙特的22种树种建立了物种分布模型(SDMs)。我们比较了(i)在皮埃蒙特范围内用250米空间分辨率的当地森林清查校准的精细尺度模型和在意大利范围内校准的区域气候模型,以及(ii)用1公里分辨率的泛欧森林清查(EU-Forest)和全球气候数据集(CHELSA v1.2)校准的粗尺度模型。(3)结合物种数据,利用CHELSA建立了数据池方法。我们通过几个指标使用空间块交叉验证和外部验证来评估模型。我们预测了RCP4.5和RCP8.5气候情景下当前和未来发生的概率。利用局地物种数据建立的模型对未来的预测效果优于利用广地物种数据建立的模型,其目前的预测反映了物种的实际分布,但在外推到未来时存在生态位截断的问题。事实上,与粗尺度模型相比,在局部尺度上校准的模型预测未来情景的变化幅度更大。整合不同程度和分辨率的物种数据是一种有效的方法。
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引用次数: 0
Evaluation and simulation of terrestrial latent heat flux globally: A collaborative effort utilizing CMIP6 climate models and eddy covariance observations 全球陆地潜热通量的评估和模拟:基于CMIP6气候模式和涡旋相关方差观测的协同努力
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-21 DOI: 10.1016/j.agrformet.2024.110371
Xinling Tian, Zhenhua Di, Yunjun Yao, Zhenwei Liu, Hao Meng, Huiying Sun, Xueyan Wang, Wenjuan Zhang
Exchanging latent heat flux (LE) through evapotranspiration impacts the atmospheric thermodynamics and water cycle. The Earth System Models (ESMs) in the Coupled Model Intercomparison Project Phase6 (CMIP6) are vital to reproduce improved LE variations globally, albeit with significant uncertainties. Meanwhile, the rational attribution to regions of LE simulations is essential for informed water resources administration and climate control. This paper presents the first comprehensive evaluation of the ability of 49 ESMs to model global terrestrial LE during the 2000–2014 period based on 205 eddy covariance (EC) observations. Utilizing the Bayesian Model Averaging (BMA) method, we analyzed the spatial-temporal variation and attribution to regions of global LE during 1980–2014 by combining the top six models with EC observations. The results showed that most ESMs overestimated LE, with an average BIAS of 7.57 W‧m−2, covering −7–17 W‧m−2. Among them, the MIROC6 model evinced the highest predictive skill at various land cover types. Moreover, the BMA-based global average terrestrial LE showed low LE values in dry and cold regions of temperate and cold zones of middle and high latitudes but evidenced high LE values in hot and humid regions of low-latitude tropical zones. The inter-annual variations of the BMA-based global annual LE exhibited a significant linear increasing trend with a 0.027 W‧m−2 slope (P-value <0.05). Further attribution to regions analyses were concluded, considering that LE trends were the same as the temperature trends in the Northern Hemisphere, especially in the middle and high latitudes. These conditions are comparable to radiation in the equatorial regions, correlating substantially with precipitation in dry and semi-dry regions across Asia, Europe, and Africa. In addition, the advantages of CMIP6 ESMs on LE simulations mainly including bias, and interannual variability characteristics were also concluded compared with CMIP5 ESMs.
通过蒸散发交换潜热通量影响大气热力学和水循环。耦合模式比对项目第6阶段(CMIP6)中的地球系统模式(esm)对于重现全球LE变化的改善至关重要,尽管存在很大的不确定性。同时,LE模拟的合理区域归属对水资源管理和气候控制具有重要意义。本文首次综合评价了49个esm在2000-2014年期间基于205个涡动相关(eddy covariance, EC)观测数据模拟全球陆地LE的能力。利用贝叶斯模式平均(BMA)方法,结合前6个模式和EC观测数据,分析了1980—2014年全球LE的时空变化及其区域归因。结果表明,大多数esm高估了LE,平均BIAS为7.57 W·m−2,覆盖了- 7 ~ 17 W·m−2。其中,MIROC6模式对不同土地覆盖类型的预测能力最高。此外,基于bma的全球平均陆地LE在中高纬度温带和寒带的干燥寒冷地区表现出较低的LE值,而在低纬度热带湿热地区表现出较高的LE值。基于bma的全球年LE年际变化呈显著的线性增加趋势,斜率为0.027 W·m−2 (p值<;0.05)。考虑到北半球特别是中高纬度地区的气温变化趋势与LE变化趋势一致,进一步将其归因于区域分析。这些条件与赤道地区的辐射相当,与亚洲、欧洲和非洲干旱和半干旱地区的降水密切相关。此外,对比CMIP5 ESMs, CMIP6 ESMs在LE模拟中的优势主要包括偏倚和年际变化特征。
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引用次数: 0
Reductions in nitrous oxide emissions in diverse crop rotations linked to changes in prokaryotic community structure 不同作物轮作中氧化亚氮排放量的减少与原核生物群落结构的变化有关
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-20 DOI: 10.1016/j.agrformet.2024.110370
Mingming Zong , Xiaolin Yang , Alberto Sanz-Cobena , Uffe Jørgensen , Klaus Butterbach-Bahl , Diego Abalos
Diverse crop rotations are increasingly recognized as key to address the global food crisis and improve environmental sustainability, including reducing nitrous oxide (N2O) emissions. However, the specific effects on N2O emissions of different crops in these rotations and the underlying incidence on microbial processes remain underexplored. In a six-year field study, we compared N2O emissions from traditional wheat-maize rotation with diverse rotations, including legumes (peanut, soybean), ryegrass, sorghum, and sweet potato. We also examined the microbial functions associated with nitrogen cycling based on functional annotation of prokaryotic taxa (FAPROTAX) analysis. Our study showed that diversified crop rotations with reduced synthetic fertilization and irrigation can reduce N2O emissions by 23 %-49 % compared to conventional rotations. These reductions were supported by increases in soil organic carbon, soil carbon/nitrogen ratio and decreases in the relative abundance of denitrifying microorganisms, particularly observed in rotations with soybean and sweet potato. However, the spring maize and peanut-based rotation had higher emission factors than traditional wheat-maize rotation due to lower initial crop nitrogen uptake and lower nitrogen use efficiency, respectively. Changes in the microbial community structures of nitrification and denitrification processes, including increased activity of ammonia-oxidizing bacteria MND1 and archaea Candidatus Nitrososphaera in legume and sweet potato rotations, and a shift in denitrifying microbes of diverse rotations (a decrease in Rhodoplanes and an increase in Paracoccus), significantly contributed to the overall reductions in emissions in all other investigated rotation systems. Understanding the microbial mechanisms that control N2O emissions from agricultural soils will enable the development of more effective and crop-specific strategies to further reduce greenhouse gas emissions.
多样化的作物轮作日益被认为是解决全球粮食危机和提高环境可持续性的关键,包括减少一氧化二氮(N2O)的排放。然而,这些轮作对不同作物N2O排放的具体影响及其对微生物过程的潜在影响仍未得到充分探讨。在一项为期六年的实地研究中,我们比较了传统小麦-玉米轮作与不同轮作的N2O排放量,包括豆类(花生、大豆)、黑麦草、高粱和甘薯。我们还基于原核分类群的功能注释(FAPROTAX)分析,研究了与氮循环相关的微生物功能。我们的研究表明,与常规轮作相比,减少合成施肥和灌溉的多样化作物轮作可以减少23% - 49%的N2O排放。土壤有机碳、土壤碳氮比和反硝化微生物相对丰度的增加支持了这些减少,特别是在大豆和甘薯轮作中观察到。春玉米轮作和花生轮作由于作物初始氮素吸收量较低和氮素利用效率较低,其排放因子高于传统小麦-玉米轮作。硝化和反硝化过程中微生物群落结构的变化,包括豆类和甘薯轮作中氨氧化细菌MND1和候选亚硝化古菌活性的增加,以及不同轮作中反硝化微生物的转变(红平面减少,副球菌增加),显著促进了所有其他轮作系统排放的总体减少。了解控制农业土壤N2O排放的微生物机制将有助于制定更有效的作物特定策略,以进一步减少温室气体排放。
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引用次数: 0
Effects of fire intensity on carbon dioxide exchange in an arctic dry heath tundra 火灾强度对北极干燥荒原冻土带二氧化碳交换的影响
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-20 DOI: 10.1016/j.agrformet.2024.110362
Wenyi Xu , Per Lennart Ambus
The frequency and intensity of wildfires in the Arctic has been increasing due to climate change. However, little is known about the effects of fire intensity on carbon dioxide (CO2) exchange in arctic tundra ecosystems. To investigate this, we conducted an experimental fire with different burn intensities (low intensity, high intensity, and unburned control) and measured surface daytime CO2 fluxes over four growing seasons in a dry heath tundra in West Greenland. We found that post-fire soil temperatures and moisture increased with increasing fire intensity, by up to 2.2 °C and 18 vol%, respectively. Fire had no effects on soil microbial biomass independent of intensity. The high-intensity fire increased soil nitrate concentrations only immediately after the fire. The ecosystem shifted from a net CO2 sink to a net CO2 source immediately after the fire, due to the reduced gross ecosystem production. One year after the fire, the low-intensity burned plots became a net CO2 sink, while the high-intensity burned plots remained a net CO2 source throughout the study period. This suggests that the time needed for the ecosystem to become a net CO2 sink increases with fire intensity. Fire intensity had no effect on soil respiration, but the high-intensity fire significantly reduced ecosystem respiration (ER) rates one and three years after the fire. This suggests that decreased ER was mainly driven by the reduced aboveground plant respiration. Over four growing seasons after the high-intensity fire, cumulated post-fire C losses exceeded the C losses during the fire. Thus, it is essential to consider the long-term C losses following fire to improve understanding of wildfire impacts on arctic tundra C dynamics. Overall, this study highlights that high-intensity fires prolong the duration of burned areas as a net CO2 source, leading to increased post-fire CO2 emissions, when compared to low-intensity fires.
由于气候变化,北极地区野火的发生频率和强度不断增加。然而,人们对火灾强度对北极苔原生态系统二氧化碳(CO2)交换的影响知之甚少。为了研究这个问题,我们在西格陵兰的干燥石楠苔原上进行了不同燃烧强度(低强度、高强度和未燃烧对照)的实验性火灾,并测量了四个生长季节的地表白天二氧化碳通量。我们发现,火灾后土壤温度和湿度随着火灾强度的增加而上升,上升幅度分别高达 2.2 °C 和 18 vol%。火灾对土壤微生物生物量没有影响,与强度无关。高强度火灾仅在火灾后立即增加了土壤硝酸盐浓度。火灾发生后,由于生态系统总产量减少,生态系统立即从二氧化碳净汇转变为二氧化碳净源。火灾一年后,低强度燃烧的地块变成了二氧化碳净吸收汇,而高强度燃烧的地块在整个研究期间仍然是二氧化碳净来源。这表明,生态系统成为二氧化碳净吸收汇所需的时间随火灾强度的增加而增加。火灾强度对土壤呼吸作用没有影响,但高强度火灾显著降低了火灾后一年和三年的生态系统呼吸率(ER)。这表明ER的降低主要是由地上植物呼吸作用的减少引起的。在高强度火灾后的四个生长季中,火灾后累积的碳损失超过了火灾期间的碳损失。因此,必须考虑火灾后的长期碳损失,才能更好地理解野火对北极苔原碳动态的影响。总之,这项研究强调,与低强度火灾相比,高强度火灾延长了作为二氧化碳净来源的燃烧区域的持续时间,导致火后二氧化碳排放量增加。
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引用次数: 0
On the application of the hockey-stick transition hypothesis to characterize turbulence within and above a deciduous forest 冰球棍过渡假说在描述落叶林中和落叶林中湍流中的应用
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-19 DOI: 10.1016/j.agrformet.2024.110342
Temple R. Lee , Sandip Pal , Praveena Krishnan , Tim B. Wilson , Rick D. Saylor , Tilden P. Meyers , John Kochendorfer , Will Pendergrass , Randy White , Mark Heuer
Turbulence governs many atmospheric processes including mixing, transport, and energy transfer. Consequently, there is a strong need for the examination and validation of existing turbulence theories. The HOckey-Stick Transition (HOST) hypothesis was proposed to challenge traditional understanding of near-surface turbulence processes derived from Monin-Obukhov Similarity Theory (MOST). Within the MOST framework, the momentum flux entirely depends upon U¯/z (i.e., the change in mean wind speed (U¯) with height (z)), but this relationship is not as straightforward under HOST. Because HOST was developed using observations over relatively uniform, homogeneous terrain, questions arise regarding HOST's applicability within and above heterogeneous forest canopies where multi-level turbulence measurements are somewhat rare but are essential for developing a unified similarity scaling applicable over complex surfaces. To this end, we used one year (1 January 2016 through 31 December 2016) of turbulence measurements sampled at eight heights along a 60-m tower within and above a mixed deciduous forest at Chestnut Ridge in eastern Tennessee in the southeastern U.S. We examined the diurnal and seasonal variability of selected turbulence parameters (i.e., friction velocity (u*) and turbulence velocity scale (VTKE)) to detail the micrometeorological characteristics of the site during the study period. We then used these turbulence measurements to evaluate HOST by determining their relationship with U¯ and to assess the dependencies of this relationship on time of day, season, wind direction, and atmospheric stability. We found that HOST is most applicable under very stable regimes, whereas the relationships between u* and U¯, and between VTKE and U¯, were more linear above the forest canopy than within the forest canopy and when the canopy was not foliated. Overall, this work builds upon previous studies that have described limitations in MOST and identifies scenarios when the HOST hypothesis may be more applicable than MOST for representing near-surface turbulence processes.
湍流控制着许多大气过程,包括混合、传输和能量转移。因此,迫切需要对现有的湍流理论进行检验和验证。冰球-棒状过渡(HOST)假说的提出挑战了基于Monin-Obukhov相似理论(MOST)对近地表湍流过程的传统理解。在MOST框架中,动量通量完全取决于∂U¯/∂z∂U¯/∂z(即,平均风速(U¯U¯)随高度(zz)的变化),但这种关系在HOST下并不那么直接。由于HOST是使用相对均匀、均匀地形的观测数据开发的,因此出现了关于HOST在异质性森林冠层内部和上面的适用性的问题,在这些地方,多级湍流测量有些罕见,但对于开发适用于复杂表面的统一相似性尺度至关重要。为此,我们使用了一年(2016年1月1日至2016年12月31日)的湍流测量数据,在美国东南部田纳西州东部的Chestnut Ridge混合落叶林中及其上方60米高塔的八个高度取样。我们检查了选定湍流参数(即摩擦速度(u*u*)和湍流速度尺度(VTKEVTKE))的日变化和季节变化,以详细描述研究期间该地点的微气象特征。然后,我们使用这些湍流测量值通过确定它们与U¯U¯的关系来评估HOST,并评估这种关系与一天中的时间、季节、风向和大气稳定性的依赖关系。我们发现HOST在非常稳定的状态下最适用,而u*u*和u¯u¯之间的关系,以及VTKEVTKE和u¯u¯之间的关系,在森林冠层以上比在森林冠层内和冠层不生叶时更线性。总的来说,这项工作建立在先前研究的基础上,这些研究描述了MOST的局限性,并确定了HOST假设可能比MOST更适用于代表近地表湍流过程的情况。
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引用次数: 0
Changes in leaf and root carbon allocation of global vegetation simulated by the optimally integrated ecosystem models 基于最优整合生态系统模型的全球植被叶片和根系碳分配变化
IF 5.6 1区 农林科学 Q1 AGRONOMY Pub Date : 2024-12-19 DOI: 10.1016/j.agrformet.2024.110366
Zeyu Duanmu , Zaichun Zhu , Weiqing Zhao , Anping Chen , Zhaoqi Wang , Sen Cao , Dajing Li , Yuhang Luo , Ranga B. Myneni
Carbon allocation in vegetation, particularly to leaves and roots responsible for resource assimilation, plays a crucial role in regulating the global carbon cycle and is highly sensitive to environmental changes. However, due to the limited observational data, the response of carbon allocation—particularly between resource-acquiring organs—to rapid global environmental changes remains unclear for global vegetation. State-of-the-art ecosystem models provide valuable insights into the spatiotemporal patterns of carbon allocation across global vegetation. In this study, we developed a weighted model average (WMA) by optimally integrating ecosystem models based on their performance in simulating the spatiotemporal changes in root and leaf carbon. The WMA well captured the satellite-observed leaf carbon trend and the spatial variations in root carbon along climate gradients (R2 = 0.82). The WMA suggested global vegetation has increasingly allocated more carbon to roots than leaves (the trend of allometric scaling relations between leaf and root: 0.0014 ± 0.0013 g g-1 yr-1, p < 0.05) during 1982–2018. Elevated atmospheric CO2 concentration was the dominant driver of changes in root/leaf carbon allocation globally (0.0010 ± 0.0005 g g-1 yr-1, p < 0.05), particularly in tropical regions. Climate change influenced carbon allocation in vegetation differently across regions, contributing to increased root carbon allocation in the Northern Hemisphere and enhanced leaf carbon allocation in tropical areas. Land use change led to more carbon being allocated to leaves than roots (-0.0003 ± 0.0006 g g-1 yr-1, p < 0.05). Overall, we tentatively quantified the changes in the carbon allocation to the leaf and root across global terrestrial vegetation under the dramatic environmental change based on WMA, which helps further understanding of the changes in the functioning of the terrestrial ecosystem and reasonable projection of changes in the future global carbon cycle.
植被的碳分配,特别是负责资源同化的叶和根的碳分配,在调节全球碳循环中起着至关重要的作用,对环境变化高度敏感。然而,由于观测资料有限,全球植被的碳分配,特别是资源获取器官之间的碳分配对全球环境快速变化的响应尚不清楚。最先进的生态系统模型为全球植被碳分配的时空格局提供了有价值的见解。在本研究中,我们基于生态系统模型在模拟根和叶碳时空变化方面的表现,建立了加权模型平均值(WMA)。WMA较好地捕获了卫星观测的叶片碳趋势和根系碳沿气候梯度的空间变化(R2 = 0.82)。WMA表明,全球植被分配给根系的碳越来越多,而不是叶片(叶与根的异速尺度关系趋势:0.0014±0.0013 gg -1年-1,p <;0.05)。大气CO2浓度升高是全球根/叶碳分配变化的主要驱动因素(0.0010±0.0005 g g-1 -1, p <;0.05),特别是在热带地区。气候变化对不同区域植被碳分配的影响不同,北半球根系碳分配增加,热带地区叶片碳分配增强。土地利用变化导致叶片比根系分配更多的碳(-0.0003±0.0006 g g-1 -1, p <;0.05)。总体而言,基于WMA初步量化了剧烈环境变化下全球陆地植被叶片和根系碳分配的变化,有助于进一步认识陆地生态系统功能的变化,合理预测未来全球碳循环的变化。
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引用次数: 0
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Agricultural and Forest Meteorology
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