Agricultural and Forest Meteorology最新文献

{"title":"Global pattern in terrestrial leaf litter decomposition: The effects of climate, litter chemistry, life form, growth form and mycorrhizal association","authors":"Xiaoxiang Zhao ,&nbsp;Qiuxiang Tian ,&nbsp;Anders Michelsen ,&nbsp;Boshen Ren ,&nbsp;Zhiyang Feng ,&nbsp;Long Chen ,&nbsp;Qinghu Jiang ,&nbsp;Rudong Zhao ,&nbsp;Feng Liu","doi":"10.1016/j.agrformet.2024.110368","DOIUrl":"10.1016/j.agrformet.2024.110368","url":null,"abstract":"<div><div>Leaf litter decomposition plays an important role in nutrient and carbon cycling in terrestrial ecosystems. However, at a global scale, the effects of climate, initial litter chemistry, and different plant functional types on litter decomposition are not fully understood. Additionally, it remains unclear whether the effects of litter chemistry on leaf litter decomposition are consistent with responses observed at local scales. Here, 1585 observations of leaf litter decomposition encompassing 861 species from 298 field studies were synthesized to investigate the effects of climate, litter initial chemistry, and various plant groups on decomposition rates. The results demonstrate that at a global scale, leaf litter decomposition rates increased with mean annual temperature (MAT), mean annual precipitation (MAP), initial litter concentrations of nitrogen (N), phosphorus (P), and magnesium (Mg), but decreased with initial lignin concentrations. Moreover, except for initial leaf litter Mg concentrations, the influence of initial leaf litter chemistry characteristics on decomposition rates were consistent at global and local scales. In woody plants, leaf litters from deciduous, broadleaf, and arbuscular mycorrhizal (AM) species exhibited faster decomposition rates than from evergreen, coniferous, and ectomycorrhizal (ECM) species leaf litters, respectively. In herbaceous plants, the leaf litter of forbs had faster decomposition rates than graminoid and leguminous plants. For all plants, leaf litter decomposition is primarily controlled by MAP and MAT globally, while for woody and herbaceous plants, leaf litter decomposition is primarily controlled by initial leaf N and P concentrations, respectively. These results indicated that various functional groups of plants play a crucial role in understanding the decomposition of leaf litter. Moreover, when investigating the effect of leaf litter initial chemistry on its decomposition, it is almost unnecessary to consider effects at different scales.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110368"},"PeriodicalIF":5.6,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823316","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}

{"title":"Risk prediction of Lecanosticta acicola spore abundance in Atlantic climate regions","authors":"David García-García ,&nbsp;Nebai Mesanza ,&nbsp;Rosa Raposo ,&nbsp;Mª Teresa Pascual ,&nbsp;Iskander Barrena ,&nbsp;Amaia Urkola ,&nbsp;Nagore Berano ,&nbsp;Eugenia Iturritxa","doi":"10.1016/j.agrformet.2024.110360","DOIUrl":"10.1016/j.agrformet.2024.110360","url":null,"abstract":"<div><div>Brown spot needle blight disease, caused by the fungus <em>Lecanosticta acicola</em>, affects pine trees across the northern hemisphere. In recent years, its incidence has expanded to new areas and host species. This is in association with climate change. Interest in understanding the basis of its epidemiology and proposing appropriate management measures has also increased. However, there is a lack of studies that characterise the relationship between spore abundance trends and climatic factors, which are essential to understand the spread of the disease. We collected spore abundance data for three years from 16 traps located in pine plantations over the Basque Country (north of Spain), the first European region where <em>L. acicola</em> was detected. A rapid change in pathogen behaviour led to serious financial losses in the forestry sector. We then modelled the relationship between spore abundance and weather variables in terms of generalised additive models. The resulting model was used to estimate the risk of disease spread over the whole area of Basque Country. We also generated a risk projection for the north of the Iberian Peninsula, an area influenced by the Atlantic climate, where the disease is currently causing severe damage. Cumulative rainfall acted as a reliable predictor of the spore abundance of the pathogen; thus, data from weather stations can be directly incorporated into early warning protocols to inform effective preventive actions.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110360"},"PeriodicalIF":5.6,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142820614","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}

{"title":"Effects of elevated ozone on evapotranspiration and energy allocation of rice ecosystem under fully open-air field conditions","authors":"Yujie Zhang ,&nbsp;Jianghua Wu ,&nbsp;Yansen Xu ,&nbsp;Yuqing Zhou ,&nbsp;Shiyun Xu ,&nbsp;Zhaozhong Feng","doi":"10.1016/j.agrformet.2024.110363","DOIUrl":"10.1016/j.agrformet.2024.110363","url":null,"abstract":"<div><div>Evapotranspiration (<em>ET</em>) and its induced perturbations in the surface energy balance have significant impacts on the carbon cycle, water cycle, and regional climate. The partitioning of <em>ET</em> (transpiration (<em>T</em>) and evaporation (<em>E</em>)) has significant implications for agricultural production and water management. Rising tropospheric ozone (O₃) concentrations currently alter leaf stomatal conductance, which may affect <em>ET</em>. Paddy fields are characterized by flooding (during most of the growth period), vigorous crop <em>ET</em>, and a high percentage of <em>E</em> in <em>ET</em>. This may cause differences in the effects of elevated O₃ on the <em>ET</em> in rice fields relative to previously reported dryland crops. Based on 3 years of <em>in-situ</em> observations, this study investigated energy allocation in a rice ecosystem using the energy balance residual method under two O₃ treatments (1.5 times ambient air (AA; E-O₃) and AA) at a Free Air O₃ Concentration Enrichment facility. E-O₃ caused a trend of higher net radiative flux (<em>R</em>_n) and sensible heat flux (<em>H</em>) in rice but only reached statistical significance on some days and at specific growth stages (e.g., jointing or booting) compared with AA. E-O₃ attenuated the degree of response in energy allocation owing to the unique land-use patterns of paddy fields and climatic conditions during rice growth. Based on the modified Priestley–Taylor model, <em>T</em> decreased significantly at the grain-filling stage, and <em>E</em> increased during the full reproductive period, causing a significant increase in <em>ET</em> on some days after exposure to elevated O₃. In conclusion, rice ecosystems have a weaker capacity to influence the water cycle and regional climate than drylands regarding rising O₃ concentrations. However, the effects of E-O₃ on <em>E</em> and <em>T</em> adversely affect the carbon cycle and agricultural production, indicating the need to optimize agricultural water management and cropping strategies under high O₃ concentration region.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110363"},"PeriodicalIF":5.6,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142816216","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}

{"title":"Revisiting snowmelt dynamics and its impact on soil moisture and vegetation in mid-high latitude watershed over four decades","authors":"Dongsheng Li ,&nbsp;Wei Ouyang ,&nbsp;Lei Wang ,&nbsp;Jing Chen ,&nbsp;He Zhang ,&nbsp;Anarmaa Sharkhuu ,&nbsp;Soyol-Erdene Tseren-Ochir ,&nbsp;Yang Yang","doi":"10.1016/j.agrformet.2024.110353","DOIUrl":"10.1016/j.agrformet.2024.110353","url":null,"abstract":"<div><div>Snowmelt is a critical water supply that affects the environmental security and sustainable development. However, the dynamic contributions of climatic factors to snowmelt and their impacts on soil moisture (SM) and vegetation growth remain unclear. In this study, by combining changes in spring snowmelt (snow water equivalent), climatic factors (precipitation and temperature), SM, and vegetation growth (normalized difference vegetation index [NDVI]) during 1982–2018, the spatiotemporal patterns in snowmelt and its mutual effects on SM and NDVI in a mid-high latitude watershed (Mongolia) were investigated. The results showed that spring snowmelt has decreased (-0.54 m/yr, <em>p</em> &lt; 0.05) in Mongolia, with cold season temperature and precipitation identified as key influencing factors. The negative association between cold season temperature and snowmelt is intensifying (-0.0010 mm/yr, <em>p</em> &gt; 0.05), while the positive influence of cold season precipitation is weakening (-0.0004 mm/yr, <em>p</em> &gt; 0.05). Additionally, snowmelt provides 30 % of SM, and rising spring temperatures, along with reduced snowmelt, is the main reasons for SM decline (0.001 m³/m³/yr, <em>p</em> &lt; 0.05). The negative impact of spring temperature on SM is growing (-0.0029 %/yr, <em>p</em> &lt; 0.05), while snowmelt's positive contribution is diminishing (-0.0011 %/yr, <em>p</em> &lt; 0.05). Furthermore, spring temperature has the strongest direct effect (positive) on vegetation, while SM exerts the greatest total influence (positive). Snowmelt indirectly affects (positive) vegetation through its role in SM. Despite vegetation increased in 60.5 % of the area, the declining trends in SM and snowmelt, alongside the reduced contribution of SM to vegetation (-0.0028/yr, <em>p</em> &lt; 0.05), suggest an increased risk of future drought. Overall, this study provides new insights into the dynamics and interrelationships between snowmelt, SM, and vegetation in mid-to-high latitude regions, offering valuable implications for sustainable development decision-making.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110353"},"PeriodicalIF":5.6,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142816215","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}

{"title":"Understanding the impacts of extreme temperature and humidity compounds on winter wheat traits in China","authors":"Tengcong Jiang ,&nbsp;Liang He ,&nbsp;Hao Feng ,&nbsp;Jianqiang He ,&nbsp;Qiang Yu","doi":"10.1016/j.agrformet.2024.110354","DOIUrl":"10.1016/j.agrformet.2024.110354","url":null,"abstract":"<div><div>Climate change has heightened the occurrence of extreme compound events, yet their impacts on crop yield traits and the variations in yield sensitivity among different varieties and management practices remain elusive. Utilizing long-term (1981–2010) wheat trait data of 85 stations administered by the China Meteorological Center (CMC) for various wheat varieties and sowing dates, we employed a linear mixed models to explore the effects of extreme atmospheric temperature and humidity compound events on wheat. Our findings revealed that the yield loss (23.24 ka ha^-1 dec^-1) was primarily driven by an increasing trend (0.25 ∼ 1.50 day dec^-1) in hot-dry days (HDD) during 1981–2010. Additionally, cold-wet days (CWD: -1.75 % per standard unit) and hot-dry days (HDD: -1.90 % per standard unit) showed similar adverse effects on yield. This similarity is primarily due to their comparable negative impacts on grain growth, with reductions in grain weight (-1.82 % for CWD and -1.65 % for HDD) and grain filling rate (-1.56 % for CWD and -1.27 % for HDD) during the heading and maturity stages of wheat. However, CWD dominated the unfavorable effects on grain number (-1.18 % ∼ -0.22 %). Canopy height and ear density were more susceptible to early extreme climatic factors. In addition, yield losses under early maturing varieties and late sowing measures were less sensitive to extreme climates. Our findings emphasize the negative impacts on yield compositions, but different changes in wheat yield under different varieties and sowing caused by CWD and HDD. Our findings could assist modelers in comprehending how extreme weather affects agricultural production, particularly in terms of variations in crop trait responses.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110354"},"PeriodicalIF":5.6,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142809816","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}

{"title":"Unlocking the potential of Airborne LiDAR for direct assessment of fuel bulk density and load distributions for wildfire hazard mapping","authors":"Olivier Martin-Ducup ,&nbsp;Jean-Luc Dupuy ,&nbsp;Maxime Soma ,&nbsp;Juan Guerra-Hernandez ,&nbsp;Eva Marino ,&nbsp;Paulo M. Fernandes ,&nbsp;Ariadna Just ,&nbsp;Jordi Corbera ,&nbsp;Marion Toutchkov ,&nbsp;Charlie Sorribas ,&nbsp;Jerome Bock ,&nbsp;Alexandre Piboule ,&nbsp;Francesco Pirotti ,&nbsp;François Pimont","doi":"10.1016/j.agrformet.2024.110341","DOIUrl":"10.1016/j.agrformet.2024.110341","url":null,"abstract":"<div><div>Large-scale mapping of fuel load and fuel vertical distribution is essential for assessing fire danger, setting strategic goals and actions, and determining long-term resource needs. The Airborne LiDAR system can fulfil such goal by accurately capturing the three-dimensional arrangement of vegetation at regional and national scales.</div><div>We developed a novel method to estimate multiple metrics of fuel load and vertical bulk density distribution for any type of vegetation. The approach uses Beer-Lambert law for inverting the ALS point cloud into vertical plant area density profiles, which are converted into vertical bulk density distribution profiles using species-specific plant traits. The approach is evaluated by comparing ALS-based vegetation profiles and fuel metrics with field-based data from southeastern France, Spain, and Portugal for a range of vegetation types.</div><div>ALS-based and field-based vertical vegetation profiles were consistent. The range of values of fuel load metrics was also consistent with field data. Good correlations and low bias were attained for simple stratified structure with R² of 0.6, 0.42 and 0.68 and bias of -5 %, -2 % and -3.3 % for canopy base height, canopy fuel load, and canopy bulk density respectively. However, correlations were low for complex vertical structures. The use of species-specific plant traits appeared relevant by lowering the deviation between field and ALS-based values for most species.</div><div>Our field-independent fuel metric estimation shows comparable performance to results in the literature based on classification approaches trained on field metrics, highlighting the generality of our direct approach. We demonstrated how our approach is more relevant than field data for defining vertical vegetation strata in complex forest structures. We showed an application of the methods by mapping multiple metrics at regional scale (6343 km²) such as canopy base height, fuel strata gap, and canopy and understory fuel loads. Our approach is adequate for feeding next generation models of wildfire risk assessment systems, enhanced by more flexible and accurate fuel data than the existing fuel typologies.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110341"},"PeriodicalIF":5.6,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142809815","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}

{"title":"Freeze-thaw processes alter the peak characteristics and temperature hysteresis of diel soil respiration in a Tibetan alpine steppe","authors":"Jianxin Zhang ,&nbsp;Liang Tang ,&nbsp;Xiaodan Wang","doi":"10.1016/j.agrformet.2024.110358","DOIUrl":"10.1016/j.agrformet.2024.110358","url":null,"abstract":"<div><div>Freeze-thaw (F-T) processes are prevalent and have the inherent potential to alter soil respiration (SR) in cold regions, which are particularly sensitive to climate warming and contribute a large uncertainty to the global carbon budget. However, the impacts of F-T processes on the diel pattern and temperature hysteresis of SR remain unclear. In this study, the Fick's law-based gradient method was employed to obtain high-temporal-resolution SR data, and a four-parameter Gaussian function was used to quantify the diel pattern of SR. The results demonstrate that the magnitude and timing of the daily SR peak exhibit considerable variability across different F-T stages, leading to a delay in the optimal time window for measuring the daily mean SR during the freezing and frozen stages. Furthermore, the daily peak value of SR is primarily regulated by soil temperature (ST) during the thawed period, whereas soil water content (SWC) exerts a more pronounced effect than ST throughout the entire freezing-frozen-thawing period. The diel hysteresis between SR and ST was observed year-round, but its direction was reversed by F-T processes. Additionally, the magnitude of the temperature hysteresis was negatively correlated with SWC. These findings have important implications for understanding the mechanisms driving SR variability and improving the accuracy of annual carbon budget estimates in cold regions.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110358"},"PeriodicalIF":5.6,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804642","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}

{"title":"How did the regional water-heat distribution in oasis area vary with the different spatial patterns and structures of shelterbelt system—A case study in Ulan Buh desert oasis","authors":"Feng Gao ,&nbsp;Kexin Lv ,&nbsp;Qun'ou Jiang ,&nbsp;Huijie Xiao ,&nbsp;Junran Li","doi":"10.1016/j.agrformet.2024.110345","DOIUrl":"10.1016/j.agrformet.2024.110345","url":null,"abstract":"<div><div>The shelterbelts system is crucial for the regional surface water and heat process, which is important for the oasis ecological environment. In this study, Ulan Buh Desert Oasis was taken as the study area. To overcome the problem of inherent water and heat difference between oases and deserts, this study divided the oasis ring structure into shelterbelt-farmland-urban zone, shrub grassland zone and desert zone. Firstly, the instant latent heat flux (LE), regarded as the link between water and heat, was estimated by the Two-Source Energy Balance (TSEB) model. Then, four landscape indexes were applied to quantify the shelterbelts spatial pattern. Finally, the Cooling Capacity Index (CCI) was proposed, and the influence of spatial pattern and shelterbelt structure on LE and CCI was explored. The results showed that, the high-LE area distribution was highly consistent with the shelterbelt system, and the LE temporal variation inside the oasis was more stable than outside. Besides, the 5 km shrub grassland combined with more than the 5 km shelterbelt near the desert area can bring about a rapid increase in the LE and generate cooling capacity. Meanwhile, in shelterbelt-farmland-urban zone, the LE was negatively correlated with patch shape regularity (SHAPE) and shelterbelt area (PLAND), and was positively correlated with the shape of the whole shelterbelt landscape (nLSI). In shrub grassland zone, the LE was negatively correlated with SHAPE and shelterbelts patches connectance (CONNECT), and was positively correlated with nLSI and PLAND. In desert zone, LE was only positively correlated with PLAND. To achieve more cooling effects, it is recommended that i) in shelterbelt-farmland-urban zone, use multi-row shelterbelt that the patches are with large area and complex shape consists of multiple belts and multiple networks (high PLAND and SHAPE), and densely clustered shelterbelt patches (low nLSI); ii) in shrub grassland zone, use the same spatial pattern as in shelterbelt-farmland-urban zone (low nLSI, high PLAND and high SHAPE), but replaced with the two-row shelterbelt; iii) in desert zone, use a large area of the two-row shelterbelt.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110345"},"PeriodicalIF":5.6,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804645","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}

{"title":"Interactive effects of management and temperature anomalies on CO2 fluxes recorded over 18 years in a temperate upland grassland system","authors":"Bruna Winck,&nbsp;Katja Klumpp,&nbsp;Juliette M.G. Bloor","doi":"10.1016/j.agrformet.2024.110343","DOIUrl":"10.1016/j.agrformet.2024.110343","url":null,"abstract":"<div><div>Temperature anomalies such as heat waves and cold spells are increasingly common, posing threats to ecosystem functioning and delivered services. Although temperature anomalies have been shown to limit broad-scale patterns of carbon sequestration, fine-scale studies on CO₂ fluxes and temperature anomalies are limited and interactions between temperature anomalies and agricultural management remain poorly understood. Using long-term data on grassland CO₂ fluxes and air temperature (2003-2021), we investigated the effects of temperature anomalies (cold, warm, extreme cold, extreme warm) on gross primary productivity and ecosystem respiration in adjacent upland mesic grasslands subjected to either extensive or intensive cattle grazing management treatments. Both warm and cold temperature anomalies occurred throughout the study period, with 40 days per year on average classed as colder or warmer compared to normal. Irrespective of management treatment and flux type, we found that temperature anomalies had a significant effect on the magnitude of CO₂ fluxes, the relationship between air temperature and CO₂ fluxes, and the occurrence of anomalous flux events. The magnitude of CO₂ fluxes was most affected by temperature anomalies at the start of the growing season, and fluxes were generally more sensitive to warm rather than cold temperature anomalies. However, cold temperature anomalies promoted asynchrony between C uptake and loss. Temperature-CO₂ flux relationships were upregulated by warm temperature anomalies in spring but down-regulated in summer and autumn, with greater reductions in flux process rates in the intensive management treatment. Nevertheless, temperature anomalies were not found to be a strong driver of flux anomalies in this study system. Collectively, our results show that grassland management interacts with the timing and nature of temperature anomalies on CO₂ fluxes and suggest that low grassland management intensity may buffer CO₂ fluxes against warm air temperature anomalies in cool temperate systems, with implications for adaptation strategies for grasslands under climate change.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110343"},"PeriodicalIF":5.6,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142789838","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}

{"title":"Towards an enhanced metric for detecting vertical flow decoupling in eddy covariance flux observations","authors":"Olli Peltola ,&nbsp;Toprak Aslan ,&nbsp;Mika Aurela ,&nbsp;Annalea Lohila ,&nbsp;Ivan Mammarella ,&nbsp;Dario Papale ,&nbsp;Christoph K. Thomas ,&nbsp;Timo Vesala ,&nbsp;Tuomas Laurila","doi":"10.1016/j.agrformet.2024.110326","DOIUrl":"10.1016/j.agrformet.2024.110326","url":null,"abstract":"<div><div>The eddy covariance (EC) technique has emerged as the method of choice for observing ecosystem–atmosphere interactions across biomes and climate zones. However, EC measurements are biased when the turbulent flow is decoupled from the underlying surface, severely limiting the applicability of the technique in observing surface–atmosphere fluxes. Friction velocity (<span><math><msub><mrow><mi>u</mi></mrow><mrow><mo>∗</mo></mrow></msub></math></span>) is typically used to detect and filter these periods from EC flux time series. The processes that control decoupling are understood qualitatively, including the strength of vertical turbulent mixing, stable stratification and canopy drag. However, the standard practice utilising <span><math><msub><mrow><mi>u</mi></mrow><mrow><mo>∗</mo></mrow></msub></math></span> misses most of these processes, resulting in a significant uncertainty in detecting decoupling. Consequently, a quantitative metric, <span><math><mi>Ω</mi></math></span>, which encapsulates all these processes in a unified framework, was recently proposed. However, it has not yet been systematically tested over a range of ecosystems and site characteristics. The objectives of this study were therefore to test the efficacy of <span><math><mi>Ω</mi></math></span> at a diverse range of EC sites, to quantify the processes controlling decoupling across sites, and to compare <span><math><mi>Ω</mi></math></span> against other decoupling metrics, such as <span><math><msub><mrow><mi>u</mi></mrow><mrow><mo>∗</mo></mrow></msub></math></span>. A similar <span><math><mi>Ω</mi></math></span> threshold value for coupling was observed at all the 45 tested EC sites, with a value of 0.59 (median; 0.5...0.63 interquartile range). This indicates that the <span><math><mi>Ω</mi></math></span> metric captured the essential features of decoupling across sites, thereby enabling deeper analyzes of the causes of decoupling. For example, <span><math><mi>Ω</mi></math></span> indicates that (1) flows above dense forest canopies can be decoupled from the forest floor also during the daytime due to canopy drag and that (2) during stable stratification decoupling is more likely with tall towers. These findings significantly enhance our scientific understanding of the underlying causes of decoupling, will inform improved analyzes of EC data and support near-surface turbulence transport analyzes in open and forested landscapes.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"362 ","pages":"Article 110326"},"PeriodicalIF":5.6,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142782977","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}