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Publisher: Elsevier   (Total: 3181 journals)

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Showing 1 - 200 of 3181 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 39, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 26, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 105, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 42, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 7)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 444, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 30, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 5, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 320, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 26, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 18, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 11, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 23)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 188, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 12, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 17, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 30, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 12, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 15, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 34, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 5)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 29, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 11, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 26, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 15)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 13)
Advances in Digestive Medicine     Open Access   (Followers: 12)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 29, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 52, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 67, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 21, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 7, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 26, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 3, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 9, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 21, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 15, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 8, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 25)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 5)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 27, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 19)
Advances in Pharmacology     Full-text available via subscription   (Followers: 17, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 68)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 2, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 424, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 38, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 54, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 385, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 12, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 483, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 32, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 45, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 8, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 12)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 11, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 54, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 58, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 66, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 47, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 13)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 37, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 29, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 36, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 50)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 267, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 32, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 28, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 67, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 25, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 5, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 211, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 25, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 227, SJR: 1.58, CiteScore: 3)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 7, SJR: 0.937, CiteScore: 2)
Animal Reproduction Science     Hybrid Journal   (Followers: 7, SJR: 0.704, CiteScore: 2)

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Similar Journals
Journal Cover
Agricultural and Forest Meteorology
Journal Prestige (SJR): 1.818
Citation Impact (citeScore): 5
Number of Followers: 18  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0168-1923
Published by Elsevier Homepage  [3181 journals]
  • Partitioning evapotranspiration and its long-term evolution in a dry pine
           forest using measurement-based estimates of soil evaporation
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Rafat Qubaja, Madi Amer, Fyodor Tatarinov, Eyal Rotenberg, Yakir Preisler, Michael Sprintsin, Dan YakirAbstractThe future of forests and their productivity in dry environments will depend on both water availability through precipitation and ecosystem and plant water use characteristics. It is increasingly recognized that better understanding water use patterns and their response to change depends on our ability to partition evapotranspiration (ET). Here, we use chamber-based direct measurements of soil evaporation (Es) in a semi-arid Pinus halepensis forest to partition ET to Es and tree transpiration (Et), to assess the daily and seasonal changes and to compare annual-scale values with measurements carried out at the same site ten years earlier. The ecosystem is characterized by a high annual Es/ET ratio of 0.26, and an Et/ET of 0.63. Es diminished in the long dry season, but as much as 74 ± 5% of the residual flux was due to the re-evaporation of nighttime moisture adsorption, which may provide critical protection from soil drying. Over the 10 years observation period concurrent increase in the transpiration ratio (TR=Et/ET; +29%) and in leaf area index (LAI; +44%) were observed, with the ratio of TR/LAI remaining constant at ~0.31, and with persistently closed hydrological balance (ET/P of 0.94–1.07). The observed Et/ET values are similar to the estimated global mean values, but are attained at a much higher aridity index (5.5) than the mean one, demonstrating the potential for expanding forestation into dry regions.
  • A parametric empirical Bayes (PEB) approach for estimating maize progress
           percentage at field scale
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Mahdi Ghamghami, Nozar Ghahreman, Parviz Irannejad, Hamid PezeshkAbstractThe Crop Progress Percentage (CPP) in a given phenology stage reflects growth status in the crop life cycle. Generally, routine field measurements of this variable are missing, hence various alternative approaches have been proposed for its estimation. Hidden Markov Models (HMMs) which follow the Bayesian structure are helpful tools for this aim. In the current study, an approach based on the parametric empirical Bayes (PEB) method is used for more accurate estimation of the maize CPP at field scale. The CPP information recorded in three experiment sites i.e. Karaj, Darab and Zarghan were used to validate the performance of the PEB method and to test the robustness. The PEB method includes a non-homogeneous HMM along with an empirical method based on fitting a gamma probability density function (PDF) on prior probabilities. Temporal sequence of phonological stages is regarded as the hidden layer and temporal sequence of NDVI and AGDD indices as the observable layer. The procedure of CPPs estimation is based on calculation of prior and posterior probabilities and an inverse normalization. The overall RMSE of the non-homogeneous HMM before applying the empirical method was 15.1, 11.5 and 7.8% for Karaj, Darab and Zarghan, respectively. However, it was found that the applied HMM fails to estimate the CPPs of final phenological stages accurately. The averaging process of the prior probabilities does not include the errors produced by factors such as climate variability or farming practices. To overcome these problems, we used an empirical Bayes method to estimate the hyperparameters of a gamma density function which was applied as a prior density. This simple approach to maintain the inter-annual variability due to non physiological factors, made the prior probabilities more flexible. The applied empirical Bayes approach (PEB) had significantly smaller RMSE (8, 7.5 and 6.4%, respectively); especially in final phenological stages, and led to more accurate prediction of the phenological dates. The findings derived by PEB are more consistent with those obtained by HMM when the inter-annual variability, mainly date of sowing, is minimum (Specifically, for Zarghan station). The proposed modified approach can be recommended for use at the field scale and serve as a promising tool especially in the regions which suffer the inter-annual variability.
  • Divergent responses of spring phenology to daytime and nighttime warming
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Lin Meng, Yuyu Zhou, Xuecao Li, Ghasserm R. Asrar, Jiafu Mao, Alan D. Wanamaker, Yeqiao WangAbstractSpring phenology (i.e., start of season, SOS) of plants in temperate regions has shifted earlier in response to increasing temperature. However, the respective influences of daytime and nighttime warming on the changes in SOS remain poorly understood although an ongoing asymmetric diurnal warming has been observed. In this study, we characterized the responses of satellite-derived SOS to daily minimum temperature (Tmin) and maximum temperature (Tmax) across Appalachian Trail regions in the Eastern United States between 2001 and 2013 using a partial correlation analysis. We found that the partial correlation coefficients between SOS and Tmin(RSOS−Tmin) are opposite in sign compared to that between SOS and Tmax(RSOS−Tmax) in 81.5% of study area. Furthermore, we found a significant decrease in RSOS−Tmin and an increase in RSOS−Tmax from cold to warm regions (P 
  • Transpiration and canopy conductance dynamics of Pinus sylvestris var.
           mongolica in its natural range and in an introduced region in the sandy
           plains of Northern China
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Lining Song, Jiaojun Zhu, Xiao Zheng, Kai Wang, Linyou Lü, Xiaolin Zhang, Guangyou HaoAbstractDetermining changes in tree transpiration and its controlling mechanisms from regions of natural distribution to planted introduction are significantly important for afforestation and forest management. Here, transpiration and canopy conductance of Mongolian pine (Pinus sylvestris var. mongolica) in natural forest (MNF) of the natural distribution region and in plantation forest (MPF) and forest-grassland (MFG) of the planted introduction region were quantified by sap flow measurements and concurrent environmental observations. The results showed that the canopy transpiration per unit leaf area (EL) averaged 1.0, 1.4, and 1.7 mm d−1 for MNF, MPF, and MFG, respectively, indicating that the transpiration rate of trees significantly increased from natural to introduction regions due to higher evaporative demand and canopy conductance. However, the significantly lower EL in MPF than in MFG was due to the higher tree density at the old stand at the MPF site. The vapor pressure deficit (VPD) explained the slightly greater variability of daily EL than solar radiation for MPF, indicating that the transpiration of MPF was limited more by VPD than radiation. Canopy conductance (GL) averaged 104.6, 109.9 and 132.2 mmol m−2s−1 for MNF, MPF, and MFG, respectively. Moreover, GL significantly declined with VPD, but the reference canopy conductance was lower in MNF and MPF than in MFG, indicating that MNF and MPF had relatively lower stomatal conductance sensitivities to VPD. These findings suggested that plantation forest had a high transpiration rate but relatively loose stomatal regulation upon water loss; thus, it was more susceptible to dieback during extreme drought years.
  • Combined TBATS and SVM model of minimum and maximum air temperatures
           applied to wheat yield prediction at different locations in Europe
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Magdalena Gos, Jaromir Krzyszczak, Piotr Baranowski, Małgorzata Murat, Iwona MalinowskaAbstractThis paper explores the idea of combining Trigonometric Exponential Smoothing State Space model with Box-Cox transformation, ARMA errors, Trend and Seasonal Components (TBATS) with Support Vector Machine (SVM) model to estimate time series of the minimum and maximum daily air temperatures in a period of six years for various climatic localizations in Europe. It was found that a combined SVM/TBATS model can predict not only seasonality but also local temperature variation between subsequent days observed in daily data. Because the SVM sub-model uses not only results of TBATS prediction as an input data, but also several meteorological values, such modelling cannot be treated as a future time series estimation. Therefore, it has a potential to be used for filling gaps in the air temperature data. As is shown in our results, the precision of air temperature prediction improves when using the combined SVM/TBATS modelling, compared with pure TBATS or SVM modelling. For various locations, which can be related with different climatic conditions, this improvement ranged from 3% up to 14% for the maximum daily air temperature and from 5% to 25% for the minimum daily air temperature. The temperature sums calculated on the base of air temperatures predicted with SVM/TBATS models and from measured values did not differ more than 300 °C (less than 1 °C per day) in majority of cases. The average error in wheat yield prediction by WOFOST and DNDC models did not exceed 12.8% and 13.3%, respectively.
  • An optimal ensemble of the Noah-MP land surface model for simulating
           surface heat fluxes over a typical subtropical forest in South China
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Ming Chang, Wenhui Liao, Xuemei Wang, Qi Zhang, Weihua Chen, Zhiyong Wu, Zechao HuAbstractAccurate estimation of land surface heat fluxes is critical to climate and air quality forecasting, which needs an appropriate parameterization in land surface models. The benchmarking method was applied to search for the optimal combination of the physical parameterization based on Noah land surface model with multi-physics options (Noah-MP). The effect of integrated physical mechanisms on the simulation of land surface energy fluxes in a typical subtropical forest (Dinghushan Forest Ecosystem Research Station) over South China is further investigated. The most sensitive process is the soil moisture threshold for evaporation while there are six processes have little or no effect on heat simulation. The optimal combination options are referred as follow: prescribed table leaf area index (LAI) and vegetation fraction, Jarvis scheme for canopy stomatal resistance, Noah soil moisture scheme, SIMGM model for runoff and groundwater, original Noah consistent scheme for surface layer drag coefficient and two-stream applied to grid-cell scheme for radiation transfer.
  • Quantitative analysis of agricultural drought propagation process in the
           Yangtze River Basin by using cross wavelet analysis and spatial
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Ronghui Li, Nengcheng Chen, Xiang Zhang, Linglin Zeng, Xiaoping Wang, Shengjun Tang, Deren Li, Dev NiyogiAbstractIt is important to understand the propagation of an agricultural drought, which is crucial for early warning. Recent studies have partly revealed this hidden process and regarded it as another critical feature of drought, but the relevant studies are still limited. Here, we propose a quantitative method to explore the full propagation process of agricultural drought by using cross-wavelets combined with multiple drought indices and spatial autocorrelation methods. The Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), Standardized Soil Moisture Index (SSI) and Vegetation Health Index (VHI) were adopted to characterize meteorological, hydrological, soil moisture and vegetation droughts, respectively. The propagation time of agricultural drought was investigated by the cross wavelet analysis. The spatial relationship of those droughts was examined by spatial autocorrelation method. Results demonstrated that the propagation time was within one month from meteorological to hydrological drought, and within two months from hydrological to soil moisture drought, and between two to three months from hydrological to vegetation drought in most areas of Yangtze River Basin, respectively. It was also found the meteorological and hydrological droughts, hydrological and soil moisture droughts, hydrological and vegetation droughts were all characterized by statistical linkages on both long and short time scales. The global Moran's Index of SPI, SRI and SSI were higher than 0.7 and the local Moran's Index were mainly High-High and Low-Low clustering, indicating those subtype droughts were closely associated with the neighboring regions. This study clearly revealed the full propagation of agricultural drought in Yangtze River Basin both from spatial and temporal perspective for the first time, which provides valuable knowledge for understanding and predicting agricultural drought.
  • Identifying large fire weather typologies in the Iberian Peninsula
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Marcos Rodrigues, Ricardo M. Trigo, Cristina Vega-García, Adrián CardilAbstractThe catastrophic events occurred in the Mediterranean basin in the last two decades have made large fires an increasingly prominent feature in the characterization of fire regimes. Large fires have turned forest and fire management focus to landscape fuels and extreme meteorological conditions at different spatial and temporal scales, since understanding fire-weather relations is essential to protect lives and assets from severe fires. For instance, synoptic conditions leading to anomalous and sudden warm episodes quickly increase fine fuel dryness, antecedent and persistent drought events decrease the moisture of coarse fuels, whereas strong winds increase fire spread by transferring heat to new burnable fuels more rapidly, or allowing spotting. ‘Aggregate’ indexes based on local meteorological variables like the Canadian Fire Weather Index (FWI) have proved useful in estimating and summarizing fire danger into straightforward numerical representations, with the caveat that a same result may be produced by different combinations of weather variables. Analyzing fire-weather and danger components separately may help to understand the relative importance of each factor, or reveal specific interactions between them that trigger specific fire typologies (i.e. wind-driven). In this work we analyzed the influence of two FWI's components and their input weather variables in large fire incidence across the entire Iberian Peninsula. We explored several spatial (four regions) and temporal (three levels of aggregation, i.e., daily, weekly and monthly) aggregations to account for potential dissimilarities on fire-weather associations in space and time. Statistical analyses involved a multi-group PCA analysis to identify large fire-weather typologies (LFWT), later submitted to optimized hierarchical clustering to reveal underlying associations among LFWT. Results revealed four distinctive LFWT, labelled: ‘heat-driven’, ‘heat wave’, ‘seasonal drought’ and ‘wind-driven’, and six cluster associations with noticeable spatial differences. The bulk of fires started in the vicinity of the ‘Sierra de Estrela’ (Portugal), under average conditions of the four typologies, but leaning towards ‘seasonal drought’ conditions. Fires in the Mediterranean side, the largest within the IP, were associated to hot and dry spells (‘heat wave’) without remarkable drought events. Most relevant combinations of LWTs included temperature, wind speed and DC at daily and monthly scale, making them the main fire-weather factors driving large fires in the Iberian Peninsula.
  • Small wetted proportion of drip irrigation and non-mulched treatment with
           manure application enhanced methane uptake in upland field
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Chaobiao Meng, Fengxin Wang, Kaijing Yang, Clinton C. Shock, Bernard A. Engel, Youliang Zhang, Lijia Tao, Xiaoxiao GuMethane oxidation in upland areas plays a critical role in the global methane budget. A three-year field experiment was conducted to investigate the effects of two soil surface treatments including soil covered with black plastic film mulch (BM) and non-mulched treatment (NM), three fertilizer treatments including chemical NPK fertilizer (CF), cattle manure (CM) and their combined application of 50% chemical NPK fertilizer and 50% cattle manure (CF+CM), and three soil wetted proportion levels under drip irrigation including: 35% (P1), 55% (P2) and 75% (P3) on methane oxidation in potato field in the arid area of northwestern China. Results showed that seasonal cumulative methane uptake value was 1.1–4.9 kg hm−2 in potato upland fields. BM treatment decreased seasonal cumulative methane uptake by 17%–50% compared to NM treatment through increasing average soil temperature by 2.0–2.5 °C, increasing average irrigation interval by 0–15% and its barricade effect of gas exchange. CM treatment increased seasonal cumulative methane uptake by 7%–9% and 14%–108% in contrast to CF+CM treatment and CF treatment, respectively, due to the low nitrogen content under CM treatment. Different soil wetted proportions didn't significantly affect methane oxidation, while 35% of soil wetted proportion had the greatest methane oxidation rate. Methane flux was quadratically correlated (p = 0.001) to soil matric potential, and the optimal soil matric potential for methane oxidation was −24 kPa. In summary, this study investigated methane uptake in potato farmland contributing to methane flux budget estimation. Manure applied without mulch had more advantage on methane oxidation, and a soil wetted proportion level of 35% was recommended in this study, for favorable for methane oxidation.Graphical abstractImage, graphical abstract
  • Projected crop water requirement over agro-climatically diversified region
           of Pakistan
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Sajjad Haider, Kalim UllahAbstractContinuously increasing evapotranspiration and seasonal water demands of crops due to rise in temperature are adversely affecting the agricultural activities around the world. In this study, projected crop water requirement (CWR) for Rabi (winter) and Kharif (summer) seasons have been analyzed over an agro-climatically diversified region of Pakistan in South Asia for 21st century. The output dataset from the Coordinated Regional Climate Downscaling Experiment (CORDEX) for South Asia, under two emission scenarios (RCP 4.5 and RCP8.5) have been used for three future time slices i.e. near future (2011–2040), mid future (2041–2070) and far future (2071–2100), respectively. Results indicate that future CWR is very high over southern parts of Pakistan and continuously increasing over the entire region, whereas significant CWR increase was observed for the months of August to November over northern and southern parts during the near future. The highest significant increase in CWR rate was recorded in August (0.24 mm/day) and September (0.22 mm/day) over the both parts of Pakistan during near and mid future under RCP4.5 at 95% confidence level. Similarly, highest significant increase in CWR rate was also observed in August (0.56 mm/day) and March (0.30 mm/day) over both parts of the country during mid future under RCP8.5. The projected seasonal CWR indicated significant increase under RCP4.5 for Kharif (0.87 mm/day) and Rabi seasons (0.43 mm/day) over the entire country during near future; whereas, it increased by 0.97 mm/day for both seasons under RCP 8.5 over the whole country during mid future. Hence, this study provides the useful information to water resource managers, agriculturists, agronomists, farmers and policy makers in order to develop an efficient contingency plan for crop water stress and to set the foundation of climate smart agriculture towards sustainable development in agriculture and water sectors of the region.
  • On the surface energy balance closure at different temporal scales
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Andrey A. Grachev, Christopher W. Fairall, Byron W. Blomquist, Harindra J.S. Fernando, Laura S. Leo, Sebastián F. Otárola-Bustos, James M. Wilczak, Katherine L. McCaffreyAbstractMeasurements of the surface energy fluxes (turbulent and radiative) and other ancillary atmospheric/soil parameters made in the Columbia River Basin (Oregon) in an area of complex terrain during a 10-month long portion of the second Wind Forecast Improvement Project (WFIP 2) field campaign are used to study the surface energy budget (SEB) and surface fluxes over different temporal scales. This study analyzes and discusses SEB closure based on half-hourly, daily, monthly, seasonal, and sub-annual (~10-month) temporal averages. The data were collected over all four seasons for different states of the underlying ground surface (dry, wet, and frozen). Our half-hourly direct measurements of energy balance show that the sum of the turbulent sensible and latent heat fluxes systematically underestimate positive net radiation by around 20–30% during daytime and overestimate negative net radiation at night. This imbalance of the surface energy budget is comparable to other terrestrial sites. However, on average, the residual energy imbalance is significantly reduced at daily, weekly, and monthly averaging timescales, and moreover, the SEB can be closed for this site within reasonable limits on seasonal and sub-annual timescales (311-day averaging for the entire field campaign dataset). Increasing the averaging time to daily and longer time intervals substantially reduces the ground heat flux and storage terms, because energy locally entering the soil, air column, and vegetation in the morning is released in the afternoon and evening. Averaging on daily to sub-annual timescales also reduces random instrumental measurement errors and other uncertainties as well as smooths out a hysteresis effect (phase lag) in the SEB relationship between different components. This study shows that SEB closure is better for dry soils compared to wet soils and the statistical dependence of the turbulent fluxes and net radiation for freezing soil surfaces appears weak, if not non-existent, apparently due to lack of the latent heat of fusion term in the traditional SEB equation.
  • Stemflow contributions to soil erosion around the stem base under
           simulated maize-planted and rainfall conditions
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Longshan Zhao, Qian Fang, Ye Yang, Hao Yang, Tonghang Yang, Hao ZhengAbstractStemflow is a primary pathway through which rainwater reaches the ground surface under crop cover. Substantial research suggests that stemflow amounts approach or exceed half the total precipitation on maize cropland; however, few studies have quantified the effect of stemflow on soil erosion during rainfall events. This study aimed to measure the effect of stemflow on soil erosion under controlled situations and determine the effects of stemflow on soil erosion. Maize stems were simulated using a 2-cm diameter PVC tube in 1.3 by 0.25 m steel boxes to introduce stemflows to the soil surface at a 10° slope. The rainfall intensities were 60, 90 and 120 mm/h; the stemflow amounts were 5, 10 and 15 g/s. The results showed that stemflow significantly increased soil erosion. As stemflow increased, the surface runoff and sediment rates sharply increased. Compared with a control slope (no stemflow), stemflow increased the surface runoff and sediment rates by more than three and twelve times, respectively. This result occurred because stemflow contributes to the formation of concentrated flows, which easily trigger rill erosion around the stem base. The sediment rate further increased with rill development. Soil erosion was small if stemflow did not occur during a rainfall event; otherwise, soil erosion was extensive due to stemflow-induced rill erosion. Our results provide new insights for the analysis of crop cover effects and soil erosion on cultivated lands. For maize-planted slopes, stemflow may also be indispensable when determining the soil erosion amount.
  • Contrasting microclimates among hedgerows and woodlands across temperate
    • Abstract: Publication date: 15 February 2020Source: Agricultural and Forest Meteorology, Volume 281Author(s): Thomas Vanneste, Sanne Govaert, Fabien Spicher, Jörg Brunet, Sara A.O. Cousins, Guillaume Decocq, Martin Diekmann, Bente J. Graae, Per-Ola Hedwall, Rozália E. Kapás, Jonathan Lenoir, Jaan Liira, Sigrid Lindmo, Kathrin Litza, Tobias Naaf, Anna Orczewska, Jan Plue, Monika Wulf, Kris Verheyen, Pieter De FrenneAbstractHedgerows have the potential to facilitate the persistence and migration of species across landscapes, mostly due to benign microclimatic conditions. This thermal buffering function may become even more important in the future for species migration under climate change. Unfortunately, there is a lack of empirical studies quantifying the microclimate of hedgerows, particularly at broad geographical scales.Here we monitored sub-canopy temperatures using 168 miniature temperature sensors distributed along woodland-hedgerow transects, and spanning a 1600-km macroclimatic gradient across Europe. First, we assessed the variation in the temperature offset (that is, the difference between sub-canopy and corresponding macroclimate temperatures) for minimum, mean and maximum temperatures along the woodland-hedgerow transects. Next, we linked the observed patterns to macroclimate temperatures as well as canopy structure, overstorey composition and hedgerow characteristics.The sub-canopy versus macroclimate temperature offset was on average 0.10 °C lower in hedgerows than in woodlands. Minimum winter temperatures were consistently lower by 0.10 °C in hedgerows than in woodlands, while maximum summer temperatures were 0.80 °C higher, albeit mainly around the woodland-hedgerow ecotone. The temperature offset was often negatively correlated with macroclimate temperatures. The slope of this relationship was lower for maximum temperatures in hedgerows than in woodlands. During summer, canopy cover, tree height and hedgerow width had strong cooling effects on maximum mid-day temperatures in hedgerows. The effects of shrub height, shrub cover and shade-casting ability, however, were not significant.To our knowledge, this is the first study to quantify hedgerow microclimates along a continental-scale environmental gradient. We show that hedgerows are less efficient thermal insulators than woodlands, especially at high ambient temperatures (e.g. on warm summer days). This knowledge will not only result in better predictions of species distribution across fragmented landscapes, but will also help to elaborate efficient strategies for biodiversity conservation and landscape planning.
  • Climate change shifts in habitat suitability and phenology of huckleberry
           (Vaccinium membranaceum)
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Janet S. Prevéy, Lauren E. Parker, Constance A. Harrington, Clayton T. Lamb, Michael F. ProctorClimate change is altering the suitable habitat and phenology of plant species around the world, with cascading effects on people and animals reliant upon those plant species as food sources. Huckleberry (Vaccinium membranaceum) is one of these important food-producing plant species that grows in the Pacific Northwest of North America. Here, we modelled how the range and phenology of huckleberry may change as the climate changes. To address this question, we first utilized citizen scientist observations, long-term plot data, and gridded climate data to identify climate variables that best predicted the current bioclimatic niche and the timing of flowering and fruit ripening of huckleberry. We then used multi-model future climate projections for 2 time periods (2041–2070 and 2071–2100) and 2 greenhouse gas emissions scenarios (RCP 4.5 and RCP 8.5) to predict how the range and the timing of flowering and fruiting would change. The modelled bioclimatic niche for the current time period was a good match for our observations, with the model predicting a high probability of occurrence where the species was observed (AUC = 0.88). Suitable habitat for huckleberry was predicted to shrink by 5–40% across the northwestern USA by the end of the 21st century, and this reduction in predicted probability of occurrence was greatest at lower elevations, across drier portions of the current range of the species, and under the higher emissions scenario. Suitable habitat was predicted to expand at higher altitudes (>3,050 m) and in more northern locations in British Columbia by 5–60% by the end of the 21st century. To predict how future phenological dates might shift, we developed thermal sum models for flowering and fruiting under current climate conditions and then used those models to predict how these events would change based on climate predictions. Our phenology models suggested flowering would advance 23–50 days (mean 35 days) and fruiting would advance 24–52 days (mean 36 days) by the end of the 21st century under the RCP 8.5 scenario; greater advances in phenology were shown over more northerly and higher altitude regions. These large shifts in potential range and phenology could greatly alter trophic relationships and the timing and location of traditional harvests in the future.Graphical abstractImage, graphical abstract
  • Detasseling increases kernel number in maize under shade stress
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Zhen Gao, Lu Sun, Jian-Hong Ren, Xiao-Gui Liang, Si Shen, Shan Lin, Xue Zhao, Xian-Min Chen, Gong Wu, Shun-Li ZhouAbstractKernel number is one of the critical components of maize yield and is sensitive to environment variation around tasseling when the tassel, stem and ear grow simultaneously. Similar to other areas in the world, the North China Plain faced reduced irradiance during the maize growing season, especially the critical window for determinating actual kernel number. Shade stress that occurs between 15 days pre-silking and 15 days post-silking significantly reduces kernel number and grain yield. In the present experiment, detasseling was conducted under 70% and 97% shade treatments to mitigate the environment stress at the 14-leaf (V14) and tasseling (VT) stages, respectively. Shading treatments significantly reduced kernel number per plant, especially when shading occurred at VT stage. Tassel removal did not relieve kernel losses under 97% shade, but detasseling did dramatically reverse the kernel losses under 70% shade. Removing tassel sink at V14 and VT promoted assimilates being apportioned to ear sink under 70% shade stress, thus encouraging more carbohydrates to be made available for ear growth. Consequently, detassseling increased soluble sugar concentration in the ear section, shortened anthesis-tasseling interval, accelerated ear growth, offering a method to improve kernel number under shade stress.
  • Mining ecophysiological responses of European beech ecosystems to drought
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Fabio Gennaretti, Jérôme Ogée, Julien Sainte-Marie, Matthias CuntzAbstractThe most accurate understanding of forest functioning during drought is crucial to improve the forecast of future forest productivity. Here we investigate the ecophysiological responses (i.e. primary production, evapotranspiration and water use efficiency) of European beech to drought events with the ecosystem model MuSICA, using as benchmark the observed fluxes at the experimental forest Hesse (France). We show that MuSICA is able to realistically simulate observed drought-induced limitations. Subsequently we use simulation experiments to provide: (1) a quantification of the reduction of ecosystem fluxes during the 2003 drought, (2) a partitioning of heat stress and water limitations during droughts, (3) an analysis of the impact of specific drought trajectories, and (4) an evaluation of the potential impact of projected climate change on the studied forest and (5) over the beech distributional range. Our results show that the 2003 drought resulted in a 17% reduction of annual gross primary production and in a 21% reduction of evapotranspiration at Hesse. The studied forest ecosystem is mostly sensitive to negative precipitation anomalies (82% of the reduced forest productivity in 2003) and almost insensitive to heat stress due to high temperatures (16%). Moreover, we show that the ecosystem fluxes are limited more by fast drought onsets in the early growing season (June–July) than by onsets later in the season. Deciphering the impact of future climate change on beech productivity is complicated by large uncertainties in projected future precipitation and in the severity of extreme dry years. Drastic reduction of ecosystem fluxes is only predicted with climate projections that show marked reductions in precipitation. However, increased CO2 fertilization in the future will counterbalance negative drought impacts. This modelling-based study improves our understanding of the functioning of an emblematic European tree species during extreme events and informs on potential future forest responses to projected climate change.
  • Evaluation and comparison of multiple evapotranspiration data models over
           the contiguous United States: Implications for the next phase of NLDAS
           (NLDAS-Testbed) development
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Baoqing Zhang, Youlong Xia, Biao Long, Mike Hobbins, Xining Zhao, Christopher Hain, Yaohui Li, Martha C. AndersonAbstractTerrestrial evapotranspiration (ET) is a major component of the surface hydrological cycle and controls land-atmosphere feedbacks by modulating the surface energy budget. Accurate ET quantification at global or regional scales is crucial for understanding variations in carbon and water cycling in a changing environment. Although various grid-based ET data models have been developed using multiple approaches, these vary in concept and physical scheme, leading to differences in performance. We examine uncertainties associated with the limitations of the physics used to assist in model selection and improvement. We evaluate multiple ET data models, including estimates derived from a variety of land surface models (LSMs) based on the operational North American Land Data Assimilation System (NLDAS) phase 2 (NLDAS-2) and the experimental NASA LIS-based NLDAS Testbed (NLDAS-Testbed) drivers, and satellite retrievals, compared to water budget-derived ET and tower observations. Overall, all models are able to capture the spatial variability of mean annual water balance-based ET (ETwb) and monthly seasonal cycles of tower ET measurements, although there is a large range of estimates. NOAH28, FLUXNET, SSEBop, LandFlux, and GLEAM perform best, as demonstrated by their higher correlation and smaller bias and RMSE values. Simple relative uncertainty analysis shows that the NLDAS-Testbed ensemble mean has a slightly lower uncertainty than that of the NLDAS-2 ensemble. Our study indicates that NLDAS-Testbed/VIC412 (NLDAS version/LSM version) is improving and NLDAS-Testbed /CLSM is deteriorating relative to NLDAS-2/VIC403 and NLDAS-2/Mosaic. NLDAS-Testbed /NOAH36 and NLDAS-Testbed /NOAHMP36 are comparable to NLDAS-2/NOAH28, although biases between models and ETwb exhibit opposite trends. These findings will help further improvement of these models and support future NLDAS development.
  • An evaluation of four years of nitrous oxide fluxes after application of
           ammonium nitrate and urea fertilisers measured using the eddy covariance
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): N. Cowan, P. Levy, J. Maire, M. Coyle, S.R. Leeson, D. Famulari, M. Carozzi, E. Nemitz, U. SkibaAbstractIn this study, we present the first long-term N2O eddy covariance dataset measured from a working farm. The eddy covariance method was used over a four year period to measure fluxes of the greenhouse gas nitrous oxide (N2O) from an intensively managed grazed grassland, to which regular applications of ammonium nitrate or urea fertilisers were spread, for two years each at the field site. The mean emission factors (EFs) reported for ammonium nitrate and urea fertiliser applications in this study over a period of 30 days after fertilisation, were 0.90 and 1.73% of the nitrogen applied, respectively, with EFs of individual events ranging between 0.13 and 5.71%. Our study accurately quantifies emission factors for multiple events and showing unambiguously that large-scale variability is real. EFs do indeed vary from one fertiliser event to another, even at the same site with the same fertiliser type under similar environmental conditions. This makes distinguishing EFs between different fertiliser types for the purposes of developing emission mitigation policy very difficult.
  • Probabilistic forecasting of crop yields via quantile random forest and
           Epanechnikov Kernel function
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Samuel Asante Gyamerah, Philip Ngare, Dennis IkpeAbstractA reliable and accurate forecasting model for crop yields is of crucial importance for efficient decision-making process in the agricultural sector. However, due to weather extremes and uncertainties, most forecasting models for crop yield are not reliable and accurate. For measuring the uncertainty in crop yield forecast, a probabilistic forecasting model based on quantile random forest and Epanechnikov kernel function (QRF-E) is proposed. The non-linear structure of random forest is applied to build the non-linear quantile regression forecast model and to capture the non-linear relationship betweeen the weather variables and crop yield. . Epanechnikov kernel function and solve-the equation plug-in approach of Sheather and Jones are used in the density estimation. A case study using groundnut and millet yield in Ghana were presented to illustrate the efficiency and robustness of the proposed technique. The values of the prediction interval coverage probability and prediction interval normalized average width for the two crops showed that, the constructed prediction intervals captured the observed yields with high coverage probability. The probability density curves show that QRF-E method has a very high ability to forecast quality prediction intervals with a higher coverage probability. The feature importance gave a score of the importance of each weather variable in building the quantile random forest model. The farmer and other stakeholders are able to realize the specific weather variable that affects the yield of a selected crop through feature importance. The proposed method and its application on crop yield dataset are the first of its kind in literature.
  • Co-elevated CO2 and temperature and changed water availability do not
           change litter quantity and quality of pine and oak
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Hyun-Jin Park, Sang-Sun Lim, Hye In Yang, Kwang-Seung Lee, Se-In Park, Jin-Hyeob Kwak, Han-Yong Kim, Seung-Won Oh, Woo-Jung ChoiElevated CO2 concentration ([CO2]) and air temperature (Tair) as well as changed soil water availability (Wsoil) may affect quantity, chemistry, and microbial decomposability of tree leaf litter. However, our understanding is limited mainly to the effect of elevated [CO2]. This study investigated the effects of elevated [CO2] and Tair in combination with two Wsoil regimes on the quantity and chemistry including the ratio of lignin to nitrogen (lignin/N) of litter produced by Pinus densiflora and Quercus variabilis saplings, and microbial respiration of the soils amended with the litters. Either elevated [CO2] or high Wsoil alone increased litter production; meanwhile elevated Tair alone decreased litter production. However, co-elevation of [CO2] and Tair did not change litter production regardless of Wsoil regime for both species. Among litter chemistry, the lignin/N, which is a robust indicator of litter decomposability, of litter was changed in parallel with litter quantity (i.e., lignin/N ratio increased when litter quantity increased and vice versa) mainly due to dilution of N. Due to the opposite effect of warming and elevated [CO2] on litter quantity, lignin/N was not changed under co-elevated [CO2] and Tair at a given Wsoil regime for both species. Other litter chemistry including non-structural carbohydrates and minerals was also affected by [CO2], Tair, or Wsoil. However, changed litter chemistry did not change the CO2 emission from the soils amended with the litters; however, addition of litter with low lignin/N and high nutrients increased microbial biomass in the soil. This study enlarges our understanding of the effects of changed climatic variables on litter quantity, chemistry, and microbial decomposability and suggests that co-elevation of [CO2] and Tair may not cause a significant change in the litter parameters regardless of Wsoil. Study with mature trees at a natural forest should further improve our understanding.Graphical abstractImage, graphical abstract
  • Elevated temperature exacerbates the effects of drought on the carbon and
           hydraulic characteristics of Robinia pseudoacacia seedlings
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Weiming Yan, Yangquanwei Zhong, Zhouping ShangguanAbstractThe rising temperature and extreme drought induced by climate change will considerably affect plant growth and survival. However, the interactive effects of elevated temperature and drought on carbon (C) balance and hydraulic traits remain unclear. In this study, we investigated the C exchange, hydraulic characteristics and total nonstructural carbohydrate (TNC) availability of different organs in Robinia pseudoacacia seedlings during drought and re-watered periods under two temperature treatments. Our study showed that drought reduced C assimilation and increased loss of plant xylem conductivity (PLC). In addition, elevated temperature exacerbated the effect of drought on the C exchange rate and hydraulic characteristics. The TNC concentrations were lower in roots than in other tissues, and seedlings exposed to drought also showed decreased TNC concentrations in specific tissues (roots, stems and leaves) and in the whole seedlings. Seedlings showed lower TNC concentrations under elevated temperature than at ambient temperature, suggesting that elevated temperature accelerated the consumption of stored TNCs. After short-term re-watered, the C exchange rate and hydraulic characteristics of drought seedlings showed larger recovery under ambient temperature than under elevated temperature. Our findings suggest that elevated temperature exacerbate the risks of hydraulic failure and C starvation in R. pseudoacacia under drought, which may increase the drought-induced seedling mortality of R. pseudoacacia in drought-prone regions under future climate scenarios.
  • Similar patterns of background mortality across Europe are mostly driven
           by drought in European beech and a combination of drought and competition
           in Scots pine
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Juliette Archambeau, Paloma Ruiz-Benito, Sophia Ratcliffe, Thibaut Fréjaville, Alexandre Changenet, Jose M. Muñoz Castañeda, Aleksi Lehtonen, Jonas Dahlgren, Miguel A. Zavala, Marta Benito GarzónBackground tree mortality is a complex demographic process that affects structure and long-term forest dynamics. Here we investigated how climatic drought intensity interacts with interspecific and intraspecific competition (or facilitation) in shaping mortality patterns across tree species ranges. To this aim, we used data from five European national forest inventories to perform logistic regression models based on individual tree mortality in Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.). We computed the relative importance of climatic drought intensity, basal area of conspecific and heterospecific trees (proxy of indirect intra- and interspecific competition or facilitation) and the effects of their interactions on mortality along the entire European latitudinal gradient of both species range. Increase in climatic drought intensity over the study period was associated with higher mortality rates in both species. Climatic drought intensity was the most important driver of beech mortality at almost all latitudes while Scots pine mortality was mainly driven by basal area. High conspecific basal area was associated with high mortality rates in both species while high heterospecific basal area was correlated with mortality rates that were high in Scots pine but low in beech. Overall, beech mortality was directly affected by climatic drought intensity while Scots pine mortality was indirectly affected by climatic drought intensity through interactions with basal area. Despite their different sensitivity to drought and basal area, the highest predicted mortality rates for both species were at the ecotone between the cool temperate and Mediterranean biomes, which can be explained by the combined effect of climatic drought intensity and competition. In the context of global warming, which is expected to be particularly strong in the Mediterranean biome, our results suggest that populations at the southern limit of species ranges may experience increased mortality rates in the near future.Graphical abstractImage, graphical abstract
  • Net neutral carbon responses to warming and grazing in alpine grassland
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Wangwang Lv, Caiyun Luo, Lirong Zhang, Haishan Niu, Zhenhua Zhang, Shiping Wang, Yanfen Wang, Lili Jiang, Yonghui Wang, Jinsheng He, Paul Kardol, Qi Wang, Bowen Li, Peipei Liu, Tsechoe Dorji, Huakun Zhou, Xinquan Zhao, Liang ZhaoAbstractIn natural grasslands, effects of warming on net ecosystem CO2 exchange (NEE) may interact with grazing. Yet, the effects of these two main drivers of terrestrial carbon cycling are typically studied in isolation, limiting our understanding of how NEE would be affected under different global change scenarios. Here, we report results of a warming experiment using infrared heaters combined with summer and winter grazing for 7-years in a Tibetan alpine grassland. We found that regardless of warming summer grazing decreased soil carbon sink (i.e., increased annual mean net biome productivity (NBP) indicated by a negative value of NBP), and warming also reduced soil carbon sink under no-grazing only during 3-years of summer grazing. However, warming and grazing did not change soil carbon sink during 4-years of winter grazing. Interactive effects between warming and grazing on annual NBP varied with year and grazing season. Overall, both warming and grazing did not alter annual mean NBP under 7-years of the rotational grazing system in summer and winter grasslands because of offsetting effects on annual mean gross primary productivity and ecosystem respiration. Annual mean soil temperature explained 58% of the variation of annual mean NBP during summer grazing, whereas seasonal mean soil moisture explained 48 and 44% of its variation during winter grazing and the two season grazing system, respectively. Together, our results suggest that rotational grazing between summer and winter alpine grasslands would result in net neutral climate feedback based on the response of annual NBP under future warming. The two season grazing system not only supports animal production but also realizes balance in the soil carbon budget under future warming.
  • Attribute parameter characterized the seasonal variation of gross primary
           productivity (αGPP): Spatiotemporal variation and influencing factors
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Weikang Zhang, Guirui Yu, Zhi Chen, Leiming Zhang, Qiufeng Wang, Yangjian Zhang, Honglin He, Lang Han, Shiping Chen, Shijie Han, Yingnian Li, Liqing Sha, Peili Shi, Huimin Wang, Yanfen Wang, Wenhua Xiang, Junhua Yan, Yiping Zhang, Donatella Zona, M. Altaf ArainAbstractThe seasonal dynamic of gross primary productivity (GPP) has influences on the annual GPP (AGPP) of the terrestrial ecosystem. However, the spatiotemporal variation of the seasonal dynamic of GPP and its effects on spatial and temporal variations of AGPP are still poorly addressed. In this study, we developed a parameter, αGPP, defined as the ratio of mean daily GPP (GPPmean) to the maximum daily GPP (GPPmax) during the growing season, to analyze the seasonal dynamic of GPP based on Weibull function. The αGPP was a comprehensive parameter characterizing the shape, scale, and location of the seasonal dynamic curve of GPP. We calculated αGPP based on the data of GPP for 942 site-years from 115 flux sites in the Northern Hemisphere, and analyzed the spatiotemporal variation and influencing factors of the αGPP. We found that the αGPP of terrestrial ecosystems in the Northern Hemisphere ranged from 0.47 to 0.85, with an average of 0.62 ± 0.06. The αGPP varied significantly both among different climatic zones and different ecosystem types. The αGPP was stable on the interannual scale, while decreased as latitude increased, which was consistent across different ecosystem types. The spatial pattern of the seasonal dynamic of astronomical radiation was the dominating factor of the spatial pattern of αGPP, that was, the spatial pattern of the seasonal dynamic of astronomical radiation determined that of the seasonal dynamic of GPP by controlling that of seasonal dynamics of total radiation and temperature. In addition, we assessed the spatial variation of AGPP preliminarily based on αGPP and other seasonal dynamic parameters of GPP, indicating that the understanding of the spatiotemporal variation of αGPP could provide a new approach for studying the spatial and temporal variations of AGPP and estimating AGPP based on the seasonal dynamic of GPP.
  • An improved single probe method for sap flow measurements using finite
           heating duration
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Ruiqi Ren, Jonas von der Crone, Robert Horton, Gang Liu, Kathy SteppeAbstractBecause of its low cost and simple fabrication, it is easy to advocate for the single probe method as a method of choice in sap flow studies. An improved single probe method with finite heating duration (F-SPHP) is verified both in cut stem segments and in the field using mature beech (Fagus sylvatica L.) trees. The F-SPHP method is based on an analytical solution of the partial differential equation for combined heat conduction and convection, which shows large relative sensitivity to thermal conductivity (K). The F-SPHP method is able to measure sap flux densities (SFD) between 2 and 36 cm3 cm−2 h−1 (heat pulse velocity (Vh): 3–60 cm h−1) in the cut stem segment experiment. This is an improvement compared to the instantaneous single probe heat pulse (I-SPHP) method which cannot accurately measure low (Vh 
  • Forest and perennial herbland cover reduce microbial respiration but
           increase root respiration in agroforestry systems
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Mark Baah-Acheamfour, Cameron N. Carlyle, Edward W. Bork, Scott X. ChangAbstractAgricultural land management practices have the potential to reduce carbon emissions from soils, especially when a reduction in microbial (heterotrophic respiration, RH) rather than root respiration (autotrophic, RA) is achieved. Soil RA and RH and their sensitivity to temperature changes were determined in the forestland and neighboring herbland (area without trees) soils of three agroforestry systems (hedgerow, shelterbelt, and silvopasture) over two growing seasons (May through September in 2013 and 2014). Over the two growing seasons, mean RA from the forestland was 32% greater than that from the herbland, while the RH in the forestland was 22% lower than that in the herbland. The sensitivity of RA to temperature was consistently greater in the forestland (3.6) than in the herbland (3.4), though the opposite was found for RH. Effects of agroforestry system on RA and RH also varied seasonally. The contribution of RH to total soil respiration was greater in each of the hedgerow (59%) and shelterbelt (55%) systems than in the silvopasture system (51%), reflecting the high RH from annual cropland within the hedgerow and shelterbelt systems. We found stronger control of RH by temperature in the hedgerow and shelterbelt, suggesting that an increase in soil temperature in response to future climatic warming could reduce the amount of carbon held in these systems as compared to the silvopasture system. Overall, the inclusion or maintenance of perennial vegetation (forest and grassland) in an annually cropped agricultural landscape could result in a net reduction in soil RH, and thereby mitigate losses of carbon from agricultural soils.
  • Inference of spatial heterogeneity in surface fluxes from eddy covariance
           data: A case study from a subarctic mire ecosystem
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Peter Levy, Julia Drewer, Mathilde Jammet, Sarah Leeson, Thomas Friborg, Ute Skiba, Marcel van OijenHorizontal heterogeneity causes difficulties in the eddy covariance technique for measuring surface fluxes, related to both advection and the confounding of temporal and spatial variability. Our aim here was to address this problem, using statistical modelling and footprint analysis, applied to a case study of fluxes of sensible heat and methane in a subarctic mire. We applied a new method to infer the spatial heterogeneity in fluxes of sensible heat and methane from a subarctic ecosystem in northern Sweden, where there were clear differences in surface types within the landscape. We inferred the flux from each of these surface types, using a Bayesian approach to estimate the parameters of a hierarchical model which includes coefficients for the different surface types. The approach is based on the variation in the flux observed at a single eddy covariance tower as the footprint changes over time. The method has applications wherever spatial heterogeneity is a concern in the interpretation of eddy covariance fluxes.Graphical abstractGraphical abstract for this article
  • Improving RAMS and WRF mesoscale forecasts over two distinct vegetation
           covers using an appropriate thermal roughness length parameterization
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): I. Gómez, V. Caselles, M.J. EstrelaAbstractLand Surface Models (LSM) have shown some difficulties to properly simulate day-time 2-m air and surface skin temperatures. This kind of models are coupled to atmospheric models in mesoscale modelling, such as the Regional Atmospheric Modeling System (RAMS) and the Weather Research and Forecasting (WRF) Model. This model coupling is used within Numerical Weather Prediction Systems (NWP) in order to forecast key physical processes for agricultural meteorology and forestry as well as in ecological modelling. The current study first evaluates the surface energy fluxes and temperatures simulated by these two state-of-the-art NWP models over two distinct vegetated covers, one corresponding to a poor and sparsely vegetated area and the other one corresponding to the tall and well-vegetated area of a forest. On the other hand, the importance of parameterizing the thermal roughness length within the LSM coupled to the corresponding atmospheric model is also evaluated. The LEAF-3 LSM is used within the RAMS modelling environment while the Noah-MP LSM is applied within WRF. Results indicate that the original version of the models underestimates the temperature during the day, more remarkably in the forested area, whereas modifications in the thermal roughness length successfully simulates the temperature and sensible heat flux forecasts over this area. This study highlights the key role of the surface exchange processes when coupling land and atmosphere models. In this regard, incorporating an extra resistance in the surface-layer parameterization through the thermal roughness length is essential to simulate well both temperatures and sensible heat fluxes, which becomes more relevant over tall and well-vegetated areas, such as a forest. This extra resistance for heat exchange prevents effective molecular diffusion in the layer between the momentum roughness length and the thermal roughness length. Additionally, an appropriate description of the canopy height permits to apply an improved surface-layer formulation over different land and vegetation covers.
  • Improved models of the effects of winter chilling on blackcurrant (Ribes
           nigrum L.) show cultivar specific sensitivity to warm winters
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Katharine Preedy, Rex Brennan, Hamlyn Jones, Sandra GordonAbstractSufficient chilling in winter is essential for many perennial crops to start growing in spring and to produce good yields. Using blackcurrants as an example we have developed improved models which can help identify varieties resilient to the variable winters expected as the climate warms. Controlled temperature experiments were used to calibrate 3 proposed models of chilling accumulation requirements for a number of commercial blackcurrant cultivars. The first model assumed a linear relationship between bud break and chilling accumulation, the second a quadratic relationship which allows for the possibility of over-chilling and the third, an asymmetric quadratic relationship in which the maximum achievable effectiveness is temperature dependent. The models were then applied to data on selected cultivars gathered from blackcurrant growers across the United Kingdom and the third model was found to provide the best fit for the data, suggesting that long warm winters do not have the same effect as short cold winters in terms of the satisfaction of chilling requirement. Further, the degree to which temperature affects maximum bud break varies by cultivar. We discuss the potential effects of differing timing of chill on the applicability of the models presented.
  • Ecosystem respiration of old and young irrigated citrus orchards in a
           semiarid climate
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Bernardo Martin-Gorriz, María M. González-Real, Gregorio Egea, Alain BailleAbstractBoth biotic and abiotic factors are involved in the seasonal variability of ecosystem respiration (Re) and its aboveground (Rag) and belowground (Rs) components. Knowledge of these factors is crutial to predict the respiration processes of structurally-distinct orchards under varying environmental conditions. This paper aims to characterize those factors in and across adult (AO) and young (YO) drip-irrigated citrus orchards over a 2-year period. Two methods for estimating Re were used and compared. In the first one (C-method) Re was calculated as the sum of Rag and Rs components, with each being estimated using organ-specific and soil respiration models previously validated and calibrated from chamber-based respiration and biometric canopy measurements. The second method was based on the determination of nighttime Re from data of early morning Net Ecosystem Exchange (NEE-method) provided by eddy covariance sensors located above the canopy. Estimates of Re by the two methods compared reasonably well. The C-method indicated that Rs was the predominant component of Re in both orchards, with a main peak in early spring (ratio Rs/Re ∼0.75 and 0.65 in AO and YO, respectively) during the period with no fruit load and minimum Rag. Data obtained with the NEE-method were used to test the performance of functional relationships between Re and abiotic factors (i.e., temperature through a Q10 function, and soil water content). It was found that a model only based on abiotic factors was unable to explain the differences in Re across sites; whereas accounting for canopy productivity and structure by introducing the leaf area index (LAI) as an additional driving variable notably increased the predictive power of the models in describing changes in Re, both seasonally and across sites. The study suggested that biotic factors explained a large part of the differences in Re between orchards, and that LAI could be an appropriate driving variable for predicting the impact of tree age and structural heterogeneity on Re.
  • Partitioning evapotranspiration with concurrent eddy covariance
           measurements in a mixed forest
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Eugénie Paul-Limoges, Sebastian Wolf, Fabian D. Schneider, Marcos Longo, Paul Moorcroft, Mana Gharun, Alexander DammAbstractPlants have an important effect on our climate: as they assimilate atmospheric CO2 through the process of photosynthesis, they also transpire water to the atmosphere and thereby influence surface temperatures. It is, however, difficult to quantify transpiration from ecosystems due to measurement limitations. Direct eddy covariance (EC) measurements are currently the best available approach to observe interactions linked to biosphere–atmosphere CO2 and water vapor exchange. While there are well-established methods to partition CO2 fluxes into the component fluxes of photosynthesis and respiration, there is still no standardized method to partition water vapor fluxes (evapotranspiration, ET) into the component fluxes of evaporation and transpiration.In this study, we used two years of concurrent below and above canopy EC measurements in a mixed deciduous forest in Switzerland to partition water vapor fluxes into the components of transpiration (biological) and evaporation (physical). We compare our results with transpiration from the ecosystem demographic (ED2) model as well as derived from plot-level sap flow measurements. EC-derived transpiration accounted on average for 74% of ET, emphasizing a considerably lower contribution from evaporation. EC and sap flow measurements showed mid-afternoon reductions in transpiration during periods of high vapor pressure deficit in summer. Reductions in ET and transpiration were found under limiting soil moisture conditions, while the ratio of transpiration to ET remained constant over the years due to the low and rather constant evaporation in this closed canopy forest. Stomatal regulation in response to enhanced atmospheric evaporative demand was also found under water-stressed conditions in the afternoon in summer. When comparing our EC-derived evaporation with the ED2 model, we found large discrepancies linked to the challenge of modeling evaporation in a light limited, yet variable environment below the canopy. A strong correlation was found for transpiration from ED2 with the EC-based estimates. Our results show the potential of concurrent below and above canopy EC measurements to partition ecosystem ET in forests.
  • Fixed and variable components of evapotranspiration in a Mediterranean
           wild-olive - grass landscape mosaic
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Nicola Montaldo, Matteo Curreli, Roberto Corona, Ram OrenAbstractDry regions are typically characterized by heterogeneous ecosystems where trees are competing with the surrounding grasses for limited amount of water. In these regions, evapotranspiration (ET) is the leading loss term in the soil water budget, and its estimate, and the dynamic contribution of each ET component (i.e. tree and grass transpiration, and dry bare soil and wet surface evaporation), are still poorly quantified. In a typical heterogeneous Mediterranean ecosystem in Sardinia, we combined eddy-covariance estimates of ET with sap flux and energy balance estimates of wild-olive tree transpiration, a common tree species of the region, and with modeled evapotranspiration from the seasonal grass. Trees located in the southern edge of clumps, thus receiving more radiation, transpired more and showed a greater sensitivity to increasing vapor pressure deficit and soil moisture than trees located in clump centers or northern edges. Transpiration of the tree clumps in the footprint (Et), summed up with the modeled evapotranspiration components of the surrounding grass (mostly transpiration during the wet season and evaporation during the dry season), matched latent heat flux measurements, lending confidence in the estimates. Proper accounting for heterogeneity of sources within the eddy covariance footprint seems to have overcome potential errors from not preserving an important assumption of the method, the land-surface homogeneity, highlighting the methods reliability in such inhomogeneous ecosystem. Compared to ET, Et of wild olives was nearly constant over the hydrologic year, insensitive to variation in soil moisture and atmospheric conditions. In contrast, under favorable spring environmental conditions (radiation, vapor pressure deficit, and soil moisture), the pasture leaf area transpires at high rates, contributing to, and dominating the high ET during that season. Conversely, in dry periods, when evapotranspiration from the grass cover is dominated by low evaporation from the, principally, bare soil, Et dominants ecosystem ET.
  • Characterizing the impact of climatic and price anomalies on agrosystems
           in the northwest United States
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Patrick Wurster, Marco Maneta, Santiago Beguerı́a, Kelly Cobourn, Bruce Maxwell, Nick Silverman, Stephanie Ewing, Kelsey Jensco, Payton Gardner, John Kimball, Zachary Holden, Xinde Ji, Sergio M. Vicente-SerranoAbstractWe present an analysis of the sensitivity of three key crops (alfalfa, barley and winter wheat) produced in the northwestern United States to climatic and agricultural market anomalies using widely used standardized indices. Rather than investigating sensitivity of crop yields (production per unit area), we focus on agricultural production (yield * harvested area) anomalies, which captures both variations in yield and the effect of decision-making factors such as allocation of cropping area. We used two well-known standardized precipitation and reference evapotranspiration (ETo) indices (SPI and EDDI, respectively) and a standardized crop value index in a multivariate linear regression analysis to determine the characteristic timing and time-scales of precipitation and ETo anomalies that best explain annual crop production anomalies. Since climatic and market factors are standardized, regression coefficients are interpreted as a sensitivity measure that captures the relative effect of climatic and agricultural markets on agricultural production. Results show that alfalfa production was most sensitive climatic anomalies while barley and wheat production was more responsive to crop prices. Sensitivity to precipitation anomalies followed gradients in precipitation, temperature, and soil moisture regimes across the study area where drier and warmer climates were associated with increased sensitivity to climatic anomalies. We found that irrigation decoupled alfalfa production from climatic variability, but the effect of irrigation on decoupling barley production was less clear. Winter wheat production was most sensitive to price anomalies, and alfalfa was least sensitive. Omitting agricultural market conditions and other farmer incentives may introduce biases in our understanding of how drought and climate change impact agricultural production.
  • Spatial examination of leaf-boundary-layer conductance using artificial
           leaves for assessment of light airflow within a plant canopy under
           different controlled greenhouse conditions
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Kensuke Kimura, Daisuke Yasutake, Atsushi Yamanami, Masaharu KitanoAbstractLeaf-boundary-layer conductance (ga), which is mainly affected by airflow near the leaf surface, is an important limiting factor on energy budgets, transpiration and photosynthesis, especially under very light-wind conditions. However, little research has been done, with a focus on the direct evaluation of ga under such conditions, because of the difficulty in measuring slower wind speeds that continuously vary in space and time. Here we propose a reasonable airflow assessment using spatiotemporal analysis of ga, with the aid of numerous artificial leaves facilitating a continuous and multipoint evaluation of ga. In our testing and development of the method, the artificial leaves consisted of thin brass sheets that sandwiched constantan micro heaters, and ga was evaluated on the basis of energy balance of the electrically heated leaves. The analysis was performed within a tomato canopy in a greenhouse under different regimes of environmental controls (air circulation, forced and natural ventilation, heating and air ductwork), thereby allowing the spatiotemporal distributions of ga within the canopy to be determined. The artificial leaves successfully captured the fluctuations in ga affected by the light airflow within the canopy, although ga was overestimated by only 2% (at most 5%) as compared to that of actual leaves owing to the buoyancy effect of electrical heating of the artificial leaves. Thus, without excessive electrical heating, the artificial leaves are considered reliable tools for airflow assessment in the greenhouse. Daytime ga values were small and equivalent to daytime stomatal conductance, even under environmental controls, thus limiting the heat transfer, transpiration and photosynthesis of the leaf. In contrast, night-time ga values were higher values than night-time stomatal conductance, which indicates the small impact of ga on heat and mass exchange via the stomata during the night-time. Spatiotemporal changes in ga substantially varied within the canopy, owing to the different environmental controls. Consequently, remarkable non-uniformities in ga appeared within the canopy, with implications for variable heat and mass exchange. These results indicate that airflow management in the greenhouse can still be improved by spatiotemporal analysis of ga.
  • Environmental drivers of stem radius change and heterogeneity of stem
           radial water storage in the mangrove Avicennia marina (Forssk.) Vierh.
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Alicia Donnellan Barraclough, Jarrod Cusens, Roman Zweifel, Sebastian LeuzingerAbstractThe dynamics of stem water storage can provide insight on a tree's capacity to face imbalances between water supply and demand, and thus maintain hydraulic function and growth under fluctuating environmental conditions. Recent work on the mangrove Avicennia marina (Forssk.) Vierh showed that stem radius change (SRC) is highly heterogeneous due to the structure of A. marina wood, composed of multiple reticulate cambia. The heterogeneity of short and long-term SRC in trees with reticulate cambia, common in dry environments, complicates the study of environmental drivers of stem water storage.In order to find the environmental drivers of stem water storage and understand the nature of this heterogeneity we analysed high-resolution SRC of A. marina for one and a half years. Nine point dendrometers measured SRC in upper, lower and mid stem of three A. marina trees in northern New Zealand. Stem radius change was detrended for growth to obtain water-related shrinking and swelling only (ΔW).Despite heterogeneity in SRC measurements, ΔW changes in A. marina still had seasonal trends of high winter and low summer diel amplitudes and strong responses to mean diel environmental conditions. Environmental drivers of ΔW were more apparent once the data was standardized to show relative changes, and segregated by upper and lower stem tiers. Moving window correlations showed stem contraction was correlated with atmospheric water demand and precipitation, whilst stem swelling was correlated with light sums more often than with measures of water availability. The correlation of stem water storage with light seen in our work provides backing for the hypothesized role of carbohydrates in the mechanism behind daytime stem swelling of A. marina water storage tissues. Our work highlights the importance of sensor locations and data analysis approaches if we are to use established SRC technologies in a larger diversity of environments and species.
  • Modeling the effect of temperature on bud dormancy of grapevines
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Hector Camargo-Alvarez, Melba Salazar-Gutiérrez, Markus Keller, Gerrit HoogenboomAbstractDormancy is an evolutionary strategy to overcome adverse conditions during winter through the interruption of growth and metabolism. Winter dormancy is divided into two phases: endodormancy when bud growth is inhibited internally, and ecodormancy when adverse environmental conditions impede growth. The study of winter dormancy is limited because the onset and transition between the two dormancy phases do not have any visual symptoms. Therefore, the goal of this study was to develop a model to predict the occurrence of the onset and release of dormancy phases and budbreak in grapevines ‘Cabernet Sauvignon’ and ‘Chardonnay’. An integrated phenological model was developed assuming that the shortening of the photoperiod induces the onset of endodormancy when a critical day length specific for each cultivar is reached. Then, a period of exposure to chilling temperatures induces the transition from endodormancy to ecodormancy, followed by a period of warm temperatures that forces budbreak. The model showed that ‘Cabernet Sauvignon’ has a longer endodormancy period caused by the cultivar-specific sensitivity to shorter photoperiods, as well as a slower completion of the chilling requirements compared to ‘Chardonnay’. For both cultivars, relatively high temperatures were effective for chilling accumulation. The base temperature for heat effect accumulation was the same for the two cultivars at 5.6 °C, while ‘Chardonnay’ had a lower heat requirement causing a shorter ecodormancy period and earlier budbreak compared to ‘Cabernet Sauvignon’. Although the trendline for predicted-versus-observed budbreak dates was significantly different from the 1:1 line, it showed a high R2 value of 0.92. The model also presented high accuracy and performance based on other evaluation statistics such as a correlation coefficient of 0.96, an RMSE of 5 days, and an agreement index of 0.95. Future updates of the model should add the temperature effect on the estimation of endodormancy onset.
  • Comparison of three calibration methods for modeling rice phenology
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Yujing Gao, Daniel Wallach, Bing Liu, Michael Dingkuhn, Kenneth J. Boote, Upendra Singh, Senthold Asseng, Tamer Kahveci, Jianqiang He, Ruoyang Zhang, Roberto Confalonieri, Gerrit HoogenboomAbstractCalibration is an essential step for all crop modeling studies. The goal of this study was to compare three commonly-used calibration methods including Ordinary Least Square (OLS), Markov chain Monte Carlo (MCMC), and Generalized Likelihood Uncertainty Estimation (GLUE) as applied to the CSM-CERES-Rice phenology model of the Decision Support System for Agrotechnology Transfer (DSSAT). The analysis was performed by considering goodness-of-fit to observations, calibrated parameter values, uncertainty of parameter estimates and predictions, and the practical implementation of methods. The results showed that the selection of the calibration method has some impacts on parameter estimates and uncertainty quantifications. In the situations where goodness-of-fit is the main criterion, OLS is the fastest and most effective method. When the uncertainty of parameter estimates and model predictions are important, the MCMC method is more reliable in quantifying uncertainties. We found that for predicting phenology in our study, the GLUE method was unrealistic in quantifying model uncertainty, because the default model error variance was unlikely small. This study showed that MCMC for model calibration, coupled with estimation of model error variance, is a promising method for quantifying prediction uncertainty and that MCMC should be incorporated into crop modeling platforms.
  • Assessments of gross primary productivity estimations with satellite
           data-driven models using eddy covariance observation sites over the
           northern hemisphere
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Xinyao Xie, Ainong Li, Jianbo Tan, Huaan Jin, Xi Nan, Zhengjian Zhang, Jinhu Bian, Guangbin LeiAbstractThe accurate quantification of gross primary productivity (GPP) has been a major challenge in global climate change research. Satellite data-driven models have been universally used as scientific tools for investigating the carbon cycle, including vegetation index (VI)-based models, light use efficiency (LUE) models, and process-based models. However, inconsistencies and uncertainties have been found in the GPP estimations from various models. The understanding of model behaviors under different climatic conditions remains unclear. In this study, three typical satellite data-driven models, namely, Moderate Resolution Imaging Spectroradiometer (MODIS) GPP (MOD17) model, Temperature and Greenness (TG) model and Boreal Ecosystem Productivity Simulator (BEPS), respectively, were compared to better understand discrepancies and uncertainties in GPP estimations at 119 northern eddy covariance (EC) sites. Due to the variations in climatic drivers of GPP, temperature, precipitation and incoming solar radiation were selected to describe climatic conditions. The results showed that BEPS and MOD17 exhibited similar performance in simulating GPP, with root-mean-square error (RMSE) values of 2.50 g C m−2 d−1 and 2.53 g C m−2 d−1, respectively, and performed slightly better than TG (RMSE = 2.98 g C m−2 d−1). Comparison between simulated GPP and EC GPP also revealed that model performance varied substantially among different vegetation types. The three models performed better for deciduous broadleaf forest, evergreen needleleaf forest, and mixed forest, in comparison to the results from evergreen broadleaf forest and crop. Specifically, all three models showed poor performance under the conditions of high temperature and low precipitation, revealing the models’ inability to characterize the impact of water stress on photosynthesis when drought occurs. Furthermore, our results indicated that GPP estimations from satellite data-driven models were also sensitive to remotely sensed data, suggesting that the high accuracy of remotely sensed data in describing vegetation canopy is important for carbon modeling. This study highlights the importance of understanding model behaviors in different vegetation types and climatic conditions, so that the model performances may be improved in future carbon cycle studies.
  • An intensity, image-based method to estimate gap fraction, canopy openness
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Mirko Grotti, Kim Calders, Niall Origo, Nicola Puletti, Alessandro Alivernini, Carlotta Ferrara, Francesco ChianucciAbstractAccurate in situ estimates of leaf area index (LAI) are essential for a wide range of ecological studies and applications. Due to the destructiveness and impracticality of direct measurements, indirect optical methods have mostly been used in the field to derive estimates of LAI from gap fraction measurements. Terrestrial laser scanning (TLS) is strongly supporting use of this active technology, which possesses several advantages compared to passive sensors. However, edge effects and partial beam interceptions are significantly challenges for the accurate retrieval of gap fraction from 3D point cloud data available from TLS, particularly in phase-shift instruments, which in turns require point cloud filtering to correct erroneous point measurements.As the limitations above influences the point cloud, we proposed a new method which is based only on the laser return intensity (LRI) information derived from raw TLS data, which are used to generate 2D intensity images. The intensity image contains all the unfiltered LRI information captured by TLS, which is used to separate gap from non-gap pixels, using a procedure comparable to the standard image analysis processing of digital hemispherical images. This allows a theoretically consistent comparison between active and passive optical measurements of gap fraction across all the zenith angle range.The method was tested in real and simulated forests. Gap fraction, canopy openness and effective leaf area index derived from real and simulated intensity TLS images were compared with those obtained using digital hemispherical photography (DHP). Results indicated that the intensity, image-based method outperformed DHP, as the higher pixel resolution of the intensity images and the larger distance covered by TLS allowed detection of many small canopy elements, particularly at higher zenith angles (longer optical distance), which are not detected in DHP. The main findings support the reliability of the intensity, image-based method to standardize protocols for TLS phase-shift scan data processing and use of the produced canopy estimates as a benchmark for passive optical measurements.
  • Tree transpiration in a multi-species Mediterranean garden
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Gianfranco Rana, Francesca De Lorenzi, Gianluigi Mazza, Nicola Martinelli, Cristina Muschitiello, Rossana M. FerraraAbstractUrban trees provide benefits and services, like improving environmental quality and mitigating impacts of climate change on human health, e.g. through the reduction of greenhouse gases effects, the removal of pollutants from the atmosphere and the improvement of water quality through interception of pollution. Tree transpiration in a multi-species urban garden in southern Italy was investigated for one year, on hourly, daily, seasonal and annual time scale. Water status of trees was determined by means of the Crop Water Stress Index (CWSI). The difference between canopy and air temperature was calculated using transpiration measurements and the canopy energy balance. Transpiration was measured by heat dissipation method (HDM) in more than 14 tree species, grouped in four classes (Olea, Citrus and Eriobotrya, Conifers and Broadleaves) according to number of specimens in the garden and similarity in plant functional category. At single tree scale, the radial trend of sap flux density was modeled considering the sapwood area, while the upscaling to the garden level was performed using the quantile method integrated by trunk diameter classification. Complete daytime time series of sap flux density were obtained by gap filling algorithms, based on multivariate models based on environmental drivers of transpiration. Tree transpiration showed that Olea and Citrus and Eriobotrya had a good adaptation to Mediterranean climates. CWSI values indicated that Conifers suffered a moderate water shortage, while the other species were subjected to higher water shortage. Conifers showed the maximum efficacy in lowering air temperature, followed by Broadleaves, Olea and Citrus and Eriobotrya. The uncertainties were evaluated by error analysis.
  • Use of a plastic temperature response function reduces simulation error of
           crop maturity date by half
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Dingrong Wu, Peijuan Wang, Chaoyang Jiang, Jianying Yang, Zhiguo Huo, Kuiqiao Shi, Yang Yang, Qiang YuAbstractUnderstanding how crop development rate responds to the environment provides the basis for evaluating the impact of climate change on crop yield. In most crop simulation models, temperature response functions of development rate during the reproductive growth period (RGP) are assumed to only vary with temperature and not with other environmental factors. However, studies have indicated that the response functions may be plastic with other factors. Until now, little attention has been paid to this type of response. Here, using extensively collected field observations and data from intentionally designed interval planting experiments with winter wheat (Triticum aestivum L.), rice (Oryza sativa L.), and spring maize (Zea mays L.), we show that temperature response functions during RGP are plastic with day of year of flowering/heading (DOYR). Coefficients of determination between DOYR and development rate were significant for 69% sites. Partial correlation coefficients between development rate, temperature, and DOYR suggest that DOYR explains almost the same variability in maturity date as temperature. The plastic model was developed by coupling DOYR with a linear temperature response function. The model can improve the fitting efficiency by 112%, while dependency between DOYR and temperature explains less than 25% of this improvement. The average RMSEs of simulated maturity date estimated by the plastic model in the three crops were 2.1, 2.5, and 3.7 d, respectively, while the corresponding values given by widely applied traditional models were 3.1, 6.5, and 7.4 d, respectively. Therefore, the plastic model can reduce simulation error by half. Moreover, simulation errors resulting from the plastic model have less systematic bias than traditional models. The plastic model simply and effectively provides accurate estimates of crop maturity and reduces the system deviation of the estimates. Coupling the plastic model of crop development with crop simulation models will likely decrease uncertainties in simulated yield under warming conditions. Additionally, results of this study will encourage future studies of other phenotype plasticity considered in current crop simulation models.
  • Phenology acts as a primary control of urban vegetation cooling and
           warming: A synthetic analysis of global site observations
    • Abstract: Publication date: 15 January 2020Source: Agricultural and Forest Meteorology, Volume 280Author(s): Yongxian Su, Liyang Liu, Jishan Liao, Jianping Wu, Philippe Ciais, Jiayuan Liao, Xiaolei He, Xiaodong Liu, Xiuzhi Chen, Wenping Yuan, Guoyi Zhou, Raffaele LafortezzaAbstractUrban vegetation can influence local air temperatures through its biophysical effects on surface energy balance. These effects produce gradients (ΔTa) between air temperature of vegetation spaces (Tveg) and air temperature of open spaces (Topen) (ΔTa=Tveg−Topen), hereafter referred to as vegetation cooling (negative values of ΔTa) and warming (positive values of ΔTa), respectively. But vegetation cooling or warming highly depends on background climate of urban areas as well as on vegetation states. Field observations are usually restricted to one or few cities, setting limitations to a general understanding. In this study, a synthetic analysis of 3634 point-scale in-situ observations from 77 global sites in 35 cites was conducted using the bootstrap sampling and hierarchical partitioning methods. Results show that vegetation cooling is generally stronger during the daytime periods, in warm seasons, at low latitude zones, for forest lands and at leaf growth stage, while vegetation warming usually occurs in the opposite contexts. Urban vegetation begins to exert considerable cooling effects when the daily mean background air temperature (BAT) is>10.0 °C, but on average has a slight warming effect when BAT is 61.7 mm/month or when area of urban vegetation is>35.2 ha. Plant growth stages (i.e., canopy leaf growth, senescence and dormancy stages) (37.6 ± 0.11%), a vegetation phenology proxy, acts as the primary biotic factor, while seasonality (23.0 ± 0.11%) and latitude (11.4 ± 0.07%) that control the background climate are two most important abiotic contributors. Our findings suggest approximate thresholds for distinguishing vegetation cooling/warming effects and provide helpful information for future urban greenspace planning aimed at mitigating local climate warming.
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