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Agric For Meteorol 2021 Jan 20;296. Epub 2020 Nov 20.

University of Minnesota - Dept. Soil, Water & Climate, St. Paul, MN, USA.

Eddy covariance (EC) measurements of ecosystem-atmosphere carbon dioxide (CO) exchange provide the most direct assessment of the terrestrial carbon cycle. Measurement biases for open-path (OP) CO concentration and flux measurements have been reported for over 30 years, but their origin and appropriate correction approach remain unresolved. Here, we quantify the impacts of OP biases on carbon and radiative forcing budgets for a sub-boreal wetland. Read More

Agric For Meteorol 2020 Aug;290:108031

Centre of Excellence PLECO (Plants and Ecosystems), Department of Biology, University of Antwerp, 2160Wilrijk, Belgium.

We explored the inter-individual variability in bud-burst and its potential drivers, in homogeneous mature stands of temperate deciduous trees. Phenological observations of leaves and wood formation were performed weekly from summer 2017 to summer 2018 for pedunculate oak, European beech and silver birch in Belgium. The variability of bud-burst was correlated to previous' year autumn phenology (i. Read More

Agric For Meteorol 2020 Aug 29;290:108026. Epub 2020 May 29.

Department of Ecology, Leopold-Franzens-University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria.

Time series of stem diameter variations (SDVs) recorded by dendrometers are composed of two components: (i) irreversible radial stem growth and (ii) reversible stem shrinking and swelling caused by dynamics in water storage in elastic tissues outside the cambium. However, SDVs measured over dead outer bark (periderm) could also be affected by absorption and evaporation of water from remaining dead bark layers after smoothing the stem surface to properly mount dendrometers. Therefore, the focus of this study was to determine the influence of hygroscopicity of a thin dead outer bark layer on the reversible component of dendrometer records of Scots pine () under field conditions. Read More

Agric For Meteorol 2020 Apr;284:107898

Computational and Analytical Sciences Department, Rothamsted Research, UK.

The effect of weather on inter-annual variation in the crop yield response to nitrogen (N) fertilizer for winter wheat () and spring barley () was investigated using yield data from the Broadbalk Wheat and Hoosfield Spring Barley long-term experiments at Rothamsted Research. Grain yields of crops from 1968 to 2016 were modelled as a function of N rates using a linear-plus-exponential (LEXP) function. The extent to which inter-annual variation in the parameters of these responses was explained by variations in weather (monthly summarized temperatures and rainfall), and by changes in the cultivar grown, was assessed. Read More

Agric For Meteorol 2020 Mar;282-283:107862

School of Agriculture Policy and Development, University of Reading, Earley Gate, Reading RG6 6AH, United Kingdom.

Winter wheat is an important crop in the UK, suited to the typical weather conditions in the current climate. In a changing climate the increased frequency and severity of adverse weather events, which are often localised, are considered a major threat to wheat production. In the present study we assessed a range of adverse weather conditions, which can significantly affect yield, under current and future climates based on adverse weather indices. Read More

Agric For Meteorol 2019 Nov 26;278. Epub 2019 Jul 26.

University of Minnesota - Dept. Soil, Water & Climate, United States.

Wetlands represent the dominant natural source of methane (CH) to the atmosphere. Thus, substantial effort has been spent examining the CH budgets of global wetlands continuous ecosystem-scale measurements using the eddy covariance (EC) technique. Robust error characterization for such measurements, however, remains a major challenge. Read More

Agric For Meteorol 2019 May 8;263:267-275. Epub 2018 Sep 8.

Institute of Ecology, University of Innsbruck, Austria.

Automated transparent chambers have gained increasing popularity in recent years to continuously measure net CO fluxes between low-statured canopies and the atmosphere. In this study, we carried out four field campaigns with chamber measurements in a variety of mountainous grasslands. A mathematic stationary point (or critical point, a point at which the derivative of a function is zero) in the CO mixing ratio time series was found in a substantial fraction of the measurements at all the sites, which had a significant influence on the performances of the regression algorithms. Read More

Agric For Meteorol 2019 Jun;271:33-45

Department of Plant Sciences, Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom.

Designing crop ideotype is an important step to raise genetic yield potential in a target environment. In the present study, we designed wheat ideotypes based on the state-of-the-art knowledge in crop physiology to increase genetic yield potential for the 2050-climate, as projected by the global climate model for the emission scenario, in two high-wheat-productive countries, the United Kingdom (UK) and New Zealand (NZ). Wheat ideotypes were optimized to maximize yield potential for both water-limited ( ) and potential ( ) conditions by using Sirius model and exploring the full range of cultivar parameters. Read More

Agric For Meteorol 2019 Jan;264:351-362

Rothamsted Research, Herts, Harpenden, AL5 2JQ, UK.

Climate change is expected to severely affect cropping systems and food production in many parts of the world unless local adaptation can ameliorate these impacts. Ensembles of crop simulation models can be useful tools for assessing if proposed adaptation options are capable of achieving target yields, whilst also quantifying the share of uncertainty in the simulated crop impact resulting from the crop models themselves. Although some studies have analysed the influence of ensemble size on model outcomes, the effect of ensemble composition has not yet been properly appraised. Read More

Agric For Meteorol 2018 Sep 1;259:329-344. Epub 2018 Jun 1.

NASA Goddard Institute for Space Studies, New York, NY, USA.

This study compares climate changes in major agricultural regions and current agricultural seasons associated with global warming of +1.5 or +2.0 °C above pre-industrial conditions. Read More

Agric For Meteorol 2018 Sep;259:364-373

Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, 68583-0915, USA.

Water productivity (WP) is a robust benchmark for crop production in relation to available water supply across spatial scales. Quantifying water-limited potential (WPw) and actual on-farm (WPa) WP to estimate WP gaps is an essential first step to identify the most sensitive factors influencing production capacity with limited water supply. This study combines local weather, soil, and agronomic data, and crop modeling in a spatial framework to determine WPw and WPa at local and regional levels for rainfed cropping systems in 17 (maize) and 18 (wheat) major grain-producing countries representing a wide range of cropping systems, from intensive, high-yield maize in north America and wheat in west Europe to low-input, low-yield maize systems in sub-Saharan Africa and south Asia. Read More

Agric For Meteorol 2017 Aug;242:109-119

U.S. Environmental Protection Agency, Retired.

Large conifer trees in the Pacific Northwest, USA (PNW) use stored water to extend photosynthesis, both diurnally and seasonally. This is particularly important during the summer drought, which is characteristic of the region. In the PNW, climate change is predicted to result in hotter, drier summers and warmer, wetter winters with decreased snowpack by mid-century. Read More

Agric For Meteorol 2018 ;252:269-282

U.S. Environmental Protection Agency, Office of Research and Development, 109 T.W. Alexander Dr., Durham, NC 27711, USA.

Increasing air temperature is expected to extend growing season length in temperate, broadleaf forests, leading to potential increases in evapotranspiration and net carbon uptake. However, other key processes affecting water and carbon cycles are also highly temperature-dependent. Warmer temperatures may result in higher ecosystem carbon loss through respiration and higher potential evapotranspiration through increased atmospheric demand for water. Read More

Agric For Meteorol 2017 Jun;240-241:35-45

Barcelona Supercomputing Center (BSC), c/ Jordi Girona 29, Barcelona 08034, Spain.

Understanding the effects of climate variability and extremes on crop growth and development represents a necessary step to assess the resilience of agricultural systems to changing climate conditions. This study investigates the links between the large-scale atmospheric circulation and crop yields in Europe, providing the basis to develop seasonal crop yield forecasting and thus enabling a more effective and dynamic adaptation to climate variability and change. Four dominant modes of large-scale atmospheric variability have been used: North Atlantic Oscillation, Eastern Atlantic, Scandinavian and Eastern Atlantic-Western Russia patterns. Read More

Agric For Meteorol 2017 May;237-238:246-256

International Rice Research Institute, Los Baños, Philippines.

The worldwide usage of and increasing citations for ORYZA2000 has established it as a robust and reliable ecophysiological model for predicting the growth and yield of rice in an irrigated lowland ecosystem. Because of its focus on irrigated lowlands, its computation ability is limited to the representation of the effects of the highly dynamic environments of upland, rainfed, and aerobic ecosystems on rice growth and yield. Additional modules and routines to quantify daily variations in soil temperature, carbon, nitrogen, and environmental stresses were then developed and integrated into ORYZA2000 to capture their effects on primary production, assimilate allocation, root growth, and water and nitrogen uptake. Read More

Agric For Meteorol 2017 May;237-238:135-142

Environmental Protection Agency of Aosta Valley, ARPA VdA, Climate Change Unit, Aosta, ITALY.

So-called CO flux partitioning algorithms are widely used to partition the net ecosystem CO exchange into the two component fluxes, gross primary productivity and ecosystem respiration. Common CO flux partitioning algorithms conceptualize ecosystem respiration to originate from a single source, requiring the choice of a corresponding driving temperature. Using a conceptual dual-source respiration model, consisting of an above- and a below-ground respiration source each driven by a corresponding temperature, we demonstrate that the typical phase shift between air and soil temperature gives rise to a hysteresis relationship between ecosystem respiration and temperature. Read More

Agric For Meteorol 2016 Oct;226-227:37-49

Institute of Ecology, University of Innsbruck, Sternwartestr. 15, 6020 Innsbruck, AUSTRIA.

In complex, sloping terrain, horizontal measurements of net radiation are not reflective of the radiative energy available for the conductive and convective heat exchange of the underlying surface. Using data from a grassland site on a mountain slope characterised by spatial heterogeneity in inclination and aspect, we tested the hypothesis that a correction of the horizontal net radiation measurements which accounts for the individual footprint contributions of the various surfaces to the measured sensible and latent heat eddy covariance fluxes will yield more realistic slope-parallel net radiation estimates compared to a correction based on the average inclination and aspect of the footprint. Our main result is that both approaches led to clear, but very similar improvements in the phase between available energy and the sum of the latent and sensible heat fluxes. Read More

Agric For Meteorol 2015 Dec;214-215:430-443

University of Natural Resources and Life Sciences (BOKU), Institute of Wood Science and Technology, Konrad-Lorenz-Straβe 24, 3430 Tulln an der Donau, Austria.

Understanding drought sensitivity of tree species and its intra-specific variation is required to estimate the effects of climate change on forest productivity, carbon sequestration and tree mortality as well as to develop adaptive forest management measures. Here, we studied the variation of drought reaction of six European species and ten provenances of planted in the drought prone eastern Austria. Tree-ring and X-ray densitometry data were used to generate early- and latewood measures for ring width and wood density. Read More

Agric For Meteorol 2015 Feb;201:187-195

Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, Berkshire, United Kingdom.

Land use change is a major threat to biodiversity. One mechanism by which land use change influences biodiversity and ecological processes is through changes in the local climate. Here, the relationships between leaf area index and five climate variables - air temperature, relative humidity, vapour pressure deficit, specific humidity and soil temperature - are investigated across a range of land use types in Borneo, including primary tropical forest, logged forest and oil palm plantation. Read More

Agric For Meteorol 2014 Jun;189-190(100):211-219

Computational and Systems Biology Department, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK.

An existing simulation model of wheat growth and development, Sirius, was evaluated through a systematic model reduction procedure. The model was automatically manipulated under software control to replace variables within the model structure with constants, individually and in combination. Predictions of the resultant models were compared to growth analysis observations of total biomass, grain yield, and canopy leaf area derived from 9 trials conducted in the UK and New Zealand under optimal, nitrogen limiting and drought conditions. Read More

Agric For Meteorol 2013 Feb;169:85-91

Hydrology and Water Resources Management Department, Ecology Centre, University of Kiel, Olshausenstrasse 40, 24098 Kiel, GERMANY.

Elucidating the causes for the energy imbalance, i.e. the phenomenon that eddy covariance latent and sensible heat fluxes fall short of available energy, is an outstanding problem in micrometeorology. Read More

Agric For Meteorol 2011 Dec;151(12):1731-1740

Institute of Ecology, University of Innsbruck, Sternwartestr. 15, 6020 Innsbruck, AUSTRIA.

Climate change is expected to affect the Alps by increasing the frequency and intensity of summer drought events with negative impacts on ecosystem water resources. The response of CO and HO exchange of a mountain grassland to natural fluctuations of soil water content was evaluated during 2001-2009. In addition, the physiological performance of individual mountain forb and graminoid plant species under progressive soil water shortage was explored in a laboratory drought experiment. Read More

Agric For Meteorol 2009 Sep;149(9):1556-1559

Institut für Ökologie, Universität Innsbruck, Sternwartestr. 15, 6020 Innsbruck, AUSTRIA.

The Penman-Monteith combination equation, which is most frequently used to derive the surface conductance to water vapour (G), implicitly assumes the energy balance to be closed. Any energy imbalance (positive or negative) will thus affect the calculated G. Using eddy covariance energy flux data from a temperate grassland and a desert shrub ecosystem we explored five possible approaches of closing the energy imbalance and show that calculated G may differ considerably between these five approaches depending on the relative magnitudes of sensible and latent heat fluxes, and the magnitude and sign of the energy imbalance. Read More

Agric For Meteorol 2009 Feb;149(2):291-302

Institut für Ökologie, Universität Innsbruck, Sternwartestr. 15, 6020 Innsbruck, Austria.

The differential design, deployment and data post-processing of open- (OP) and closed-path (CP) eddy covariance systems is a potential source of bias for ongoing global flux synthesis activities. Here we use a unique six year data set of concurrent CP and OP carbon dioxide (CO) and water vapour (HO) eddy covariance flux measurements above a temperate mountain grassland in Austria to explore the consequences of these differences on a long-term basis. The theoretically based transfer function approach was able to account and correct for the differences in low-pass filtering between the two systems. Read More