A5009972805- Plant Water Relations and Carbon Dynamics
- Atmospheric and Environmental Gas Dynamics
- Climate variability and models
- Atmospheric chemistry and aerosols
- Tree-ring climate responses
- Climate change and permafrost
- Peatlands and Wetlands Ecology
- Plant responses to elevated CO2
- Soil Carbon and Nitrogen Dynamics
- Methane Hydrates and Related Phenomena
- Forest ecology and management
- Cryospheric studies and observations
- Meteorological Phenomena and Simulations
- Aeolian processes and effects
- Geology and Paleoclimatology Research
- Hydrology and Watershed Management Studies
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Remote Sensing in Agriculture
- Forest Management and Policy
- Hydrocarbon exploration and reservoir analysis
- Plant Ecology and Soil Science
- Spectroscopy and Laser Applications
- Soil and Unsaturated Flow
- Fire effects on ecosystems
ETH Zurich
2014-2023
Board of the Swiss Federal Institutes of Technology
2005-2021
Instituto de Ciencias Agrarias
2015-2020
Charles Humbert 8
2017-2020
École Polytechnique Fédérale de Lausanne
2004-2018
Lawrence Berkeley National Laboratory
2014
University of Bern
1998-2011
Ecosystem Sciences
2010
Institute of Plant Biology
2007
University of Pennsylvania
2006
Abstract The FLUXNET2015 dataset provides ecosystem-scale data on CO 2 , water, and energy exchange between the biosphere atmosphere, other meteorological biological measurements, from 212 sites around globe (over 1500 site-years, up to including year 2014). These sites, independently managed operated, voluntarily contributed their create global datasets. Data were quality controlled processed using uniform methods, improve consistency intercomparability across sites. is already being used...
Summary Synthesis of results from several Arctic and boreal research programmes provides evidence for the strong role high‐latitude ecosystems in climate system. Average surface air temperature has increased 0.3 °C per decade during twentieth century western North American forest zones. Precipitation also increased, but changes soil moisture are uncertain. Disturbance rates have forest; example, there been a doubling area burned America past 20 years. The disturbance regime tundra may not...
Abstract Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem balance is uncertain. We investigated dissolved organic (DOC), inorganic (DIC), methane (CH 4 ), at forests, grasslands, croplands across Europe. Biogenic contributions DIC were estimated by means its δ 13 C signature. Leaching biogenic was 8.3±4.9 g m −2 yr −1 for 24.1±7.2 14.6±4.8 croplands. DOC equalled 3.5±1.3 5.3±2.0 4.1±1.3 The average flux total 19.4±4.0 ....
Summary This paper summarizes and analyses available data on the surface energy balance of Arctic tundra boreal forest. The complex interactions between ecosystems their are also examined, including climatically induced shifts in ecosystem type that might amplify or reduce effects potential climatic change. High latitudes characterized by large annual changes solar input. Albedo decreases strongly from winter, when is snow‐covered, to summer, especially nonforested regions such as wetlands....
Summary Separating continuously measured stem radius ( SR ) fluctuations into growth‐induced irreversible expansion GRO and tree water deficit‐induced reversible shrinkage (TWD) requires a conceptualization of potential growth processes that may occur during periods shrinking expanding below precedent maximum. Here, we investigated two physiological concepts: the linear LG concept, assuming growth, versus zero ZG no shrinkage. We evaluated mechanisms underlying these concepts assessed their...
Summary We assessed how the seasonal variability of precipitation δ 2 H and 18 O is propagated into soil xylem waters temperate trees, applied a hydrological model to estimate residence time distribution in soil, identified temporal origin water taken up by Picea abies Fagus sylvatica over 4 yr. Residence times varied between few days several months increased with depth. On average, 50% consumed trees throughout year had precipitated during growing season, while 40% preceding winter or even...
The timing of diel stem growth mature forest trees is still largely unknown, as empirical data with high temporal resolution have not been available so far. Consequently, the effects day-night conditions on tree remained uncertain. Here we present first comprehensive field study hourly-resolved radial seven temperate species, based 57 million underlying points over a period up to 8 yr. We show that grow mainly at night, peak after midnight, when vapour pressure deficit (VPD) among lowest. A...
Temperate tree species differ in their physiological sensitivity to declining soil moisture and drought. Although species-specific responses drought have often been suggested be the result of different water uptake depths, empirical evidence for such a mechanism is scarce. Here we test if differences depths can explain previously observed temperate trees depth varies response moisture. For this purpose, employed stable oxygen hydrogen isotopes xylem that collected over course three growing...
Abstract. As part of the quality assurance and control activities within CarboEurope-IP network, a comparison eddy-covariance software was conducted. For four five-day datasets, CO2 flux estimates were calculated by seven commonly used packages to assess uncertainty due differences in post-processing. The datasets originated from different sites representing applied instrumentation canopy structures cover wide range realistic conditions. Data preparation, coordinate rotation implementation...
Abstract This paper presents results of 1 year (from March 25, 2003 to 24, 2004, 366 days) continuous measurements net ecosystem CO 2 exchange (NEE) above a steppe in Mongolia using the eddy covariance technique. The steppe, typical central Mongolia, is dominated by C 3 plants adapted continental climate. following two questions are addressed: (1) how do NEE and its components: gross production (GEP) total respiration ( R eco ) vary seasonally? (2) NEE, GEP, respond biotic abiotic factors?...
CO 2 exchange between lake water and the atmosphere was investigated at Toolik Lake (Alaska) Soppensee (Switzerland) employing eddy covariance (EC) method. The results obtained from three field campaigns two sites indicate importance of convection in driving gas flux across water‐air interface. Measurements were performed during short (1–3 day) periods with observed diurnal changes stratified convective conditions lakes. Over EC net efflux 114 ± 33 mg C m −2 d −1 , which compares well 131...
Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric dioxide because potential accelerating effects positive climate–carbon cycle feedbacks. However, directly observed CO2 with atmosphere across biomes continents are lacking. Here we present data describing net ecosystem (NEE) factors as measured using eddy covariance method at 125 unique sites in various over six a total 559 site-years. We find that...
The first full greenhouse gas (GHG) flux budget of an intensively managed grassland in Switzerland (Chamau) is presented. three major trace gases, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were measured with the eddy covariance (EC) technique. For CO2 concentrations, open-path infrared analyzer was used, while N2O CH4 concentrations a recently developed continuous-wave quantum cascade laser absorption spectrometer (QCLAS). We investigated magnitude these emissions after...
Lakes are large sources of methane, held to be responsible for 18% the radiative forcing, atmosphere. Periods lake overturn (during fall/winter) short and therefore difficult capture with field campaigns but potentially one most important periods methane emissions. We studied emissions using four different methods, including eddy covariance measurements, floating chambers, anchored funnels, boundary model calculations. Whereas first three methods agreed rather well, estimates were 5-30 times...
CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsSpecials 39:261-274 (2009) - DOI: https://doi.org/10.3354/cr00811 Tree phenology and carbon dioxide fluxes: use of digital photography for process-based interpretation at ecosystem scale H. E. Ahrends1,2,*, S. Etzold2, W. L. Kutsch3, R. Stoeckli4, Bruegger1, F. Jeanneret1, Wanner1, N. Buchmann2, Eugster2 1Institute Geography, University...
Abstract. Atmospheric inverse modelling has the potential to provide observation-based estimates of greenhouse gas emissions at country scale, thereby allowing for an independent validation national emission inventories. Here, we present a regional-scale study quantify methane (CH4) from Switzerland, making use newly established CarboCount-CH measurement network and high-resolution Lagrangian transport model. In our reference inversion, prior were taken "bottom-up" Swiss Greenhouse Gas...