Petra D'Odorico

Swiss Federal Institute for Forest, Snow and Landscape Research WSL | WSL

The Amazon forest experienced severe droughts in 2005 and 2010; however, the extent to which precipitation anomaly affects the vegetation productivity remains controversial (1, 2). Hilker et al. (3) report significant correlations (P < 0.05) between the El Niño southern oscillation (ENSO) and the Amazon vegetation greenness based on the improved mo...

A R T I C L E I N F O Keywords: PlanetScope Dendrometer Intra-annual tree growth Radial growth phenology index (RGPI) Remote sensing A B S T R A C T Radial stem growth is a key ecosystem process resulting in long-term carbon sequestration. Despite recognition of its importance to global carbon cycling, high uncertainties remain regarding how radial...

Land carbon dynamics in temperate and boreal ecosystems are sensitive to environmental change. Accurately simulating gross primary productivity (GPP) and its seasonality is key for reliable carbon cycle projections. However, significant biases have been found in early spring GPP simulations of northern forests, where observations often suggest a la...

Global warming and droughts push forests closer to their thermal limits, altering tree carbon uptake and growth. To prevent critical overheating, trees can adjust their thermotolerance (Tcrit), temperature and photosynthetic optima (Topt and Aopt), and canopy temperature (Tcan) to stay below damaging thresholds. However, we lack an understanding of...

Die Waldbewirtschaftung kann bei der Entwicklung wirtschaftlich tragfähiger Strategien zur Milderung der Auswirkungen durch den Klimawandel eine wichtige Rolle spielen. Dazu müssen unter anderem Waldmonitoring-Kapazitäten ausgebaut und neue Technologien eingesetzt werden, die es ermöglichen, effizient, flächendeckend und frühzeitig Anzeichen von St...

Forests account for nearly 90 % of the world's terrestrial biomass in the form of carbon and they support 80 % of the global biodiversity. To understand the underlying forest dynamics, we need a long-term but also relatively high-frequency, networked monitoring system, as traditionally used in meteorology or hydrology. While there are numerous exis...

Precise delineation of individual tree crowns is critical for accurate forest biophysical parameter estimation, species classification, and ecosystem modelling. Multispectral optical remote sensors mounted on low-flying unmanned aerial vehicles (UAVs) can rapidly collect very-high-resolution (VHR) photogrammetric optical data that contain the spect...

Vertical gradients in the canopy represent a major challenge for scaling from foliar photosynthesis to ecosystem-level CO2 fluxes. We tested whether accounting for independent gradients of carboxylation capacity (Vcmax) and photosynthetic electron transport (Jmax) improves estimates of forest net ecosystem CO2 exchange (NEE). We modified the proces...

Future climate will be characterized by an increase in frequency and duration of drought and warming that exacerbates atmospheric evaporative demand. How trees acclimate to long-term soil moisture changes and whether these long-term changes alter trees' sensitivity to short-term (day to months) variations of vapor pressure deficit (VPD) and soil mo...

Monitoring early tree physiological responses to drought is key to understanding progressive impacts of drought on forests and identifying resilient species. We combined drone-based multispectral remote sensing with measurements of tree physiology and environmental parameters over two growing seasons in a 100-y-old Pinus sylvestris forest subject t...

The future climate will be characterized by an increase in frequency and duration of drought and warming that exacerbates atmospheric evaporative demand. How trees acclimate to long-term soil moisture changes and whether these long-term changes alter trees' sensitivity to short-term (day to months) variations of vapor pressure deficit (VPD) and soi...

Diffuse radiation generally increases photosynthetic rates if total radiation is kept constant. Different hypotheses have been proposed to explain this enhancement of photosynthesis, but conclusive results over a wide range of diffuse conditions or about the effect of canopy architecture are lacking. Here, we show the response of canopy photosynthe...

Phenology is an important indicator of environmental variation and climate change impacts on tree responses. In conifers, monitoring phenology of photosynthesis through remote sensing has been unreliable, because needle foliage varies little throughout the year. This is challenging for modelling ecosystem carbon uptake and monitoring phenology for...

While foliar photosynthetic relationships with light, nitrogen, and water availability have been well described, environmental factors driving vertical gradients of foliar traits within forest canopies are still not well understood. We, therefore, examined how light availability and vapour pressure deficit (VPD) co-determine vertical gradients (bet...

Photosynthetic phenology is an important indicator of annual gross primary productivity (GPP). Assessing photosynthetic phenology remotely is difficult for evergreen conifers as they remain green year‐round. Carotenoid‐based vegetation indices such as the photochemical reflectance index (PRI) and chlorophyll/carotenoid index (CCI) are promising too...

Carotenoid pigments play an important role in the seasonal regulation of photosynthesis and photoprotection of overwintering conifers. Because the seasonal changes in the rate of photosynthetic CO 2 assimilation are linked to changes in carotenoid pigment composition, it has been suggested that carotenoid sensitive vegetation indices might be used...

Photosynthetic CO2 responses (A/Ci curves, where Ci is intercellular [CO2]) are used to understand how photosynthesis responds to changing environmental conditions and to predict the responses of plant carbon uptake to future climatic conditions. Simultaneous measurements of chlorophyll fluorescence allows determining the partitioning of energy bet...

Forests play a major role as global carbon sinks, and in order to understand global carbon cycles, it is necessary to determine climate change effects on the sink strength of forests. While ecophysiological processes at the molecular and leaf level are well understood, it remains controversial how they can be integrated over space and time to net e...

In support of climate change mitigation strategies and food security, there is an ever-increasing requirement to understand the key drivers of cropland yields and carbon (C) budgets. Process-based crop models, driven by meteorological observations, can provide realistic simulations and diagnosis of the variability in crop C budgets. However, the fi...

The presence or absence of leaves within plant canopies exert a strong influence on the carbon, water and energy balance of ecosystems. Identifying key changes in the timing of leaf elongation and senescence during the year can help to understand the sensitivity of different plant functional types to changes in temperature. When recorded over many...

Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System co...

Biophysical and biochemical traits of foliage and twigs at the top of tree canopies provide essential information on trees' ecophysiology. Conventional methods used for canopy sampling are typically time consuming and costly, while the very canopy tops are still out of reach unless a canopy crane is used. Thus, we developed a novel twig sampling me...

Croplands are involved in the exchange of carbon dioxide (CO2) between the atmosphere and the biosphere. Furthermore, soil carbon (C) stocks play an important role in soil fertility. It is thus of great interest to know whether intensively managed croplands act as a net source or sink of atmospheric CO2 and if soil C stocks are preserved over long...

While leaves’ photosynthetic responses to light and water availability are well understood, there is still no consensus about the factors driving the vertical gradient of photosynthesis within forest canopies. This has hampered the upscaling from leaf-level photosynthesis measurements to canopy and landscape levels needed for carbon exchange models...

Croplands are involved in the exchange of carbon dioxide (CO2) between the atmosphere and the biosphere. Further- more, soil carbon (C) stocks play an important role in soil fertility. It is, thus, of great interest to know whether croplands act as a net source or sink of atmospheric CO2, and if soil C stocks are preserved over long timescales. The...

To include within-canopy leaf acclimation responses to light and other resource gradients in photosynthesis modelling, it is imperative to understand the variation of leaf structural, biochemical and physiological traits from canopy top to bottom. In the present study, leaf photosynthetic traits for top and bottom canopy leaves, canopy structure an...

Similar maximum photosynthetic capacity along the canopy indicates that in the upper canopy, where light is abundant, water availability might limit photosynthesis. Consequently, chlorophyll investments are reduced. Higher water-use efficiency in the upper canopy indicates water limitation, which might restrict photosynthesis during times of high...

Northern terrestrial ecosystems have shown global warming-induced advances in start, delays in end, and thus increased lengths of growing season and gross photosynthesis in recent decades. The tradeoffs between seasonal dynamics of two opposing fluxes, CO2 uptake through photosynthesis and release through respiration, determine the influence of the...

Accurate and reliable estimates of gross primary productivity (GPP) are required for monitoring the global carbon cycle at different spatial and temporal scales. Because GPP displays high spatial and temporal variation, remote sensing plays a major role in producing gridded estimates of GPP across spatiotemporal scales. In this context, understandi...

Light use efficiency (LUE) models are widely used to simulate gross primary production (GPP). However, the treatment of the plant canopy as a big leaf by these models can introduce large uncertainties in simulated GPP. Recently, a two-leaf light use efficiency (TL-LUE) model was developed to simulate GPP separately for sunlit and shaded leaves and...

We present the Airborne Prism Experiment (APEX), its calibration and subsequent radiometric measurements as well as Earth science applications derived from this data. APEX is a dispersive pushbroom imaging spectrometer covering the solar reflected wavelength range between 372 and 2540 nm with nominal 312 (max. 532) spectral bands. APEX is calibrate...

Citizen science, time series records over long periods of time, and wide geographic areas offer many opportunities for scientists to answer questions that would otherwise be impractical to investigate. Citizen scientists currently play active roles in a wide range of ecological projects; however, observer biases such as varying perception of events...

Canopy structural parameters are often used to give adequate representation of vegetated ecosystems for various purposes including primary productivity, climate system, water and carbon gas exchanges, and radiation extinction. Canopy structural parameters are usually described using several pseudo-synonymous terms, often measuring different compone...

Remote sensing of long-term vegetation monitoring relies on the analysis of multisensor and multitemporal time-series measurements. Cross-sensor calibration is therefore important to prevent artifacts in the temporal signal due to inherent differences in sensors configurations. Variations in spectral response functions (SRFs) are among the major ca...

The APEX system is fully operational since 2011 and ready to provide well-calibrated data as standard processing output of the APEX PAF and the VITO CDPC to the user community. We sincerely hope that the freely available APEX Open Science Data Set will assist the community in gaining insights into the huge potential of APEX and help in assessing it...

Die Fernerkundung ist heutzutage wahrscheinlich die wertvollste Methode um Parameter, die Prozesse unserer Umwelt definieren, quantitativ und global zu messen. Für eine korrekte Interpretation dieser Messungen ist das Verständnis aller Faktoren die den Messprozess beeinflussen entscheidend. Im Idealfall beinhaltet die Messung des reflektierten Sonn...

Accurate spectral calibration of airborne and spaceborne imaging spectrometers is essential for proper preprocessing and scientific exploitation of high spectral resolution measurements of the land and atmosphere. A systematic performance assessment of onboard and scene-based methods for in-flight monitoring of instrument spectral calibration is pr...

The Airborne Prism EXperiment (APEX) is an airborne pushbroom imaging spectrometer for Earth observation. Its products will become available in 2011. APEX is currently prepared for final acceptance configuration completing final hardware upgrades, refined calibration methodologies and test flights. APEX is composed of an airborne dispersive pushbro...

The Airborne Prism EXperiment (APEX) is an airborne pushbroom imaging spectrometer for Earth observation. Its products will become available in 2011. APEX is currently prepared for final acceptance configuration completing final hardware upgrades, refined calibration methodologies and test flights. APEX is composed of an airborne dispersive pushbro...

Spectral performance of an airborne dispersive pushbroom imaging spectrometer cannot be assumed to be stable over a whole flight season given the environmental stresses present during flight. Spectral performance monitoring during flight is commonly accomplished by looking at selected absorption features present in the Sun, atmosphere, or ground, a...

ESA APEX (Airborne Prism EXperiment) is a project for the realisation of an airborne dispersive pushbroom imaging spectrometer, a dedicated data Processing and Archiving Facility (PAF, hosted at VITO) and a Calibration Home Base (CHB, hosted at DLR) for instrument calibration operation. It has been developed by a joint Swiss-Belgian consortium. The...

Spectral performance of an airborne dispersive pushbroom imaging spectrometer cannot be assumed to be stable over a whole flight season given the environmental stresses present during flight. Spectral performance monitoring during flight is commonly accomplished by looking at selected absorption features present in the Sun, atmosphere, or ground, a...

The In-Flight Characterization (IFC) facility of the Airborne Prism Experiment (APEX) is presumably the first onboard characterization unit implemented in an airborne imaging spectrometer. This study is meant to test methodologies for the retrieval of temporal relative center wavelength drifts based on IFC data. A rare Earth material filter with a...

APEX (Airborne Prism EXperiment) is a project being developed by a joint Swiss-Belgian consortium on behalf of the European Space Agency ESA-PRODEX programme. It comprises an airborne dispersive pushbroom imaging spectrometer, a Calibration Home Base (CHB) for instrument calibration operations and a dedicated data Processing and Archiving Facility...

During their life span, imaging spectrometers are likely to be affected by deviations in spectral performances. Such fluctuations are mainly due to vibrations and temperature/pressure changes at the moment of launch or aging of the instrument. Prior to taking the spectrometer to the laboratory for a time-consuming re-characterization and re-calibra...

The airborne ESA-APEX (Airborne Prism Experiment) hyperspectral mission simulator is described with its distinct specifications to provide high quality remote sensing data. The concept of an automatic calibration, performed in the Calibration Home Base (CHB) by using the Control Test Master (CTM), the In-Flight Calibration facility (IFC), quality f...