Publications by authors named "Tommaso Julitta"

A hyperspectral field sensor (FloX) was installed in Adventdalen (Svalbard, Norway) in 2019 as part of the Svalbard Integrated Arctic Earth Observing System (SIOS) for monitoring vegetation phenology and Sun-Induced Chlorophyll Fluorescence (SIF) of high-Arctic tundra. This northernmost hyperspectral sensor is located within the footprint of a tower for long-term eddy covariance flux measurements and is an integral part of an automatic environmental monitoring system on Svalbard (AsMovEn), which is also a part of SIOS. One of the measurements that this hyperspectral instrument can capture is SIF, which serves as a proxy of gross primary production (GPP) and carbon flux rates.

View Article and Find Full Text PDF
Article Synopsis
  • Sun-induced fluorescence (SIF) is a valuable tool for assessing vegetation's gross primary production (GPP), but its effectiveness can be compromised during extreme weather events like heatwaves.
  • The 2018 European heatwave led to a reversal in the typical GPP-SIF relationship in evergreen broadleaved trees, primarily due to nonphotochemical quenching (NPQ) that protects plants from high light intensity.
  • This study reveals that extreme heat stress alters the energy allocation in plants, impacting the NPQ-SIF-GPP dynamics, highlighting limitations in current models that don't fully capture these complex interactions.
View Article and Find Full Text PDF

Recent advances in leaf fluorescence measurements and canopy proximal remote sensing currently enable the non-destructive collection of rich diurnal and seasonal time series, which are required for monitoring vegetation function at the temporal and spatial scales relevant to the natural dynamics of photosynthesis. Remote sensing assessments of vegetation function have traditionally used actively excited foliar chlorophyll fluorescence measurements, canopy optical reflectance data and vegetation indices (VIs), and only recently passive solar induced chlorophyll fluorescence (SIF) measurements. In general, reflectance data are more sensitive to the seasonal variations in canopy chlorophyll content and foliar biomass, while fluorescence observations more closely relate to the dynamic changes in plant photosynthetic function.

View Article and Find Full Text PDF

The global outbreak of the coronavirus pandemic has led to a significant reduction of traffic and traffic-related urban air pollution. One important pollutant in this context is NO2. Sudden change in NO2 emissions related to reduction of urban traffic due to infection protection measures can be detected in Düsseldorf, Germany with continuous measurements of down-welling light with a RoX automated field-spectrometer.

View Article and Find Full Text PDF
Article Synopsis
  • Leaf fluorescence is a key method for monitoring plant health and photosynthetic activity, providing insights into plant development and stress levels through red and far-red chlorophyll fluorescence maps.
  • Research on loblolly pine plantations in North Carolina revealed that younger stands have significantly higher red fluorescence yield compared to mature ones, suggesting a link to photosynthetic limitations in aging trees.
  • To improve the analysis of fluorescence data affected by pixel mixing in satellite images, the Canopy Cover Fluorescence Index (CCFI) was proposed, demonstrating the potential to better understand forest dynamics and responses to climate change.
View Article and Find Full Text PDF

Sun-induced fluorescence (SIF) in the far-red region provides a new noninvasive measurement approach that has the potential to quantify dynamic changes in light-use efficiency and gross primary production (GPP). However, the mechanistic link between GPP and SIF is not completely understood. We analyzed the structural and functional factors controlling the emission of SIF at 760 nm (F ) in a Mediterranean grassland manipulated with nutrient addition of nitrogen (N), phosphorous (P) or nitrogen-phosphorous (NP).

View Article and Find Full Text PDF