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Meelis Mölder

Research engineer

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Detection and attribution of an anomaly in terrestrial photosynthesis in Europe during the COVID-19 lockdown

Author

  • Angela Che Ing Tang
  • Christophe R. Flechard
  • Nicola Arriga
  • Dario Papale
  • Paul C. Stoy
  • Nina Buchmann
  • Matthias Cuntz
  • John Douros
  • Silvano Fares
  • Alexander Knohl
  • Ladislav Šigut
  • Guillaume Simioni
  • Renske Timmermans
  • Thomas Grünwald
  • Andreas Ibrom
  • Benjamin Loubet
  • Ivan Mammarella
  • Luca Belelli Marchesini
  • Mats Nilsson
  • Matthias Peichl
  • Corinna Rebmann
  • Marius Schmidt
  • Christian Bernhofer
  • Daniel Berveiller
  • Edoardo Cremonese
  • Tarek S. El-Madany
  • Mana Gharun
  • Damiano Gianelle
  • Lukas Hörtnagl
  • Marilyn Roland
  • Andrej Varlagin
  • Zheng Fu
  • Bernard Heinesch
  • Ivan Janssens
  • Natalia Kowalska
  • Jiří Dušek
  • Giacomo Gerosa
  • Meelis Mölder
  • Eeva Stiina Tuittila
  • Denis Loustau
Show all

Summary, in English

Carbon dioxide (CO2) uptake by plant photosynthesis, referred to as gross primary production (GPP) at the ecosystem level, is sensitive to environmental factors, including pollutant exposure, pollutant uptake, and changes in the scattering of solar shortwave irradiance (SWin) − the energy source for photosynthesis. The 2020 spring lockdown due to COVID-19 resulted in improved air quality and atmospheric transparency, providing a unique opportunity to assess the impact of air pollutants on terrestrial ecosystem functioning. However, detecting these effects can be challenging as GPP is influenced by other meteorological drivers and management practices. Based on data collected from 44 European ecosystem-scale CO2 flux monitoring stations, we observed significant changes in spring GPP at 34 sites during 2020 compared to 2015–2019. Among these, 14 sites showed an increase in GPP associated with higher SWin, 10 sites had lower GPP linked to atmospheric and soil dryness, and seven sites were subjected to management practices. The remaining three sites exhibited varying dynamics, with one experiencing colder and rainier weather resulting in lower GPP, and two showing higher GPP associated with earlier spring melts. Analysis using the regional atmospheric chemical transport model (LOTOS-EUROS) indicated that the ozone (O3) concentration remained relatively unchanged at the research sites, making it unlikely that O3 exposure was the dominant factor driving the primary production anomaly. In contrast, SWin increased by 9.4 % at 36 sites, suggesting enhanced GPP possibly due to reduced aerosol optical depth and cloudiness. Our findings indicate that air pollution and cloudiness may weaken the terrestrial carbon sink by up to 16 %. Accurate and continuous ground-based observations are crucial for detecting and attributing subtle changes in terrestrial ecosystem functioning in response to environmental and anthropogenic drivers.

Department/s

  • Dept of Physical Geography and Ecosystem Science

Publishing year

2023-12-10

Language

English

Publication/Series

Science of the Total Environment

Volume

903

Document type

Journal article

Publisher

Elsevier

Topic

  • Physical Geography

Keywords

  • Aerosol optical depth
  • Air quality
  • COVID-19
  • Eddy covariance
  • Gross primary production
  • Shortwave irradiance

Status

Published

ISBN/ISSN/Other

  • ISSN: 0048-9697