Remotely-sensed detection of effects of extreme droughts on gross primary production.
Severe droughts strongly impact photosynthesis (GPP), and satellite imagery has yet to demonstrate its ability to detect drought effects. Especially changes in vegetation functioning when vegetation state remains unaltered (no browning or defoliation) pose a challenge to satellite-derived indicators. We evaluated the performance of different satellite indicators to detect strong drought effects on GPP in a beech forest in France (Hesse), where vegetation state remained largely unaffected while GPP decreased substantially. We compared the results with three additional sites: a Mediterranean holm oak forest (Puéchabon), a temperate beech forest (Hainich), and a semi-arid grassland (Bugacpuszta). In Hesse, a three-year reduction in GPP following drought was detected only by the Enhanced Vegetation Index (EVI). The Photochemical Reflectance Index (PRI) also detected this drought effect, but only after normalization for absorbed light. In Puéchabon normalized PRI outperformed the other indicators, while the short-term drought effect in Hainich was not detected by any tested indicator. In contrast, most indicators, but not PRI, captured the drought effects in Bugacpuszta. Hence, PRI improved detection of drought effects on GPP in forests and we propose that PRI normalized for absorbed light is considered in future algorithms to estimate GPP from space.
Center of Excellence PLECO (Plant and Vegetation Ecology), Biology Department, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.|CREAF, Cerdanyola del Vallès 08913, Catalonia, Spain.
Sara
S
Vicca
Center of Excellence PLECO (Plant and Vegetation Ecology), Biology Department, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.
Manuela
M
Balzarolo
CREAF, Cerdanyola del Vallès 08913, Catalonia, Spain.|CSIC, Global Ecology Unit, CREAF-CEAB-UAB, Cerdanyola del Vallés 08913, Catalonia, Spain.
Iolanda
I
Filella
UMR 1137 Ecologie et Ecophysiologie Forestières, INRA, 54280 Champenoux, France.
André
A
Granier
Thünen Institute of Climate Smart Agriculture, Bundesallee 50, 38116 Braunschweig, Germany.
Mathias
M
Herbst
Bioclimatology, University of Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
Alexander
A
Knohl
UMR 1137 Ecologie et Ecophysiologie Forestières, INRA, 54280 Champenoux, France.
Bernard
B
Longdoz
Silviculture and Forest Ecology of the Temperate Zones, University of Göttingen, Büsgenweg 1, 37077 Göttingen, Germany.
Martina
M
Mund
MTA-SZIE Plant Ecology Research Group, Szent István University, Páter K. 1, 2103 Gödöllő, Hungary.
Zoltan
Z
Nagy
MTA-SZIE Plant Ecology Research Group, Szent István University, Páter K. 1, 2103 Gödöllő, Hungary.
Krisztina
K
Pintér
CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, F-34293, Montpellier cedex 5, France.|Universidade Federal de Lavras, Departamento de Biologia, CP 3037, CEP 37200-000, Lavras, MG, Brazil.
Serge
S
Rambal
Laboratory of Geo-Information Science and Remote Sensing, Wageningen University, Droevendaalsesteeg 3, Wageningen 6708 PB, The Netherlands.
Jan
J
Verbesselt
CREAF, Cerdanyola del Vallès 08913, Catalonia, Spain.|CSIC, Global Ecology Unit, CREAF-CEAB-UAB, Cerdanyola del Vallés 08913, Catalonia, Spain.
Aleixandre
A
Verger
Department of Statistics, Faculty of Economics and Statistics, Universität Innsbruck, Universitätsstr. 15. 6020 Innsbruck, Austria.
Achim
A
Zeileis
CREAF, Cerdanyola del Vallès 08913, Catalonia, Spain.|CSIC, Global Ecology Unit, CREAF-CEAB-UAB, Cerdanyola del Vallés 08913, Catalonia, Spain.
Chao
C
Zhang
CREAF, Cerdanyola del Vallès 08913, Catalonia, Spain.|CSIC, Global Ecology Unit, CREAF-CEAB-UAB, Cerdanyola del Vallés 08913, Catalonia, Spain.
Josep
J
Peñuelas
D055864:Droughts; D065928:Forests; D005602:France; D010788:Photosynthesis; D058998:Remote Sensing Technology