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Responses of the reflectance indices PRI and NDVI to experimental warming and drought in European shrublands along a north–south climatic gradient

Mänd, Pille and Hallik, Lea and Peñuelas, Josep and Nilson, Tiit and Duce, Pierpaolo and Emmett, Bridget A. and Beier, Claus and Estiarte, Marc and Garadnai, János and Kalapos, Tibor and Schmidt, Inger Kappel and Kovács-Láng, Edit and Prieto, Patricia and Tietema, Albert and Westerveld, Joke W. and Kull, Olevi (2010) Responses of the reflectance indices PRI and NDVI to experimental warming and drought in European shrublands along a north–south climatic gradient. Remote Sensing of Environment, Vol. 114 (3), p. 626-636. ISSN 0034-4257. Article.

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DOI: 10.1016/j.rse.2009.11.003

Abstract

The aim of this study was to evaluate the use of ground-based canopy reflectance measurements to detect changes in physiology and structure of vegetation in response to experimental warming and drought treatment at six European shrublands located along a North–South climatic gradient. We measured canopy reflectance, effective green leaf area index (green LAIe) and chlorophyll fluorescence of dominant species. The treatment effects on green LAIe varied among sites. We calculated three reflectance indices: photochemical reflectance index PRI [531 nm; 570 nm], normalized difference vegetation index NDVI680 [780 nm; 680 nm] using red spectral region, and NDVI570 [780 nm; 570 nm] using the same green spectral region as PRI. All three reflectance indices were significantly related to green LAIe and were able to detect changes in shrubland vegetation among treatments. In general warming treatment increased PRI and drought treatment reduced NDVI values. The significant treatment effect on photochemical efficiency of plants detected with PRI could not be detected by fluorescence measurements. However, we found canopy level measured PRI to be very sensitive to soil reflectance properties especially in vegetation areas with low green LAIe. As both soil reflectance and LAI varied between northern and southern sites it is problematic to draw universal conclusions of climate-derived changes in all vegetation types based merely on PRI measurements. We propose that canopy level PRI measurements can be more useful in areas of dense vegetation and dark soils.

Item Type:Article
ID Code:5691
Status:Published
Refereed:Yes
Uncontrolled Keywords:Chlorophyll fluorescence, climate change, drought, green LAI, NDVI, PRI, reflectance indices, remote sensing, soil reflectance, VULCAN, warming
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/03 Arboricoltura generale e coltivazioni arboree
Divisions:002 Altri enti e centri di ricerca del Nord Sardegna > CNR-Consiglio Nazionale delle Ricerche > Istituto di biometeorologia, Sassari
Publisher:Elsevier
ISSN:0034-4257
Copyright Holders:© 2009 Published by Elsevier
Deposited On:07 Mar 2011 18:46

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