<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Garbulsky, Martín F.</style></author><author><style face="normal" font="default" size="100%">Penuelas, Josep</style></author><author><style face="normal" font="default" size="100%">Gamon, John</style></author><author><style face="normal" font="default" size="100%">Inoue, Yoshio</style></author><author><style face="normal" font="default" size="100%">Filella, Iolanda</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">The photochemical reflectance index (PRI) and the remote sensing of leaf, canopy and ecosystem radiation use efficienciesA review and meta-analysis</style></title><secondary-title><style face="normal" font="default" size="100%">Remote Sensing of Environment</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">ciency</style></keyword><keyword><style  face="normal" font="default" size="100%">gross primary productivity</style></keyword><keyword><style  face="normal" font="default" size="100%">index</style></keyword><keyword><style  face="normal" font="default" size="100%">MODIS</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical re fl ectance</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical reflectance index</style></keyword><keyword><style  face="normal" font="default" size="100%">radiation use ef fi</style></keyword><keyword><style  face="normal" font="default" size="100%">radiation use efficiency</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2011///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://linkinghub.elsevier.com/retrieve/pii/S0034425710002634</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">115</style></volume><pages><style face="normal" font="default" size="100%">281 - 297</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Traditional remote sensing techniques allow the assessment of green plant biomass, and therefore plant photosynthetic capacity. However, detecting how much of this capacity is actually realized is a more challenging goal. Is it possible to remotely assess actual carbon ﬂuxes? Can this be done at leaf, canopy and ecosystem scales and at different temporal scales? Different approaches can be used to answer these questions. Among them, the Photochemical Reﬂectance Index (PRI) derived from narrow-band spectroradiometers is a spectral index increasingly being used as an indicator of photosynthetic efﬁciency. We examined and synthesized the scientiﬁc literature on the relationships between PRI and several ecophysiological variables across a range of plant functional types and ecosystems at the leaf, canopy and ecosystem levels and at the daily and seasonal time scales. Our analysis shows that although the strength of these relationships varied across vegetation types, levels of organization and temporal scales, in most reviewed articles PRI was a good predictor of photosynthetic efﬁciency or related variables with performances at least as good as the widely used NDVI as indicator of green biomass. There are possible confounding factors related to the intensity of the physiological processes linked to the PRI signals, to the structure of the canopies and to the illumination and viewing angles that warrant further studies, and it is expected that the utility of PRI will vary with the ecosystem in question due to contrasting environmental constraints, evolutionary strategies, and radiation use efﬁciency (RUE; the ratio between carbon uptake and light absorbed by vegetation) variability. Clearly, more research comparing ecosystem responses is warranted. Additionally, like any 2-band index that is affected by multiple factors, the interpretation of PRI can be readily confounded by multiple environmental variables, and further work is needed to understand and constrain these effects. Despite these limitations, this review shows an emerging consistency of the RUE–PRI relationship that suggests a surprising degree of functional convergence of biochemical, physiological and structural components affecting leaf, canopy and ecosystem carbon uptake efﬁciencies. PRI accounted for 42%, 59% and 62% of the variability of RUE at the leaf, canopy and ecosystem respective levels in unique exponential relationships for all the vegetation types studied. It seems thus that by complementing the estimations of the fraction of photosynthetically active radiation intercepted by the vegetation (FPAR), estimated with NDVI-like indices, PRI enables improved assessment of carbon ﬂuxes in leaves, canopies and many of the ecosystems of the world from ground, airborne and satellite sensors.</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;publisher: Elsevier Inc.</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Goerner, A</style></author><author><style face="normal" font="default" size="100%">Reichstein, M</style></author><author><style face="normal" font="default" size="100%">Rambal, S</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Estimation of Photosynthetic Light Use Efficiency in Semi-Arid Ecosystems with the MODIS-Derived Photochemical Reflectance Index</style></title><secondary-title><style face="normal" font="default" size="100%">Geoscience and Remote Sensing Symposium, 2008. IGARSS</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Drought</style></keyword><keyword><style  face="normal" font="default" size="100%">light use efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical reflectance index</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><volume><style face="normal" font="default" size="100%">1</style></volume><pages><style face="normal" font="default" size="100%">756-758</style></pages><isbn><style face="normal" font="default" size="100%">9781424428083</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Direct estimations of light use efficiency from satellite data could reduce the uncertainties in data-oriented models of primary productivity. We analysed the potential of the photochemical reflectance index (PRI) based on MODIS data to approximate LUE of a Mediterranean Quercus ilex forest. Spectal band 1 (620-670 nm) turned out to be the best alternative reference band (the recommended 570 nm band does not exist on MODIS). Radiance correction with standard procedures (6S, dark object subtraction) did not improve the PRI-LUE relationship compared to the at-sensor reflectance version. The influence of surface anisotropy on the PRI signal was much reduced by constraining the observations to satellite data acquisitions with near nadir viewing angles.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Penuelas, J</style></author><author><style face="normal" font="default" size="100%">Filella, I</style></author><author><style face="normal" font="default" size="100%">Llusia, J</style></author><author><style face="normal" font="default" size="100%">Siscart, D</style></author><author><style face="normal" font="default" size="100%">Piñol, J</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comparative field study of spring and summer leaf gas exchange and photobiology of the mediterranean trees Quercus ilex and Phillyrea latifolia</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Experimental Botany</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">fluorescence</style></keyword><keyword><style  face="normal" font="default" size="100%">intrinsic water use efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">net photosynthetic rates</style></keyword><keyword><style  face="normal" font="default" size="100%">phillyrea latifolia</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical reflectance index</style></keyword><keyword><style  face="normal" font="default" size="100%">photosynthetic radiation-use-efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">reflectance</style></keyword><keyword><style  face="normal" font="default" size="100%">Stomatal conductance</style></keyword><keyword><style  face="normal" font="default" size="100%">summer</style></keyword><keyword><style  face="normal" font="default" size="100%">water index</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1998</style></year></dates><volume><style face="normal" font="default" size="100%">49</style></volume><pages><style face="normal" font="default" size="100%">229-238</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Summer-induced changes in gas exchange, fluorescence and reflectance were measured on leaves of two co-occurring Mediterranean small trees, Quercus ilex and Phillyrea latifolia, in May, June and July 1996 in Central Catalonia (NE Spain). The humid 1996 summer only produced mild water stress conditions. However, photosynthesis (A) and stomatal conductance (gs) decreased in June and July in both species. In June P. latifolia had higher net photosynthetic rates and lower stomatal conductances than Q. ilex, thus exhibiting higher instantaneous plant water use efficiencies. In agreement with these results, the photo-chemical reflectance index (PRI, calculated as (R570-R531)/(R531+R570)) of P. latifolia was lower, suggesting a possible lower xanthophyll de-epoxidation state. However, P. latifolia had lower ΔF/F′ and therefore a lower electron transport rate (ETR). The behaviour of PRI confirmed previous studies indicating a strong relationship between PRI, ΔF/F′ , and photosynthetic radiation-use efficiency (PRUE). PRI offers a simple, portable means of assessing PRUE with the potential for remote sensing applications. Finally, the possible ecological consequences of these results on the behaviour of the two species studied under the predicted warmer and drier conditions of global change are discussed.</style></abstract><notes><style face="normal" font="default" size="100%">10.1093/jxb/49.319.229</style></notes><research-notes><style face="normal" font="default" size="100%">10.1093/jxb/49.319.229</style></research-notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Penuelas, J.</style></author><author><style face="normal" font="default" size="100%">Filella, I.</style></author><author><style face="normal" font="default" size="100%">Llusia, J.</style></author><author><style face="normal" font="default" size="100%">Siscart, D.</style></author><author><style face="normal" font="default" size="100%">Piñol, J.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comparative field study of spring and summer leaf gas exchange and photobiology of the mediterranean trees Quercus ilex and Phillyrea latifolia</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Experimental Botany</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">fluorescence</style></keyword><keyword><style  face="normal" font="default" size="100%">intrinsic water use efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">net photosynthetic rates</style></keyword><keyword><style  face="normal" font="default" size="100%">phillyrea latifolia</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">photochemical reflectance index</style></keyword><keyword><style  face="normal" font="default" size="100%">photosynthetic radiation-use-efficiency</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">reflectance</style></keyword><keyword><style  face="normal" font="default" size="100%">Stomatal conductance</style></keyword><keyword><style  face="normal" font="default" size="100%">summer</style></keyword><keyword><style  face="normal" font="default" size="100%">water index</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1998</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1998///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://jxb.oxfordjournals.org/content/49/319/229.abstract</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">49</style></volume><pages><style face="normal" font="default" size="100%">229 - 238</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Summer-induced changes in gas exchange, fluorescence and reflectance were measured on leaves of two co-occurring Mediterranean small trees, Quercus ilex and Phillyrea latifolia, in May, June and July 1996 in Central Catalonia (NE Spain). The humid 1996 summer only produced mild water stress conditions. However, photosynthesis (A) and stomatal conductance (gs) decreased in June and July in both species. In June P. latifolia had higher net photosynthetic rates and lower stomatal conductances than Q. ilex, thus exhibiting higher instantaneous plant water use efficiencies. In agreement with these results, the photo-chemical reflectance index (PRI, calculated as (R570-R531)/(R531+R570)) of P. latifolia was lower, suggesting a possible lower xanthophyll de-epoxidation state. However, P. latifolia had lower ΔF/F′ and therefore a lower electron transport rate (ETR). The behaviour of PRI confirmed previous studies indicating a strong relationship between PRI, ΔF/F′ , and photosynthetic radiation-use efficiency (PRUE). PRI offers a simple, portable means of assessing PRUE with the potential for remote sensing applications. Finally, the possible ecological consequences of these results on the behaviour of the two species studied under the predicted warmer and drier conditions of global change are discussed.</style></abstract><issue><style face="normal" font="default" size="100%">319</style></issue><notes><style face="normal" font="default" size="100%">10.1093/jxb/49.319.22910.1093/jxb/49.319.229</style></notes></record></records></xml>