<?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%">Filella, Iolanda</style></author><author><style face="normal" font="default" size="100%">Penuelas, Josep</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Altitudinal differences in UV absorbance, UV reflectance and related morphological traits of Quercus ilex and Rhododendron ferrugineum in the Mediterranean region</style></title><secondary-title><style face="normal" font="default" size="100%">Plant Ecology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Altitude</style></keyword><keyword><style  face="normal" font="default" size="100%">carotenoids/chlorophyll a ratio</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf hair density</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean Region</style></keyword><keyword><style  face="normal" font="default" size="100%">ndpi</style></keyword><keyword><style  face="normal" font="default" size="100%">pri</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">rhododendron ferrugineum</style></keyword><keyword><style  face="normal" font="default" size="100%">slw</style></keyword><keyword><style  face="normal" font="default" size="100%">Thickness</style></keyword><keyword><style  face="normal" font="default" size="100%">uv absorbing compounds</style></keyword><keyword><style  face="normal" font="default" size="100%">uv reflectance</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1999///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.springerlink.com/index/m8hl41013mvtx776.pdf</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">145</style></volume><pages><style face="normal" font="default" size="100%">157 - 165</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">We studied the variations in different physiological parameters associated with UV-B radiation defense: UV-B radiation absorbance, UV-visible spectral reﬂectance, carotenoids concentration, leaf thickness, SLW (speciﬁc leaf weigth) and trichome density in Quercus ilex growing at 200 and 1200 m and Rhododendron ferrugineum growing at 2200 m. We examined the role of these parameters as protection mechanisms in an altitudinal gradient of increasing UV radiation in northern Catalonia and in sun and shade leaves. The concentration of UV-B radiation absorbing pigments was 15% higher in sun leaves of Q. ilex at 1200 m than in those from 200 m altitude. Sun leaves of R. ferrugineum presented concentrations three times higher than those of Q. ilex. Reﬂectance ranged between 5% (in the region 300–400 nm) and 12% (in the region 280–300 nm). The variation of reﬂectance with altitude followed an inverse trend respect to absorbance in the 280–300 nm region, with higher values the lower the altitude, but in the 300–400 nm region, reﬂectance of the lower site was the lowest. In both species and altitudes sun leaves presented higher concentrations of UV-B radiation absorbing pigments and UV reﬂectance than shade leaves. Quercus ilex trees of the higher location presented higher NDPI (Normalized Difference Pigment Reﬂectance Index) values, indicating higher carotenoids/chlorophylla ratio. Actual measurements of carotenoid/chlorophyll a ratio conﬁrmed this pattern. The photochemical reﬂectance index (PRI) presented higher values the higher the location indicating lower photosynthetic radiation-use efﬁciency. Speciﬁc leaf weight (SLW) and leaf thickness were larger in Q. ilex trees of higher location than in those of lower location. In both sites, sun leaves also presented larger SLW values than shade leaves. Adaxial leaf hair density in sun leaves was signiﬁcantlly higher in the lower location. UV absorption and linked morphological traits (SLW, leaf thickness measured in Q. ilex) presented the larger differences among studied plants at different altitudes and seem to be the dominant UV protecting mechanisms.</style></abstract></record></records></xml>