<?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%">Sala, A</style></author><author><style face="normal" font="default" size="100%">Sabate, S</style></author><author><style face="normal" font="default" size="100%">Gracia, Carlos</style></author><author><style face="normal" font="default" size="100%">Tenhunen, J D</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Canopy structure within a Quercus ilex forested watershed: variations due to location, phenological development, and water availability</style></title><secondary-title><style face="normal" font="default" size="100%">Trees-Structure and Function</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Canopy structure</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf area index</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean sclerophylls</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">water deficit</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1994</style></year></dates><pages><style face="normal" font="default" size="100%">254-261</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Spatial and temporal changes in canopy structure were studied in 1988 and 1989 in a Mediterranean Q u e r c u s ilex forest in north-eastern Spain. Due to differences in precipitation patterns the 1989 growing season was drier than the 1988 growing season. Sampling was conducted in parallel at two sites which represent endpoints along a slope gradient within a watershed (ridge top at 975 m, and valley bottom at 700 m). At both sites, similar inter-annual changes in canopy structure were observed in response to differences in water availability. Samples harvested in the upper 50 cm of the canopy during 1989 exhibited a de- crease in both average leaf size and the ratio of young to old leaf and stem biomass relative to samples obtained in 1988. At the whole canopy level, a decrease in leaf pro- duction efficiency and an increase in the stem to leaf bio- mass ratio was observed in 1989. Temporal changes in canopy leaf area index (LAI) were not statistically sig- nificant. Average LAI values of Q. ilex at the two sites were not significantly different despite differences in tree stature and density (4.6 m 2 m -2 at the ridge top, and 5.3 m 2 m -2 at the valley bottom). Vertical distribution of leaves and stems within the canopy was very similar at the two locations, with more than 60% of the total LAI in the uppermost metre of the canopy. The possible significance of such an LAI distribution on the canopy carbon budget is discussed.</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%">Sala, Anna</style></author><author><style face="normal" font="default" size="100%">Tenhunen, John D</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Site-specific water relations and stomatal response of Quercus ilex in a Mediterranean watershed</style></title><secondary-title><style face="normal" font="default" size="100%">Tree Physiology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Mediterranean sclerophylls</style></keyword><keyword><style  face="normal" font="default" size="100%">oak forest</style></keyword><keyword><style  face="normal" font="default" size="100%">oak watershed</style></keyword><keyword><style  face="normal" font="default" size="100%">Osmotic potential</style></keyword><keyword><style  face="normal" font="default" size="100%">Stomatal conductance</style></keyword><keyword><style  face="normal" font="default" size="100%">water potential</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1994</style></year></dates><volume><style face="normal" font="default" size="100%">14</style></volume><pages><style face="normal" font="default" size="100%">601-617</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Intraspecific variations in the water relations and stomatal response of Quercus ilex L. were analyzed under field conditions by comparing trees at two locations within a Mediterranean watershed (l'Avic, Catalonia, NE Spain). Distinct environmental gradients exist between the two sites (referred to as ridge top at 975 m and valley bottom at 700 m) with greater soil depth for water storage, reduced radiation, reduced wind and higher water vapor pressure deficits at the valley bottom than at the ridge top. Osmotic adjustment and changes in tissue elasticiity did not significantly increase drought resistance in the trees studied. The leaf-to-air vapor pressure difference (Δw) threshold for inducing stomatal closure was higher at the ridge top (15.6 kPa MPa−1 ± 0.5 SE) than at the valley bottom (9.8 kPa MPa−1 ± 1.0 SE). However, increases in Δw beyond the threshold were followed by greater reductions in leaf conductance of trees at the ridge top than at the valley bottom. At both sites, maximum leaf conductance was related to predawn shoot water potential which, in turn, was related to watershed stream flow. The effects of water deficits during the dry summer of 1989 were more severe in trees at the valley bottom than at the ridge top. During periods of high evaporative demand, site-specific differences in the control of water loss led to more conservative water use by trees at the ridge top and, thus, to even greater drought avoidance (higher predawn water potentials) in late summer.</style></abstract><notes><style face="normal" font="default" size="100%">10.1093/treephys/14.6.601</style></notes><research-notes><style face="normal" font="default" size="100%">10.1093/treephys/14.6.601</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%">Caritat, A.</style></author><author><style face="normal" font="default" size="100%">Molinas, M.</style></author><author><style face="normal" font="default" size="100%">Oliva, M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">El crecimiento radial del alcornoque en cinco parcelas de alcornocal de Girona</style></title><secondary-title><style face="normal" font="default" size="100%">Scientia gerundensis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">cork-oak</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean sclerophylls</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber L.</style></keyword><keyword><style  face="normal" font="default" size="100%">Radial growth</style></keyword><keyword><style  face="normal" font="default" size="100%">wood rings</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1992</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1992///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://dugi-doc.udg.edu/handle/10256/5328</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">18</style></volume><pages><style face="normal" font="default" size="100%">73 - 83</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Tree rings of Quercus suber L. are porous and difficult to read because of the irregular growth rhythm. Radial growth has been measured in five experimental plots situated in the region of Girona (Catalonia, NE Spain). Cores of ten standard trees of each plot were extracted using a Pressler borer. In three plots woody disks from standard trees were also obtained. Tree rings were examinated under binocularlens. The CATRAS computer program (Anio1,1983 ) was used to find statistical parameters. Tree rings have an average width changing from 1,21 to 3,74 mm, while average standard deviation varies from 0,24 to 1,88 mm. and autocorrelation from 0,008 to 0.894 . These values are similar to those found in other Mediterranean Quercus, like Q. ilex L. The studied cork-oak plots ,with diametrical classes between 5 and 57 cm, show regular growth characteristic of young forest. The St. Hilari plot has the maturest trees, (diametrical classes from 24 to 57 cm) and this fact was reflectedin thegrowthcurve. Suddengrowthincreases are attributed to forestry management measures like clearing or selective cutting down. The effects of periodic cork extractions could no be clearly appreciated in this study.</style></abstract></record></records></xml>