<?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%">López, B</style></author><author><style face="normal" font="default" size="100%">Sabate, S</style></author><author><style face="normal" font="default" size="100%">Gracia, C A</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Fine-root longevity of Quercus ilex</style></title><secondary-title><style face="normal" font="default" size="100%">New Phytologist</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Fine root longevity</style></keyword><keyword><style  face="normal" font="default" size="100%">Holm oak</style></keyword><keyword><style  face="normal" font="default" size="100%">minirhizotron</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">vertical longevity pattern</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><publisher><style face="normal" font="default" size="100%">Blackwell Science Ltd</style></publisher><volume><style face="normal" font="default" size="100%">151</style></volume><pages><style face="normal" font="default" size="100%">437-441</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">* • Fine-root longevity and phenology were studied in a Quercus ilex (holm oak) forest in Prades (NE Spain). Differences were investigated among roots that had appeared in different seasons and at different depth intervals, differentiating between white and brown roots. * • Using minirhizotrons installed in March 1994, 1211 roots were monitored every 3 wk from June 1994 to March 1997. * • Mean and median fine-root longevity were 125 ± 4 d and 67 d, respectively. Longevity of summer and winter roots was greater than that of spring and autumn roots. Although roots appeared and disappeared throughout the year, the rate of appearance was greatest in spring. Maximum longevity occurred at a soil depth of 20–30 cm. Differences among 10-cm depth intervals were due to the number of days that roots were brown, since roots remained white for a similar number of days, independent of soil depth. * • Temperate soil temperatures and lignotubers permitted the appearance of roots throughout the year. Holm oak fine roots might be more efficient during the first 50 d of their life before the white roots become less efficient brown roots.</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%">Sabate, S</style></author><author><style face="normal" font="default" size="100%">Sala, Anna</style></author><author><style face="normal" font="default" size="100%">Gracia, C A</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Nutrient content in Quercus ilex canopies: seasonal and spatial variation within a catchment</style></title><secondary-title><style face="normal" font="default" size="100%">Plant and Soil</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Canopy</style></keyword><keyword><style  face="normal" font="default" size="100%">nutrient content and dynamics</style></keyword><keyword><style  face="normal" font="default" size="100%">nutrient resorption</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1995</style></year></dates><volume><style face="normal" font="default" size="100%">168-169</style></volume><pages><style face="normal" font="default" size="100%">297-304</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 nutrient content were studied in 1988 and 1989 in a Mediterranean Quercus ilex ssp. ilex L. forest in north-eastern Spain. Sampling was conducted in parallel at two sites which represent endpoints along a slope gradient within a small catchment (ridge top at 975 m and valley bottom at 700 m). Deeper soils resulted in significantly higher N and P concentrations, and N content on a leaf area basis at the valley bottom site. In contrast, K concentration in leaves was significantly higher at the ridge top site, where soil K concentration was also higher. At both sites, N and P content on a leaf area basis was highest at the top of the canopy, where leaf area is highest. N resorption efficiency decreased from top to bottom of the canopy. Results suggested a minor role of shaded leaves as nutrient storage sites. Lower P resorption efficiency was found at the ridge top site. Seasonal changes of P and N concentration on a leaf area basis suggest P replenishment, and to a lesser degree N, during periods of lower growth activity due to low temperatures, but coinciding with higher water availability (autumn-early spring period). Thus, N and P resorption from the remaining foliage in the canopy took place, and to a larger degree at the valley bottom site, coinciding with a slightly higher leaf area index and productivity at this site.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>3</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Gracia, C A</style></author><author><style face="normal" font="default" size="100%">Sala, A</style></author><author><style face="normal" font="default" size="100%">Sabate, S</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">ASPECTOS ECOFISIOLOGICOS RELACIONADOS CON LA PRODUCCION DE LOS ENCINARES MEDITERRANEOS</style></title><secondary-title><style face="normal" font="default" size="100%">Congreso Forestal Español, Lourizán - Pontevedra. 1993</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">ecophysiology</style></keyword><keyword><style  face="normal" font="default" size="100%">L.A.I.</style></keyword><keyword><style  face="normal" font="default" size="100%">productivity</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1993</style></year></dates><pub-location><style face="normal" font="default" size="100%">Pontevedra</style></pub-location><pages><style face="normal" font="default" size="100%">209-218</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The productivity of Quercus ilex forests is low in relation to other tree species. Waterand nutrients are often the most important limiting factors. Nevertheless the ecophysiological traits of this specie could help to explain the observed patterns of productivity. Leaf area index of european evergreen-oak forests is rather constant with values about 5. The energetic cost of formation and maintenance of the leaves of Quercus ilex accounts for more than 50 per cent of total carbon fixed by the trees. The resproutig ability of evergreen oaks could explain the high density and low mean diameter of these populations. The high proportion of living tissues in this type of structuni increases the respiration costs of the stems and branches. As a consequence, an important fraction of carhon fixed by leaves is used to maintain the structure of the community which contribute to explain the low observed net primary production of Quercus ilex forests</style></abstract></record></records></xml>