<?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%">Campelo, F.</style></author><author><style face="normal" font="default" size="100%">GUTIÉRREZ, E.</style></author><author><style face="normal" font="default" size="100%">Ribas, M.</style></author><author><style face="normal" font="default" size="100%">Nabais, C.</style></author><author><style face="normal" font="default" size="100%">Freitas, H.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Relationships between climate and double rings in Quercus ilex from northeast Spain</style></title><secondary-title><style face="normal" font="default" size="100%">Canadian Journal of Forest Research</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">chronology (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">double rings</style></keyword><keyword><style  face="normal" font="default" size="100%">Drought</style></keyword><keyword><style  face="normal" font="default" size="100%">growth pattern</style></keyword><keyword><style  face="normal" font="default" size="100%">growth rings</style></keyword><keyword><style  face="normal" font="default" size="100%">Precipitation</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2007///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://dx.doi.org/10.1139/X07-050</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">37</style></volume><pages><style face="normal" font="default" size="100%">1915 - 1923</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The influence of climatic factors on tree-ring width and the formation of double rings was studied in Quercus ilex L. growing in a coppice stand left unmanaged for 22 years. Ten trees were felled and discs were taken every 30 cm from bole and dominant branches. Dendrometer bands were installed on 10 nearby trees and the data recorded were used to confirm the accuracy of our tree-ring identification. They were also used to relate the seasonal radial growth pattern to double-ring formation. Double rings were frequent and occurred consistently along the stem. Two types of double rings could be recognized according to their width: type I, with the extra growth band accounting for approximately 50% of the tree ring; and type II, with a narrow extra growth band. Type I double rings were formed when approximately 1/2 of the growing-season precipitation occurred during the second growth period of the season and after the summer drought. Type II double rings occurred when approximately 1/3 of the precipitation in the growing season occurred after the summer drought. The formation of double rings was triggered by rainfall in summer and the extra growth-band width was related to summer and autumn environmental conditions. Double rings in Q. ilex can potentially be used in dendroclimatological studies, as they are formed in response to climatic conditions within the growing season.</style></abstract><issue><style face="normal" font="default" size="100%">10</style></issue><notes><style face="normal" font="default" size="100%">doi: 10.1139/X07-050doi: 10.1139/X07-050The following values have no corresponding Zotero field:&lt;br/&gt;publisher: NRC Research Press</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%">Campelo, F</style></author><author><style face="normal" font="default" size="100%">Gutiérrez, E</style></author><author><style face="normal" font="default" size="100%">Ribas, M</style></author><author><style face="normal" font="default" size="100%">Nabais, C</style></author><author><style face="normal" font="default" size="100%">Freitas, H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Relationships between climate and double rings in Quercus ilex from northeast Spain</style></title><secondary-title><style face="normal" font="default" size="100%">Canadian Journal of Forest Research</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">chronology (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">double rings</style></keyword><keyword><style  face="normal" font="default" size="100%">Drought</style></keyword><keyword><style  face="normal" font="default" size="100%">growth pattern</style></keyword><keyword><style  face="normal" font="default" size="100%">growth rings</style></keyword><keyword><style  face="normal" font="default" size="100%">Precipitation</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year></dates><publisher><style face="normal" font="default" size="100%">NRC Research Press</style></publisher><volume><style face="normal" font="default" size="100%">37</style></volume><pages><style face="normal" font="default" size="100%">1915-1923</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The influence of climatic factors on tree-ring width and the formation of double rings was studied in Quercus ilex L. growing in a coppice stand left unmanaged for 22 years. Ten trees were felled and discs were taken every 30 cm from bole and dominant branches. Dendrometer bands were installed on 10 nearby trees and the data recorded were used to confirm the accuracy of our tree-ring identification. They were also used to relate the seasonal radial growth pattern to double-ring formation. Double rings were frequent and occurred consistently along the stem. Two types of double rings could be recognized according to their width: type I, with the extra growth band accounting for approximately 50% of the tree ring; and type II, with a narrow extra growth band. Type I double rings were formed when approximately 1/2 of the growing-season precipitation occurred during the second growth period of the season and after the summer drought. Type II double rings occurred when approximately 1/3 of the precipitation in the growing season occurred after the summer drought. The formation of double rings was triggered by rainfall in summer and the extra growth-band width was related to summer and autumn environmental conditions. Double rings in Q. ilex can potentially be used in dendroclimatological studies, as they are formed in response to climatic conditions within the growing season.</style></abstract><notes><style face="normal" font="default" size="100%">doi: 10.1139/X07-050</style></notes><research-notes><style face="normal" font="default" size="100%">doi: 10.1139/X07-050</style></research-notes></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%">Leal, Sofia</style></author><author><style face="normal" font="default" size="100%">González-Pérez, Aranzazu</style></author><author><style face="normal" font="default" size="100%">Vasquez-Piqué, Javier</style></author><author><style face="normal" font="default" size="100%">Spiecker, Heinrich</style></author><author><style face="normal" font="default" size="100%">Pereira, Helena</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">VÁZQUEZ-PIQUÉ, JAVIER</style></author><author><style face="normal" font="default" size="100%">Pereir, Helena</style></author><author><style face="normal" font="default" size="100%">GONZÁLEZ-PÉREZ, ARANTZAZU</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">cork oak wood a hard material to sample and to measure</style></title><secondary-title><style face="normal" font="default" size="100%">Suberwood2005: New challenges for integration of cork oak forests and products, Scientific and Technical Conference, Huelva, Spain, 20, 21 and 22 October 2005.</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Anatomy</style></keyword><keyword><style  face="normal" font="default" size="100%">growth rings</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber L.</style></keyword><keyword><style  face="normal" font="default" size="100%">sampling</style></keyword><keyword><style  face="normal" font="default" size="100%">wood growth</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year></dates><publisher><style face="normal" font="default" size="100%">Universidad de Huelva</style></publisher><pub-location><style face="normal" font="default" size="100%">Huelva</style></pub-location><pages><style face="normal" font="default" size="100%">456</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Different studies within the Suberwood project required measurements of wood growth in cork oak trees (Quercus suber L.), including tree ring analysis, as a basis to analyse the influence on tree growth of stress effects, namely those deriving from climatic conditions (i.e. water deficit) or from the cork extraction. The research partners have experienced serious difficulties in these tasks and some examples are presented and discussed. The first difficulty regards sampling because cork oak harvesting is forbidden in Portugal and advantage has to be taken from legally authorised tree fellings. The available material therefore consists mainly in thinning material (young trees), dead or diseased trees, and trees with damaged stems due to improper cork harvesting, which are useless for such studies. In most cases the information concerning the stand management is lacking, namely regarding the time of cork extraction and of other silvicultural operations (i.e. pruning). Therefore the experimental design regarding treatments and repetitions often cannot follow the conventional statistical guidelines. The cork oak wood also has anatomical and structural features that bring considerable complexity for ring definition. The wood has a semi-ring porosity with poor growth ring definition and it is very difficult, and frequently impossible, to accurately identify growth rings and to link measurements to a certain year. Additionally cork extraction disturbs wood growth and anatomy. Different observation approaches were tested: overall microscopical observations, continuous radial measurement of vessel dimensions and density, continuous radial microdensitometric profiles, cambial wounding. The use of non-destructive samples (i.e. cores or small wood samples) adds to the uncertainty encountered. Stem discs offer a better observation but differences among different radii are often very large.</style></abstract></record></records></xml>