Las masas actuales de Quercus petraea en Galicia

The presence and characterization of Quercus petraea in the northwest of the Iberian Peninsula have been slightly studied. Although Rivas (1987) restricts his filings to the Orocantábrica Province, subsequent studies have confirmed the presence of Quercus petraea out of this place. The present investigation was undertaken to study the placing and dasometry of that specie in Galicia (Spain). Twenty-two plots with Quercus petraea as dominant specie were studied. Data about placing characteristics (location, orography, fisiografia, vegetation...) and stand variables (diametrical measurements, height, and sticks extraction for analysing of ages and growths) were checked. Basic parameters of dasometric characterization were obtained in cabinet, and subsequently the statistic analysis of multiple variables was used to study and classify stands. With both studies, we can assure that it is possible to speak of two big groups of stands: one of them clearly has typical features of hybridisation with Quercus robur and Quercus pyrenaica, that are localized near Orocantábrica Province; and the other group, that does not present those hybridisation features, is localized in the more oriental mountains. Finally, this classification in confirmed with other results as weight parameters, age, growth, etc. Consequently, the more pure stands produce data of greater maturity and a clear relation between their distribution and the classic idea of their preference by shady exhibitions is not observed in this area.La presencia y caracterización de Quercus petraea en el noroeste de la Península Ibérica han sido poco estudiadas. Aunque Rivas (1987) limita a la Provincia Orocantábrica sus manifestaciones, trabajos posteriores han constatado la presencia de dicha especie fuera de esa zona. Se presenta a continuación información acerca de la localización y dasometría de la especie dentro de la zona en la que está presente en Galicia. Los datos analizados corresponden a un total de 22 parcelas de muestreo pobladas con Quercus petraea como especie dominante. En ellas se han tomado datos sobre características de la estación (localización, orografía, fisiografía, vegetación...) y de la masa (mediciones diametrales, de altura y extracción de bastones para análisis de edades y crecimientos). En gabinete se obtienen parámetros de caracterización dasométrica básicos, para luego realizar un análisis estadístico de variables múltiples para el estudio y clasificación de las masas. Combinando ambos estudios nos permiten asegurar que se puede hablar de dos grandes bloques de masas: las que claramente manifiestan rasgos de hibridación con Quercus robur o con Quercus pyrenaica, que se sitúan en los límites de la Provincia Orocantábrica; y las que no, siendo estas últimas las de las montañas más orientales. Finalmente, esta misma división se ratifica con otros resultados, como son los parámetros de masa, edad, crecimiento, etc. Consecuentemente, las masas más puras arrojan datos de mayor madurez y no se observa en esta área una relación clara entre su distribución y la clásica idea de su preferencia por exposiciones de umbría

Site Index Model For Natural Stands Of Rebollo Oak ( Quercus pyrenaica Willd.) In Galicia, NW Iberian Peninsula

Dados da an\ue1lise de tronco de 56 \ue1rvores dominantes de Quercus pyrenaica Willd. de florestas naturais da Galicia (NW Pen\uednsula Ib\ue9rica) foram utilizados para avaliar quatro equa\ue7\uf5es dinamicas de \uedndice de sitio obtidas com a Abordagem Generalizada de Diferen\ue7a Alg\ue9brica (GADA). Todas as equa\ue7\uf5es s\ue3o baseadas na idade invariante e diretamente estimam a altura e o \uedndice de sitio. Os ajustes foram feitos utilizando uma estrutura de dados que incluiam todos os poss\uedveis intervalos de crescimento. A formula\ue7\ue3o GADA teve base no modelo Bertalanffy- Richards, considerando a ass\uedntota e do padr\ue3o inicial como par\ue2metros relacionados \ue0 produtividade do sitio. Assim, recomenda-se o modelo na previs\ue3o do crescimento em altura e classifica\ue7\ue3o de sitios para povoamentos naturais de carvalho negro na Galicia. A autocorrela\ue7\ue3o foi analisada com um teste de res\uedduos utilizando Durbin's t-teste, sem chegar a um resultado significativo de autocorrela\ue7\ue3o entre os dados.Data from stem analysis of 56 dominant trees of Quercus pyrenaica Willd., in natural stands in Galicia (NW Iberian Peninsula), were used to evaluate four dynamic site equations derived with the Generalized Algebraic Difference Approach (GADA). All the equations are base-age invariant and directly estimate height and site index from any height and age. The fittings were made using a data structure involving all possible growth intervals. The GADA formulation derived on the basis of the Bertalanffy- Richards model by considering the asymptote and the initial pattern parameters as related to site productivity. It is therefore recommended for height growth prediction and site classification for natural stands of rebollo oak in Galicia. The autocorrelation was analyzed with a test of residuals using Durbin\u2019s ttest without reaching a manifest result of autocorrelation between managed data

Influence of geographical location, site and silvicultural parameters, on volatile composition of Quercus pyrenaica Willd. wood used in wine aging

For the current study, the volatile and semi-volatile composition of several samples of Quercus pyrenaica wood from NW Spain were analyzed and compared. The research was performed on a wide sample set of more than 100 samples (test tubes) obtained from different stands of this species. The relationship between some silvicultural and site parameters and volatile composition was studied. Altitude seemed to be the most influential parameter on the volatile composition. However, other factors such as distance from tree center, average annual precipitation, and number of trees per hectare whose effects on the volatile compounds were not significant. The influence of soil texture was not a determining factor while geographical location seemed to have a more specific impact on the extractive volatile content. The content of all extractable compounds studied allowed a good separation of oak samples of the same species according to their geographical origin. © 2011 Elsevier B.V.Peer Reviewe