Miguel Angel Saz Sánchez

Age, climate and intra-annual density fluctuations in Pinus halepensis in Spain

Intra-annual density fluctuations (IADFs) in tree rings of Aleppo pine (Pinus halepensis) are considered to be among the most promising wood anatomical features in dendrochronological studies. They provide environmental information in addition to those obtained from tree-ring widths. We used a network of 35 sites in Spain, ranging from nearly desert to temperate climate. We analysed tree-ring series of 529 trees to study IADF frequencies, and their dependence on climatic factors and cambial age. The results showed that IADF frequency is age dependent, with its maximum at the cambial age of 27 years (evaluated at breast height). The frequencies varied across the network and at different sites we recorded that 0.3% to 33% of the analysed tree rings contained IADFs. They were more frequent where and when the temperatures were higher, summer drought was intense and autumn was the main precipitation season. IADF formation was particularly related to high minimum temperatures and wet conditions in late summer and autumn. These results suggest that IADF formation is not related to stressful conditions during summer but to favourable conditions during autumn. These conditions promote cambial reactivation and consequently formation of wider tree rings.

Las precipitaciones de la época cálida en el sur de la provincia de Alicante desde 1550 a 1915

In this paper we analyze the main anomalies of spring and summer precipitation in the south of the province of Alicante (SE of Spain), reconstructed using dendroclimatological techniques. We have identified an alternation of dry periods (1598-1651, 1671-1687 and 1764-1781) and humid (1650-1670 and 1688-1739) of different duration and intensity. In the 19th century the rainfall anomalies are shorter, although of similar intensity.