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Trees (2011) 25:443453DOI 10.1007/s00468-010-0519-5
ORIGINAL PAPER
Climatic control of intra-annual wood density uctuations of Pinus pinaster in NW Spain
Vicente Rozas Ignacio Garca-Gonzlez
Rafael Zas
Received: 20 July 2010 / Revised: 3 November 2010 / Accepted: 11 November 2010 / Published online: 30 November 2010 Springer-Verlag 2010
Abstract Tree rings of Pinus pinaster often contain intra-annual density uctuations (IADFs), which have been attributed to the succession of dry and rainy periods typical of Mediterranean climate, but their formation has not been studied yet under Atlantic climate. We analyzed the occurrence and climatic signicance of replicated IADFs in ten monospecic stands in NW Spain. The frequency of IADFs was higher than previously reported for this species under Mediterranean conditions and consistently decreased with increasing elevation. The formation of bands of late-wood-like tracheids within the earlywood was favored by dry previous August, cold previous winter and dry April. Bands of earlywood-like tracheids within the early late-wood were also favored by low winter temperatures. However, their occurrence was geographically heterogeneous, with two groups of stands being dened by their distances to the shoreline. In coastal stands, cold May August triggered IADFs formation, while in inland stands their formation was favored by dry MayJuly. Regional winter temperatures and April water balance were strongly related to the East Atlantic (EA) pattern, which greatly
conditioned the occurrence of IADFs in the earlywood and the early latewood. By contrast, the presence of bands of earlywood-like tracheids in the late latewood was independent of the EA pattern, being strongly related to warm conditions in spring and especially to a wet October. The link between regional climate and the EA pattern strongly controlled the physiological processes that determine intra-annual growth dynamics and short-term cell enlargement of P. pinaster in NW Spain.
Keywords Dendrochronology False tree-rings
Pinus pinaster Atlantic climate Water balance
East Atlantic pattern
Introduction
The integration of the effects of several environmental factors operating at multiple time scales on tree-ring growth makes difcult to understand the underlying mechanisms responsible for triggering intra-annual cambial activity and growth dynamics (Fritts 2001). In fact, cambial activity in conifers may vary at a shorter time scale within the growing season, leading to the formation of intra-annual bands of tracheids with distinctive appearance, differing from those typical of...