Seasonal Dynamics of Wood Formation in Pinus Halepensis from Dry and Semi-Arid Ecosystems in Spain

Abstract

The seasonal dynamic s of cambial activity, wood formation , occurrence of false rings (FR), and tangential bands of resin canals (RC) were investigated in Pinus halepensis from three Mediterranean dry and semi-arid ecosystems in Spain. We collected intact tissues of phloem, cambium, and outer xylem at monthly intervals throughout 2004 from each time six trees at the three sites. Cell divisions in the cambium in all trees started before our first sampling in mid-March and ceased between November and December. Cambial activity was characterized by two maxima; one in spring and another in autumn. Trees still grew in summer but at a very low rate. The first solitary RC were formed in May or June and tangential bands ofRC in June or July. In general , tangential bands ofRC were observed in wider growth rings . The formation of tangential bands of RC seems to be induced by drought in the second half of the growing season . FR were formed as a result of cambial reactivation in autumn and were observed in growth rings that contained more than 50 cells in a radial row.It appears that summer drought and early autumn precipitation play an important role in false-ring formation.

Changes in climate-growth relationships and IADF formation over time of pine species (Pinus halepensis, P. pinaster and P. sylvestris) in Mediterranean environments

“…Previous studies in the Mediterranean area showed a high frequency of IADFs in latewood (de Luis et al, 2007;Vieira et al, 2010;Rozas et al, 2011;Campelo et al, 2013;Novak et al, 2013). However, the low frequency of IADF type L and the high frequency of IADF type E observed in our samples indicate a higher occurrence of water stress episodes inhibiting cell division and enlargement during the first part of the growing season.…”

Xylem Phenology of <i>Fagus sylvatica</i> in Rarău Mountains (Eastern Carpathians, Romania)

“…The results showed that June had the highest importance in the radial growth, an observation that has also been confirmed by other studies (Bouriaud et al, 2004;Michelot et al, 2012;Oladi et al, 2011). However, the maturation of cells (complete lignification process) continues even after the cessation of the cambial division (Gricar et al, 2005;De Luis et al, 2007). A significant statistical relationship was observed between the leaf phenophases and the phases of annual ring formation, especially among the unfolding process and the activation of cambium (Cufar et al, 2008;Michelot et al, 2012;Prislan et al, 2013).…”

Crossdating Juniperus procera from North Gondar, Ethiopia

“…This association has also been noted by other authors. De Luis et al (2007) report that false rings are more frequent in wide rings in Pinus halepensis Mill. from Spain.…”