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

Abstract

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.

The value of crossdating to retain high‐frequency variability, climate signals, and extreme events in environmental proxies

“…False rings are generally caused by a stressful period during the growing season and can be distinguished through crossdating and careful inspection of wood anatomy (Speer, 2010). Rates vary greatly among species and site, and in extreme cases, false rings can occur in as many as a third (Copenheaver et al, 2010;Palakit et al, 2012;Novak et al, 2013Novak et al, , 2014 to 80% of all increments (Marchand & Filion, 2012;Battipaglia et al, 2014). Without crossdating, locally absent rings and false rings would contribute to the overall error rate, although additional error would almost certainly occur.…”

Summer drought reconstruction in northeastern Spain inferred from a tree ring latewood network since 1734

“…The relationship between latewood growth and evapotranspiration during summer has already been explored in recent work from the Pyrenees, using maximum latewood density [Büntgen et al, 2008;Dorado-Liñán et al, 2012]. Further studies are needed to assess this finding since in other species growing at lower altitudes under stronger summer stress, the reduction of photosynthetic activity during summer is compensated by the species' ability to resume growth in autumn when conditions are favorable [de Luis et al, 2007;Novak et al, 2013;Martinez del Castillo et al, 2016;Prislan et al, 2016]. In light of projected global warming, a higher water demand during summer would translate into a decrease in latewood width, which may have implications on forest sustainability.…”

“…Since latewood substantially contributes to stem mechanical stability and stores large amounts of water, a lower proportion of this xylem tissue would tend to reduce drought resistance [Domec and Gartner, 2002;Martinez-Meier et al, 2008, de Luis et al, 2011. Further studies are needed to assess this finding since in other species growing at lower altitudes under stronger summer stress, the reduction of photosynthetic activity during summer is compensated by the species' ability to resume growth in autumn when conditions are favorable [de Luis et al, 2007;Novak et al, 2013;Martinez del Castillo et al, 2016;Prislan et al, 2016]. Intraspecific plasticity of cambial phenology of P. sylvestris and P. uncinata needs to be studied in more detail to better evaluate the ecological consequences these our findings.…”

Intra-annual density fluctuations (IADFs) inPinus nigra(J. F. Arnold) at high-elevation in the central Apennines (Italy)

“…Recently, new analytical methods have been developed to disentangle IADFs triggering factors. Novak et al (2013) assessed the IADF climatic signal in Pinus halepensis in Spain applying a three-parameter Weibull function to remove the effect of cambial age on IADFs frequency. Campelo et al (2015) removed direct (indirect) ring-width (cambial age) effects from IADFs chronologies after standardizing with a Chapman function.…”

“…Therefore, a binary dataset assigning the value 1 for presence or 0 for absence of IADFs in each tree ring in a core was built. There are different approaches to develop IADFs chronologies, and correcting the bias introduced by changing sample depth over time (Osborn et al 1997), by cambial age (Novak et al 2013), and by size . To calculate the IADFs frequency through time, and with varying sample depth, the method of Osborn et al (1997) was applied.…”