Plastic bimodal xylogenesis in conifers from continental Mediterranean climates

Abstract

Summary Seasonal radial‐increment and xylogenesis data can help to elucidate how climate modulates wood formation in conifers. Few xylogenesis studies have assessed how plastic xylogenesis is in sympatric conifer species from continental Mediterranean areas, where low winter temperatures and summer drought constrain growth. Here, we analysed intra‐annual patterns of secondary growth in sympatric conifer species (Juniperus thurifera, Pinus halepensis and Pinus sylvestris). Two field sites (xeric and mesic) were evaluated using dendrometers, microcores and climatic data. A bimodal pattern of xylogenesis characterized by spring and autumn precipitation and subsequent cambial reactivation was detected in J. thurifera at both study sites and in P. halepensis at the xeric site, but was absent in P. sylvestris where growth was largely controlled by day length. In the xeric site J. thurifera exhibited an increased response to water availability in autumn relative to P. halepensis and summer cambial suppression was more marked in J. thurifera than in P. halepensis. Juniperus thurifera exhibited increased plasticity in its xylogenesis pattern compared with sympatric pines, enabling this species to occupy sites with more variable climatic conditions. The plastic xylogenesis patterns of junipers in drought‐stressed areas may also provide them with a competitive advantage against co‐occurring pines.

Minimum wood density of conifers portrays changes in early season precipitation at dry and cold Eurasian regions

“…5) could be caused by a late peak of earlywood formation in Mongolian sites. This agrees with our knowledge of xylogenesis with maximum rates of tracheid production in Spanish pines occurring in May (Camarero et al 2010). …”

“…Then, we calculated a second PCA based on the Pearson correlations obtained by relating the treering variables with monthly climate data (mean temperature, precipitation) to summarize climate-growth and climate-density associations. Climate variables were considered from September prior to tree-ring formation up to October of the growth year based on previous studies on climate-growth relationships and xylogenesis (Kirdyanov et al 2007, Camarero et al 2010. The number of retained principal components in the first PCA was two because they explained at least 50% of the data variance (Jolliffe 2002).…”

Growth response to climate and drought change along an aridity gradient in the southernmost Pinus nigra relict forests

“…Our results agree with previous dendroecological research performed in P. Mediterranean conifers (Camarero et al 2010). regional scales on precipitation recorded at local scales.…”

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

“…Climate change is resulting in both positive and negative trends in tree growth, the latter frequently observed in drought-stressed environments (Camarero et al, 2010). The influence of climatic variables on growth can be modified over time (Andreu et al, 2007) and previous studies showed a changing association between climatic variables and growth of Pinus species in the Mediterranean area (Bogino & Bravo, 2008;Vieira et al, 2010;Campelo et al, 2013).…”