Adaptive anatomy of Pinus halepensis trees from different Mediterranean environments in Spain

Abstract

A study was conducted on the variation in growth, biomass, juvenile wood anatomy, and needle morphology of Pinushalepensis Mill. from three Spanish regions of provenance characterized by environmental differences, without the influence of the site factor. Seeds collected from two progenies in each region were planted in a single plot, and the trees were felled at the age of 7 years. The results showed significant differences between provenances, as well as the genetic or environmental influence on the traits analyzed. Trees adapted to moderate summer drought conditions (Inland Catalonia region) are primarily characterized by higher average values for height, diameter, biomass, cell wall thickness, inter-tracheid wall strength, pit membrane diameter, torus diameter, bordered pit aperture diameter, and ray tracheid abundance in comparison with trees adapted to severe summer drought conditions (Southern region and Balearic Islands region). The greater structural requirements of trees from the Inland Catalonia region, subjected to higher weight and wind loads, resulted in thick cell walls. Moreover, the large pits and more abundant ray tracheids in trees from this provenance would allow more efficient water transport and greater water storage capacity, respectively. The differences found between provenances suggest the adaptive nature of the anatomy of this species, which demonstrates the importance of the region of provenance when choosing reproduction material for reforestation.

Diurnal dynamics of water transport, storage and hydraulic conductivity in pine trees under seasonal drought

“…Although embolism repair has been reported in conifers (Borghetti et al 1998, McCulloh et al 2011) and in P. halepensis specifically (Borghetti et al 1991), its mechanism is yet to be resolved. If ray parenchyma cells and non-structural carbohydrates (NSCs) are involved, as suggested by Brodersen & McElrone (2013), P. halepensis has both components at notable levels (Esteban et al 2010, Klein et al 2014a. Live parenchyma cells are also expected in the young branches studied here (13 ± 1 years, see Methods).…”

Influence of climate variables on resin yield and secretory structures in tapped Pinus pinaster Ait. in central Spain

“…Under a situation of more limited resource availability, such as the higher plant competition and lower soil water retention in Melque, the plastic response to favorable environmental variables could be hampered (Valladares et al, 2007). This lower plasticity in resin yield could be due to a genetic adaptation that establishes a lower capacity to synthesize and store secondary defense metabolites, resulting in lower resin flow fluctuations (Paine and Stephen, 1987;Mattson and Haack, 1987;Moreira et al, 2008;Esteban et al, 2010). The higher resin yield per tree found in Armuña, the stand with lower tree density, would support earlier work in lodgepole pine (Waring and Pitman, 1985), in which both tree vigor and resistance to bark beetle attacks increased when canopy density was reduced, suggesting that tree vigor could reflect the ability of trees to produce defensive compounds following attack.…”

“…In P. taeda, peak resin flows appeared to be associated with moderate water deficit periods (Ruel et al, 1998;Lombardero et al, 2000). Furthermore, earlier studies on Pinaceae xylem anatomy showed that harsh environmental conditions such as high temperatures, aridity and cold winters are associated with higher frequencies and greater sizes of resin canals (Zamski, 1972;Rigling et al, 2003;Martín et al, 2010;Esteban et al, 2010), whereas an increment of annual or summer rainfall is negatively correlated with these traits (Wimmer and Grabner, 1997;O'Neill et al, 2002). Thus it is also hypothesized that constitutive and traumatic resin canal formation and de novo resin synthesis processes will be influenced by the climate characteristics of the current and the previous year.…”

Dimensions of Mechanical Fibres in Paulownia elongata S. Y. Hu Wood from Different Habitats

“…Esteban et al (2010) and Vilotić and Knežević (1994) state that ecological environmental circumstances have affected signifi cantly not only the properties of the tree, but also the dimensions of its conductive cells. Venugopal and Liangkuwang (2007) state that there is an obvious correlation between climatic parameters, activities of vascular cambium and xylem formation.…”