Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats

Abstract

We investigated relationships between whole-tree hydraulic architecture and stomatal conductance in Pinus palustris Mill. (longleaf pine) across habitats that differed in soil properties and habitat structure. Trees occupying a xeric habitat (characterized by sandy, well-drained soils, higher nitrogen availability and lower overstory tree density) were shorter in stature and had lower sapwood-to-leaf area ratio ( A S : A L ) than trees in a mesic habitat. The soil-leaf water potential gradient ( Ψ Ψ Ψ Ψ S − − − − Ψ Ψ Ψ Ψ L ) and leaf-specific hydraulic conductance ( k L ) were similar between sites, as was tissuespecific hydraulic conductivity ( K S ) of roots. Leaf and canopy stomatal conductance ( g S and G S , respectively) were also similar between sites, and they tended to be somewhat higher at the xeric site during morning hours when vapour pressure deficit ( D ) was low. A hydraulic model incorporating tree height, A S : A L and Ψ Ψ Ψ Ψ S − − − − Ψ Ψ Ψ Ψ L accurately described the observed variation in individual tree G Sref ( G S at D = = = = 1 kPa) across sites and indicated that tree height was an important determinant of G Sref across sites. This, combined with a 42% higher root-to-leaf area ratio ( A R : A L ) at the xeric site, suggests that xeric site trees are hydraulically well equipped to realize equal -and sometimes higherpotential for conductance compared with trees on mesic sites. However, a slightly more sensitive stomatal closure response to increasing D observed in xeric site trees suggests that this potential for higher conductance may only be reached when D is low and when the capacity of the hydraulic system to supply water to foliage is not greatly challenged.

Corrigendum to: New handbook for standardised measurement of plant functional traits worldwide

“…References on theory, significance and large datasets: Chiba (1991); Eamus and Prior (2001); Maherali and DeLucia (2001); Mäkelä and Vanninen (2001);McDowell et al (2002); Preston and Ackerly (2003); Addington et al (2006); Buckley and Roberts (2006); Maseda and Fernández (2006); Wright et al (2006); Cornwell et al (2007); Litton et al (2007).…”

Morphological traits and water use strategies in seedlings of Mediterranean coexisting species

“…scorpius, R. officinalis, and U. parviflorus showed significantly higher root-to-photosynthetic area ratio (A R :A P ) values than M. communis. This parameter is related to plant hydraulic architecture, associated to the amount of water that can be extracted from the soil and transported to leaves (Addington et al 2006). A high A R :A P favors the ability to extract water from soil by increasing the surface in contact with soil to better supply to the photosynthetic organs (Ewers et al 2000;Hacke et al 2000).…”

“…The capacity for water transport from soil to leaves is highly dependent on root architecture (Addington et al 2006;Chirino et al 2008), which is important in both determining how plants respond to water availability and in setting maximum rates of gas exchange (Brodribb and Feild 2000;Hubbard et al 2001).…”

Relationships Between Tree Height and Carbon Isotope Discrimination

“…Height itself may be restricted in a homeostatic manner, i.e. reduced height growth facilitates maintenance of g c above critically low thresholds, even for plants with short maximum heights (Addington et al 2006;Ryan et al 2006). Equation 10.3 is based on the premise that irreversible embolism is avoided in part through constraining g s during periods of water limitation, and does not include variation in light or leaf properties, for example, so it provides only an approximate hypothesis about how gas exchange varies with size.…”