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Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats
Author(s) -
ADDINGTON R. N.,
DONOVAN L. A.,
MITCHELL R. J.,
VOSE J. M.,
PECOT S. D.,
JACK S. B.,
HACKE U. G.,
SPERRY J. S.,
OREN R.
Publication year - 2006
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2005.01430.x
Subject(s) - deserts and xeric shrublands , stomatal conductance , habitat , hydraulic conductivity , soil water , agronomy , ecology , botany , biology , environmental science , hydrology (agriculture) , geology , photosynthesis , geotechnical engineering
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 S − Ψ L ) and leaf‐specific hydraulic conductance ( k L ) were similar between sites, as was tissue‐specific 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 S − 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 higher – potential 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.