Data from: Pushing the limits to tree height: could foliar water storage compensate for hydraulic constraints in Sequoia sempervirens

1. The constraint on vertical water transport is considered an important
factor limiting height growth and maximum attainable height of trees. Here
we show evidence of foliar water storage as a mechanism that could
partially compensate for this constraint in Sequoia sempervirens, the
tallest species. 2. We measured hydraulic and morpho-anatomical
characteristics of foliated shoots of tall S. sempervirens trees near the
wet, northern and dry, southern limits of its geographic distribution in
California, USA. 3. The ability to store water (hydraulic capacitance) and
saturated water content (leaf succulence) of foliage both increased with
height and light availability, maintaining tolerance of leaves to water
stress (bulk leaf water potential at turgor loss) constant relative to
height. 4. Transverse-sectional area of water-storing, transfusion tissue
in leaves increased with height, while the area of xylem tissue decreased,
indicating increasing allocation to water storage and decreasing reliance
on water transport from roots. 5. Treetop leaves of S. sempervirens absorb
moisture via leaf surfaces and have potential to store more than five
times the daily transpirational demand. Thus, foliar water storage may be
an important adaptation that helps maintain physiological function of
treetop leaves and hydraulic status of the crown, allowing this species to
partially compensate for hydraulic constraints and sustain turgor for both
photosynthesis and height growth.