INVESTIGADORES
SCHOLZ Fabian Gustavo
congresos y reuniones científicas
Título:
Expensive and hydraulically efficient leaves maintain to cold desert shrubs active during the dry season
Autor/es:
71. SCHOLZ FG, BUCCI SJ, PEREYRA D, GOLDSTEIN G.
Reunión:
Congreso; 99 ESA Annual Meeting; 2014
Resumen:
Background/Question/Methods
Temporal and spatial variation in water availability is one of the
main drivers of ecological diversity in arid ecosystems. Leaf hydraulic
conductance (Kleaf) is a key trait governing plant
hydraulics, water use and gas exchange under water deficit conditions.
As the transpiration stream in leaves occurs through vascular and
extra-vascular tissues, a suite of morphological and anatomical traits
implying substantial carbon investment can affect Kleaf. We investigated the relationships between Kleaf
and drought resistance traits in shrub species of the Patagonian steppe
and its functional relationship with leaf phenology. Leaf hydraulics
and water relations traits and leaf mass per area (LMA) were determined
in seven shrub species including deciduous and functionally deciduous
species with more restricted soil water access and evergreen species
tapping water from deeper soil layers.
Results/Conclusions Evergreen species had access to more stable
water sources; however their leaves exhibited traits related to drought
tolerance compared to leaves from deciduous and functionally deciduous
species with relatively shallow roots and lower soil water availability.
Leaves from evergreen species had lower osmotic potentials, solute
content, and hydraulic capacitance and higher modulus of elasticity and
leaf mass per area. Nevertheless these species had higher Kleaf both
on area and mass basis and stomatal conductance than species exposed to
larger water deficits. The strong positive relationships observed
between LMA and Kleaf on both area and mass basis suggests
that leaf water use and hydraulic efficiency are not optimized in
species that maximize carbon gain possibly because they are uncoupled
from seasonal changes in soil water availability by exploring deeper and
wetter soil layers. However the construction of leaves with long
lifespan (evergreen species) with high resistance to hydraulic failure
and turgor loss, and the production of roots achieving deeper soil water
sources implies a large energy cost with negative consequences on
carbon gain at whole-plant level as photo-assimilates are allocated to
roots, to active osmotically compounds and probably to a higher density
of leaf vasculature.