High diversity of anatomical and hydraulic strategies of dominant
Amazonian savanna woody species
Abstract
Amazonian savannas are isolated patches of open habitats found within an
extensive matrix of tropical forest. Climate in Amazonia is
transitioning to a state where savannas are more likely to occur than
forests, but the hydraulic functioning of savannas species in Amazonian
vegetation remain unknown and unexplored. We measured 22 leaf, wood and
hydraulic traits, including embolism resistance (as P50), hydraulic
safety margin and isotope-based water use efficiency, for the seven
dominant woody species (75% of biomass) in an Amazonian savanna plants.
We found a wide variation in resistance to embolism (-1.66 ±0.06 MPa and
-5.07±0.46 MPa) and structural anatomy with species investing in three
different functional strategies to tolerance the drought. (1) species
with high leaf succulence have less efficient water use increase Gmax,
minimizing the risk for xylem. (2) Species that have higher embolism
resistance by reinforcement of the intervascular walls of the longest
vessels. (3) Species that decrease the spread of embolism by thickening
of the membrane of the intervascular pit of short vessel elements. Our
results suggest no unique dominant functional strategy among Amazonian
savanna species illustrating the multiple ways to adapt to increasing of
seasonality in those environments.