COS 179-4 - CANCELLED - Wood traits vary with water availability and age in a semi-arid shrub

Background/Question/Methods

Background/Questions/Methods

Climate models predict precipitation variability in drylands will become more extreme in the future, altering soil water availability with consequences for plant water relations and growth and reproduction. However, phenotypic plasticity, may provide long-lived species a mechanism to mitigate environmental stress by allowing for production of tissues more suitable to an altered precipitation regime. At the same time, these shifts in morphology may canalize plant developmental trajectories to influence other plant processes. Xylem traits that determine the functional potential for water transport reflect this dichotomy well in that plasticity may allow for tissues suited to a particular precipitation season while the permanence of these tissues may impact future growth and function. We investigated how wood traits in Artemisia californica vary over a precipitation gradient as a function of age and how this variation impacts the fitness components of growth and reproduction. We hypothesized that 1) wood anatomical traits would become more conductive as plants got older, 2) plants grown in higher water treatments would be more conductive, and 3) plants would experience interactive effects of water and age on wood traits, such that older plants in high water treatments would have wood traits that are more than additively conductive.

Results/Conclusions

Results/Conclusions

In general, xylem traits became more conductive as plants got older and under higher water availability, with convergence in trait values as plants aged and in water abundant scenarios. These changes in xylem anatomy established strong potential conductivity trajectories and point to the importance of xylem trait plasticity during establishment. These changes will be important to consider under future precipitation regimes as they may impact plant function and ultimately population age structure.