PS 36-182 - Developing a Continental-Scale Perspective on Wood Water Storage and Capacitance

Background/Question/Methods

Trees have structural and functional characteristics that allow them to withstand drought conditions, including the ability to store and mobilize water in the wood that can be utilized to maintain hydraulic integrity and prevent xylem embolism when drought strikes. Water stored in wood may play a critical role in a tree’s drought resistance; however, not all stored water is equally available for transpiration. Wood water capacitance is a trait that describes the amount of water released given a change in the water potential of the tree; however, this trait has historically been challenging to measure with a common methodology across many species in numerous locations. Our research seeks to address the role wood water storage and capacitance have in response to drought. We measured wood water storge and capacitance using tree wood cores collected from common tree species around the United States and complemented this with information on wood structure.

Results/Conclusions

We collected cores from up to 4 different species from each of 7 sites across the United States spanning 6.2 to 16.8 °C mean annual temperature, 445 to 1203 mm mean annual precipitation and comprising of both angiosperms and gymnosperms. Our analysis found no clear relationships between wood water storage and capacitance. Mean wood water capacitance was 567 ± 140 kg m^-3 MPa^-1, with a standard deviation among sites of 223 kg m^-3 Mpa^-1 and a mean standard deviation within sites of 261 kg m^-3 Mpa^-1. Thus, we observe similar standard deviations within sites as among sites. Consistent with prior research, we found no clear differences in capacitance between angiosperms and gymnosperms. Initial analysis also indicated no clear relationships between capacitance and climate; however, ongoing research will greatly increase the number of sites included in the analysis. We present complementary analysis of wood structure that advances our understanding of the wood anatomical traits that govern capacitance. Building a database of wood water capacitance using unified methods will facilitate our understanding of, and ability to model, tree water relations in a changing environment.