1. The spring fling: Sapflow during thaw- refreeze cycles The spring fling: Sapflow during thaw- refreeze cycles Michele L. Pruyn Dept. of Biological Sciences Plymouth State University http://www.nps.gov/plants/pubs/chesapeake/plant/446.htm

2. http://nhmapleexperience.com/nh_syrup.php http://extension.unh.edu/nhoutside/trees/ Spring Tease

3. Birch compared to other Northern Hardwoods Shallowest root system of the northern hardwoods (Yanai et al. 2008, Fahey and Hughes, 1994). Root vs. Stem Pressure in Refilling Birches generate root pressure to remove xylem embolism in early spring, unlike sugar maple, which uses stem pressure (Cirelli et al. 2008) Especially Susceptible to Xylem Cavitation (Maherali et al. 2004) If roots are damaged from soil freezing, may not be able to generate enough root pressure to remove emboli in the spring, this can lead to permanent blockage of xylem vessels (Zhu et al. 2001)

4. Shallow Rooting Depth in Yellow Birch Yanai et al. 2008

5. Advantage of Stem Pressure in pre-bud break sapflow. Sugar Maple Yellow Birch Lack of pitting between vessels and other xylem cells sequester sap in the vessel elements – favors a build up of pressure in the xylem.

6. Evolution of resistance to water-stress-induced xylem cavitation in woody plants Maherali et al. (2004)

7. Rustad et al. (2012) in prep We wondered how the trees might be readying for budbreak and how is sapflow involved in this process?

9. Soils data courtesy of Amey Bailey

10. Courtesey of Jordan Christ

11. Courtesy of Lindsey Rustad

12. The Relationship between leaf emergence and water conducting properties of stems Lechowicz (1984) American Naturalist

13. Acknowledgements Plymouth State University & Center for the Environment Hubbard Brook Experimental Forest Summer REU Program Hubbard Brook Researchers, especially Ms. Amey Bailey, Drs. Scott Bailey, Lindsay Rustad and Ruth Yanai for inspirational discussion. Undergraduates: Maegan Gagne, Melissa Lanfranco, Brita Stepe, Kristin Grenier, Darius Harrison, Amanda Hook, Clifton French, Jess Brennan Graduate Students: Jordan Christ & James VanGyzen PSU Botany and Plant Physiology Classes

14. Charles P.-A. Bourque, Roger M. Cox, Darren J. Allen, Paul A. Arp, Fan-Rui Meng. (2005) Spatial extent of winter thaw events in eastern North America: historical weather records in relation to yellow birch decline. Global Change Biology 11:9, 1477-1492 Cirelli D., Jagles R and Tyree MT. (2008). Toward an improved model of maple sap exudation: the location and role of osmotic barriers in sugar maple, butternut and white birch. Tree Physiology 28:1145-1155. Cox RM, Malcolm JW (1997) Effects of duration of a simulated winter thaw on dieback and xylem conductivity of Betula papyrifera. Tree Physiology, 17, 397–404. Cox RM, Zhu XB (2003) The effects of a simulated thaw on xylem cavitation, residual embolism, spring dieback, and shoot growth in yellow birch. Tree Physiology, 23, 615–624. Maherali H, Pockman WT and Jackson RB (2004) Adaptive variation in the vulnerability of woody plants to xylem cavitation. Ecology 85:2184-2199. Yanai, RD, Fisck MC, Fahey TJ, Cleavitt NL and Park BB (2008) Identifying roots of nothern hardwood species: patterns with diameter and depth. Can J For Res 38: 2862-2869 Zhu XB, Cox RM, Arp PA (2000) Effects of xylem cavitation and freezing injury on dieback of yellow birch (Betula alleghaniensis) in relation to a simulated winter thaw. Tree Physiology, 20, 541–547. Zhu XB, Cox RM, Meng F-R et al. (2001) Responses of xylem cavitation, freezing injury and shoot dieback to a simulated winter thaw in yellow birch seedlings growing in different nursery culture regimes. Forest Ecology and Management, 145, 243–253.

15. Questions? http://www.nps.gov/plants/pubs/chesapeake/plant/446.htm