Background

• Hubbard Brook whole-watershed transpiration response to wollastonite (CaSiO3) addition

(Green et al. 2013)

Background

• Measuring sap flow is one method to estimate transpiration (Granier, 1987)

• Taking sap flow measurements at MELNHE wollastonite plots could help clarify mechanisms underlying HB W1 transpiration response

• Preliminary sap flow measurements from HB Ca suggest increased transpiration in wollastonitetreatment (Zahor et al. 2013)

Research Question

• Does a wollastonite addition increase tree transpiration?

• Expect that it does, possibly due to increased xylem and fine root growth

• Alternatively, sap flow measurements could reflect the transition to decreased transpiration observed in W1 (Green et al. 2013)

Methods

• Sap flow measured by the Granier method: reference probe 10 cm below thermocouple heating probe with constant source of heat, measures temperature difference (ΔT) (Granier, 1987)

• Measurements collected by data logger every 30 seconds, average recorded every 15 minutes

• ΔT converted to sapflux (Js, g x m2 x s-1) using BaseLiner software (Oren and Parashkevov, 2012)

(Max Planck Institute for Biogeochemistry)

Methods

• Sap flow to be measured in wollastonite and control plots at mature stands in Bartlett Experimental Forest (C8), Hubbard Brook Experimental Forest (Ca) and Jeffers Brook

• 9 canopy trees measured per plot: 3 American beech, 3 sugar maple and 3 yellow birch

• Measurements collected for ~5 days per stand

Results

0

5

10

15

20

25

171.5 172 172.5 173 173.5 174 174.5 175 175.5 176 176.5 177

Sap

flu

x (J

s, g

x m

2 x

s-1

)

Ordinal Date and Time

Bartlett C8

C8 Control AB

C8 Control SM

C8 Control YB

C8 Ca AB

C8 Ca SM

C8 Ca YB

Results- Bartlett C8

Results- Bartlett C8

Results- Bartlett C8

Results- Hubbard Brook

Results- Hubbard Brook

Results- Hubbard Brook

Changes to Methods

• To increase statistical power, decided to measure 5 sugar maple and 5 yellow birch trees per plot at Jeffers Brook

Results- Jeffers Brook

Results- Jeffers Brook

Results- Jeffers Brook

Results- Jeffers Brook

Conclusion

• Data suggests increased sap flow in Bartlett C8 and Jeffers Brook, but decreased sap flow in Hubbard Brook

• Statistical analysis

• Consider additional covariates and research questions moving forward, why is Hubbard Brook different?

• Continuous dataset to work with!

• Step toward understanding how CaSiO3 impacts forest health and hydrology amidst acid rain, could influence management techniques

References & Acknowledgements

• Granier, A. (1987). Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements. Tree Physiology 3: 309-320.

• Green, M.B., et al. (2013). Decreased water flowing from a forest amended with calcium silicate. Proceedings of the National Academy of Sciences110(15):5999-6003.

• Oren, Parashkevov, & Duke University. (2012). BaseLiner (Version 2.4.2) http://ch2oecology.env.duke.edu/orenlab/sofware.html

• Michele Pruyn

• Mariann Johnston

• Mark Green

• Ruth Yanai

• Adam Wild, our glorious leader

• Shoestring Crew