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Comparing Sapflow Methods: Granier vs. Heat Ratio

Comparing Sapflow Methods: Granier vs. Heat Ratio. Clarissa Lyons (Smith College 2013) Kate Bussell (Transylvania University 2012). Motivation. Slide courtesy of Matt Green. Forest Water Balance. Intro, cont.

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Comparing Sapflow Methods: Granier vs. Heat Ratio

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  1. Comparing Sapflow Methods: Granier vs. Heat Ratio Clarissa Lyons (Smith College 2013) Kate Bussell (Transylvania University 2012)

  2. Motivation Slide courtesy of Matt Green

  3. Forest Water Balance

  4. Intro, cont. Two different methods are being employed in the MELNHE plots: the Granier method and the heat ratio method (HRM) Heat-based sapflow techniques are the most widely used methods for sapflow measurement

  5. Heat Ratio Method An improvement of the compensation heat pulse method by Burgess et al. (2001) Method being used by researchers at UNH, led by Heidi Asbjornsen Measures the ratio of the increase in temperature at points equidistant from the line heater following the release of a heat pulse

  6. Below: Thermocouple placement within sensor Sapflow tree in Bartlett Experimental Forest (C8)

  7. Granier Method Developed by André Granier in 1985 Method used by Dr. Michele Pruyn and team from PSU Constant heat source Sapflow calculated from difference in temperature between two thermocouples

  8. Comparison Results

  9. Results, cont.

  10. Special Thanks to Our Contributors Dr. Michele Pruyn, Assistant Professor of Plant Biology, Plymouth State University Adan Hernandez, Graduate Student, University of New Hampshire Dr. Heidi Asbjornsen, Associate Professor of Ecosystem Ecology, University of New Hampshire Dr. Ruth Yanai, Professor of Forest and Natural Resources Management, SUNY ESF Craig See, Master’s Student, SUNY ESF Mark Green, Assistant Professor of Hydrology, Plymouth State University

  11. References Burgess, S.O. et al. (2001). An improved heat pulse method to measure low and reverse rates of sap flow in woody plants. Tree Physiology, 21, 589-598. Granier, A. et al. (1996). Transpiration of trees and forest stands: short and long-term monitoring using sapflow methods. Global Change Biology, 2, 265-274. Granier, A. et al. (1987). Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements. Tree Physiology, 3, 309-320. Kostner, B. et al. (1998). Sapflow measurements in forest stands: methods & uncertainties. Annals of Forest Science, 55, 13-27.

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