2009 Harvard Forest REU Student Symposium Abstracts
Jennifer Levye - Harvard University
Implications of Sectoral Variation in Red Oaks and Red Maples on Sap Flow Measurements
Radial variation or sectoriality of sap flow and nutrient distribution in trees has been observed in many contexts. Trees can partition the distribution of nutrients based on the areas of the stem require resources. Our aim in this study was to determine if this partitioning of sap flow was present in forest trees focusing on the implications of sectoriality for sap flow measurement methods. We used Granier's style thermal dissipation probes in red maple and red oaks on the Prospect Hill tract at Harvard Forest to look for patterns in variation of sap flow around the trunk. By inserting either two or three probes in the trunks of trees, we collected sap flow velocity data from April to July, then focused analysis on high-flow days in the late spring and summer. The red oak species seemed to show patterns of variation among the sensors; maples did not show significant variation between probes. The amount of variation found in red oaks could have implications for sap flow measurements since using too few probes per tree could result in significant underestimation or overestimation of total sap flow. Further research is needed to understand the extent of the variation in oaks, and to determine whether variation could be detected in red maples if more sensors were used.
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