Essays - by Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe/ |
Stephen
Saupe
Biology Department
College of St. Benedict/St. John's University
Collegeville, MN 56321
Appendix 1 provides a copy of the raw data from this experiment.
Sugar Concentration. Sugar concentration in the sap of the trees studied ranged from 1.5 � 6.0%. The mean concentration of all trees on all days was 3.0% with a std dev of 0.5%. During the course of the season, the average [sugar] in the trees sampled varied considerably (Fig 1), however, there was a slight trend toward increasing concentrations increasing for the first few days followed by a slow decline. Similarly, the concentration of sugar in the sap of a given tree also varied significantly over the season (Fig 2). There was a positive correlation (r = 0.55) between tree diameter and the average concentration of sucrose in sap over the course of the season (Fig 4).
Sap Flow. The number of trees that were producing sap on any given day during the season varied from none to all of the them. On average, 67% of the study trees produced sap on a sample day (Fig 3). In trees that had multiple taps, on just 61% of the days were all the taps in the same tree running (Table 1).
Table 1. | Table 2. |
Figure 3 | Figure 4 |
Table 1. Percent of taps that were running |
|
Tree # |
% of days during season in which all taps were running |
4 |
75.0 |
6 |
55.6 |
7 |
50.0 |
8 |
62.5 |
Acknowledgements:
Many thanks to my Plant Physiology (BIOL327) class for
helping to collect data.