Citation. Pearson, L. C.; Lawrence, D. B. 1957-58. Photosynthesis in aspen bark during winter months. Proceedings of the Minnesota Academy of Science 25-26:101-107.   [1464  CC]

Abstract. Quaking aspen, Populus tremuloides Michx., is probably the most widely distributed tree on the north American continent. Much of its range is characterized by long winters and is generally thought of as being more suitable for evergreen conifer species which are photosynthetically active during the winter months, even at temperatures below 0 degrees C. as indicated by Parker (1953). By use of the spectrophotometer, Pearson and Lawrence (1958) demonstrated that the green pigments in aspen bark are chlorophylls (a) and (b). Per unit area, these pigments were more abundant in bark than in leaves during the early part of the growing season but more abundant in leaves later in the summer. Isolating regions of bark by completely removing the phloem around such regions made possible measurement of photosynthetic activity with an iodine starch test. They reported that aspen bark was photosynthetically active during the summer months. The following experiment was designed to ascertain whether or not aspen can carry on photosynthesis in its leafless condition during the winter.

Keywords. quaking aspen, Populus tremuloides, bark photosynthesis