DISTANCE AND BARK PHOTOSYNTHESIS IN ASPEN TREES IN THE FRONT RANGE Lauren Kendle Winter Ecology Spring 2012

Background Information  An analysis of 60 species indicated that there were photosynthetic processes in the bark  Aspen Trees had the highest level of bark chlorophyll (Wittman and Pfanz, 2011)  Photosynthesis in the bark is reduced to a quarter of summertime production during the winter ( Solhaug and Haugen, 1998)  Chlorophyll is arranged in the tree to maximize photosynthesis (Pfanz et al., 2002)

Question and Hypothesis  Question: Are Aspens able to adjust the amount of chlorophyll in the bark if there is a tree or an object blocking the direct sunlight?  Hypothesis: The closer the object or tree is to the Aspen should result in more chlorophyll because so the tree can compensate for the decreased amount of sunlight.

Methods  Paint Chip Analysis  Measured at breast height on the sun- facing side  Took Picture  Recorded information from location

Methods continued  Photoshop to standardize photos  Sampled Green Pigmentation  Averaged Green Pigmentation  Used R for analysis of data  Many limitations of in data collection

Results

Results Continued… excluding group 1

Results  Hypothesis was not supported  For the Categorical Data P value = R-squared  For data for blocked trees only P Value = R-squared = 0.05

Discussion  The Data did not support the hypothesis  Maybe confounding variables Age of trees Aspect Amount of sunlight blocked Human influence in second sample site  Aspens are highly competitive species and optimize the light received by increasing chlorophyll per unit of area (Aschan et al., 2001)

Further questions  Is the age of the tree related to the chlorophyll content?  Would changing the methods produce different results?  Machine measurement of CO 2 or O 2  What other factors may influence the chlorophyll content? Soil Water Aspect

Conclusions  Hypothesis was not supported in this study  Not enough information collected  No significant relationships based on the data collected  Methods may not have adequately assessed levels of photosynthesis

Literature Cited Aschan, G., C. Wittmann, and H. Pfanz Age-dependent bark photosynthesis of aspen twigs. Trees, 15: Foote, K.C. and M. Schaedle Physiological characteristics of photosynthesis and respiration in stems of Populus tremuloides michx. Plant Physiology 58: Pfanz, H., G. Aschan, R.Langenfeld-Heyser, C. Wittman, and M. Loose Ecology and ecophysiology of tree stems: corticular and wood photosynthesis. Naturwissenchaften 89: Roakowski, P., Y. Li, and P. B. Reich Local ecotypic and speicies range-related adaptation influence photosynthetic temperature optima in deciduous broadleaved trees. Plant Ecology, 213: Solhaug, K.A. and J. Haugen Seasonal variation of photoinhibition of photosynthesis in bark from Populus tremula l. Photosynthetica 35: Wullschleger, S.D., D. J. Weston, and J. M. Davis Populus response to edaphic and climate cues: emerging evidence from systems biology research. Critical Reivews n Plan Science, 28: