DISTANCE AND BARK PHOTOSYNTHESIS IN ASPEN TREES IN THE FRONT RANGE

Lauren KendleWinter 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

1.0 1.5 2.0 2.5 3.0

11

01

30

15

0

Distance and Greenness

distance ranking

gre

en

ne

ss

Results Continued… excluding group 1

Results

Hypothesis was not supported For the Categorical Data

P value = 0.672 R-squared -0.04042

For data for blocked trees only P Value = 0.248 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 CO2 or O2

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. 2001. Age-dependent bark photosynthesis of aspen twigs. Trees, 15:431-437

Foote, K.C. and M. Schaedle. 1976. Physiological characteristics of photosynthesis and respiration in stems of Populus tremuloides michx. Plant Physiology 58:91-94.

Pfanz, H., G. Aschan, R.Langenfeld-Heyser, C. Wittman, and M. Loose. 2002. Ecology and ecophysiology of tree stems: corticular and wood photosynthesis. Naturwissenchaften 89:147-162

 Roakowski, P., Y. Li, and P. B. Reich. 2011. Local ecotypic and speicies range-related

adaptation influence photosynthetic temperature optima in deciduous broadleaved trees. Plant Ecology, 213:112-125.

Solhaug, K.A. and J. Haugen. 1998. Seasonal variation of photoinhibition of photosynthesis in bark from Populus tremula l. Photosynthetica 35:411-417.

Wullschleger, S.D., D. J. Weston, and J. M. Davis. 2009. Populus response to edaphic and climate cues: emerging evidence from systems biology research. Critical Reivews n Plan Science, 28:368-374.