Correlation Between Autumnal Leaf Senescence and Age in Acer

platanoides (Norway Maple)

Yana RadenskaEDTEP 586

Question

Is there any correlation between age and the timing of autumnal leaf senescence in the Norway maple tree?

In other words, if I went out on a single Fall day, looked at a bunch of trees of the same species (Norway maples, in this case), would I see any difference between smaller and larger trees in terms of what percentage of the leaves had turned colors other than green?

Initial Model

Assumptions

Environmental factors are the same– Temperature– Day length– Amount of sunlight

Variation in leaf loss within species is negligible

Diameter at Breast Height is a good indicator of age

Methods

Observations performed on 10/29/05Observed 33 Maple trees, E8 and road on campusData taken

– % of leaf senescence (as determined by two people)

– Location (using GPS)

– Orientation (using a compass)

– Circumference (to determine Diameter at Breast Height)

– Other factors (such as substantial shade)

Data Collection

ResultsDBH v. % Leaf Senescence

y = 6.4877x - 9.7962

R2 = 0.613

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16

Diameter at Breast Height in Inches

% L

eaf

Sen

esce

nce

Culminating Argument

Causal mechanisms– DNA in all organisms degrades during the process of

replication as the organism ages

– Older organisms have more dysfunctional DNA (through replication errors and shorter telomeres)

– DNA is used to produce specific proteins that are used to build the varying components (such as chlorophyll) needed to keep leaves alive and green, thus older trees should have non-green and dead leaves

Culminating Argument Cont.

Explanation– Data show that there appears to be a positive correlation

between tree age and leaf senescence

– Older trees had more brown leaves

– HOWEVER… correlation != causation

– Further study is needed to substantiate causation

Revised Model

Selected ReferencesThe Chemistry of Fall Colors. October 14th, 2005. USDA Forest Service.

http://www.fs.fed.us/r2/recreation/fallcolors/chemistry/The Scientific Basis for Autumn. June 29th, 2003. NCNatural. http://

ncnatural.com/wildflwr/fall/science.htmlAndersson, A. et al. A Transcriptional Timetable of Autumn Senescence.

Genome Biology, 2004. 5: R24. http://genomebiology.com/2004/5/4/R24.

Special thanks to Margaret Jones, Renata Green, Dawn Rubstello, Mark Windschitl, Scott Braswell, and Elizabeth Thomas.