1. Correlation Between Autumnal Leaf Senescence and Age in Acer platanoides (Norway Maple) Yana Radenska EDTEP 586

2. 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?

3. Initial Model

4. 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

5. Methods  Observations performed on 10/29/05  Observed 33 Maple trees, E8 and road on campus  Data 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)

6. Data Collection

8. Results

9. 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

10. 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

11. Revised Model

12. Selected References The Chemistry of Fall Colors. October 14 th, 2005. USDA Forest Service. http://www.fs.fed.us/r2/recreation/fallcolors/chemistry/ http://www.fs.fed.us/r2/recreation/fallcolors/chemistry/ The Scientific Basis for Autumn. June 29 th, 2003. NCNatural. http://ncnatural.com/wildflwr/fall/science.html http://ncnatural.com/wildflwr/fall/science.html Andersson, A. et al. A Transcriptional Timetable of Autumn Senescence.Genome Biology, 2004. 5: R24.http://genomebiology.com/2004/5/4/R24.http://genomebiology.com/2004/5/4/R24 Special thanks to Margaret Jones, Renata Green, Dawn Rubstello, Mark Windschitl, Scott Braswell, and Elizabeth Thomas.