This document summarizes a study on the phenology of leaf senescence in birch and maple trees. The study found that trees fertilized with nitrogen retained leaves significantly longer than unfertilized trees. Maple leaf retention was unaffected by fertilization treatment. Additionally, trees in older stands retained leaves longer than those in younger stands. The authors conclude that nutrient availability, especially nitrogen, can delay autumn leaf abscission and promote a longer growing season in trees. Future work may involve sorting litter by species and adding additional collection periods.

1. Phenology of Leaf Senescence:
it’s LIT(ter)🔥!
Maddy Morley SUNY College of Environmental Science and Forestry
Griffin Walsh Yale University
Mentor: Dr. Ruth Yanai SUNY College of Environmental Science and Forestry 1
Adam Wild

2. Introduction
• Trees time their senescence to maximize their growing season while
reabsorbing nutrients before frost.
• Snapchat for Science: Comparing Leaf Retention on Nitrogen and
Phosphorus-Fertilized Birch and Maple Trees
Low Rank High RankTaking birch and maple canopy photos 2
Madison Morley

3. Leaf Retention Findings • N treated trees dropped
significantly more leaves than
N+P plot (p < 0.001).
• Maple leaf retention showed
no significant response to
treatment (p = 0.60). 3
Birch Leaf Retention
Maple Leaf Retention

4. Hypotheses
• Fertilized trees will drop more leaf mass later in the autumn
compared to the unfertilized trees.
• Old stand trees will drop more leaf mass later in the autumn than
younger stand trees.
4Adam Wild

5. Methods
• Four collection periods:
• October 8th
• Oct. 17th - 18th
• Oct. 22nd – 24th
• November 5th – 6th
Litter being sorted before
being dried and weighed
Systematic basket
placement in each plot 5
Gretchen Lasser
Madison Morley
Litter collection

6. Data Analysis
• Cumulative fraction
6
1 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛
𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠
1 + 2 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠
𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠
1 + 2 + 3 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠
𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠
1 + 2 + 3 + 4 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠
𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑖𝑜𝑛𝑠Madison Morley

7. Results
Young
Mid-
aged
Old
7
Collection 1 (Oct. 8th)
- Young stand trees have
dropped more leaf litter
(p = 0.05).
- N treated trees have
retained more leaves
(p = 0.06).
Collection 2
(Oct. 17th-18th)
- N treated trees have
retained more leaves
(p = 0.01).
- P treated trees have
retained more leaves
(p = 0.07).
Collection 3
(Oct. 22nd-24th)
-N treated trees have
retained more leaves
(p = 0.02).
Collection (number)

8. Conclusions
• Nutrients (especially N) delay autumn leaf abscission in trees.
• The availability of nutrients promote a longer growing season.
• Trees in older stands retain their leaves longer than those in young-
age stands.
• Stands that vary in age have different species compositions and species have
unique timing of leaf fall.
• Remember Snapchat for Science!
8
• Sort the litter in some of the stands by species
• Add spring 2017 litter to our collection periods
Next steps

9. Acknowledgments
• Dr. Ruth Yanai
• Adam Wild
• Yanai’s B9 Lab Family
• Shan Shan
• Dr. Yanai’s High School Team
• 2017 MELNHE Field Crew!!!
9
Yang Yang
Alex Young
Gretchen LasserMadison Morley

10. Questions?
10
Mt. Washington!!!
…Cool!
Madison Morley