1. Sugar maple leaf traits respond
to nitrogen, phosphorus, and
vertical gradients
Alexander Young
• Ruth Yanai
• Rakesh Minocha
• John Drake
• Danilo Fernando

2. Tree canopies: a vertical gradient of light
• Foliar traits should be distributed to optimize light use efficiency

3. Tree canopies: a vertical gradient of light
• Foliar traits should be distributed to optimize light use efficiency
0
-10
-20
Light Intensity
0
-10
-20
Light Intensity

4. Tree canopies: a vertical gradient of light
• Foliar traits should be distributed to optimize light use efficiency
0
-10
-20
Light Intensity
“sun” leaf
“shade” leaf

5. Tree canopies: a vertical gradient of leaf size
• Foliar traits should be distributed to optimize light use efficiency
“sun” leaf
“shade” leaf
Leaf area (cm2)
mass(g)

6. Tree canopies: a vertical gradient of leaf size
• Foliar traits should be distributed to optimize light use efficiency
0
-10
-20
Specific Leaf Area (cm2/g)
“sun” leaf
“shade” leaf
Leaf area (cm2)
mass(g)
*SLA increases with leaf width*

7. Tree canopies: a vertical gradient of Nitrogen
• Foliar traits should be distributed to optimize light use efficiency
0
-10
-20
Nitrogen (mg/g)
“sun” leaf
“shade” leaf
Nitrogen: (mg/g)

8. Tree canopies: a vertical gradient of Nitrogen
• Foliar traits should be distributed to optimize light use efficiency
0
-10
-20
Nitrogen (mg/g)
“sun” leaf
“shade” leaf
Nitrogen: (mg/g)
*N concentration increases with leaf width*

9. Models with no vertical variation in nitrogen overestimate
carbon assimilation by up to 60% (Coble et al. 2016. Tree physiology)

10. Climbing
vs
shotgun
sampling

11. Do nutrient treatments alter the gradient of
foliar traits within sugar maple canopies?
• Specific leaf area
• Leaf nitrogen
• Chlorophyll A
- +
- Control N
+ P NP
N
P

12. Are particular foliar traits important drivers
of nutrient treatment response?
Leaf chemistry
• Dilute acid soluble ions, Total ions

13. PC2
PC1
Are particular foliar traits important drivers
of nutrient treatment response?
No underlying pattern
Leaf chemistry
• Dilute acid soluble ions, Total ions
Are particular foliar traits important drivers
of nutrient treatment response?

14. PC2
PC1
PC2
PC1
No underlying pattern Underlying pattern in data
Leaf chemistry
• Dilute acid soluble ions, Total ions
Are particular foliar traits important drivers
of nutrient treatment response?

15. 3 Mature Stands
4 nutrient treatments
1 ~20m tall tree per plot
12 trees

16. Results

17. Leaves from 24 m
Leaves from 14 m

18. Specific leaf area is
higher in N+P and N

19. Specific leaf area is
higher in N, and N+P

20. Nitrogen concentration
is higher in N+P and N

21. Specific leaf area is
higher in N, and N+P
Nitrogen concentration
is higher in N, and N+P

22. Chlorophyll concentration
is higher in N+P and N

23. Specific leaf area is
higher in N, and N+P
Nitrogen concentration
is higher in N, and N+P
Chlorophyll concentration
is higher in N, and N+P

24. Chl A
N
SLA
PC1 (69%)
PC2(23%)
Sun to shade leaves on PC1 (Chlorophyll A)

25. Ca
K
Mg
Soluble Ions
Mg
P
P
Zn
Mn
Ca
Zn
K
Total Ions
Mn
PC1 (89%)PC1 (39%)
PC2(24%)
PC 1 (39%)
PC2(5%)
Soluble Ions

26. Acknowledgements
• P.I.’s Dr. Ruth Yanai, Dr. Melany Fisk
• Dr. Rakesh Minocha, Stephanie Long
• John Drake, Danilo Fernando
• Jeff Merriam
• Summer crew 2017 and 2018
• NSF-REU “Canopy Herbivory and Tardigrades”

27. Future Directions