1. Foliar N and P Resorption
by Species and Treatment
Dan Hong
Tim Fahey
Melany Fisk
Mariann Johnston
Ruth Yanai
2. Before the leaves fall…
• Trees retranslocate nutrients
from senescing leaves
Nutrient conservation and
recycling prior to frost
damage
= foliar resorption
Tree growth
Soil fertility
Forest health
3. Single element hypothesis
The resorption of an element
should be lower when that
element is in high supply.
Multiple element hypothesis
The resorption of an element
should be affected by other
elements available.
Nutrient Availability
NutrientResorption
N Availability
PResorption
P Availability
NResorption
??
Multiple element interaction
4. Single element hypothesis
The resorption of an element
should be lower when that
element is in high supply.
Multiple element hypothesis
The resorption of an element
should be affected by other
elements available.
Nutrient Availability
NutrientResorption
N Availability
PResorption
P Availability
NResorption
?
Multiple element interaction
See et al. 2015. Ecology
5. Single element hypothesis
The resorption of an element
should be lower when that
element is ADDED.
Multiple element hypothesis
The resorption of an element
should be affected by other
elements ADDED.
Nutrient Addition
NutrientResorption
N Addition
PResorption
P Addition
NResorption
Multiple element interaction
6. Research questions:
• How do foliar concentration and resorption vary
with respect to nutrient additions (N, P, N+P & )?
• How do species vary with nutrient additions?
• Does the pattern of resorption change over time
with nutrient additions?
• If so, do certain species resorb more nutrients earlier in
the litterfall season, or later?
7. Field Methods
• Green leaves collected by tree
in August of 2015 and 2016.
• Litter collected in 2015 by plot.
• Litter collected in 2016 by tree
and by plot.
Stand
Green Leaves & Litter
C1
C4
C6
C8
C9
HBM
HBO
JBM
JBO
Trip1: 10/7 – 10/9
Trip2: 10/17 – 10/19
Trip3: 10/21 – 10/23
Trip4: 11/4 – 11/6
2015
BE, RM
BE, RM
BE, RM
BE, SM
BE, SM
BE, RM, SM
BE, SM
BE, SM
BE, SM
2016
BE, PC, WB
PC, WB, YB
PC, WB, YB
YB
YB
WB, YB
YB
PC, WB, YB
YB
Kara Phelps Me
8. Laboratory Methods
• P and other elements by Optima 5300
DV ICP-OES (Perkin-Elmer)
• Green leaves were ashed and hotplate-digested
• Others are being microwave-digested by MARS 6
Microwave Digestion System (CEM)
• N by a FlashEA 1112 analyzer (Thermo Scientific)
9. N
N treatment
p < 0.0001
P treatment
p < 0.05
N * P
p < 0.19
Species
p < 0.0001
2015 Green
Solid N:P of 14-16
Dotted N:P of 10-20
10. P
N treatment
p < 0.70
P treatment
p < 0.0001
N * P
p < 0.51
Species
p < 0.15
2015 Green
Solid N:P of 14-16
Dotted N:P of 10-20
11. N:P
N treatment
p < 0.0001
P treatment
p < 0.0001
N * P
p < 0.30
Species
p < 0.05
2015 Green
Solid N:P of 14-16
Dotted N:P of 10-20
13. N
N treatment
p < 0.003
P treatment
p < 0.97
N * P
p < 0.98
Species
p < 0.0001
Green leaf P concentrations (mg/g)
1 2 3 4 5
GreenleafNconcentrations(mg/g)
20
30
40
50
BE
PC
WB
YB
2016 Green
Solid N:P of 14-16
Dotted N:P of 10-20
14. P
N treatment
p < 0.01
P treatment
p < 0.0001
N * P
p < 0.40
Species
p < 0.0001
Green leaf P concentrations (mg/g)
1 2 3 4 5
GreenleafNconcentrations(mg/g)
20
30
40
50
BE
PC
WB
YB
2016 Green
Solid N:P of 14-16
Dotted N:P of 10-20
15. N:P
N treatment
p < 0.0001
P treatment
p < 0.0001
N * P
p < 0.12
Species
p < 0.0001
Green leaf P concentrations (mg/g)
1 2 3 4 5
GreenleafNconcentrations(mg/g)
20
30
40
50
BE
PC
WB
YB
2016 Green
Solid N:P of 14-16
Dotted N:P of 10-20
16. BE
0 6 12 18 24
Ca(mg/g)
4
6
8
10
12
14
PC WB YB
Con N P NP Ca
p < 0.002
Ca
Con N P NP Ca Con N P NP Ca Con N P NP Ca
BE
0 6 12 18 24
Mg(mg/g)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
PC WB YB
p < 0.07
Mg
Con N P NP Ca Con N P NP Ca Con N P NP Ca Con N P NP Ca
Al, B, Fe, K, Mn, Na,
S, Sr, Zn
17. What now…?
• 250 green leaf samples
• 826 litter samples
Thank you and stay tuned!
Editor's Notes
Make sure the title matches the content. Maybe just green?
Foliar nutrient concentrations are good indicators of growth, soil fertility, and forest health. They can provide a snapshot of how trees allocate their nutrients under different conditions, such as elevated levels of N and P.
Craig See found that P resorption efficiency increased with soil N.
P resorption increased with soil P, which goes against the hypothesis.
P resorption was high with low resin-available P in Oe. N resorption was high with low
Craig See found that P resorption efficiency increased with soil N.
P resorption increased with soil P, which goes against the hypothesis.
P resorption was high with low resin-available P in Oe. N resorption was high with low
Don’t talk about time yet? Add a slide at the end about future work. Are leaves more sensitive to N or P.
Mention highschool students.
Adding N increased N concentrations, pushing it towards P-limitation.
Adding P increased P concentrations but decreased N concentrations, to a point of co-limitation or even towards N-limitation.
Adding N and P together prompted a shift towards co-limitation.
BE remained in the P-limited zone even with P addition, but maples seemed to accumulate more P.
Foliar N:P ratios increased with N and decreased with P addition.
The solid and dotted lines delineate co-limitation between N:P of 14-16 and 10-20, respectively.
Adding N increased N concentrations, pushing it towards P-limitation.
Adding P increased P concentrations but decreased N concentrations, to a point of co-limitation or even towards N-limitation.
Adding N and P together prompted a shift towards co-limitation.
BE remained in the P-limited zone even with P addition, but maples seemed to accumulate more P.
Foliar N:P ratios increased with N and decreased with P addition.
The solid and dotted lines delineate co-limitation between N:P of 14-16 and 10-20, respectively.
Adding N increased N concentrations, pushing it towards P-limitation.
Adding P increased P concentrations but decreased N concentrations, to a point of co-limitation or even towards N-limitation.
Adding N and P together prompted a shift towards co-limitation.
BE remained in the P-limited zone even with P addition, but maples seemed to accumulate more P.
Foliar N:P ratios increased with N and decreased with P addition.
The solid and dotted lines delineate co-limitation between N:P of 14-16 and 10-20, respectively.
P resorption efficiency declined with P addition, but no effect of N or P addition on N resorption efficiency
Adding N increased N concentrations and decreased P concentrations, pushing it towards P-limitation.
Adding P increased P concentrations, to a point of co-limitation or even towards N-limitation.
Adding N and P together prompted a shift towards co-limitation.
PC accumulated more N than the birches. PC accumulated more P than BE and WB.
Foliar N:P ratios increased with N and decreased with P addition.
Adding N increased N concentrations and decreased P concentrations, pushing it towards P-limitation.
Adding P increased P concentrations, to a point of co-limitation or even towards N-limitation.
Adding N and P together prompted a shift towards co-limitation.
PC accumulated more N than the birches. PC accumulated more P than BE and WB.
Foliar N:P ratios increased with N and decreased with P addition.
Adding N increased N concentrations and decreased P concentrations, pushing it towards P-limitation.
Adding P increased P concentrations, to a point of co-limitation or even towards N-limitation.
Adding N and P together prompted a shift towards co-limitation.
PC accumulated more N than the birches. PC accumulated more P than BE and WB.
Foliar N:P ratios increased with N and decreased with P addition.
