1.
Does soil nitrogen control phosphorus
resorption in a co-limited system?
Craig See
SUNY-ESF
Photo: USFS

2.
Before the leaves fall. . .
•Nutrients move from leaves to stem
tissues
•Resorption Efficiency = percent of leaf
nutrients resorbed before abscission
•Resorption efficiencies vary
•Critical for plant nutrient
conservation

3.
Ryan and Bormann 1982
NITROGEN PHOSPHORUS

4.
Single element hypothesis:
The resorption of a nutrient should be higher
when that nutrient is in low supply
Soil phosphorus
phosphorusresorption
phosphorusresorptionphosphorusresorption
Soil phosphorus
Soil phosphorus

5.
Multiple element hypothesis:
In a co-limited system, the resorption of an
element should depend on the relative availability
of all limiting elements.
Soil Nitrogen
phosphorusresorption

6.
METHODS
• 18 30x30m plots in 6
stands at BEF
• 1 quantitative soil pit
per plot
• 5 litter baskets
• Resorption data for up
to 5 trees/species/plot
Bartlett Experimental Forest

7.
Methods
• Stands Sampled 2009, 2010
• Fresh leaves sampled
August, litter sampled in
October
RE=(G-L)/G
RE=Resorption Efficiency
G=Green leaf nutrient concentration
L=Litter nutrient concentration

8.
Soil Phosphorus (mg/m2
)
0 10 20 30 40 50 60
PhosphorusResorptionEfficiency
0.0
0.2
0.4
0.6
0.8
1.0
No detectable
correlation
between soil P
and P resorption
for any of the
species studied.

9.
Total soil N was
positively correlated
with P resorption
efficiency in 4 of 6
species:
American beech (p<0.01)
yellow birch(p=0.04)
white birch (p=0.05)
sugar maple (p=0.07)

10.
Soil Nitrogen (mg/m2
)
)
100 200 300 400 500 600
PhosporusResorptionEfficiency
0.3
0.4
0.5
0.6
0.7
0.8
0.9
BEFC1
BEFC2
BEFC4
BEFC6
BEFC8
BEFC9

11.
Soil N (mg/m2
)
200 250 300 350 400 450 500
PhosphorusResorptionEffeciency
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
R2= 0.89
P<0.01

12.
Possible mechanism
Phospholipases, nucleases cost N
(and C) to produce…

13.
Conclusions
• P resorption correlates positively with soil
N, but not with P.
• Relationship is stronger at the community
level, when weighted by the species
composition of litterfall.
Future research: Post-fertilization resampling

14.
Thank you!
Ruth Yanai
Melany Fisk
Matt Vadebonceour
Shoestring Crew