hb2013 see resorption
TRANSCRIPT
Does soil nitrogen control phosphorus resorption in a co-limited system?
Craig See
SUNY-ESF
Photo: USFS
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
Ryan and Bormann 1982
NITROGEN PHOSPHORUS
Single element hypothesis:
The resorption of a nutrient should be higher when that nutrient is in low supply
Soil phosphorus
ph
osp
ho
rus
reso
rpti
on
ph
osp
ho
rus
reso
rpti
on
ph
osp
ho
rus
reso
rpti
on
Soil phosphorus
Soil phosphorus
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
ph
osp
ho
rus
reso
rpti
on
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
Methods
• Stands Sampled 2009, 2010
• Fresh leaves sampled August, litter sampled in October
RE=(G-L)/G
RE=Resorption EfficiencyG=Green leaf nutrient concentrationL=Litter nutrient concentration
Soil Phosphorus (mg/m2)
0 10 20 30 40 50 60
Ph
osp
ho
rus R
eso
rptio
n E
ffic
ien
cy
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.
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)
Soil Nitrogen (mg/m2)
)
100 200 300 400 500 600
Ph
os
po
ru
s R
es
orp
tio
n E
ffic
ien
cy
0.3
0.4
0.5
0.6
0.7
0.8
0.9
BEFC1
BEFC2
BEFC4
BEFC6
BEFC8
BEFC9
Soil N (mg/m2)
200 250 300 350 400 450 500
Ph
osp
ho
rus R
eso
rpti
on
Eff
ecie
ncy
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
R2= 0.89P<0.01
Possible mechanism
Phospholipases, nucleases cost N (and C) to produce…
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
Thank you!
Ruth Yanai
Melany Fisk
Matt Vadebonceour
Shoestring Crew