Can leaf mass & foliar nutrient concentration explain species growth rates in northern hardwood stands?

Presented by: Shinjini GoswamiGraduate Research AssistantMiami University, OHContact: goswams@muohio.edu

Co-limitation

• Can arise in couple ways-1. Productivity of all trees respond additively to N+P additionsOR2. Productivity of one species might respond to N whereas another might respond to P:Community level co-limitation

• Broad question- Species specific growth responses to nutrient availability

N or P or Ca or all????

Introduction

• Growth efficiency- Trees with high efficiency accumulate more biomass per unit leaf mass

• Measured as productivity per unit leaf mass

• Expect it to increase with availability of the limiting nutrient

• Foliar N:P ratios indicate nutrient limitations &/or co-limitation; <10 indicates N limitation and >20 indicates P limitation Koerselman 1996, Gusewell 2004

• If species differ in growth efficiencies relative to different nutrients, could contribute to co-limitation

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C1 C2 C3 C4 C5 C6 C7 C8 C9 HBM HBO JBM JBO

0

5

10

15

20

25

30

35

40

45

Yellow BirchWhite BirchStriped MapleSugar MapleRed SpruceRed OakRed MaplePin CherryHemlockFirBeechAspen (BA+QA)AshBa

sal A

rea

for l

ive

tree

s in

2011

(m2/

ha)

Species composition in MELNHE stands

C6 C8 C90

5

10

15

20

25

30

BeechFo

liar N

:P

C6 C8 C90

5

10

15

20

25

30

35Yellow Birch

Folia

r N:P

C8 C90

2

4

6

8

10

12

14

16

18

20

Sugar Maple

Folia

r N:P

Foliar N:P by species in mid and old stands (different nutrient status)

Green- midRed- old

No specific pattern

12 14 16 18 20 22 24 260

0.00050.001

0.00150.002

0.00250.003

0.00350.004

0.00450.005

C8-1

C8-2

C8-3

C8-4

C9-1C9-2C9-3

C9-4

R² = 0.866440479337323

C8 & C9 Beech

N:P

Prod

uctiv

ity/

leaf

mas

s

0.6 0.8 1 1.2 1.4 1.6 1.80

0.00050.001

0.00150.002

0.00250.003

0.00350.004

0.00450.005

R² = 0.917267912422406

C8 & C9

BELinear (BE)SMYB

Foliar P concentration (mg/g leaf mass)

Prod

uctiv

ity/

leaf

mas

s

12 14 16 18 20 22 24 260

0.00050.001

0.00150.002

0.00250.003

0.00350.004

0.00450.005

C8-1

C8-2

C8-3

C8-4

C9-1C9-2C9-3

C9-4

R² = 0.866440479337323

C8 & C9 Beech

N:P

Prod

uctiv

ity/

leaf

mas

s

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.60

0.00050.001

0.00150.002

0.00250.003

0.00350.004

0.00450.005

C6-1

C6-2C6-3

C6-4 C8-1C8-2

C8-3

C8-4C9-1

C9-2 C9-3C9-4

R² = 0.632213661592773

C6, C8 & C9 Beech

Foliar P concentration (mg/g leaf mass)

Prod

uctiv

ity/

leaf

mas

s

I hypothesize that Beech is limited by P in the old stands.

14 16 18 20 22 24 26 28 300

0.001

0.002

0.003

0.004

0.005

0.006

0.007

C6-1C6-2

C6-3

C6-4

C8-3

C8-4

C9-1C9-2 C9-3C9-4

C6, C8 & C9 Yellow Birch

N:P

Prod

uctiv

ity/

leaf

mas

s

14 16 18 20 22 24 26 28 300

0.001

0.002

0.003

0.004

0.005

0.006

0.007

C6-1 C6-2

C6-3

C6-4

C8-3

C8-4

C9-1 C9-3C9-4

R² = 0.549499436928599

C6, C8 & C9

YBLinear (YB)

Foliar N concentration (mg/g leaf mass)

Prod

uctiv

ity/

leaf

mas

s

I hypothesize that Yellow Birch is limited by N in the old stands.

Conclusions

• Trends suggest Beech growth efficiency is limited by P, and Yellow Birch efficiency is limited by N

• Species specific traits may indicate co-limitation

• With the fertilizer treatments we are testing whether nutrient additions indicate co-limitation