Recognizing and Capitalizing on Site Resource

Pools That Accrete With Consecutive Intensive

Managed Rotations

Eric J. Jokela Professor of Silviculture and Forest Nutrition

School of Forest Resources & Conservation, University of Florida

Overview

Nutrient management as a component of

southern pine plantation Silviculture

What limits a site’s productive potential?

What are the growth impacts due to

fertilization?

Do treatment responses carry over to the next

rotation?

When visioning about the

future – it can be useful to

think about the past.

However, changes that occurred

in the past can not always predict

the future, but they can be useful

for defining the framework for

reaching the new objectives.

P added

Plantations - Intensive Management

Number of Acres of Southern

Pine Plantations in the U.S.

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

45,000,000

1952 1962 1970 1977 1985 1999 2010

USFS FIA Data

Background

• Soil nutrient supply broadly limits forest productivity throughout the southeastern U.S.

• Regional trials indicate that soil nutrient limitations can be mitigated using a variety of silvicultural techniques (e.g., site preparation, fertilizer additions and understory competition control).

• In contrast to the 1980’s, nutrient management is now practiced on a rotation-long basis.

Liebig’s Law of the Minimum

Resource Deficiencies

Multiple Deficiencies Often Limit Tree Growth

(N and P are Deficient on Most Soils in the South)

But Resource Availability

Will Still Limit Growth of Even the Best Genotypes

Genetics Determines the Potential Nutrient

Demand of the Tree

Poor Genotype Good Genotype

Tree Improvement

Families vary in their

response to management intensity

2000

2500

3000

3500

4000

4500

5000

5500

L H

Ste

m V

olu

me

(ft

3/a

c)

Culture

Loblolly PPINES, Age 12, Waverly, GA

L1L2L4L5L7L8

2000

2500

3000

3500

4000

4500

5000

5500

L H

Ste

m V

olu

me

(ft

3/a

c)

Culture

Loblolly PPINES, Age 12, Sanderson, FL

L1

L2

L4

L5

L7

L8

L6

Consistent

response

Interaction

Contribution of Silvicultural Practices to

Productivity Improvements and Rotation

Lengths in Managed Southern Pine Stands

0

2000

4000

6000

8000

1940 1950 1960 1970 1980 1990 2000 2010

Establishment Decade

Vo

lum

e a

t H

arv

es

t

(ft3

/ a

c)

0

10

20

30

40

50

60

Ro

tati

on

ag

e (

ye

ars

)

Natural Stand Planting Site Prep Fertilization

Weed Control Tree Improve Biotech/Clonal Rotation Age

Redrawn from: Fox, T.R., E.J. Jokela and H.L. Allen. 2007. The development of pine plantation

silviculture in the southern United States. J. Forestry 105:337-347.

Coordinating Treatments is Central

to Integrated Forest Management

***

LEVEL 1

***

Nutrient

ManagementGenetic

Deployment (growth, I, D)

Competition

Control

Density

Management

22

22

3

3

3 3

C

L

I

M

A

T

E

S

O

I

L

S

Soil Variability

Site Specific Silvicultural

Fertilization Prescriptions Based on Soils,

Geology, Genetics and Stand Conditions

Soil Map as a GIS Layer

CRIFF

Soil

Groups

A B C

D E F G

Organic Matter Content

Very Poorly

Drained Clay

With Shallow Bt

Poorly Drained

Sandy Clay Loam

with 4-6” Surface

Somewhat Poorly Drained

Sandy Clay Loam

with >20” Surface

Poorly Drained

Spodic with

Sandy Clay Loam

Nitrogen Availability

High

High

Low

Low

CRIFF A CRIFF A CRIFF B CRIFF C

P Deficiency – Slash pine in Florida on a

CRIFF A group soil

Tufted needles,

sparse crown

FERTILIZATION

Primarily N and P

Near Establishment

and at Mid-rotation

Early Nutrient Management Can Dramatically

Alter Stand Development and Productivity

CRIFF A – 13 yr-old Loblolly

Gulf Co, FL

No Fert or Weed Control

433 ft3/ac (30 m3/ha)

Fert + Weed Control

4212 ft3/ac (295 m3/ha )

Typical Fertilizer Application Rates

for Southern Pines

• Near Time of Planting: 35-50 lbs N/ac, 25-50

lbs P/ac (elemental rate)

– If K is needed (40-60 lbs/ac elemental)

– If B is needed (1 lb/ac elemental)

– If Cu is needed (3-5 lbs/ac elemental)

– If Mn is needed (10-20 lbs/ac elemental)

• Mid-Rotation (closed canopy)

– 175-200 lbs N/ac, 25-50 lbs P/ac

– Other nutrients (listed above, if necessary)

Loblolly Pine Mid-rotation Fertilization

8-Year Growth Responses

Growth

responses are

always greater

to N+P than

either element

alone.

Pinus elliottii

Age (years)

6 7 8 9 10 11 12 13 14

Mean A

ll-S

ided L

AI

(m2

m-2

)

0

2

4

6

8

10

12

Control

Herbicide

Fertilize

Fert+Herb

Soil Nutrient Supply Controls Leaf Area

Development and Growth

Martin and Jokela 2004

Estimate Leaf Area

From the Ground

Leaf Area Charts

Nutrient Supply

Controls Leaf Area

Development and

Fertilizer Response

LAI effects on Growth Response to Fertilizer

R2 = 0.48

0

10

20

30

40

50

60

70

80

90

0 1 2 3 4

LAI

Sta

nd

ard

ize

d r

es

po

ns

e

SR = ((Treatment Growth - Stand Average Growth) / std dev) x (cv + 100)

Rojas 2004

LAI Class

0 - 1.3

1.3 - 3.5

> 3.5

Estimated Stand Peak LAI

Differences in Loblolly Pine Site Index(25 yrs)

Among Treatments (IMPAC)

• Control: 64

• Weed Control: 74

• Fertilizer: 86

• Fertilizer + Weed 87

Jokela et al. 2010, J. For: 109:338-347Jokela et al. 2010, JOF

CONTROL FERTILIZER + WEED CONTROL

IMPAC Experiment – Age 19 yrs (Gainesville, FL)

Treatment = C

Diameter Class Midpoint (in)

4 6 8 10 12 14 16

Sta

nd

ing

Vo

lum

e

(ft3

ac

-1)

0

250

500

750

1000

1250

1500

1750Treatment = W

Diameter Class Midpoint (in)

4 6 8 10 12 14 16

Sta

nd

ing

Vo

lum

e

(ft3

ac

-1)

0

250

500

750

1000

1250

1500

1750

Treatment = F

Diameter Class Midpoint (in)

4 6 8 10 12 14 16

Sta

nd

ing

Vo

lum

e

(ft3

ac

-1)

0

250

500

750

1000

1250

1500

1750Treatment = FW

Diameter Class Midpoint (in)

4 6 8 10 12 14 16

Sta

nd

ing

Vo

lum

e

(ft3

ac

-1)

0

250

500

750

1000

1250

1500

1750

Pinus taeda

Pulp = 61%C/S = 30%Saw = 9%

Total Vol.=

2370 ft3 ac-1

Pulp = 26%C/S = 65%Saw = 9%

Total Vol.=

3980 ft3 ac-1

Pulp = 12%C/S = 62%Saw = 25%

Total Vol.=

4560 ft3 ac-1

Pulp = 14%C/S = 65%Saw = 21%

Total Vol.=

5250 ft3 ac-1

Volume Distribution - Age 25 Spodosols

Nutrient

management

increases stand

value by increasing

the % of “grade”

material produced.

< 39% Control

> 86% Fert. + Weed

What About Potassium and

Micronutrients?No Problem!

Problem!

Cu deficiency on wet Spodosol

Bunnell, FL loblolly pine

Can micronutrient deficiencies limit

production?

Sub-acute nutrient stresses can be induced by

intensive management.

B, Mn, Cu, Zn – micronutrients of concern

Slash pine response to Mn additions over 16 yrs

32 ft3/ac/yr above control

Source: Jokela et al. 1991. Soil Sci. Soc. Am. J.

Loblolly Pine Response to K and Micronutrient Fertilization

Carlson et al. 2014

A,AE E, Bh Bh, Bh2, E' Bt

0

1

2

3

4

510203040

Zn

Cu

Loblolly pine site

Co

ncen

trati

on

(p

pm

)

Co

ncen

trati

on

(p

pm

)

A E, A2,Bh Bh,E Btg, Bt1

0

1

2

3

4

510203040

Slash pine site

Taxonomically similar Spodosols, but with much

different levels of micronutrient supply.

Vogel and Jokela 2011. SSSAJ 75:1117-1124.

Location of K and Micronutrient Deficiencies on Pleistocene

Terraces in Georgia

The effects of micronutrients additions

can be long-lasting, however.

Mn levels

Pine Foliage

Control 48 ppm

MnSO4 199 ppm

Source: Jokela et al. 1991

after 16 yrs

Gallberry Foliage

54 ppm

264 ppm

Multi-Rotation Nutrient Management

• We are not managing first-rotation

stands anymore; prescriptions do change.

• Management in previous rotations

undoubtedly impacts conditions in this

rotation

Two year-old loblolly pine - Florida

ControlFert + Herb

Phosphorus

Stand Age (yrs)

1 2 3 4

P A

ccum

ulat

ion

(kg

ha-1

)

0

5

10

15

20

25

30

Nitrogen

Stand Age (yrs)

1 2 3 4N A

ccum

ulat

ion

(kg

ha-1

)

0

50

100

150

200

250

73

60

62

8

6

8

Rapidly growing

stands have high

nutrient

demands (total)

during the crown

development

phase.

Loblolly pine

Spodosols

Understanding and

Managing the

Understory Community

• Competitors vs. nutrient

cyclers

• Trading herbicide for

fertilizer may have

sustainability

implications (especially

on sandy soils)

– Forest floor C

– Soil C at depth

– Nutrient sink/source

Site Description and Experimental Design Near Gainesville, FL

• Two randomized complete block designs: actively managed retreated & untreated carryover

• Four treatments each :- C, F, FW, W (in retreated), and CC, CF, CFW, CW (in untreated)

• Soil: Poorly drained Pomona Fine Sand

Total aboveground loblolly pine biomass accumulation for second rotation loblolly pine stands growing at the IMPAC II study on Spodosols in north Florida. Error bars represent standard deviations.

Inter-rotational comparison of total aboveground biomass of

4-year old loblolly pine growing at the IMPAC studies

Aboveground biomass accumulation (pine and understory

vegetation) at age 2 years

A

B

B

a

A A

ab

b a

A A

a

A

B

B

b

a a

Actively managed

retreated

Untreated carryover

16% (Andropogan

sp.)

42% (Ilex

glabra)

23% (Serenoa repens)

89% (Andropogan sp.)

CF CFW

0

2000

4000

6000

8000

10000

12000

14000

16000

C F FW W

Ab

ove

gro

un

d b

iom

ass (

lb/a

c)

0

2000

4000

6000

8000

10000

12000

14000

16000

CC CF CFW CW

Ab

ove

gro

un

d b

iom

as (

lb/a

c)

Total nutrient accumulation in aboveground biomass of

pine and understory at age 2 years

Actively managed retreated plots Untreated carryover plots

a

bb

ab a

b

aa

a

b

a

a

0

20

40

60

80

100

120

140

160

180

C F FW W

N c

on

ten

t (l

b/a

c)

0

20

40

60

80

100

120

140

160

180

CC CF CFW CW

N c

on

ten

t (l

b/a

c

-1

1

3

5

7

9

11

13

15

CC CF CFW CW

P c

on

ten

t (l

b/a

c)

Understory Loblolly pine

a

bb

ab

ABA

C BC

AB A B B

A A A A

A A A A0

2

4

6

8

10

12

14

16

C F FW W

P c

on

ten

t (l

b/a

c)

Understory Loblolly pine

Total nutrient accumulation in aboveground biomass of

pine and understory at Age 2 years

Actively managed retreated plots Untreated carryover plots

a

b

aba

a

a

ba

a

ab

ba a

b

aa

0

0.5

1

1.5

2

2.5

3

C F FW W

Mn

con

ten

t (l

b/a

c)

0

0.5

1

1.5

2

2.5

3

CC CF CFW CW

Mn

con

ten

t (l

b/a

c)

0

0.5

1

1.5

2

C F FW W

Zn

con

ten

t (l

b/a

c)

Understory Loblolly pine

0

0.5

1

1.5

2

CC CF CFW CW

Zn

con

ten

t (l

b/a

c)

Understory Loblolly pine

A AA A

AB A C BC

A A AB

ABA BC

C

Soil P supply and aboveground pine

biomass in untreated carryover plots

0

5

10

15

20

25

30

0

2

4

6

8

10

12

14

16

18

20

CC CF CFW CW

Soil s

upply

rate

(mic

rogra

ms/1

0cm

2/8

w

ee

k) a

t 15

cm

de

pth

Ab

ove

gro

un

d p

ine

bio

ma

ss a

t a

ge

3

ye

ar

(Mg

/ha

)

Aboveground pine biomass Soil P supply rate

R² = 0.6875Ab

ove

gro

un

d p

ine

b

iom

ass

Soil P supply rate

Subedi et al. 2014

Harper et al. 2012

Potassium carryover dynamics and optimal application policies in cotton production

Agricultural Systems, Volume 106, Issue 1, 2012, 84 - 93

http://dx.doi.org/10.1016/j.agsy.2011.10.014

Nutrient Carryover Evidence in Agricultural Systems

-- Cotton (TN)

Effects of Fertilizer Treatments on

Stand Nutrient Pools at Age 25

N Pool (kg/ha)

Control OSP + NK GRP

Slash Pine

Biomass

112 234 150

Forest Floor 118 552 277

Understory 16 24 13

TOTAL 246 810 440

Harding and Jokela (1994)

Bioavailable

sources

remains on

site

Effects of Fertilizer Treatments on

Stand Nutrient Pools at Age 25

P Pool (kg/ha)

Control OSP + NK GRP

Slash Pine

Biomass

5.4 9.2 16.2

Forest Floor 4.8 19.2 12.3

Understory 0.7 1.2 0.9

TOTAL 10.9 29.6 29.4

Harding and Jokela (1994)

Bioavailable

sources

remains on

site

0

2

4

6

8

10

12

14

16

0

100

200

300

400

500

600

0 17.5 35 70 P C

on

ten

t in

Fore

st F

loo

r (k

g/h

a)

Sta

nd

Vo

lum

e (m

3/h

a)

P Fertilizer Application Rate (kg/ha)

P Fertilization Effects on Stand Volume and Forest Floor Nutrient Content (Age 29)

Residual

Bioavailable P

Carryover

Comerford et al. (2002)

The rapid recycling of nutrients through organic residues has

the potential to enhance long-term productivity beyond the

immediate benefits derived from fertilizer uptake.

Polglase et al. (1992)

Forest Floor/Understory Plants –

Nutrient Sink / Source

Conclusions• Rotation long nutrient management is beneficial for

optimizing southern pine growth potential on a variety of

forest sites;

• Documenting a site’s management (nutrient) history and

growth performance is essential.

• Early results suggest that loblolly pine is growing better in

the second rotation than the first rotation (ƒ – residual

nutrient (P) carryover, seedling genetics, site preparation,

atmospheric CO2 levels).

• Understory vegetation and the forest floor served as

important sink for P in the previous rotation, which

then subsequently became a nutrient source in the

second rotation.

• Understanding site nutrient carryover capacity

through long-term trials will aid optimal (biologic,

economic yields) fertilizer prescriptions.

Thank you.

Genotype x Environment

Increasing site resources

and/or reduction in stress

Incr

easi

ng

Cro

p Y

ield

Genotype D

Genotype A

Genotype B

Genotype C