5/10/2012 1

Boreal mixedwood forests: Linking early

performance of white spruce with future yield

Victor Lieffers, Zhili Feng and Ken Stadt

5/10/2012 2

Regulatory Instruments

Establishment and Performance Surveys

Stocking

Minimum Height

Free-to-grow assessment

Focus on 10 m2 plots

0

5/10/2012 3

Topics

Stocking

Mortality

Competition

FTG standards

5/10/2012 4

The Data

Stand Dynamics Systems – Juvenile PSPs

Mature mixedwood PSPs

Data from operational Establishment and

Performance Surveys

5/10/2012 5

Stocking

5/10/2012 6

Morisita Index of Dispersion

Regular Random Clumped

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MI ~ 0 MI > 10

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MI = 1

5/10/2012 7

0

0.2

0.4

0.6

0.8

1

1.2

0 4000 8000 12000 16000

Density (stem/ha)

Sto

ck

ing

(%

)

f itted MI = 0.2

fitted MI = 1.0

fitted MI = 4.0

fitted MI = 10.0

Real data

5/10/2012 8

MIaa

MI

DAaa

eS

43

2

1

)1(1

a1 = 1.7273,

a2 = 0.7608,

a3 = 1.0582,

a4 = 0.0353

n = 620,

P < 0.001,

R2 = 0.97,

RMSE = 0.070).

5/10/2012 9

Mortality of Spruce

5/10/2012 10

0.0

0.5

1.0

1.5

All planted Leading trees All planted Leading trees

At stand age 6-13 At stand age 13-23

An

nu

al m

ort

ality

ra

te (

% y

ear-1

)

sht ≤ -1.0

-1.0 < sht ≤ -0.5

-0.5 < sht ≤ 0

0 < sht ≤ 0.5

0.5 < sht ≤ 1.0

sht > 1.0

(n=2148) (n=1436) (n=1559) (n=934)

Juvenile stands

5/10/2012 11

0

2

4

6

8

10

0 1-2 3-5 >5

Neighbouring spruce density (stems/mil-ha)

An

nu

al m

ort

ality

rate

(%

yea

r-1)

sdbh ≤ -1.0

-1.0 < sdbh ≤ -0.5

-0.5 < sdbh ≤ 0

0 < sdbh ≤ 0.5

0.5 < sdbh ≤ 1.0

sdbh > 1.0

n =

49

17

n =

24

7

n =

19

09

n =

23

9

n =

22

4

n =

20

32

n =

33

6

n =

11

7

n =

21

6

n =

18

5n

= 1

53

n =

14

8

n =

19

5

n =

6

n =

7

n =

5

n =

11

n =

3

n =

2

Spruce Mortality in Mature Mixedwoods

5/10/2012 12

0

200

400

600

0 20 40 60 80 100

Stocking of merchantable trees (%)

Mer

cha

nta

ble

vo

lum

e (m

3/h

a)

SI 15

SI 5

SI 25

Mature PSPs

5/10/2012 13

4 3

2 ) 1 ( 1

a a stock a SI e a Volume

a1 = 49.4616

a2 = 5.6478

a3 = 1.1324

a4 = 0.7017

R2 = 0.5404

MSE = 66.34

5/10/2012 14

MI = 1.0

0

20

40

60

80

100S

tock

ing

(%

)

m=0.1%

m=0.7%

m=1.5%

m=3.0%20 40 60 80 100

Stand Age

5/10/2012 15

Conclusions

Stocking is defined by stem density and

spatial dispersion

Leading trees that were small or large had

no difference in mortality

Full volume of Sw can be attained by 30-

40% stocking at maturity

Mortality over the life of stand is uncertain

but very important

Free-to-Grow Standard

Competition index placed in regulation

5/10/2012 17 1, 1.5 or 1.78 m

Free-To-Grow Standard

2/3 height

A FTG tree is

usually big

5/10/2012 18

Trees designated FTG usually are

bigger and faster growing

5/10/2012 19

FTG crop trees

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40 45

Deciduous density (# tree/milha)

Wh

ite s

pru

ce

heig

ht

increm

en

t (c

m)

Not FTG crop trees

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40 45

Deciduous density (# tree/milha)

Wh

ite s

pru

ce

heig

ht

increm

en

t (c

m)

FTG (mixedwood standard - 49 stands)

FTG Not FTG

Mean = 27 cm Mean = 23 cm

5/10/2012 20

We must be careful if we include

the size of the subject in the

competition model.

5/10/2012 21

Why do big trees grow fast?

Low competition

Superior microsite

Superior genetics

Few insects/diseases

Superior mycorrhizae

5/10/2012 22

Free-to-Grow Criterion

Does not isolate effects of competition

from other factors affecting growth.

5/10/2012 23

How to judge a competition index

Competition Index

Tree

Growth

5/10/2012 24 1, 1.5 or 2 m

Asymmetric Competition

Light is intercepted up by the hardwood

Non- FTG

5/10/2012 25 1, 1.5 or 2 m

FTG Spruce

Large spruce has an advantage

over a small spruce

5/10/2012 26

Plot of height and height increment

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7

Height (m)

Heig

ht

incre

men

t (c

m)

5/10/2012 27

White spruce Ht increment vs. deciduous volume (per plot)

y = -4.3009x + 26.06

R 2 = 0.0108

0

20

40

60

80

0 0.5 1 1.5 2 2.5 3

Deciduous volume (m3/milha)

Wh

ite

sp

ruc

e

ht

inc

rem

en

t (c

m)

5/10/2012 28

Judging Asymmetric Competition

Unclear with large trees.

5/10/2012 29

Expected size frequency distribution when half of crop

trees are FTG

Big trees respond

because of lack

of competition

5/10/2012 30

Expect greater variation in the distributions of growth of

leading trees when 50% of plots FTG

5/10/2012 31

SW leading trees by conifer standard

0

10

20

30

40

50

60

70

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

FTG%

CV

of

Incr

emen

t (%

)49 stands, 12-13 years old, boreal mixedwoods

Height Increment

5/10/2012 32

Possible Implications

No shift in growth frequency distribution

with FTG

FTG standard is not a good measure of

competition

Need other theories to understand

asymmetric competition

5/10/2012 33

Why is this Important?

Silvicultural investments

Change in forest structure of mixedwoods

5/10/2012 34

Thank You

Supporters: Mixedwood Management Association

West Fraser & Weyerhaeuser

NCE-SFM

5/10/2012 35

Further Evidence

No detectable increase in mortality of

spruce (>8 yrs old) in stands with aspen

Very small loss in height growth of spruce

in aspen stands, once spruce is 1m tall.

Normal Size – Frequency distribution

Ht

Frequency

5/10/2012 37

CJFR 26:1002-1107

5/10/2012 38

Distribution with asymmetric competition

5/10/2012 39

Height normality analysis (leading tree)

0

2

4

6

8

10

- 3.6 - 3.2 - 2.8 - 2.4 - 2 - 1. 6 - 1.2 - 0.8 - 0.4 0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6

0

2

4

6

8

10

Standardized deviate of height

Fre

qu

ency

(%

)

Untended stands

76% stands are normal

CV = 45

Tended stands

88% stands are normal

CV=45

5/10/2012 40

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140

STAND AGE (YEARS)

LIG

HT

TR

AN

SM

ISS

ION

(%

)

2002, For Chronicle 78: 137-145

Light transmission in pure aspen stands of Alberta

5/10/2012 42

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Burn pile

Normal

20 year-old MOF plots

5/10/2012 46

Annual mortality:

SDS leading trees: 7 dead / 949, M=0.1%

SDS all planted trees: 52 dead/ 1585, M=0.4%

Duffy Plot underplant M = 0.7% after 5-42 yrs

PSP: M = 1% for the average (Yang 2002)

M = 2% for the worst case (Yang 2002)