Adaptive silvicultural systems to maintain biodiversity and ...

ADAPTIVE SILVICULTURAL
SYSTEMS TO MAINTAIN
BIODIVERSITY AND
PRODUCTION
Victor Lieffers
Dept. of Renewable Resources
University of Alberta
Canada

Boreal forest of Western Canada

Objectives:
Examine light in boreal mixedwood forests
– ‘light bottle neck’.
Importance of forestry regulations
Variable Retention and its interaction with
silvicultural practices.

sunflecks
Light gap

Calamagrostis in deep shade
Calamagrostis in a clearcut

1.2
Calamagrostiscanadensis
1.0
20
Frequency
0.8
0.6
15
10
Cover(%)
0.4
0.2
5
0.0
0
0 10 20 30 40 50
Lightransmitance(%)

Light Bottleneck
Light over the course of stand development

LIGHT TRANSMISSION (%)
100
90
80
Boreal Aspen Stands
70
60
50
40
30
20
10
0
0 20 40 60 80 100 120 140
STAND AGE (YEARS)
9/15/2011 9

Crown Placement in short (juvenile) and tall (mature) stands
juvenile
mature

Max Crown Overlap = 0.697 – (0.02 * D30)
n=60
Crown overlap declines as trees become larger

8 m tall pine stand, 22 years old

20 m tall pine stand, 80+ years old
crown shyness is the empty space between crowns

Crown shyness & Tree biomechanics
Friction

100
92 Lodgepole pine stands.
90
Stand Canopy Closure (%)
80
70
60
50
40
r 2 = 0.482
30
20
4 6 8 10 12 14 16 18 20 22
Stand Height (m)

40 % crown closure
(slender and 15 m)
.

Some managed stands deepen
the ‘light bottleneck’
Full stocking of shade tolerant species

Sitka spruce plantation

Norway Spruce
Loss of understory vegetation
9/15/2011 22

Some practices weaken the bottleneck
Pine stands in Sweden

Rich understory of ericaceous shrubs and mosses

Silvicultural Regulations
Large impact on forest structure
and biodiversity
Often developed independently of
other management goals

Free-To-Grow Standard
(Competition index placed into regulation)
< Height of the
conifer
9/15/2011 1.78 m
29

This spruce tree fails the conifer FTG standard
9/15/2011 30

Herbicides t meet Free-to-grow
9/15/2011 33

Success leads to monocultures
9/15/2011 35

Tended spruce plantation – extreme light bottleneck coming soon

Silviculture Regulations
Uniformity of forests
Lowers stand and landscape biodiversity
High costs

Variable Retention
Biodiversity
Coarse wood material
Life boating species (green trees)

Landscape cuts – up to 500 Ha

Partial removal of aspen to protect understory spruce

Understory protection

Started 1998
~7000 Ha
Diff. levels of retention:
(1, 10, 20, 50 and 75%)
Diff stand types:
Conifer, mixed decid.
3 replicates of each.

One cutting cell

Coarse woody debris

Coarse woody material
Needed for beetles,
mosses,
snails, slugs

Tree Survival
How long do the green trees live

50
Aspen 5 years
67/20/15
53/13/12 A
A
Aspen 10 years
40
30
53/14/2
A 67/16/2
A
79/13/8
B
Standing Dead
Fallen Dead
Death:
Cumulative Mortality (%)
20
10
0
50
40
79/8/3
B
110/6/1
B
Spruce 5 years
262/24/2
B
Spruce 10 years
110/11/10 262/35/17
B B
Big trees
Small live
crowns
30
20
85/7/11
A
58/4/5
AB
85/10/15
58/5/11 A
A
121/5/15
B
10
0
155/3/7
121/5/3
270/9/2
BC 155/3/1
C
270/4/1
C
CD
D
10 20 50 75 100 10 20 50 75 100
Retention Intensity (%)

Spruce tends to blow down

Expect continued elevated mortality.

Aspen regeneration

Aspen regeneration at 8 years

Spruce Regeneration

Compartment 932
Block H
Seed Trees
Red lines are transects
Evaluated

% Stocking
100
80
60
40
20
D XX CC UC
C C
C C
CD
XX
CX
U C
UCU
X
CUUU
UX
X C
DX
CU
U
UC
U UX
U
DXX
D X
DU
XX
C
X
Clear Cut
D
C
X
U
Chapman - Richards Curve
Deciduous
Conifer
Mixedwood
Deciduous Dominated - Conifer understory
Stocking on
each transect
0
D D X
100
C
C
C C C
10%
D X
C
C
20%
80
X
UU
UC
X
X XUX
X
C
U
C
U U
X C C X
U X XXX
CX
C
C
% Stocking
60
40
20
D X UC
X
U C UX
C
D DU
X C
X C UD
U
D
U
UC
X
U
X
DD CU
UU U C
D U CUX
X X
DD C
U
X U
D
U UX
U
D
CC
U D
C XX
C
X
X
C
0
DD
DX XCC
U
D
CC U
100
D
C
50%
75%
80
D
U
U
D
U
UC
C
CX
X
C
U
U
X
X
% Stocking
60
40
20
X
D D
D
X
D XU
DDD
DU
C
UU
U
D U C
X
U X
U
C X
XC
C
C
X
C
CX
C
X
X
C
DC
C
D
DU
DX
D DU
C
D
UD
U X X
DU
DUUU
D C
DU
C X D
X
C X
X X
X
C
X C
XXC
C C
C C C
0
DD DX
X
UC
DU UD
C
X
X
X
0 50 100 150 200 250 300
Seed Trees ha -1
0 50 100 150 200 250 300
Seed Trees ha -1

Best reg.
Trails
Clearcuts.

Linking Silviculture to
Biodiversity
Longterm effects of manipulating
stocking
Silvicultural regulations are critical
Variable Retention

Thank you
Canfor, DMI, NCEsfm, NSERC
(EMEND core crew, CFS, Summer Students)
John Spence, Jan Volney Kevin Solaik, Simon
Landhausser, Ken Stadt, Heather Fish.
J
Can. J. For. Res. 40: 1821–1832
For. Ecol. Manage. 259: 383-389
For. Ecol. Manage. 255: 3744-3749
J. Appl. Ecol. Submitted

Thank you