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2010 Western Mensurationists Meeting
Response of crown and canopy structure to stand density regime in western
conifers
Doug Maguire Giustina Professor of Forest Management Director, Center for Intensive Planted-forest SilvicultureCollege of ForestryOregon State University
Topics
Crown and canopy structure of western conifers
Crown structure
Spacing effects on crown structure– Pringle Butte lodgepole-ponderosa pine
mixed species spacing trials– Lookout Mountain ponderosa pine-
grand fir mixed species spacing trials
Other silvicultural influences
Needs and directions
Topics
Crown and canopy structure of western conifers
Crown structureSpacing effects on crown structure– Pringle Butte lodgepole-ponderosa pine
mixed species spacing trials– Lookout Mountain ponderosa pine-
grand fir mixed species spacing trials
Other silvicultural influences
Needs and directions
Why crown structure ?
Crown and canopy structure of western conifers
Crown size drives growth and vigor
Why crown structure ?
Crown and canopy structure of western conifers
Crown size and its aggregate as canopy structure is key element in wildlife habitat (structural diversity) Crown area profile
height
Crown area
Why crown structure ?
Crown and canopy structure of western conifers
Crown size influences wood quality (branch size, crown wood core, microanatomy )?
Josza and Middleton 1994
Branch diameter
Crown wood core
Why crown structure ?
Crown and canopy structure of western conifers
Crowns ARE the tree-atmosphere interface (gas and heat exchange, light interception) z
y
x
wc
3.5 0
N o rth
uc
uc
vc
vc
L
L
h
Why crown structure ?
Crown and canopy structure of western conifers
Crowns represent potentially utilizable biomass (biofuel feedstock)
$
Why crown structure ?
Crown and canopy structure of western conifers
Crown structure influences fire behavior
Crown length?
Resolution of crown structure for differing objectives
What level of detail do we need for the purpose at hand?
(Crown ratio)
Crown length and
crown width?
Resolution of crown structure for differing objectives
Crown length and crown width and
biomass?
Resolution of crown structure for differing objectives
(leaf, branch, . . .)
First-order (primary) branches?
Resolution of crown structure for differing objectives
Branches of all orders with detailed spatial information?
Resolution of crown structure for differing objectives
Spatial structure of all branches and leaves, or all structural modules?
Resolution of crown structure for differing objectives
Resolution of crown structure for differing objectives
Resolution of crown structure for differing objectives
As with any model, the objective or question dictates the appropriate
level of detail
For given objective and level of detail, does silviculture influence crown structure?
Topics
Crown and canopy structure of western conifers
Crown structure
Spacing effects on crown structure–Pringle Butte lodgepole-ponderosa pine
mixed species spacing trials–Lookout Mountain ponderosa pine-
grand fir mixed species spacing trials
Other silvicultural influences
Needs and directions
Pringle Butte and Lookout Mountain mixed species spacing trials
Pringle Butte and Lookout Mountain mixed species spacing trials
6.5 miles
Lookout Mountain
Pringle Butte
Wickiup Reservoir
Crane Prairie Reservoir
La Pine
Pringle Butte ponderosa pine x lodgepole pine spacing trial
• Five initial spacings: 6, 9, 12, 15, 18 ft• Three species mixes:
• pure PP• pure LP • 50:50 mix PP/LP
• Planted in 1967• PP/bitterbrush/snowbrush/sedge plant association• Site index approximately 60 ft at 50 years• Elevation ~ 4600 ft• Annual precipitation ~24 inches
Pringle Butte ponderosa pine x lodgepole pine spacing trial
18 x 18 ft
6 x 6 ft
Lookout Mountain ponderosa pine x grand fir spacing trial
• Three initial spacings: 6, 12, 18 ft• Three species mixes:
• pure PP• pure GF • 50:50 mix PP/GF
• Planted in 1974• Mixed conifer/snowbrush/chinkapin plant association• Site index approximately 90 ft at 50 years• Elevation ~ 5100 ft• Annual precipitation ~39 inches
Lookout Mountain ponderosa pine x grand fir spacing trial
18 x 18 ft
6 x 6 ft
Mixed species spacing trials
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
Measurement schedule
Pringle Falls
Lookout Mountain
Mixed species spacing trialsGarber and Maguire 2004 Forest Science
Standing volume ~proportional to initial spacing
Mixed species spacing trials
Periodic annual increment starting to level out across spacings
15-20 yrs
20-25 yrs
25-34 yrs
Mixed species spacing trials
Interaction of spacing and species composition on relative height development.
LP
PP
PP
GF
Vs.
Mixed species spacing trials
Implications for canopy structure, ladder fuels, spatial variation in crown bulk density.
Intensive crown sampling
Sean Garber M.S. Thesis
Meticulous lab analysis of branches
Mixed species spacing trials
Relative amount of foliage
Shift in relative foliage and branch distribution among different initial spacings influence spatial pattern in crown bulk density
Pringle Butte ponderosa pine x lodgepole pine spacing trial
Pringle Butte ponderosa pine x lodgepole pine spacing trial
3 6 9 12 15 18 210
1
2
3
4
5
6
7
8
Foliage bulk density by spacing
lppureflpmixfpppurefppmixf
Spacing (ft)
Fo
lia
ge
bu
lk d
en
sit
y (
kg
/m3
)
Pringle Butte ponderosa pine x lodgepole pine spacing trial
LP
PP
3 6 9 12 15 18 210
2
4
6
8
10
12
14
16
18
20Branchwood bulk density by spacing
lppureblpmixbpppurebppmixb
Spacing (ft)
Bra
nc
hw
oo
d b
ulk
de
ns
ity
(k
g/m
3)
Pringle Butte ponderosa pine x lodgepole pine spacing trial
LP
PP
3 6 9 12 15 18 210
5
10
15
20
25
30Crown bulk density by spacing
lppureclpmixcpppurecppmixc
Spacing (ft)
Cro
wn
bu
lk d
en
sit
y (
kg
/m3
)Pringle Butte ponderosa pine x lodgepole pine spacing trial
LP
PP
Vs.
Spacing effects on crown recession
More rapid recession at closer spacings implies:- Loss of biomass- Accumulation of fuel
Plantation age (years)
0 20 40 60 80 100
Hei
ght
(m)
0
10
20
30
40
Res
idua
l tre
es h
a-1
0
500
1000
1500
2000
2500
3000
0
10
20
30
40
50
Sta
nd d
ens
ity in
dex
(tr
ees
ha-1
)
0
200
400
600
800
1000
Res
idua
l tre
es h
a-1
0
200
400
600
Sta
nd d
ens
ity in
dex
(tr
ees
ha-1
)
0
200
400
600
Ave
rage
dbh
(cm
)
0
10
20
30
40
50
Three initial spacings Three thinning intensities
1.8 m
3.7 m
5.5 m
Light
Moderate
Heavy
L
M
H
HML
1.8
1.8
3.7
3.7
5.5
5.5
Lookout Mountain
Pringle Butte
Total height
Height to crown base
0 20 40 60 80 100
Hei
ght
(m)
0
10
20
30
40
Total heightby spacing
Height to crown base by spacing
Ave
rage
dbh
(cm
)
5.53.71.8
1.83.75.5
Ponderosa pine simulations based on initial conditions at Pringle & Lookout
Three initial spacings grown out 100 years:
6-ft12-ft18-ft
Thinning at years 25, 50 and 75, and all grown out 100 years:
Residual SDI(% of max):
55%41%27%
TPH
SDI
DBH
HT
0 20 40 60 80 100
De
ad
bra
nch
dia
me
ter
(cm
)
0
10
20
30
40
50
Stand age (years)
0 20 40 60 80 100
Pe
rio
dic
an
nu
al b
ran
ch m
ort
alit
y
(no
ha-1
yr-1
)
0
5000
10000
15000
20000
25000P
eri
od
ic a
nn
ua
l bra
nch
mo
rta
lity
(kg
ha-1
yr-1
)
0
200
400
600
800
1000
1200
1400
1600
Lookout Mountain Pringle Butte1.8
3.7
5.5
1.8
1.8
1.8
1.8
3.73.7
3.7
3.7
3.7
1.8
5.55.5
5.55.5
5.5
Ponderosa pine simulations based on initial conditions at Pringle & Lookout
Number of branches
Branch necromass
Branch diameter
Stand age (years)
0 10 20 30 40 50 60 70 80
Bra
nch
mor
talit
y (M
g/ha
/yr)
0.0
0.5
1.0
1.5
2.0
2.5
6-ft
12-ft
18-ft
Annual branch mortality for ponderosa pine under different initial spacings
Spacing effects through:- Time to crown closure- Rate of height growth after closure
Plantation age (years)
0 20 40 60 80 100
Per
iodi
c an
nual
bra
nch
mor
talit
y
(kg
ha-1
yr-1
)
0
200
400
600
800
1000
1200
1400Lookout Mountain
Pringle Butte
6-ft
12-ft
18-ft
Annual branch mortality for ponderosa pine under different initial spacings
Site quality effect through rate of height growth rate of crown rise
Plantation age (years)
0 20 40 60 80 100
Bra
nch
mor
talit
y (k
g ha
-1yr
-1)
0
200
400
600
800
1000
Annual branch mortality for ponderosa pine under different thinning regimes
Thinning effect through temporary arrest of crown rise
0
100
200
300
0 20 40 60 80 100
Plantation age (years)
0 20 40 60 80 100
0
100
200
300
Cum
ula
tive n
ecr
om
ass
(M
g h
a-1)
Lookout Mountain Pringle Butte
5.5-m spacing
1.8-m spacing
5.5-m spacing
1.8-m spacing
Branch (suppression + tree mortality)Branch (suppression mortality)
Branch + bole mortality
Branch suppression mortality
Branches from tree mortality
Boles from tree mortality
Total cumulative necromass under different initial spacings (Mg/ha)
Cu
mula
tive n
ecr
om
ass
(M
g h
a-1)
0
20
40
60
80
100
120
140
Plantation age (years)
0 20 40 60 80 100
0
20
40
60
80
100
120
140
0 20 40 60 80 100
Branch (suppression + tree mortality)Branch (suppression mortality)
Branch + bole mortality
Lookout Mountain Pringle FallsLight thinning
Heavy thinning
Light thinning
Heavy thinning
Branch suppression mortality
Branches from tree mortality
Boles from tree mortality
Total cumulative necromass under different thinning regimes (Mg/ha)
Topics
Crown and canopy structure of western conifers
Crown structure
Spacing effects on crown structure– Pringle Butte lodgepole-ponderosa pine
mixed species spacing trials– Lookout Mountain ponderosa pine-
grand fir mixed species spacing trials
Other silvicultural influencesNeeds and directions
buds
Interwhorl branches
Few interwhorl branches surviving
Douglas-fir crown development from bud set through suppression mortality
Branch measurements by tree climbing
Branch measurements by destructive sampling
Diameter and height of individual Douglas-fir branches
Annual segments of main stem
Douglas-fir
(Maguire et al. 1994)
max branch size
number of branches
relative size of branches
relative position of branches
Reasonable fit to average distribution of branches
Mean of 142 annual stem segments
But how plastic is this distribution with respect to tree attributes affected by silvicultural treatments?
Simulate branch occurrence as inhomogeneous Poisson process
Changing Poisson mean, λ
Changing probability of bud set or branch initiation
Poisson regression with log link function (generalized linear model)
η = ln(λ) = β0 + β1X1 + β2X2 + . . . + βkXk
where λ = mean of Poisson distribution
Annual height growth
Live crown length
Long stem segment (rapid growth)
Response of interwhorl branches in Douglas-fir to thinning
more non-nodal buds
same number of nodal buds
control thinned
0 2 4 6 8 10 12 14 16 18 200.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Tree 703-878
SimulatedObserved
Branch diameter (mm)
He
igh
t (m
)
Simulation of primary branching structure, stochastic or otherwise
0
1
2
3
4
5
6
7
8
0 10 20 30
Branch diameter (mm)
Heigh
t (m)
Pinus contorta
Tsgua heterophylla
Pseudotsuga menziesii
Pinus ponderosa
Abies grandis
Larix laricina
Maximum branch diameter profiles
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 5 10 15 20 25 30 35
Branch diameter (mm)
Dept
h int
o cr
own
(m)
Tsuga heterophylla
Larix decidua x leptolepis
Pseudotsuga menziesii
Abies grandis
Pinus ponderosa
Pinus contorta
Number of primary branches per meter of stem
0
10
20
30
40
50
60
clonaltamarack
westernhemlock
grand fir Douglas-fir lodgepolepine
red spruce mesicponderosa
pine
dryponderosa
pine
Species
Bra
nche
s pe
r m
eter
Highest in clonal tamarack
Most variable in Douglas-fir (but largest sample size)
Topics
Crown and canopy structure of western conifers
Crown structure
Spacing effects on crown structure– Pringle Butte lodgepole-ponderosa pine
mixed species spacing trials– Lookout Mountain ponderosa pine-
grand fir mixed species spacing trials
Other silvicultural influences
Needs and directions
Driving forces
Needs and Directions
Improved G&Y models with dynamic link to determinants of stand productivity
Predicting response of forests to climate change
Estimating net primary production and sustainable level of biomass as energy feedstock
Designing fire resistant stands and landscapes
Specifics
Needs and Directions
Crown profiles to better characterize distribution of foliage and non-photosynthetic tissues, leaf area density, crown bulk density
Age class dynamics and implications for photosynthetic efficiency
Nutrient content with respect to sampling and requirements for optimal nutrition
Foliage sampling in CIPS fertilization trials
Thanks to Doug Mainwaring for assistance with many past and ongoing projects
Thank YOU for your kind attention !
0
1
2
3
4
5
6
7
8
0 10 20 30
Branch diameter (mm)
Heigh
t (m)
Western hemlock (Tsuga heterophylla)
less visible pattern in size and distribution
annual segments end in one large branch
western hemlock
0
1
2
3
4
5
6
0 10 20 30
Branch diameter (mm)
Height
(m)
Clonal tamarack (Larix laricina)
similar to Douglas-fir, although no distinct whorl
Lodgepole pine (Pinus contorta)
distinct whorls, but this species can have two cycles in some years (polycyclic)
ponderosa pine (Pinus ponderosa)
very consistent unicyclic whorl structure
relative uniformity in branch size within a whorl
Grand fir (Abies grandis)
structure generally similar to Douglas-fir, but whorl branches attached at almost exactly the same height (horizontal branch angles)
Simulate branch occurrence as inhomogeneous Poisson process
Increasing Poisson mean, λIncreasing probability of bud or branch set
Does stand density regime influence the
number of primary branches initiated along the stem?
Does stand density regime influence the
number of primary branches surviving along the stem?
Needle primordia within bud of Douglas-fir, set at end of growing season
(branches formed from axillary buds, but bud primordia not initiated until spring)
Axillary bud primordia (initiated ~ April 1):
Aborted
Latent
Vegetative
Seed cone
Pollen cone
vegetative
latentaborted
pollen cone
seed cone
bud primordia
Douglas-fir bud (Allen and Owen):
needle primordia
bud primordia
Percentage of axillary bud primordia that develops into various bud types in Douglas-fir
vegetative
latent
early aborted
seed cone
pollen cone
early aborted
latent
vegetative
buds 14.1 15.7 8.7 10.9 11.3 6.7
age 50 30 15 50 30 15
Allen and Owen
A - Extended bud of Douglas-fir
B - Extended bud with scales and some needles removed
Developing axillary bud
Does stand density regime influence the
number of bud primordia initiated or
surviving along the stem?
Apparently not known (?)
Does stand density regime influence the
number of primary branches initiated or
surviving along the stem?
Limited evidence does suggest that number of branches per length of stem does respond to growing conditions.
Response of precommercially thinned Douglas-fir relative to unthinned controls
non-nodal buds
nodal buds(Maguire 1983)
0
50
100
150
200
250
300
Terminal leadergrowth
Branch leader growth Terminal nodal buds Terminal non-nodalbud density
Lateral nodal buds Lateral non-nodalbud density
Attribute
Thi
nned
res
pons
e as
% o
f co
ntro
l density of non-nodal branches
Maguire 1983
Response of precommercially thinned Douglas-fir relative to unthinned controls
Response of precommercially thinned Douglas-fir relative to unthinned controls
more non-nodal buds
same number of nodal buds
control thinned
Lookout Mountain
Kelsey
Anomalies
Landscape canopy complexity and continuity
Anomalies
Kapur in Malaysia (Dryobalanops spp. )
Bulk density
Potential for simulating the process by which are buds set in a select few leaf axilsBranch position by height and azimuth
Particularly appealing for Pseudotsuga, Abies, Picea species that have interwhorl branches grading into whorl branches
Pont (2001) Use of phyllotaxis to predict arrangement and size of branches in Pinus radiata.