Date post: | 13-Jan-2016 |
Category: |
Documents |
Upload: | austin-hopkins |
View: | 215 times |
Download: | 2 times |
to understand growth responses to competition control treatments
USING ECOPHYSIOLOGY RESEARCH
Bill Parker – Ontario Forest Research Institute
and
Doug Pitt – Canadian Forest Service
Key ecological features of white pine and white spruce regeneration
• Intermediate in shade tolerance, slow initial growth
• Favoured by sheltered, moderate microenvironment
• Maximum height growth at 50% sunlight
• Maximum diameter and volume at 100% sunlight
• Weevil and blister rust damage to open grown white
pine seedlings
• Susceptibility of white spruce to spring frost damage
Seedling microclimate Seedling physiology
• May – October
• Light (PFD), Ta, RH
• Soil moisture (SMC), Ts
• Periodic assessment
• Net photosynthesis (Pn), etc.
• Relative growth rates
White pine restoration and shelterwood sites (ON)
1. Treatments: none (C), herbaceous only (H), woody only (W), and both (B)
2. Microclimate – growing seasons 1- 4
3. Seedling physiology – growing seasons 2- 4
Soil moisture availability differs with treatment over time
Day of year
140 160 180 200 220 240 260 280
SMC
(%)
6
8
10
12
14
16
18
20
22
24
26
CHWB
Day of year
140 160 180 200 220 240 260 280
SMC
(%
)
6
8
10
12
14
16
18
20
22
24
26
May June July August September May June July August September
Growing season 1 Growing season 4
Restoration site
Light availability differs with treatment over time
Years of treatment
1 2 3 4
Lig
ht
(%)
0
20
40
60
80
100
CHWB
Restoration site
Maximumheight
Treatments affect photosynthesis through light and SMC
Light (PFD: umol m-2 s-1)
0 400 800 1200 1600 2000
Pn (u
mol
CO
2 m
-2 s
-1)
0
2
4
6
8
10
12
CHWB
SMC (%)
10 12 14 16 18
Pn (u
mol
CO
2 m
-2 s
-1)
0
2
4
6
8
10
12
r = 0.77, p < 0.0001 r = 0.50, p < 0.002
Restoration site
Light (%)
0 20 40 60 80 100
RVR
0
30
60
90
120
150
180
CHWB
Soil heat sum
1000 1050 1100 1150 1200 1250
RH
R
1
2
3
4
5
6Restoration site
r = 0.88, p < 0.001 r = 0.67, p < 0.002
Growth driven by treatment effects on light and soil warming
In shelterwoods, less treatment influence on soil moisture…
Day of year
120 140 160 180 200 220 240 260 280
SMC
(%)
6
8
10
12
14
16
18
20
22
24
26
Day of year
140 160 180 200 220 240 260 280
SMC
(%)
8
10
12
14
16
18
20
22
24
26
28
CHWB
May June July August September May June July August September
Growing season 1 Growing season 4
Shelterwood
…and light due to the dominant effect of overstory on microclimate / resources
Years of treatment
1 2 3 4
Lig
ht
(%)
0
20
40
60
80CHWB
ShelterwoodMaximumheight
Treatments affect photosynthesis through light and SMC
Light (PFD: umol m-2 s-1)
0 200 400 600 800
Pn (u
mol
CO
2 m
-2 s
-1)
1
2
3
4
5
6
7
8
CHWB
SMC (%)
10 12 14 16 18 20
Pn (u
mol
CO
2 m
-2 s
-1)
1
2
3
4
5
6
7
8r = 0.63, p < 0.001 r = 0.59, p < 0.001
Shelterwood
Light (%)
25 30 35 40 45 50
RHR
1
2
3
4
5
6
Light (%)
25 30 35 40 45 50
RVR
0
20
40
60
80
100
120
140
CHWB
Shelterwood
r = 0.91, p < 0.0001 r = 0.85, p < 0.001
Growth driven by treatment effects on light
Boreal mixedwood site (ON)
1. Treatments: none (C), herbaceous only (H), woody and herbaceous (B), radial woody only (RW), radial both (RB)
2. Microclimate – growing seasons 1- 4
3. Seedling physiology – growing seasons 3 - 4
Treatments have little effect on soil moisture availability
Day of year
140 160 180 200 220 240 260 280 300
SM
C (
%)
25
30
35
40
45
50
55
60
CHBRBRW
Growing season 4
May June July August September
Boreal mixedwood
Radial and broadcast woody control increase light levels
Year of treatment
1 2 3 4
Lig
ht
(%)
0
20
40
60
80
100
CHBRBRW
Maximumheight
Boreal mixedwood
Treatments have little effect on photosynthesis
Years of treatment
3 4
Pn
(u
mo
l C
O 2 m
-2 s
-1)
0
1
2
3
4
5
6
7C H B RB RW
A
B
ABABAB
NS
Boreal mixedwood
Light and humidity interact to regulate photosynthesis
Light (PFD: umol m-2 s-1)
0 500 1000 1500 2000
Pn (u
mol
CO
2 m
-2 s
-1)
0
2
4
6
8
10CHBRBRW
VPD (kPa)
0 1 2 3 4 5 6
Pn (u
mol
CO
2 m
-2 s
-1)
0
2
4
6
8
10Boreal mixedwood
r = -0.31, p < 0.00250% light
Leaf gas exchange of white spruce is sensitive to humidity
VPD (kPa)
0 1 2 3 4 5 6
Gw
v (
mm
ol H 2O
m-2
s-1
)
0
20
40
60
80
100
120
140
160
CHBRBRW
r = -0.54, p < 0.001
Boreal mixedwood
This response improves WUE in open environments
Light (PFD: umol m-2 s-1)
0 500 1000 1500 2000
WU
E (
um
ol C
O 2 m
ol H 2
O-1
)
0
10
20
30
40
50
60
70
80CHBRBRW
r = 0.40, p < 0.001
Boreal mixedwood
Do competition control treatments influence spring frost damage?
Damage is dependent on:
1. Minimum air temperature
2. Light levels after frost event
Lower temperature and higher light increase frost damage
Time
0 100 200 300 400 500 600 700
Ta (
oC)
-8
-6
-4
-2
0
2 C
H B RB RW
Time
900 1100 1300 1500 1700
Ligh
t (um
ol m
-2 s
-1)
0
400
800
1200
1600
2000June 6, 2007
Herbaceous layer presentWoody layer present
Boreal mixedwood
White pine in clearcuts:
• Competition for light and H2O
with herbaceous and woody
vegetation
White pine in shelterwoods:
• Competition for light is most
important
Boreal mixedwood:
• Sheltered environment assists
white spruce regeneration
Thanks to all for their support!!
Conclusions