Transcript Disease and Insect Effects on Ecosystem Processes

Disease and Insect Effects
on Ecosystem Processes
in the context of Climate Change
Christa Mulder
UAF
Conceptual Overview
Δ competition
or facilitation
Herbivores
and
Pathogens
Community
composition
Plant
populations
(mortality,
growth rates) Dominant or
keystone
Climate Change
Ecosystem
Processes
OUTBREAK SPECIES
Herbivores
and
Pathogens
Community
composition
Plant
populations
(mortality,
growth rates)
Dominant or
keystone
NON-OUTBREAK SPECIES
Δ competition
or facilitation
Herbivores
and
Pathogens
Plant
populations
(mortality,
growth rates)
Ecosystem
Processes
Community
composition
Δ abundance
dominant or
keystone
Ecosystem
Processes
Overview
Outbreak species:
1) Alder (Alnus tenuifolia) and canker
2) Spruce and spruce budworm
3) Aspen and leafminer
Non-outbreak species: parasite communities
on…
1) Alder (Alnus viridis)
2) Cranberry (Vaccinium vitis-idaea)
3) Rose (Rosa acicularis)
2005 Canker (Valsa melanodiscus) Survey on A. tenuifolia
(Roger Ruess and colleagues)
Quartz Creek - Kenai Region
Alder Shrub - Tanana River
100
100
40
500
20
0
3000
Live without canker
Live with canker
Dead from canker
Other dead
2000
1000
20
2
3
4
5
6
7
8
9
0
10
0
0
1
2
DBH Diameter Class (cm)
3
4
5
6
7
DBH Diameter Class (cm)
Alder Shrub - Eagle River Anchorage Basin
100
80
3000
Live without canker
Live with canker
Dead from canker
Other dead
2000
60
719 stems / 3 plots
40
1000
20
0
0
0
1
2
3
4
5
6
7
DBH Diameter Class (cm)
8
9
10
Proportion Infected or Dead (%)
1
1745 stems / 3, 18X18 m plot
40
0
0
60
8
9
10
Proportion Infected or Dead (%)
60
719 stems / 3 plots
Density (stems ha-1)
Density (stems ha-1)
Live without canker
Live with canker
Dead from canker
Other dead
1000
80
Density (stems ha-1)
80
1500
Proportion Infected or Dead (%)
4000
100
Eagle River
Quartz Creek
Tanana
80
60
Y = 1.3897 + 0.7187*X
r2 = 0.67, P<0.0001
40
20
0
0
20
40
60
80
Proportion of Basal Area Dead from Canker (%)
100
Proportion of Total Nodule Biomass Live (% tree-1)
Proportion of Leaf Area Dead from Canker (%)
Effects of canker on whole-stand N inputs are driven by declines in nodule
biomass associated with ramet mortality
Eagle River
Quartz Creek
Tanana
100
80
60
40
Y = 96.08 - 0.76 X
20
r2 = 0.63, P < 0.0001
0
10
30
50
70
90
Proportion of Canopy Dead from Canker (% tree-1)
a
13
a
11
9
b
7
5
Eagle River
Quartz Creek
Tanana
Proportion Basal Area or Leaf Area Dead From Canker (%)
N Fixation Rate (mol N g noduleDWT-1 hr-1)
Also appears to be an effect of canker infection on N fixation rate (at the nodule
level)
a
25
% Basal Area Dead
% Leaf Area Dead
20
A
a
A
15
10
b
B
5
0
Eagle River
Quartz Creek
Tanana
An inoculation experiment with Alnus viridis (green alder) and Valsa melanodiscus:
Susceptibility to infection and the physiological effects of disease development
(Jenny Rohrs-Richey)
1) Investigate the susceptibility of green alders (Alnus
viridis ssp. fruticosa, synonym =A. crispa) to infection
by Valsa melanodiscus under water stress.
2) Monitor the response of the water transport system to
infection and colonization.
3) Determine if alders respond to disease by adjusting
water use efficiency.
4) Measure the effect of disease development on
photosynthesis (light saturation pt., quantum
efficiency).
Greenhouse Experiment
June 1
Aug 23
Two Weeks After Inoculation
Necrotic lesion
Pycnidia
Water Availability and Disease Incidence
35
30
25
Infected
Alders
20
Well watered
Water limited
15
10
5
0
Trial I
Trial II
Well-watered plants are less likely to become infected than water-limited plants
(early in the growth season)
Light Curves for Well Watered Alders
Photosynthesis
(μmol CO2m-2s-1)
12
10
8
6
NONINFECTED
4
INFECTED
2
0
0
25
50
100 250 500 750 1000 1500 2000 2500
Irradiance(μmol m-2s-1)
Photosynthesis
(μmol CO2m-2s-1)
Non-infected plants fix
more carbon than infected
plants… but only if they
are well-watered.
Light Curves for Water Limited Alders
8
7
6
5
4
3
2
1
0
NONINFECTED
INFECTED
0
25
50 100 250 500 750 1000 1500 2000 2500
Irradiance(μmol m-2s-1)
Stomatal Regulation of Photosynthesis
Well Watered
Photosynthesis
(μmol CO2m-2s-1)
12
10
8
6
NONINFECTED
4
INFECTED
2
0
0
0.05
0.1
0.15
0.2
Conductance (mol H2 Om-2s-1)
Photosynthesis
(μmol CO2m-2s-1)
Water Limited
9
8
7
6
5
4
3
2
1
0
0.03
INFECTED
NONINFECTED
0.04
0.05
0.06
0.07
0.08
Conductance (mol H2 Om-2s-1)
0.09
0.1
Water Use Efficiency
(μmol CO2 m-2s-1(μmol H20 m-2s-1))
Infected Alders Adjust WUE
14
12
10
Well watered
NONINFECTE
D
8
6
Water limited
INFECTED
4
2
0
25
50
100
250
500
750 1000 1500 2000 2500
Irradiance (μmol m-2s-1)
Spruce bud-worm on white spruce
(Picea glauca)
Glenn Juday and colleagues
Date of spruce budworm heat requirement at Fairbanks
Deg. C
Threshold = 8.0
GDD =
243
1905
158
1915
1925
moth @437.4
Linear (moth @437.4)
year
1935
1945
1955
1953?
1965
1975
1985
1995
1975?
163
Julian date
168
173
178
183
188
193
198
1988 1993
1990 1995
2004
2005
heat/drought
limitation
2005
spruce budworm
damage
1995
1993
BARK
2006
2004
2003
2002
2001
2000
1999
1998
1997
1996
1992
1991
1990
Fairbanks Summer Temperature and W. Spruce Growth
(BNZ LTER - 2PLS; 1902:2007; n = 2 trees)
3-yr weighted May:Aug Temperature
11.0
1.1
11.5
1.0
0.8
12.5
0.7
13.0
0.6
13.5
0.5
0.4
14.0
0.3
14.5
0.2
15.0
0.1
15.5
0.0
1907 1917 1927 1937 1947 1957 1967 1977 1987 1997 2007
y ear
mean ring-width (mm)
0.9
12.0
May:Aug T (deg. C)
mean tree 5&8
Summer temperature vs. w. spruce growth
(Bonanza Creek LTER -2 Parks Loop South; 1906-2006; n = 12 trees)
mean sample ring width (mm)
1.2
r2 = 0.32
1.0
0.8
0.6
1912 volcanic
ash?
0.4
2004 record hot
KILL ZONE
0.2
1993 & 95 spruce budworm defoliation
0.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
previous May:Aug T (deg C)
17.0
18.0
19.0
20.0
Aspen leaf miner moth(Phyllocnistis populiella)
(Diane Wagner, Pat Doak, Linda DeFoliart, Jenny
Schneiderheinze)

Univoltine

Adults emerge in May
before leaf-out, mate

Lay eggs on both sides of
new leaves

Eggs digest cuticle, sink
into leaf
Aspen leaf miner moth
(Phyllocnistis populiella)

Larvae restricted to one
side of leaf

cannot switch sides

cannot exit and reenter

Consume epidermal cells as
move during instars I – III

Separation of cuticle from
mesophyll causes white
appearance of mines
300
250
200
150
100
50
0
19
74
19
77
19
80
19
83
19
86
19
89
19
92
19
95
19
98
20
01
20
04
20
07
AK area infested (ha*1000)
Aspen leaf miner infestation
of Alaskan forests
R. Werner, US Forest Service flyovers
Aspen leaf miner infestation
of Bonanza Creek LTER
250
200
Aspen leaf miner
Tortrix
150
100
50
0
19
75
19
77
19
79
19
81
19
83
19
85
19
87
19
89
19
91
19
93
19
95
19
97
19
99
20
01
20
03
20
05
20
07
Aspen leaf miners
(N per m2 foliage)
300
Year
R. Werner, www.lter.uaf.edu and pers. comm.
Bottom mining reduces photosynthesis
(µmol CO2 m-2 s-1)
Net photosynthesis
25
20
15
10
5
0
0
20
40
60
80
100
% Mining on leaf bottom
L. Defoliart, Wagner et al. in review
Bottom mining reduces photosynthesis
a
8
(µmol CO2 m-2s-1)
Net Photosynthesis
10
a
6
4
b
2
0
Neither
Top
Bottom
Surface mined
J. Schneiderheinze, Wagner et al. in review
Bottom mining disrupts stomatal function
-26
0.10
-27
a
(mol m-2s-1)
Conductance
0.06
b
0.04
Leaf 13C
a
0.08
-28
-29
-30
-31
0.02
-32
-33
0.00
Neither
Top
Bottom
Surface mined
0
20
40
60
80
100
% Bottom mining
Wagner, Defoliart, Doak, Schneiderheinze in review
Top mining affects water balance
65
% Leaf H2O
60
55
50
45
40
0
20
40
60
% Leaf top mined
80
100
Date of leaf abscission
Leaf mining leads to early leaf abscission
16-Oct
15
30
5
1-Oct
5
16-Sep
45
1-Sep
16-Aug
0
1-25 26-50 51-75 76-100
Percent leaf mining damage
Data: L. Defoliart
Diameter change (mm)
Mining reduces aspen growth
BNZ
1.0
ED
0.8
0.6
0.4
0.2
0.0
2005 2006 2007
2005 2006 2007
Year
Control
Sprayed
Wagner, Defoliart, Doak, Schneiderheinze in review.
Summary
1)
Outbreak pathogen (canker) on a keystone shrub
species (alder):
•
•
•
2)
Outbreak herbivore on a dominant tree white spruce
greatly reduces growth (C fixation)
•
3)
reduces fixation rates of nodules on infected trees
reduces carbon fixation rates via reduced stomatal
conductance
climate change: reduced water availability may increase
susceptibility to this disease
Combined with increased temperature could result in massive
die-offs
Outbreak herbivore reduces photosynthetic rates (C
fixation) and stomatal conductance in a dominant tree
species (trembling aspen)
Non-outbreak species on leaves
(Christa Mulder & Bitty Roy)
Alnus viridis (alder):
13 herbivores
9 pathogens
Rosa acicularis (rose):
11 herbivores
13 pathogens
Vaccinium vitis-idaea
(cranberry):
5 herbivores
7 pathogens
-1
2002
-3
2003
2004
2005
ay
ju
ne
ju
ly
au
g
6
temperature
5
100
4
80
3
60
2
40
1
20
0
0
-2
2006
-20
-40
-60
difference from longterm mean
precipitation (mm)
A
m
ay
ju
ne
ju
ly
au
g
m
ay
ju
ne
ju
ly
au
g
m
ay
ju
ne
ju
ly
au
g
m
ay
ju
ne
ju
ly
au
g
m
difference from long-term mean temp (C)
Summer temperature and precipitation,
2002-2006
120
precipitation
Winter temperature and snow depths,
2002-2006
-300
B
temperature
snow depth
8
-250
6
-200
-150
4
-100
2
-50
b
fe
de
c
oc
t
ap
r
b
fe
de
c
oc
t
ap
r
b
fe
de
c
oc
t
ap
r
b
fe
de
c
oc
t
ap
r
b
fe
-2
de
c
0
0
50
-4
100
-6
150
-8
2001-2002
2002-2003
2003-2004
2004-2005
2005-2006
difference from longterm mean snowdepth in mm
difference from longterm mean temp in degrees C
oc
t
10
Total damage patterns 2002-2006
A
ALNUS
10
other
pathogen
herbivore
20
a
15
a
a
10
E
VACCINIUM
b
a
5
8
7
6
5
4
ab
a
a
bd
d
2002
a
ab
1
2003
2004
2005
2006
a
bc
bc
0
2002
C
ROSA
other
pathogen
herbivore
14
% of leaf area damage
b
ab
c
0
16
ab
3
2
c
other
pathogen
herbivore
9
% of leaf area damage
% of leaf area damaged
25
12
10
a
8
ab
6
ab
b
4
2
a
b
b
a
0
2002
2003
2004
2005
2006
2003
2004
2005
2006
•Fairly constant total biological damage
•Relative contribution of herbivores vs.
pathogens varies
Herbivory patterns by feeding mode
B
3
ALNUS
b
14
12
b
10
a
a
a
leafroll
mining
sucking
chewing
a
a
8
b
6
b
a
a
4
a
a
a
a
2
a
a
b
a
Percent of leaf area damaged
Percent of leaf area damaged
16
F
2.5
2
1.5
1
0.5
a
0
2003
2004
2005
2006
Percent of leaf area damaged
D
mining
sucking
chewing
ROSA
7
6
a
5
b
4
a
3
a
a
2
b
b
b
1
0
2002
2003
2004
2005
2006
bc
c
bc
0
2002
8
a
ab
2002
mining
sucking
chewing
VACCINIUM
2003
2004
2005
2006
•Fairly low damage in record hot year for all
three species
•Lowest sucking damage in record hot year
for all three species
•Highly variable relative contributions by
different guilds
Impacts of herbivores and
pathogens on reproduction in alder
2.5
Log10 (mean # catkins per branch)
A
female catkins
male catkins
2
1.5
1
0.5
2.5
C
0
5
10
15
20
25
30
Herbivore damage (mean % leaf area per tree)
Herbivore damage is
negatively related to catkin
production
Pathogen damage is positively
related to catkin production
35
female catkins
male catkins
40
Log10 (mean # catkins per branch)
0
2
1.5
1
0.5
0
-1
5
10
15
Pathogen damage (mean % leaf area per tree)
20
Woolly alder sawfly, Eriocampa ovata
Nitrogen Fixation Rate (mol N g-1 hr-1)
160
a
140
b
120
b
100
80
60
c
40
0
15
25
40
Defoliation (%)
Ruess, R. W., M. D. Anderson, J. S. Mitchell, and J. W. McFarland. 2006. Effects of defoliation on growth and
N2-fixation in Alnus tenuifolia: Consequences for changing disturbance regimes at high latitudes. Ecoscience
13:402-412.
Mortality in cranberry
• Cranberry ramet mortality rates
are high (15-75% over the
course of 4-5 years, or 3-15%
per year)
• Winter-warm sites had higher
rates of mortality and high
rates of “red-brown dieback”
• Cause and effect are unclear
– Could be physical damage
– Could be a disease attacking
already dying leaves
– Could be caused by a disease
Climate change and herbivores /
pathogens: Alder
Warmer, drier summer conditions may favour pathogens…
• Higher pathogen levels in warmer years, and at warmer sites
in 2004 (record hot dry year)
• BUT: sucking insects were lower at warm sites or in warm
years
• Cold winters may favour herbivores:higher damage
following winters with higher minimum temperatures
Climate change and herbivores /
pathogens: cranberry and rose
Cranberry:
• Sucking and mining damage were
greater at sites with warmer winter
temperatures (in 2004) and in
warmer years
Rose:
• Between years, total herbivore
damage and sucking damage were
lower when summer temperatures
were higher
Summary
• TOTAL damage levels are fairly constant across
years for all three species
• COMPOSITION of the parasite communities
varies greatly between years
• Relationships with environmental characteristics
depend on the feeding mode
• For alder, these damage levels may be high
enough to substantially reduce N fixation rates
• Cranberry ramet mortality rates are high… but
cause is unclear.
OUTBREAK SPECIES
Community
composition
?
Herbivores
and
Pathogens
Plant
populations
(mortality,
growth rates)
?
Ecosystem
Processes
Dominant or N fixation,
C fixation,
keystone
transpiration
NON-OUTBREAK SPECIES
Δ competition
or facilitation
Herbivores
and
Pathogens
Plant
populations
(mortality,
growth rates)
Community
composition
Δ abundance
dominant or
keystone
Ecosystem
Processes
Gaps
• Are the outbreak species fundamentally different from
non-outbreak species, or can many of the numerous
non-outbreak species become outbreak species with
major impacts?
• Loss of dominant species will change species
composition… how will that affect ecosystem processes?
• Non-outbreak species:
– How does low-level (<20%) damage affect photosynthesis, water
balance, N fixation?
– how do they affect community dynamics (composition)? How in
turn does this affect ecosystem processes?
Links to thresholds and regime
changes
• Spruce bud-worm: may reduce the
temperatures at which massive tree die-offs
occur
• Alder and canker: could hot, dry conditions
(have) increase(d) susceptibility to the point
where outbreaks are possible?
• Could warm winters increase overwintering
survival of herbivore species on alder to the
point where they become outbreak species?
Links to Invasive Plants
• Future research (Mulder lab): how do
biotic factors, including herbivores and
pathogens, accelerate or retard the
advance of invasives in burned habitat?
– Potential for acceleration:
• “Enemy release” from soil pathogens
• Introduction of new plant pathogens to natives
– Potential for deceleration:
• Herbivory
• Pathogens on invasives