Transcript Herbivory and predation

Reading for next lectures
•
Textbook Chapters 8, 10, 12, 13
Seminars
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Dr. Julia Koricheva, University of Turku,
Finland. Direct and indirect costs of
plant resistance to herbivores. EECB
seminar Thurs Feb 26, 4:00 PM OSN 120
Outline
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2.
3.
4.
5.
Herbivory in Australian woodland
Introduction to community ecology
Introduction to ecosystems ecology
Community concepts
Ecosystems analysis
Questions
How does herbivory affect woodland
species?
Does habitat alter response to grazing
or impact of herbivores?
Do different herbivores have different
effects?
Photo: Taronga Zoo, Sydney NSW
Photo: CSIRO Wildlife and Ecology
Burrendong Dam Study Area
 Approx. 100 km2 in the
Central West Slopes region,
NSW, Australia near the
center of White Box
distribution.
Mosaic of eucalypt
woodland, native pine
woodland, cleared grassland,
and alluvial flats.
Study Design
Fencing treatments
established in January
and February 1997
4 treatments (control,
stock fence, kangaroo
fence, rabbit fence)
2 habitats (eucalypt
woodland, cleared
grassland)
Study Design
25m by 25m fences, four replicates
Woodland
Grassland
control
stock
control
stock
kangaroo
complete
kangaroo
complete
Four Blocks
Four Blocks
Study Design
Transplants:
Eucalyptus albens, Callitris glaucophylla, and
Themeda australis. Planted in grassland and
woodland plots in Apr 1998.
Summary
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Three groups of grazing animals:
Four treatments:
Two habitats:
Three target species:
Monitored survival for all species, and created
models based on size growth for trees.
Browse preferences
75
75
70
70
65
60
65
EUCALYPTUS
60
CALLITRIS
55
55
50
50
45
45
40
40
35
35
30
30
25
25
20
20
15
15
10
10
5
5
0
0
CATTLE
KANGAROO
RABBIT
Grassland
SHEEP
CATTLE
KANGAROO
RABBIT
Woodland
SHEEP
Eucalyptus mortality
C
a
te
g
o
rize
dP
lo
tfo
rV
a
ria
b
le
:S
T
A
T
U
S
1
2
1
0
C-control
S-Stock
K-Kangaroo
R-Rabbit
8
STATUS
# Trees Dead
6
4
2
0
±
S
td
.D
e
v.
-2
1
C
2
S
3
K
H
A
B
IT
A
T
:G
Grassland
4
R
T
R
E
A
T
M
E
N
1
C
2
S
3
K
H
A
B
IT
A
T
:W
Woodland
4
R
±
S
td
.E
rr.
M
e
a
n
Callitris Mortality
C
a
te
g
o
rize
dP
lo
tfo
rV
a
ria
b
le
:S
T
A
T
U
S
1
1
C-control
1-control
S-Stock
2-Stcock
3-Kangaroo
K-Kangaroo
R-Rabbit
4-Rabbit
9
7
STATUS
# Trees Dead
5
3
1
±
S
td
.D
e
v.
-1
C1
2
S
3
K
4
R
H
A
B
IT
A
T
:G
Grassland
C1
S2
K3
H
A
B
IT
A
T
:W
T
R
E
A
T
M
E
N
Woodland
R4
±
S
td
.E
rr.
M
e
a
n
Themeda mortality
C
a
te
g
o
rize
dP
lo
tfo
rV
a
ria
b
le
:S
T
A
T
U
S
2
6
C-control
S-Stock
K-Kangaroo
R-Rabbit
2
2
1
8
STATUS
# Plants Dead
1
4
1
0
6
2
±
S
td
.D
e
v.
-2
C1
2
S
3
K
H
A
B
IT
A
T
:g
4
R
Grassland TR
E
A
T
M
E
N
1
C
2
S
3
K
H
A
B
IT
A
T
:w
Woodland
4
R
±
S
td
.E
rr.
M
e
a
n
“Life history” transition diagram
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Transitions between 5 size (height) classes for
trees; final stage is “escape from herbivory”.
Models created for each habitat and treatment
combination.
P
P
P
P
P
S
1
P
11
P
P
S
S
[<25 cm]
S
1
P
21
P
0
P
S
[25 - 49 cm]
0
S
[50 - 74 cm]
0
S
52
0
0
[ >100 cm]
0
Matrix Two
5
S
0
[<25 cm]
S
0
S
0
[25 - 49 cm]
0
S
0
0
0
P
0
0
P
P
P
P
S
[ >100 cm]
5
P
P
15
P
P
53
P
44
P
35
52
43
34
P
25
P
P
P
51
42
33
24
P
P
P
5
41
32
23
14
P
P
P
S
4
31
22
13
[75 - 100 cm]
P
P
P
S
3
21
12
[50 - 74 cm]
S
2
11
3
S
S
1
4
0
25
55
53
2
0
P
P
54
42
1
0
P
P
44
43
P
S
4
24
5
P
23
[75 - 100 cm]
5
31
3
0
P
4
S
33
22
3
S
45
41
0
P
2
S
P
21
1
P
S
4
18
P
51
S
2
34
3
P
P
Matrix One
P
S
23
22
15
24
13
2
P
P
P
S
12
25
P
P
14
35
54
P
45
55
Proportion reaching escape height (100 cm)
Grassland
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Woodland
Callitris glaucophylla
Eucalyptus albens
-r -k -s
+r -k -s
+r +k -s
+r +k +s
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
years since planting
Summary
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Plants in productive environment better
able to compensate (more rapid growth)
High herbivory rate in unfenced low
productivity habitats prevented “escape”.
This could have population consequences
even though mortality was fairly low.
Differences in herbivore preference could
be translated to community composition.
Interaction between competition and
herbivory…tradeoff.
Community and ecosystems ecology
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Community ecology: study of all organisms
(plants?) in a given area. = synecology;
species/organism based.
Ecosystems ecology: study of energy and
matter flows, productivity, and cycling.
Process/energy based.
Community and ecosystems ecology
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Forest and range ecosystem function,
management, and productivity can be
viewed from either community or
ecosystem viewpoint:
Community
Ecosystem
Disturbance and
succession, S&T
models, diversity,
functional groups,
ecological sites and
potential vegetation
Productivity, stability,
resource capture and
efficiency, “landscape
function”, plant-soil
interactions, carbon
balance
Historic community concepts
Clements (1905): “super-organism” concept.
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Plant species associate/co-occur in a predictable way,
proceeding to a “climax” configuration determined by
climate.
A community has emergent organism-like properties;
can be classified into distinct idealized types.
In North America, 3 climax types: grassland, scrub and
forest. Divided into subtypes (e.g. true grasslands VS
sedge meadows; sagebrush VS desert scrub VS
chaparral; coastal VS montane forest), then into
“associations” (= communities).
Distinctions often driven by most obvious plant species
(e.g. trees)
Basis for ecological site types, potential vegetation,
and community classifications used by BLM and USFS
Historic community concepts II
Gleason (1917): individualistic concept
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Each species responds individually to environment and
species around it.
There are no predictable associations or emergent
“organismal” properties
Plant associations do exist – we can see them, describe
them, relate them to environment; BUT they are due
simply to juxtaposition of individual plants
“[the community] is not an organism, but merely a
coincidence”
Some argue that Gleason downplays importance of site
characteristics (soils, water, nutrients) too much…
Current understanding
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Closer to Gleason’s than to Clements’s view
Communities are identifiable, but boundaries can
be vague
“Climax” now used for communities undisturbed
long enough to pass through several generations
of dominant species
“Super-organsism” concept still shows up in
some definitions of ecosystems and ecosystem
management
“Ecological site” descriptions try to include
ecosystem properties as well as vegetation
composition
Ecosystems ecology
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Concerned with nutrient fluxes,
biogeochemical cycles, and energy balances.
Ecosystems analysis (p 358 text).
– Long term monitoring of ecosystem (watershed).
– Measurement of nutrient and water fluxes
andcycling, as well as productivity.
– Create nutrient budgets.
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Other means of investigating: microcosms;
computer simulations.