1. Plant
ecophysiological
measurements
at
TERN
Supersites
A
crucial
link
between
vegeta1on
modeling,
biodiversity
and
ecosystem
func1on
Owen
Atkin,
Keith
Bloomfield
and
Lasantha
Weerasinghe
Division
of
Plant
Sciences,
Research
School
of
Biology
Australian
Na1onal
University

2. Importance
of
vegeta1on
• Ecosystem
hydrology,
net
CO2
exchange
and
primary
produc1vity
• Global
C
cycle
and
atmospheric
[CO2]

3. Plant
physiological
traits
crucial
for
ecosystem
func1oning
Traits
such
as:
• Structure
and
chemistry
of
above/below-­‐ground
organs
• Leaf
metabolism
(e.g.
photosynthesis,
respira1on)
• Plant
water
rela1ons

4. Variability
in
foliar
traits:
Acacia
Acacia genus
Acacia tetragonophylla
• Contras1ng
leaf
traits
in
species
adapted
to
inland
and
coastal
regions
Acacia melanoxylon

5. TERN
Supersites
• Opportunity
to
iden1fy
key
drivers
controlling
H2O
movement,
C-­‐exchange
and
biodiversity
across
a
wide
range
of
contras1ng
Australian
ecosystems

6. TERN
Supersites
Plant
ecophysiology
(2010-­‐2014)
FNQ
Cape
Tribula1on
Alice
FNQ
Mulga
Robson
Ck
Calperum
Mallee
Cumberland
Greater
Western
EucFACE
Woodlands
Warra
Tall
Eucalypt

7. Plant
physiology
measurements
Sampling
frequency
• 2
1mes
per
year
• wet/dry
or
winter/summer
Canopy
posi1ons
• Upper/mid
canopy,
under-­‐storey
Species
selec1on
and
sampling
• Number
of
species
sampled
varies
among
Supersites,
depending
on
species
diversity
• Within-­‐tree
sampling

8. Plant
physiology
measurements
Leaf
and
branch
analyses
• Wide
range
of
leaf
chemistry
and
structure
measurements,
as
well
as
structure
of
water-­‐transpor1ng
cells
in
branches/stems
Plant
water
rela1ons
• Quan1fica1on
of
traits
that
reflect
whether
a
plant
is
undergoing
water
stress
(or
vulnerable
to),
and
the
capacity
to
transport
water
up
from
the
soil
to
leaves
Leaf
gas
exchange
measurements
• Standardized
measurements
of
photosynthesis
and
respira1on
• CO2-­‐response
&
light-­‐response
curves
of
photosynthesis
• Temperature
response
curves
of
respira1on

9. Cape
Tribula1on
–
FNQ
Lowland
tropical
wet
forest
• MAT
=
28oC
• Completed
campaign:
September
2010
• Upcoming
campaign:
March
2014
• Crane
used
to
compare
upper-­‐
&
lower-­‐canopy
leaves
• 16
canopy
species
• 10
understorey
species

10. Cape
Tribula1on
–
FNQ
Lowland
tropical
wet
forest
Mass - based
Impact
of
canopy
posiHon
Area - based
5 50
(A) (B) a
c
4 a 40
b
a
• Sun-­‐exposed
leaves
are
thicker/
Leaf [N] (mg g )
a
Leaf [N] (g m -2)
-1
c
Leaf
N
3 30
a
2 20
1
denser
and
have
higher
area-­‐
10
based
N
and
P
concs
0 0
0.35 6
(C) c (D)
a
0.30 5
than
lower,
shaded
leaves
d
0.25
Leaf [P] (mg g )
Leaf [P] (g m )
-1
4
-2
0.20 b
Leaf
P
a
3
0.15 a a
a
2
• Rates
of
photosynthesis
&
0.10
0.05 1
0.00 0
respiraHon
higher
in
upper
250 50
(E) c b (F) d
Leaf mass per unit area (g m )
-2
d
Specific leaf area (m kg )
-1
200 40
canopy
leaves
than
lower
canopy
2
b
150 c 30
Structure
and
understorey
leaves
100 a 20
a
50 10
0 0
Upper only Upper Lower Understory Upper only Upper Lower Understory
Canopy position Canopy position

11. Robson
Creek
–
FNQ
Upland
tropical
wet
forest
• MAT
=
20oC
• Completed
campaign:
September
2012
• Upcoming
campaign:
March-­‐April
2014

12. Warra
–
Tasmania
Temperate
wet
forest
• MAT
=
9oC
• Completed
campaign:
March
2012
• Upcoming
campaign:
July
2013

13. Comparison
of
wet-­‐forest
sites
Leaf
chemistry,
structure
and
photosynthesis
25
20
[N] mg g-1 DM
Leaf
N
15
30
10
5
0
25
Photosynthe1c
capacity
Amax (umol CO2 m-2 s-1)
1.6
1.4
20
[P] mg g-1 DM
1.2
1.0
Leaf
P
0.8 15
0.6
0.4
160 10
140
LMA g m-2
120
5
Structure
100
0
tion reek Warr
a
80
bula nC
n k a
latio Cree Warr
Cape
Tribu Robson
Cape Tri R obso
Location
Location

14. Comparison
of
wet-­‐forest
sites
Respira1on-­‐temperature
response
curves
8
FNQ - Cape Tribulation
9oC MAT FNQ -Robson Creek
mol CO2 m-2 s-1)
Tasmania - Warra
6
o
20 C MAT
o
4 28 C MAT
Respiration (m
2
0
10 20 30 40 50 60
Leaf temperature (0C)

15. Comparison
of
wet-­‐forest
sites
Respira1on-­‐leaf
nitrogen
rela1onships
• Climate
models:
N
ogen
used
to
predict
leaf
metabolic
rates
(e.g.
at
common
measuring
temperature
of
25oC)
• Rdark
at
25oC:
Warra
>
Robson
Ck
>
Cape
Tribula1on
Leaf
area-­‐based
Leaf
dry
mass-­‐based
9oC
MAT
20oC
MAT
9oC
MAT
20oC
MAT
28oC
MAT
28oC
MAT

16. Comparison
of
wet-­‐forest
sites
Some
tenta1ve
conclusions
•
Photosynthe1c
capacity
highest
at
warmest
site
Cape
Tribula1on,
FNQ
• Respiratory
capacity
highest
at
coldest
site
Warra,
Tasmania
• Implica1ons
for
our
understanding
of
how
temperature
impacts
on
net
carbon
exchange
in
wet
forests
of
eastern
Australia

17. Time
table
of
upcoming
campaigns
Number
Site
campaigns
Start
date
Dura1on
End
date
1
Water
rela1ons
methods
at
UTS
25-­‐Feb-­‐13
2
27-­‐Feb-­‐13
2
Warra,
TAS:
winter
visit
8-­‐Jun-­‐13
16
24-­‐Jun-­‐13
3
Robson
Creek
&
Cape
Trib,
FNQ:
wet
season
31-­‐Mar-­‐14
25
25-­‐Apr-­‐14
4
Calperum
Mallee,
SA:
summer
visit
5-­‐Mar-­‐13
15
20-­‐Mar-­‐13
5
Calperum
Mallee,
SA:
winter
visit
8-­‐Jul-­‐13
15
23-­‐Jul-­‐13
6
Gt
West
Woodlands,
WA:
summer
visit
3-­‐Apr-­‐13
16
19-­‐Apr-­‐13
7
Gt
West
Woodlands,
WA:
winter
visit
9-­‐Sep-­‐13
15
24-­‐Sep-­‐13
8
EucFACE,
NSW:
summer
visit
13-­‐Jan-­‐14
11
24-­‐Jan-­‐14
9
EucFACE,
NSW:
winter
visit
9-­‐Jun-­‐14
11
20-­‐Jun-­‐14
10
Alice
Mulga,
NT:
summer
visit
7-­‐Feb-­‐13
6
13-­‐Feb-­‐13
11
Alice
Mulga,
NT:
winter
visit
7-­‐Jul-­‐14
11
18-­‐Jul-­‐14

18. Linkages
with
TERN
infrastructure
e-­‐MAST
(ecosystem
Modeling
And
Scaling
infrasTructure)
• Physiological
data
will
enable
development
and
tes4ng
of
a
new
genera1on
of
biosphere-­‐atmosphere
models
4ed
firmly
to
observa4ons
and
that
take
account
of
the
diversity
of
physiological
responses
across
species
OzFlux
towers
• Will
provide
data
needed
to
disentangle
ecosystem
CO2
fluxes
into
canopy
and
non-­‐canopy
components

19. The
way
forward:
some
science
ques1ons
• Do
contras1ng
ecosystems
differ
in
their
physiological
vulnerability
to
extreme
weather
events
such
as
droughts
and
heat-­‐waves?
• Can
physiological
‘1pping
points’
be
iden1fied
and
if
so,
do
they
differ
among
environments?
• What
drives
the
1ming
of
phenological
events
such
as
leaf-­‐drop
&
flowering
in
the
absence
of
marked
temp
or
day-­‐length
signals?