drought resistance of amazon trees reflects a low vulnerability to cavitation: results from a large...
TRANSCRIPT
Drought resistance of Amazon trees reflects a low vulnerability to cavitation: results from a
large scale rainfall exclusion experiment.
Drought resistance of Amazon trees reflects a low vulnerability to cavitation: results from a
large scale rainfall exclusion experiment.
Gina CardinotGina Cardinot1,21,2,, Missy Holbrook,, Missy Holbrook3 3 & Daniel Nepstad& Daniel Nepstad2,42,4Gina CardinotGina Cardinot1,21,2,, Missy Holbrook,, Missy Holbrook3 3 & Daniel Nepstad& Daniel Nepstad2,42,4
The Woods HoleThe Woods Hole
Research CenterResearch Center
Funded by:
11Federal University of Rio de JaneiroFederal University of Rio de Janeiro22IPAM-Amazon Institute of Environmental ResearchIPAM-Amazon Institute of Environmental Research33Harvard UniversityHarvard University44Woods Hole Woods Hole Woods Hole Woods Hole RResearchesearch CeCennterter
In terrestrial ecosystems, plants form the principal pathway for water movement from soil to atmosphere, and their ability to supply leaves with water is a prerequisite for CO2 uptake.
However, the capacity of the xylem to transport water from the soil to the leaves is itself at risk during periods of drought due to the increased potential for cavitation .
Studies of xylem hydraulic properties in the field are important tools for understanding how plants respond to ecosystem changes .
Our research focuses on the effects of drought on the water transport capacity of
Amazonian rainforest trees.
Our goal is to understand the extent to which cavitation results in a loss of hydraulic conductivity, potentially leading to stomatal
closure, leaf shedding, and tree death.
Floresta Nacional do Tapajós-Santarém/PA
Projeto Seca Floresta (throughfall exclusion
experiment)
Our research was carried out within the context of
the world’s largest rainfall exclusion experiment.
Eastern Amazônia; Pará State/Brazil)
Study Site Layout
Dry Plot
Wet Plot
two 1-ha plots, of which one is a control and one in which rainfall reaching the forest floor
has been reduced by 50% since 2000.
The oxisol soil is highly weathered and clayey in texture. The water table is more than 100 m deep.
The panels cover ~75% of the ground area. They are left in place during the ~6 month
wet season between January and July.The treatment prevents ~50% of incoming
precipitation from entering the soil.Baseline measurements were made for 1 yr
prior to throughfall exclusion, beginning in Jan 1999
Rainfall exclusion since 2000
Coussarea racemosa - Rubiaceae
Miconia engensis - Melastomataceae Poecilanthe effusa - Fabaceae
Escheweilera pedicellata - Lecythidaceae
. We chose four species which are common in this area
Field pressure-drop flow meter:
•Xylem specific conductivity
•Ks=F/L(∆P*Asw)
•Leaf specific condutictivity
•Kl=F/L(∆P*LA)
ResultsResults
Soil Water (TDR): Surface depletion in Yr 1; depletion at depth Yr 2.
TDR probes under construction.
Precipitação
0
20
40
60
80
100
120
140
160
1/1
/99
1/3
/99
1/5
/99
1/7
/99
1/9
/99
1/1
1/9
9
1/1
/00
1/3
/00
1/5
/00
1/7
/00
1/9
/00
1/1
1/0
0
1/1
/01
1/3
/01
1/5
/01
1/7
/01
1/9
/01
1/1
1/0
1
1/1
/02
1/3
/02
1/5
/02
1/7
/02
1/9
/02
1/1
1/0
2
1/1
/03
1/3
/03
1/5
/03
1/7
/03
1/9
/03
1/1
1/0
3
Data
Pre
cip
ita
çã
o (
mm
)
VWC 0-200cm
300
350
400
450
500
550
600
650
700
750
800
9/2
/99
31/3
/99
20/5
/99
9/7
/99
28/8
/99
17/1
0/9
9
6/1
2/9
9
25/1
/00
15/3
/00
4/5
/00
23/6
/00
12/8
/00
1/1
0/0
0
20/1
1/0
0
9/1
/01
28/2
/01
19/4
/01
8/6
/01
28/7
/01
16/9
/01
5/1
1/0
1
25/1
2/0
1
13/2
/02
4/4
/02
24/5
/02
13/7
/02
1/9
/02
21/1
0/0
2
10/1
2/0
2
29/1
/03
20/3
/03
9/5
/03
28/6
/03
17/8
/03
6/1
0/0
3
25/1
1/0
3
14/1
/04
4/3
/04
Data
VW
C (
mm
)
VWC 200-1100cm
2500
2700
2900
3100
3300
3500
3700
3900
9/2
/99
31/3
/99
20/5
/99
9/7
/99
28/8
/99
17/1
0/9
9
6/1
2/9
9
25/1
/00
15/3
/00
4/5
/00
23/6
/00
12/8
/00
1/1
0/0
0
20/1
1/0
0
9/1
/01
28/2
/01
19/4
/01
8/6
/01
28/7
/01
16/9
/01
5/1
1/0
1
25/1
2/0
1
13/2
/02
4/4
/02
24/5
/02
13/7
/02
1/9
/02
21/1
0/0
2
10/1
2/0
2
29/1
/03
20/3
/03
9/5
/03
28/6
/03
17/8
/03
6/1
0/0
3
25/1
1/0
3
14/1
/04
4/3
/04
Data
VW
C (
mm
)
Tratamento Controle
Daily rain
LAI
3
4.5
6
7.5
4/1
4/0
0
5/2
9/0
0
7/1
3/0
0
8/2
7/0
0
10/1
1/0
0
11/2
5/0
0
1/9
/01
2/2
3/0
1
4/9
/01
5/2
4/0
1
7/8
/01
8/2
2/0
1
10/6
/01
11/2
0/0
1
1/4
/02
2/1
8/0
2
4/4
/02
5/1
9/0
2
7/3
/02
8/1
7/0
2
10/1
/02
11/1
5/0
2
12/3
0/0
2
2/1
3/0
3
3/3
0/0
3
5/1
4/0
3
6/2
8/0
3
8/1
2/0
3
9/2
6/0
3
Data
LA
I (m
2m
-2)
Tratamento Controle
Figura 12. Instrumento para as medidas de LAI.
C.racemosa e E. pedicellata - Estação Seca/98
0102030405060708090
Horas do dia
Sa
p f
lux
de
ns
ity
(g
/m2
/s)
matamata caferana matamata Control caferana Control
E. pedicellata Estação Seca/2002
0
10
20
30
40
50
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
Hora
Sap
flu
x d
en
sit
y (
g/m
2/s
)
Matamatá dry Matamatá Control
C. racemosa - Estação Seca/2002
0
5
10
15
20
25
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
01:3
6
05:3
6
09:3
6
13:3
6
17:3
6
21:3
6
Hora
Sap
flu
x d
ensi
ty (
g/m
2/s)
Caferana Dry Caferana Control
Sap
flu
x d
ensi
tyS
ap f
lux
den
sity
Miconia engensis (Melastomataceae)
LWP (MPa)
-7 -6 -5 -4 -3 -2 -1 0
PLC
(%)
0
20
40
60
80
100
Coussarea racemosa (Rubiaceae)
LWP (MPa)
-7 -6 -5 -4 -3 -2 -1 0
PLC
(%)
0
20
40
60
80
100
Poecilanthe effusa (Fabaceae)
LWP (MPa)
-10 -8 -6 -4 -2 0
PLC
(%)
0
20
40
60
80
100
Escheweilera pedicelata (Lecythidaceae)
LWP (MPa)
-6 -5 -4 -3 -2 -1 0
PLC
0
20
40
60
80
100
Vulnerability curvesVulnerability curves
Percent Lost of Conductivity (PLC) vs Leaf water Percent Lost of Conductivity (PLC) vs Leaf water potentialpotential
PLC 50% = -3.9 MPa
PLC 50% = -3.9 MPaPLC 50% = -3.6 MPa
PLC 50% = -4.9 MPa
Xylem – specific conductivityXylem – specific conductivityKs- M. egensis
0.0
1.0
2.0
3.0
4.0
5.0
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out03
Season
Ks (k
g/m
2/s/
MPa
)
seca control
Ks- C.racemosa
0.0
0.5
1.0
1.5
2.0
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out03
Season
Ks (k
g/m
2/s/
MPa
)
seca control
Ks- E. pedicilata
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out03
Season
Ks (k
g/m
2/s/
MPa
)
seca control
Ks- P.effusa
0.0
0.5
1.0
1.5
2.0
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out03
Season
Ks (k
g/m
2/s/
MPa
)
seca control
Leaf hydraulic conductivityLeaf hydraulic conductivity
Kl- E.pedicilata
0.0E+00
2.0E-05
4.0E-05
6.0E-05
8.0E-05
dry season/02 dry season/03
Season
Kl (
Kg
/s/m
/MP
a)
seca control
Kl- C. racemosa
0.0E+00
5.0E-05
1.0E-04
1.5E-04
2.0E-04
dry season/02 dry season/03
Season
Kl (
Kg
/s/m
/MP
a)
seca control
Kl- M.egensis
0.0E+00
2.0E-05
4.0E-05
6.0E-05
8.0E-05
1.0E-04
dry season/02 dry season/03
Season
Kl (
Kg
/s/m
/MP
a)
seca control
Kl- P.effusa
0.0E+00
2.0E-05
4.0E-05
6.0E-05
8.0E-05
dry season/02 dry season/03
Season
Kl (
Kg
/s/m
/MP
a)
seca control
a.
a.
a.
a.
a.a.
a. a. a.
b. c.
c.
a.
a.
a.
b.**
*
*
PLC--Native embolismPLC--Native embolism
PLC- M.egensis
0
5
10
15
20
25
30
35
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out 03
Season
PLC
(%)
control seca
PLC- C. racemosa
0
5
10
15
20
25
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out 03
Season
PLC
(%)
control seca
PLC- P. effusa
0
5
10
15
20
25
30
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out 03
Season
PLC
(%)
control seca
PLC- E. pedicellata
0
5
10
15
20
25
30
35
Early dryseason_ago02
Late dryseaon_nov 02
Rainseason_feb03
Dry season_out 03
Season
PLC
(%)
control seca
Leaf water potential - PredawnLeaf water potential - Predawn
Predawn- Escheweilera pedicellata (Matamatá)
-2
-1.5
-1
-0.5
0
01/2
1/00
03/0
4/00
08/0
6/00
13/0
7/00
10/0
8/00
15/0
9/00
11/0
1/00
11/3
0/00
02/0
6/01
04/0
5/01
05/3
0/01
07/3
1/01
09/2
6/01
11/2
8/01
01/2
9/02
03/2
6/02
05/2
9/02
08/0
2/02
10/0
2/02
11/2
8/02
02/0
4/03
04/0
8/03
6/5/
2003
07/1
7/03
10/1
/200
3
Data
LWP
(MPa
)
Parcela Controle Parcela Seca
Predawn-Coussarea racemosa (Caferana)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
001
/21/
00
03/0
4/00
08/0
6/00
13/0
7/00
10/0
8/00
15/0
9/00
11/0
1/00
11/3
0/00
02/0
6/01
04/0
5/01
05/3
0/01
07/3
1/01
09/2
6/01
11/2
8/01
01/2
9/02
03/2
6/02
05/2
9/02
08/0
2/02
10/0
2/02
11/2
8/02
02/0
4/03
04/0
8/03
6/5/
2003
07/1
7/03
10/1
/200
3
Data
LW
P (
MP
a)
Leaf water potential - PredawnLeaf water potential - Predawn
Predawn-Poecilanthe effusa (Gema de ovo)
-3
-2.5
-2
-1.5
-1
-0.5
001/2
1/0
0
03/0
4/0
0
08/0
6/0
0
13/0
7/0
0
10/0
8/0
0
15/0
9/0
0
11/0
1/0
0
11/3
0/0
0
02/0
6/0
1
04/0
5/0
1
05/3
0/0
1
07/3
1/0
1
09/2
6/0
1
11/2
8/0
1
01/2
9/0
2
03/2
6/0
2
05/2
9/0
2
08/0
2/0
2
10/0
2/0
2
11/2
8/0
2
02/0
4/0
3
04/0
8/0
3
Data
LW
P (
MP
a)
Predawn-Miconia egensis (Papaterra)
-3
-2.5
-2
-1.5
-1
-0.5
0
05/3
0/01
06/2
6/01
07/3
1/01
08/2
8/01
09/2
6/01
10/3
0/01
11/2
8/01
12/1
8/01
01/2
9/02
02/2
4/02
03/2
6/02
04/2
6/02
05/2
9/02
06/2
6/02
08/0
2/02
09/0
3/02
10/0
2/02
11/0
7/02
11/2
8/02
12/1
8/02
02/0
4/03
02/2
6/03
04/0
8/03
05/0
8/03
Date
LW
P (
MP
a)
Parcela Controle Parcela Seca
Drought resistance exhibited by Amazon tropical rainforest trees allows them to maintain physiological function and xylem continuity despite the marked seasonality in rainfall in the eastern Amazon.
The forest shows a complex responses to drought
Pleistocene climatic change - Plant respond as specie
These data also help us to refine our forest models
THANKS!
David Ray, Holbrook Lab-Peter Melcher, William Riker, Paul Lefebvre, Paulo Brando, Wanderley Rocha, Williams Castro and field technicians (Levi Seixas, Osvaldo Portela e Roberto Baena).
CAPES fellowship to Cardinot