Fertilization and irrigation effects on
production and light use efficiency in a
loblolly pine plantation:
a tree level perspective
José Luiz Stape – NCSU
Otávio C. Campoe - IPEF
Tim Albaugh, Lee Allen (NCSU),
Tom Fox (VT), Rafael Rubilar (UdeC), Dan Binkley (CSU)
17th Biennial Southern Silvicultural Research Conference
Shreveport LA March 5th 2013
Southeast Tree Research
and Education Site
SETRES
2x2
Fertilization x Irrigation
4 Blocks
0.62 acre plots
U.S. Forest Service
North Carolina State
University
Duke University
Virginia Tech
SETRES1: Standing volume
Standing Volume (m 3/ha)
300
250
+Nutrients+Water
200
+Nutrients
150
+Water
100
Control
50
0
1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Data from Albaugh et al 1998, 2004, 2006, 2008, and unpublished
SE US: SETRES site
Control
Nutrients + Water
+Nutrients+Water
+Nutrients
+Water
Control
Data from Albaugh et al 1998, 2004
SETRES: Volume Growth - Leaf Area
And for a tree level interpretation ?
How LAI and LUE vary across tree sizes ?
Implications for Thinning,
Fertilization, Remote Sensing…
Control
Nutrients + Water
Does size matter?
Growth = biomass
production
APAR = amount of
light absorbed
LUE = amount of
biomass produced
per amount of
light absorbed
Binkley, Stape (2010)
Overall pattern
Larger trees within a stand tend to absorb more light and use it
more efficiently in growing wood…
Greater growth of large trees
typically results from a combination
of
1 – Increased APAR (↑leaf area)
2 - Increased LUE
…but exactly how much for
Loblolly Pine ?
Overall pattern
Larger trees within a stand tend to absorb more light and use it
more efficiently in growing wood…
To address that we need:
- A tree-level canopy
light
model
Greater growth of large trees
typically results from a combination
- Accurated recorded data
at
tree-level
of
Increased APAR (↑leaf area)
And we had1 – that:
- Increased LUE
- MAESTRA 2Model
- SETRES dataset
…but exactly how much for
Loblolly Pine ?
What is MAESTRA model
3-D process-based model for calculating absorbed radiation,
transpiration and photosynthesis of individual trees
Inputs
Tree position → focal and neighbors
Canopy Structure → leaf area and seasonality, crown size
and shape, leaf angles, needles
optical characteristics.
Weather → mainly incoming PAR
MAESTRA estimates mean intercepted solar radiant energy (per square meter of
foliage) PAR and NIR wave bands, using the radiative transfer model of Norman
and Welles (1983)
For those interested, just Google it (“Maestra Model”)
How MAESTRA sees the trees
Control
I+F
↑ ANPP
= Incoming light
↑ APAR
RESULTS
Stand Level Production
Suggests ↑ LUE
~3X
Control
~2X
I+F
Tree leaf area was linearly related with tree APAR for all treatments
Higher leaf area gives advantages in light absorption
Larger trees in a stand were more productive than
smaller trees due to higher APAR and elevated LUE
Aboveground biomass (%, small to large)
Biometric variables
Increasing resource availability accentuated the
differences between dominant and
non-dominant trees among treatments
Control
Small X Large trees:
I+F
Small X Large trees:
2.2-fold larger DBH
59% taller
54% longer crown
3.2-fold more leaf area
2.6-fold larger DBH
74% taller
75% longer crown
3.7-fold more leaf area
Larger trees in a stand were more productive than
smaller trees due to higher APAR and elevated LUE
Aboveground biomass (%, small to large)
Production Ecology
Fertilization
increased the growth of the largest trees by 2-fold
(from 4.3 to 8.6 kg tree-1 year-1)
25% higher APAR (11 to 13.7 GJ tree-1 year-1)
75%from higher LUE (0.39 to 0.63 gMJ-1)
Irrigated + Fertilization
tripled productivity of the largest trees
(13.2 kg tree-1 year-1)
19% higher APAR (15.1 GJ tree-1 year-1)
81%from higher LUE (0.87 gMJ-1)
And for a tree level interpretation ?
- Better initial silvicultural treatments
to assure more uniform stands
- Thinning from below is the way to go
- Weed control after thinning
- Fertilization after thinning
- MAESTRA model for breeding...
Control
Nutrients + Water