Transpiration and canopy conductance of European beech Fagus sylvatica L. in a natural and a mature

1
Transpiration and canopy conductance of European
beech (Fagus sylvatica L.) in a natural and a
mature managed stand
Lise Dalsgaard1Teis Nørgaard Mikkelsen2Annemarie
Bastrup-Birk11Danish Centre for Forest,
Landscape and Planning, KVL2Risø National
Laboratory
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
2
Introduction
Studies of European beech transpiration mostly in
even-aged forest (e.g. Ladefoged 1963, Herbst
1995, Magnani et al. 1998, Granier et al. 2000,
Dellwik 2003, Granier et al. 2003)
Stands differing in age had similar
maximum transpiration per m2 leaf area.
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
3
Introduction
Studies of European beech transpiration mostly in
even-aged forest (e.g. Ladefoged 1963, Herbst
1995, Magnani et al. 1998, Granier et al. 2000,
Dellwik 2003, Granier et al. 2003)
Stands differing in age and site conditions had
similar canopy conductance.
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
4
Introduction
gs gsref -m . lnD (Oren et al. 1999)
The mean stomatal conductance was lower in tall
trees than in small trees
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
5
Aim and hypotheses
Aim To compare transpiration and canopy
conductance in European beech between a
natural (uneven-aged) and a managed
(even- aged) homogenous stand Hypotheses Due to
the presence of short trees the canopy
conductance is more sensitive to the air vapour
pressure deficit in an uneven-aged than in an
even-aged stand Tall trees have a lower
reference leaf level conductance than short
trees and a lower sensitivity to the air vapour
pressure deficit
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
6
Measurement sites

Naturalforest
NAT MAN Natural Managed mature
Suserup Forest Lille Bøgeskov Forest LAI
(m2 / m2) 4.6 4.2 BA (m2 / ha) total 39.1
(beech 28.9) 28.7 Diameter (cm) 19 38 Height
(m) top 28 (mean 13) 25 Density (n /
ha) 733 283 Species Fagus sylvatica L. Fagus
sylvatica L. Fraxinus excelsior L. Quercus
robur L. Ulmus glabra Huds.
Managed forest
Photo Katrina S. Einhorn
Photo Teis N. Mikkelsen
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
7
Methods Sapflow and meteorology
Granier method (heat dissipation) (Granier 1985,
1987, Granier et al. 1996) NAT 12 trees 11-70
cm diameter MAN 12 trees 35-44 cm
diameter Light Air temperature Relative air
humidity Windspeed Precipitation Soil moisture
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
8
Methods scaling of transpiration
From sensor to tree
From tree to plot
MAN Measured sap flux density was scaled to 77
of stand basal area NAT Measured sap flux
density was scaled to the projected crown
area not including overlap
sap flux density decreases with increasing xylem
depth
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
9
Methods canopy conductance
Penman-Monteith
ga f(windspeed, roughness, height)
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
10
Methods leaf conductance for individual trees
(Köstner et al. 1992)
E is related to the simulated tree leaf area
model tRAYci (Brunner 1998)
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
11
Results daily transpiration
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
12
Results diurnal transpiration
R20.73 P0.03
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
13
Results canopy conductance
gc gcref -m . lnD
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
14
Results leaf conductance for individual trees
gLtree gLtree-ref -m . lnD
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
15
Conclusions
Daily transpiration responded similarly to light
and vpd. Daily transpiration was slightly
higher at the managed than at the natural site.
Probably due primarily to a higher leaf area,
though differences in the diurnal curves for
transpiration also may have contributed. The
managed stand may have experienced more
limitations to transpiration at high air vapour
pressure deficit than the natural stand. Canopy
conductance did not differ between the two
sites. Variation in the individual tree leaf
level conductance was not explained by tree
height.
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)
16
Thank you !
IUFRO Landscape Ecology Conference, Sept. 26-29,
2006 Locorotondo, Bari (ITALY)