CANOPY TRANSPIRATION OF MOUNTAIN MIXED FOREST AS A FUNCTION OF
ENVIRONMETAL CONDITIONS IN BOUNDARY LAYER
Katarina Strelcova1, Jiri Kucera2, Peter Fleischer3, Stefano Giorgi4,
Erika Gomoryova1, Jaroslav Skvarenina1, Lubica Ditmarova5
1
Technical University, Forestry Faculty in Zvolen, Slovakia; e-mail: strelcov@vsld.tuzvo.sk
2
Environmental Measuring Systems, Brno, Czech Republic
3
State Forest of Tatra National Park – Research Station, Vysoke Tatry, Slovakia
4
Universita della Tuscia, Viterbo, Italy
5Institute of Forest Ecology, Slovak Academy of Sciences, Zvolen, Slovakia
The canopy transpiration and stomata conductance of mountain mixed forest was investigated during
summer 2006 at research plot Smrekovec in Tatra National Park in Slovakia after heavy windstorm in
November 2004 on the area of 12 000 hectares. The research plot is situated in untouched forest at
altitude 1249 m on the southern oriented slope (Figure 1). The forest is mixed with 80% of spruce
trees and 20% of larch trees (711 trees per ha – DBH 14 cm and more) with rich under storey
vegetation, 120 years old, 7-th vegetation level, soil type is dystric cambisol.
Whole tree sap flow based on up to dated stem tissue heat balance method was continuously
measured in nine 120-years old larch and spruce trees. Stem basal area was used for tree-canopy upscaling. The Penman-Monteith equation was parameterized using a new three-parameter equation
describing stomata status as a function of solar radiation and vapour pressure deficit (VPD) based on
the assumption that the stomatal conductivity – gc depends on solar radiation and VPD values
according a suitable formula – e.g. Lohamar, 1980. Meteorological parameters were measured on the
top of eddy stuff tower above investigated forest. Two virtual monocultures (of the same number of
trees) were assumed for characterizing of both species. The tree transpiration and stomata
conductance were calculated for the whole measured period for both spruce and larch virtual forests.
Figure 1: Localisation of the research plot in Tatra National Park
The contribution of both considered species to the whole water budget was found fairly proportional to
their tree number. The average daily canopy transpiration was ca 1.0 mm during August – September
time period and it reached maximum 2 mm a day. Spruce trees were less sensitive to vapour pressure
deficit than larch, which started to close stomata rapidly under low vapour pressure deficit values
(Figure 2).
Key words
sap flow, larch, spruce, biological and meteorological factors, Tatra National Park
Figure 2: Tree transpiration measured and calculated in the rather wet subperiod and the stomatal
conductance. Virtual spruce and larch forest
Keywords: Sap flow, Larch, Spruce, Biological and meteorological factors, Tatra National Park