Abstracts for the 5th International GAME Conf.
3-5 October 2001
Aichi Trade Center
Nagoya Japan
WATER EXCHANGE OF PERMAFROST FOREST VEGETATION IN CENTRAL YAKUTIA
Maximov T.C. (1), Maximov A.P. (1), Kononov A.V. (1)
(1) Institute for Biological Problems of Cryolithozone, Siberian Division of Russian Academy of Sciences
Multiyear (1995-2000) water status observations of forests of different formation-typological structure in Yakutia are summarized in relation to ecophysiological peculiarities of plants and climatic conditions.
Within the framework of GAME-Siberia these studies were carried out at the Forest Station "Spasskaya Pad' " of Institute for Biological Problems of Cryolithozone SD RAS located at 40 km north of Yakutsk, in the following ecosystems:
- larch forest (Laricetum vacciniosum) of ca. 160 years old, with medium solodic, sandy loam and sod-forest type soils.
- pine forest (Pinetum arctostaphylosum), ca. 150 years old; sod-forest and sandy loam soil.
- birch forest (Betuletum mixtoherbosum), ca. 160 years old; sod-forest, weakly podzolized and sandy soil.
Physiological parameters were obtained using an IRGA KIP-9010, Japan, with measurement intervals of 30 min, flow rate - 0.64 l min-1. Xylem water potential (XWP) readings were done by pressure chamber method using a tenziometer DIK-7000. Soil moisture content (SMC) was determined by classic gravimetric method.
Tree species have typical pattern of multiyear seasonal dynamics of XWP in the form of concave curve with its gradual increase in the row larch (-0.84 -3.12 MPa) birch (
-0.38 -2.74 MPa) pine (-0.43 -2.47 MPa), which is explained by morpho-physiological features of the trees. Forest floor vegetation, in common, has inverse seasonal trend compared to the wood species, with the biggest XWP amplitude ( -0.28 -3.12 MPa).
The results of coefficient and regression analyses for summary soil moisture content and XWP have showed their statistically reliable degree only for the pine forest and more or less - for the birch one, while it is virtually zero for the larch forest. Estimating decomposition of total ecosystem correlation into their components has revealed that the basic background of the total correlation is made by wood species.
Therefore, in the vegetation period of 1999 (cool and humid by hydrological conditions) the highest values of transpiration intensity ( TI) were marked in the first half of July. During the vegetation period, birch leaves transpired at the average rate of 0.57 g H2O dm-2h-1, that is three times lower of the data of 1998 (1.59 g H2O dm-2h-1) and does not differ from the data obtained in 1997 (0.5 g H2O dm-2h-1). Basically, diurnal run of TI is described by a two-peaked curve with maxima at early morning and afternoon hours depending on the phase of plant development and weather conditions.
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Institute for Biological Problems of Cryolithozone, Siberian Division of Russian Academy of Sciences | |
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