The experiment site was situated in the central forest reserve of the region Tver, which is about 300 km west of Moscow in European Russia (220–270 m a.s.l.). This area has been protected and used for scientific research since 1931 (Vygodskaya et al. 2002). It extends over an area of 21380 ha, surrounded by a buffer zone of 43000 ha.
The climate of the area is moderately continental, with an annual mean temperature of 3.9°C, an annual precipitation of 711 mm, and a May to September precipitation of 397 mm. Snowmelt generally occurs in late March or early April, while first snowfall usually takes place in early to mid-November.
The geological underground consists of quaternary loamy sediments covering Devonian limestone. Owing to acidic and dense clay soils and a flat topography, this area is dominated by large bogs and forest on poorly drained soils.
The flora shows typical characteristics of the southern taiga including Linnaea borealis L., Trientalis europaea L. and Maianthemum bifolium L. (F.W. Schmidt), although the reserve could be classified into the nemoral deciduous zone according to its geographical location. The dominant tree species are spruce (Picea abies (L.) H. Karsten), birches (Betula pendula Roth, Betula pubescens Ehrh.), aspen (Populus tremula L.) (Miniaev & Konechnaya 1976).
Large parts of the forest reserve are visibly affected by past wind throw events, and these appear to be the natural mechanism of regeneration in this region (Ulanova 2000). Several thousand hectares of forest were affected in strong storm events.
The bog's vegetation is dominated by Sphagnum ssp. growing in inundated hollows, while ridges that project above the free water surface are dominated by ericaceous shrubs (Vaccinium microcarpum, V. uliginosum) and other herbaceous plants like Eriophorum vaginatum, Rubus chamaemorus, Carex pauciflora (Kurbatova et al., 2002)
The eddy covariance measurements were carried out in the centre of a large wind throw area that was disturbed in 1996, and extended over about 1000 m from north to south and 400 m from east to west. The area covered a long, gentle south-exposed slope presenting diversity of conditions in nutrient supply and moisture.
Before the wind throw event, the stand in the first layer had been dominated by spruce with an admixture of birches and aspen. In flat positions with oligotrophic conditions (up to 15% of area), willows and rowan were found in subtree layers and green mosses and sometimes sphagnum in lower layers. The drained parts of the slope presented richer vegetation with lime, maple and common hazel in subtree layer and nemoral herbs on the ground. Almost all the older trees had been uprooted. Some regenerating trees had already started to take over after the main canopy was destroyed,and had already reached a few metres of height. The wind throw was surrounded by a 25 m tall spruce forest (Knohl et al., 2002)
At the same time, the eddy covariance measurements were performed with the same instrumental setup in a nearby forest (Picea abies, 110&thinspyr, unmanaged and with peat overlaying the soil) and in a nearby sphagnum bog (Kurbatova et al. 2002; Milyokova et al. 2002).
Carbon dioxide, water vapour, heat and momentum fluxes were measured at a height of 8 m 30 × 30 cm solid aluminium tower, from July 11 to October 10, 1998 using the eddy covariance technique (Aubinet et al. 2000).
Power was supplied by a solar panel system (ASE 50-PWX, ASE GmbH, Germany) in combination with a generator (Honda EX 1000, Honda, Tokyo, Japan), which was located at the edge of the wind throw perpendicular to the main wind direction. The generator was only used in situations after more than 2 days in a row of covered sky and in October, when sunlight was not enough to recharge the batteries at the solar system.
Variables & Instruments (exemplary ... not all sites had same instrumentation)
- Eddy covariance - CO2, water vapor, momentum, heat (Gill R3, LI6262-3)
- CO2 measurements - Carbocap CO2-Sensor (GMP343)
- Wind velocity - cup anemometer A100R, Vector Instruments
- Air pressure - pressure transmitter PTB101B, Vaisala
- Air temperature and humidity - temperature-humidity-sensor HMP35D, Vaisala
- Precipitation - heated tipping bucket rain gauge, Young
- Net radiation - pyradiometer LXG055, Dr Lange
- Photosynthetically active radiation - photosynthetic photon flux density (PPFD)sensor LI-190SA, LiCor Inc.
- Net global radiation or albedo - pyranometer CM 14, Kipp and Zonen
- Soil moisture - soil moisture probes ML-2x, DeltaT
- Soil heat flux at 8 postions in 5 cm depth - soil heat flux plates HP3/CN3, Rimco
- Meteorological data - datalogger Dl 3000, Delta-T
- Flux data - notebook
- Profile - datalogger CR23X and CR10X, Campbell Scientific
Knohl, Alexander : Kohlendioxid-, Wasserdampf- und Wärmeaustausch eines durch Windwurf gestörten Waldökosystems in der west-russischen Taiga. - Jena : Max-Planck-Institut für Biogeochemie, 1999
Knohl, A., Kolle, O., Minayeva, T. Y., Milyukova, I. M., Vygodskaya, N. N., Foken, T., Schulze, E.-D. (2002). Carbon dioxide exchange of a Russian boreal forest after disturbance by wind throw. Global Change Biology, 8(3), 231-246.
Lafont, S., Kergoat, L., Dedieu, G., Chevillard, A., Karstens, U., Kolle, O. (2002). Spatial and temporal variability of land CO2 fluxes estimated with remote sensing and analysis data over western Eurasia. Tellus, Series B - Chemical and Physical Meteorology, 54(5), 820-833
Langendörfer, U., Cuntz, M., Ciais, P., Peylin, P., Bariac, T., Milyukova, I., Kolle, O., Naegler, T., Levin, I. (2002). Modelling of biospheric CO2 gross fluxes via oxygen isotopes in a spruce forest canopy: a 222Rn calibrated box model approach. Tellus, Series B - Chemical and Physical Meteorology, 54(5), 476-496
Kurbatova, J., Arneth, A., Vygodskaya, N. N., Kolle, O., Varlargin, A. V., Milyukova, I. M., Tchebakova, N. M., Schulze, E.-D. (2002). Comparative ecosystem-atmosphere exchange of energy and mass in a European Russian and a central Siberian bog I. Interseasonal and interannual variability of energy and latent heat fluxes during the snowfree period. Tellus, Series B - Chemical and Physical Meteorology, 54(5), 497-513.
Milyukova, I. M., Kolle, O., Varlagin, A. V., Vygodskaya, N. N., Schulze, E.-D., Lloyd, J. (2002). Carbon balance of a southern taiga spruce stand in European Russia. Tellus, Series B - Chemical and Physical Meteorology, 54(5), 429-442
Ramonet, M., Ciais, P., Nepomniachii, I., Sidorov, K., Neubert, R. E. M., Langendörfer, U., Picard, D., Kazan, V., Biraud, S., Gusti, M., Kolle, O., Schulze, E.-D., Lloyd, J. (2002). Three years of aircraft-based trace gas measurements over the Fyodorovskoye southern taiga forest, 300 km north-west of Moscow. Tellus, Series B - Chemical and Physical Meteorology, 54(5), 713-734.
Schulze, E.-D., Lloyd, J., Kelliher, F. M., Wirth, C., Rebmann, C., Lühker, B., Mund, M., Knohl, A., Milyukova, I. M., Schulze, W., Ziegler, W., Varlagin, A. B., Sogachev, A. F., Valentini, R., Dore, S., Grigoriev, S., Kolle, O., Panfyorov, M. I., Tchebakova, N., Vygodskaya, N. N. (1999). Productivity of forests in the Eurosiberian boreal region and their potential to act as a carbon sink - a synthesis. Global Change Biology, 5(6), 703-722.
Schulze, E.-D., Vygodskaya, N. N., Tchebakova, N. M., Czimczik, C. I., Kozlov, D. N., Lloyd, J., Mollicone, D., Parfenova, E., Sidorov, K. N., Varlagin, A. V., Wirth, C. (2002). The Eurosiberian Transect: an introduction to the experimental region. Tellus, Series B - Chemical and Physical Meteorology, 54(5), 421-428.
Wirth, C., Schulze, E.-D., Lloyd, J., Kelliher, F. M., Rebmann, C., Lühker, B., Vygodskaya, N. N., Schulze, W., Ziegler, W., Milukova, I., Valentini, R., Sogachev, A., Varlagin, A., Panfyorov, M., Grigoriev, S., Kusnetzova, W., Zimmermann, R. (1998). Productivity and carbon sink capacity of russian boreal forests.International workshop: Ecological and economic problems in the woodlands of Russia.