The Institute for Biological Problems in the Cryolithozone, Siberian Division of the Russian Academy of Sciences, Yakutsk, and the Vrije Universiteit, Amsterdam (Dep. of Hydrology and Geo-Environmental Sciences) are investigating the carbon and water exchange of taiga and tundra ecosystems in eastern Siberia.

Measurements are using eddy correlation systems and soil flux chambers in a larch/birch forest near Yakutsk (Spasskaya Pad Field Station) and at a tundra site near Chokhurdakh in the Indigyrka lowlands (Kytalyk reserve). From 2004 onwards, this research has been extended with flux chamber measurements of methane fluxes and a survey of active layer thickness and temperature. The aim is to estimate the annual exchange rates and their interannual variability, and to determine the sensitivity to environmental factors of the fluxes. The present flux data show considerable annual variations. The 2005 and 2006 campaign has been funded by the Vrije Universiteit and NWO (Dutch Organization of Scientific Research) and is a continuation of research in the EU TCOS (Terrestrial Carbon Observation System) project. In the fall of 2006 this research is continued for three years as a Darwin Centre for Biogeology project (NWO funded). Cooperation with the Alfred Wegener Institute in Potsdam, operating a research station in the Lena Delta, has been established and resulted in an INTAS grant application. Further grant applications have been submitted (Dutch-Russian Scientific Cooperation Fund) to establish a more permanent research facility at the tundra site that will provide a longer time series of carbon exchange data, hydrology and permafrost dynamics.

In collaboration between the Vrije Universiteit Amsterdam and the Gent University in Belgium (P. Van den Haute and D. Vandenberghe) Optical Stimulated Luminescence dating has been performed on the Late Weichselian (periglacial) coversand series in the southern Netherlands. The timing of aeolian deposition and permafrost degradation has been established. The results will be published in the Journal of Quaternary Science. In addition, the Late Weichselian coversand - loess transition in the southern Netherlands has been sampled for a methodological study to date both sediments that are supposed to be of the same age, as they occur in the same stratigraphical position, and to compare the luminescence properties of the different aeolian sediments.

Jef Vandenberghe (vanj@falw.vu.nl)