Monitoring of Carbon Dioxide and Water Vapor Cycles at the “Log Tayozhny” Experimental Site (National Park “Valdaysky”)

Abstract

The "Log Tayozhny" experimental site accounts for 75-year history of hydrologic and environmental studies. Intensive research and monitoring of greenhouse gas fluxes have been initiated at the site at the end of 2000s with the use of eddy covariance and closed chamber techniques. The eddy covariance measurements started in May 2010 and were terminated for technical reasons in August 2011. The evaporation and CO 2 flux exchange were measured over this period. For the calendar year (August 16, 2010 to August 15, 2011), the total evaporation was 324 mm, which comprises 41% of annual precipitation. The southern taiga spruce forest is a sink of atmospheric carbon with net-absorption of about 300 g C m-2 yr-1. However, in 2010, during the abnormally hot summer period, the ecosystem became the source of carbon dioxide. Average threshold temperature for such a switch of carbon balance sign is 28°C.