Forest Ecosystem Carbon Fluxes After Stand-Replacing Disturbance

A large area of Estonian hemiboreal forest is recovering from clear-cut harvesting and reflecting carbon (C) balance of the stand. Such a stand-replacing disturbance have considerable impact on forest ecosystems carbon dynamics, turning ecosystems from C-sinks into C-sources. Stands may require several years for recovery to C-sink status. For better understanding of net ecosystem CO2 exchange (NEE) we used eddy covariance (EC) method. EC technique gives opportunity to measure NEE in two different aged stands (6- and 8-year old stands), which are located in south-east Estonia, Europe. Studied stands which already were 6- and 8-years old, were acting as a light C-sinks. Mean summertime (June to September) measured NEE of both stands for 2014 was -1.536 u00b5mol m-2 s-1. In June, July, August and September NEE was -4.671, -2.254, -0.739 and -0.236 u00b5mol m-2 s-1, respectively. Measured mean CO2 concentration was 337.75 ppm and mean temperature was 15u00b0 C.Stands had similar patterns of carbon exchange and results showed clear correlation between C fluxes and ecosystem responses to environmental conditions. Weather conditions played a key role in the rapid rise in NEE results. NEE result was driven primarily by early-growing-season temperature and length. Meteorological data confirm ecosystem also depends on climate variability and water vapor.