Critical periods and critical values explaining fluxes inter-annual variability in a temperate mixed forest

In order to explain inter-annual variability of Net Ecosystem CO2 Exchange (NEE) above a mixed temperate forest, two approaches were followed:
•Detection of critical periods using the R-squared of the regression between annual NEE and cumulated NEE on a mobile window.
•Identification of critical values of a threshold used to decompose annual and seasonal NEE in two components.