Based on 5-year data of monthly sum of GPP and ET, Fig. 4
shows that the seasonal pattern of WUE was not evident, similar to the results reported by Jones (1992) for wheat and barley,
Reichstein et al. (2007) for Mediterranean evergreen forests, Jassal
et al. (2009) for Douglas fir and Brümmer et al. (2012) for a coniferous
forest.