“…Based on our previous findings of links between ET and thermal regime in the studied fens (Volik, Kessel, et al, 2020), we hypothesized that WUE is strongly related to net radiation (Qnet) and interannual WUE variability results from the interaction among thermal and moisture conditions. Since elevated electrical conductivity has a negative effect on plant productivity (Volik et al, 2018, 2019, 2021) and ET (Phillips et al, 2016; Volik, Kessel, et al, 2020), we hypothesized that WUE was significantly lower at a saline fen compared to freshwater fens. In addition, natural disturbances (i.e., wildfire) could affect WUE as a negative effect of wildfire on ET was observed (Volik, Kessel, et al, 2020).…”