“…This method has often been used to understand the impact of environmental variables on the C cycle (see reviews by Brüggemann et al, 2011;Kuzyakov & Gavrichkova, 2010;Mencuccini & Hölttä, 2010), even though recent studies have highlighted the need to deal with confounding effects, which might modify the isotope signal between assimilation and respiration. Such effects include diel variations of δ 13 C in respired CO 2 , postphotosynthetic and respiration fractionation and damping of the 13 C signal as it is transferred below ground (Gessler, Tcherkez, Peuke, Ghashghaie, & Farquhar, 2008;Kodama et al, 2008;Werner & Gessler, 2011). Furthermore, in recent years, biological controls (ontogeny, physiological adaptation to biotic and abiotic environment) have emerged as additional important drivers of short-term C dynamics and its isotope signature (e.g., Bathellier et al, 2008;Ghashghaie & Badeck, 2014;Ghashghaie et al, 2015;Salmon, Barnard, & Buchmann, 2011Salmon, Buchmann, & Barnard, 2016).…”