4.3 | Weak thermal acclimation response of respiration
Consistent with most previous studies, dark respiration increased exponentially, leading to high rates of CO2 loss at high temperature. Treatment plants had lower temperature sensitivity of respiration (indicative of Type I acclimation, Atkin & Tjoelker 2003; Slot & Kitajima 2015). Nonetheless, thermal acclimation of respiration was moderate, with limited adjustment of AcclimTset and no indication of homeostasis. While growth at elevated temperature tends to reduce respiration (Atkin & Tjoelker 2003; Slot & Kitajima 2015), growth at elevated CO2 tends to increase respiration (Leakey et al. 2009). As with stomatal responses, the patterns we observed represent the balance of responses to elevated temperature and doubling of CO2, and consistent with Dusenge et al. (2020), the responses to temperature seemingly stronger than the responses to CO2.