At the beginning of the rain exclusion experiment the mean root respiration rates per g root dry mass (Fig. 5a) were similar across plots, in the range 4.3–6.6 nmol CO2 g 1 s 1. During the last 3 wk of rain exclusion, the mean root respiration decreased to 3.7–4.8 nmol CO2 g 1 s 1 which was significantly lower (P = 0.002) compared with the control plots (4.3–
6.6 nmol CO2 g 1 s 1). The temperature sensitivity of root