Figure 4.

The gross behavior in the well watered tree's average hourly water content (black squares) (A) is well correlated with environmental variables such as air temperature (r = −0.93, N = 24, p = 5e–11), relative humidity (r = 0.89, N = 24, p = 9e–9) and PPFD (r = −0.77, N = 24, p = 1e–5, blue squares), showing that the variation in water content is due to the tree responding to its surroundings. In contrast, the small variation in the water content (red squares) for the water limited tree (B) is well correlated with the average hourly temperature changes (blue squares, r = 0.78, N = 24, p = 9e-6) at the detector, since rapid changes in temperature produce a thermal gradient across the sample coil and limit the accuracy of the temperature model. Error bars come from the standard error.