Fig. 3. (a) Mean soil respiration (squares) and mean soil temperature at the 10-cm depth (triangles) (b) predicted gravimetric water contents in the Oi and Oe/Oa horizons, (c) volumetric soil water content at the 5-cm mineral soil depth, and (d) daily precipitation of a mixed deciduous forest at Harvard Forest from June to October 2001. Error bars represent the standard error of mean soil respiration rate (n = 3).