Fig. 2.

Dynamics of water-soluble carbohydrates in root tissues and of ¹³C in soil-respired CO₂ and microbial biomass before and after the rainfall event. (A) The ratio of root-soluble sugars between trees from naturally dry nonirrigated and irrigated plots before as well as 3 d and 2 wk after the rainfall event. The data for the time before the rainfall event were taken from ref. 25, where root samples were collected during a dry period in summer. (B and C) The temporal course of ¹³C in the soil CO₂ flux in the nonirrigated and irrigated plots after pulse labeling (at t = 0 d) before and after the rainfall event. (D and E) The ¹³C incorporation into soil microbial biomass (on a m² soil surface basis) in the nonirrigated and irrigated plots labeled before or after the rainfall event. Error bars indicate SD in A and SE in B to E. The asterisk in A indicates significant differences at P < 0.05 according to Student’s t test (n = 3). n.s., not significant.