Fig. 6. A schematic diagram illustrating the changes in C pools before drying and after the rewetting of the dried soil. The carbon pools and the arrows showing the contribution of each of these C pools to total CO₂ production are conceptual representations of the hypotheses presented in this paper. Carbon pool size, in micrograms of C per gram of soil (µg C g soil^-1)(values not in parentheses), and ¹⁴C enrichment, in becquerels of 14C per gram of C (Bq ¹⁴C g C^-1)(values in parentheses), are indicated for each box. The size and enrichment of each C pool are estimated based on our measurements for the oak soil. The size of each box is equivalent to the estimated size of the carbon pool. We hypothesize that cytoplasmic solutes (indicated by the dashed box) are the major source of C mineralized after rewetting, however, the size and enrichment of this pool could not be directly measured.