CO2 fluxes of cryptogamic crusts

SUMMARY The relationship between carbon dioxide exchange of Microcoleus‐ and Scytonema ‐dominated cryptogamic crusts and resaturation time was measured in the laboratory with a modified discrete sampling technique and infrared gas analysis. Maximum net photosynthetic rate of Microcoleus was 187 nmol CO 2 m −2 s −1 and of Scytonema was 111 nmol CO 2 m −2 s −1 for rehydration to 100% soil saturation. Both crust types demonstrated a slow rise in resaturation respiration and took 2 days to become fully active after the (first rehydration to 100% soil saturation after long‐term dryness, and only one day to become active after the second rehydration cycle.