Figure 1.
Photographs showing the soil surface colour in crust pieces before (A) and 20 minutes after addition of water (B).
Figure 2.
Pigment concentrations (mg g−1 crust) from the top (<1 mm) and bottom (1–10 mm) layers of crusts (n = 3) after addition of water at different time intervals as analyzed using high performance liquid chromatography (HPLC).
Note that the pigment concentrations at T0 were obtained from extracts of crust pieces directly after wetting.
Figure 3.
Spectral imaging showing the reflectance variation of a crust surface before (A) and 60 minutes after addition of water (B) in vertically and horizontally positioned crust pieces.
Chl a and PC indicate the spectral signals for chlorophyll a and phycocynin absorption, respectively at different time intervals (indicated in hours in the insert) after addition of water (C). The change of these two pigments during a wetting period of 180 minutes is shown (D). The concentration of Chl a showed an increase with time in crust pieces monitored from the top and from the sides (E).
Figure 4.
The percentage of 13C label in the newly synthesized Chl a determined using MALDI-TOF mass spectrometry and the decrease of 13C labeled bicarbonate in the medium (n = 3).
Figure 5.
Net oxygen production and recovery of respiration and photosynthesis was monitored in the wet crust piece using oxygen microsensor measurements.
The time after wetting is indicated at the bottom of each profile. Note that respiration started within 4 minutes and increased up to 13 minutes, after which oxygen was produced via photosynthesis and net oxygen production reached a maximum after 118 minutes. The oxygen profiles did not shift upward and oxygen maxima stayed at the same depth, indicating the absence of upward migration of cyanobacteria.