Mires of Tierra del Fuego 1 2 5 4 3 With contributions of: Erwin Adema (RUG) Hans Joosten (Uni-Greifswald) John Couwenberg (Uni-Greifswald) Christiaan Fritz (Uni-Greifswald) Olivier Ogliati (Uni-Greifs.;fotos) Jan Sliva (Uni-Munchen; fotos)
The spring forest Andorra mire The spring forest is situated on thin peat where much groundwater discharges. Shifting groundwater flows create opportunities for trees at one site, but may drown trees somewhere else. Strong winds can easily put these trees down.
The spring area Andorra mire The original spring mire could have looked like this, showing spring water coming in and proceeding through the fen peat to the river. Such a mire is extremely sensitive to erosion of inflowing surface water. The results of the German students show that the spring fen was later blocked by the bog expansion.
The bog margin Andorra mire The bog has a small lagg zone and sometimes small rivulets are formed. Both have low values in EC (ca. 40 µS/cm). Only the rivulets that cross the bog have higher values of about 130 µS/cm 40 40 130 7m
Hans Joosten made a boring in this Sphagnum and Astelia pumila vegetation: under the Sphagnum was over 60 cm of Sphagnum peat, while under the Astelia was 60 cm of Astelia peat, followed by Sphagnum peat. Apparently competition between Sphagnum magallanicum and Astelia can be a stable state for hundreds of years. In most situations Astelia is pushing Sphagnum back to the pool EC = 126
In many pools algae appear to be dominant. The algae may compete with Sphagnum magellanicum for nutrients and CO2. EC values are always higher in the algae soup. Further research on the competition for CO2 and nutrients would be very interesting ( Sphagnum , Astelia and Algae ). If the algae win, this could explain the lack of accumulation in the pools (over 50 cm deep). Moat mires
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