Colonisation of Spartina on a tidal water divide, Danish Wadden Sea

The spread of Spartina on a tidal water divide has been followed in subsequent aerial photos. Spartina first appeared in the area in 1964, it spread rapidly to 1976. From 1976 to 1988 a significant die-back is observed. This die-back was more than recovered in 1995. Apart from the tidal range, no single physical factor (number of storm surges, rise in mean sea level, temperature) in itself appears to account for the spread. The die-back period had a number of cold winters, which points to the role of ice in the Spartina die-back. Spartina may establish at levels of+0.16 m DNN. Coherent Spartina vegetation cover is observed at +0.30 to +0.40 m DNN on the tidal water divide. In comparison with the local tidal range, possible future planting of Spartina in salt marsh management strategies should take place at levels, which are inundated no more than 5 hours per tidal cycle.