Rate of establishment and seasonal immersion of Spartina in Mariager Fjord, Denmark

Spartina (Sp. × townsendii H. & J. Groves and Sp. anglica Hubbard) was introduced in Mariager Fjord in 1948. The present study of a 154 ha sample area is based partly on topographic mapping and partly on photogrammetric plotting. The total area covered with vegetation was almost constant 1.0 × 10⁵ m² from 1945 to 1959. Spartina was planted in the study area in 1959, and spread rapidly. In 1978 the vegetation covered an area of 2.1 × 10⁵ m². It is suggested that this very high rate of establishment could be due to seasonal fluctuations in water levels. As the sea level is often low in spring, the sample area can be dry for up to 9 d at a stretch. This allows the roots to become anchored in the sand.