PhD ceremony Ms. R.M. Veeneklaas: Adaptation and dispersal of native invasive salt-marsh species Elytrigia atherica

PhD ceremony: Ms. R.M. Veeneklaas, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Adaptation and dispersal of native invasive salt-marsh species Elytrigia atherica

Promotor(s): prof. J.B. Bakker, prof. R. Bijlsma

Faculty: Mathematics and Natural Sciences

In the past decades the native species Elytrigia atherica has rapidly spread on the salt marshes along the Wadden Sea coast, which led to monospecific stands of grass and low biodiversity. The rapid spread of E. atherica on mainland and back-barrier marshes is mainly a consequence of succession, concluded Roos Veeneklaas. At young successional stages the incidence of E. atherica is restricted to the high marsh. In time of succession E. atherica gradually spreads to lower elevation of the salt marsh. But additionally, in time of succession, the incidence of E. atherica decreases on the salt marshes far from the sea, due to decrease of sediment input and accelerated sea level rise. Dispersal through seedlings and rhizomes are both important in the rapid spread of E. atherica. At young successional stages and lower salt marshes E. atherica establishes through seedlings. Successful seedling establishment is strongly related to suitable abiotic and biotic factors, such as gaps and nutrient availability. Once successfully established as a seedling the spread of E. atherica can occur through rhizomes and rapidly out compete other species. E. atherica can spread and invade clonally from high marsh to lower marsh, or spread clonally as an isolate patch on a lower marsh.

When abiotic conditions, namely inundation frequency and drainage, are optimal for E. atherica, this species can dominate the marsh within a few years. But when drainage conditions decrease, as a result of succession, maintenance or climate change, E. atherica will disappear, as this species does not like ‘wet feet’.