Fecundity and mortality in populations of Salicornia europaea agg. at Skallingen, Denmark

Abstract

Seedlings of the annual, Salicornia europaea (sensu stricto), germinated in the outer marsh sand flats at Skallingen in early May, and the relative growth rates of root and shoot were high during the establishment phase. Mortality of plants, which was not density‐dependent, was greater than 70% in most plots from early May to early October, as a result of wave action, desiccation and the presence of algal mats. Salicornia ramosissima was present in the outer and inner marshes mixed with Puccinellia maritima. Seedling densities of this annual were high, and in early May growth rates were lower than those for Salicornia europaea. Overall mortality of plants from early May to early October was density‐independent. Mortality of S. ramosissima in the inner marsh was only 50% from May to October, whereas the mortality of S. ramosissima in the outer marsh was 95% in the same period.Different levels of seed production per plant, which reflected differences in plant architecture, were evident between the two micro‐species.Reciprocal transplants from the inner marsh failed to survive on the outer marsh sand‐flat. Mean seed production per plant in plants transplanted from the outer marsh sand‐flat to the inner marsh was only 10% of the value of the control populations. The distances of seed dispersal were different in the outer and inner marsh. Low recruitment occurred in areas cleared of Salicornia plants in the inner marsh, unlike the situation in the outer marsh sand‐flat where tides dispersed seed.