Welche Interaktionen bestehen zwischen den beiden Halophyten Spergularia media (L.) C. Presl und Suaeda maritima (L.) Dumort. ?

Abstract

Landschulz, C.: Are there interactions between the two halophytes Spergularia media (L.) C. Presl and Suaeda maritima (L.) Dumort.? – Hercynia N.F. 42 (2009): 69–91.Man-made inland salt marshes which are the result of the potash industry have become more and more important as a habitat for rare or endangered species whose habitat has been the erroding primary costal and inland salt marshes. The aim of this study was to analyse the reasons for the community composition of the both endangered halophytes Spergularia media and Suaeda maritima. Their occurrence at a secondary inland salt marsh at the potash dump in Teutschenthal-Bahnhof was investigated. Thereby the growth of both objective species and soil characteristics were studied. According to the topographic conditions the study area was divided in dry low-saline habitats and wet high-saline habitats. Soil samples were taken to determine the following edaphic factors: conductivity, soil moisture content, pH and concentration of Na+, K+, Ca2+, Mg2+, SO4 2-, Cl- and CO3 2-. The occurrence of Spergularia media and Suaeda maritima were compared with these soil characteristics. On the other hand both halophytes were placed together in a competition experiment in the greenhouse to examine if the two species interact. By using two different types of soil, a saline and non saline one, the effects of different salinity on the growth and interactions between Spergularia media and Suaeda maritima were investigated. The results of the competition experiment as well as of the investigation in the field have shown no explicit indices of interspecific competition between Spergularia media and Suaeda maritima. In fact both species have their specific niche which allows them undisturbed growing within the same micro-habitat. The most important variables which explained the occurrence of both halophytes within salt marsh communities seemed to be the salinity and the soil moisture content. Interestingly at the greenhouse experiment Spergularia media and Suaeda maritima had the best growth with non-saline soil although in literature both species are often classified as obligatory halophytes. These category problems show the need of phrasing uniform criteria for the classification of halophytes to the types “optional” and “obligatory”.