Morphologische und ökologische Grundlagen der Vorlandsicherung durchPuccinellia maritima (Gramineae)

Abstract

Investigations on the influence of daylength, light intensity, inundation and accretion tolerance on the morphological and ecological characteristics ofPuccinellia maritima in connection with the role of increasing salinity and temperature (results of former investigations) lead to a deeper understanding of the role this species plays in land reclamation and preservation of coastal areas. The results obtained indicate that the species exhibits a temperature — related seasonal dimorphism with short-stem growth at daylengths up to about 12 h light/day (vernal and autumnal types, caespitose growth) and a long-stem growth at daylength of about 16 h and more light/day (aestival type, stoloniferous growth). Increasing salinity (above 10‰ S) and inundation with artificial sea water (25‰ S) reduce stem and leave development. Accretion of long-stems with sand +3% peat-mixture up to 30 cm yields in 5‰ S further development of runners under long-day conditions and longation of short-stems (up to 10 cm) up to the new soil-surface level. Three shortstem types and two long-stem types can be distinguished. These results explain the natural responses of the species, the forming of the Puccinellietum maritimae within the allogene succession and its role in land preservation. The species is a facultative halophyte which occupies, due to competition from other species, the lower part of its inundation amplitude, utilising its high-salt tolerance. Its aestival long-stem and its autumnal/vernal short-stem production increases the sedimentation rate of soil particles during inundation; the following accretion leads to an elongation of short-stems up to the new soil level, and to an increased production of adventitious roots; the latter results in soil fixation.