Plant Traits of Phalaris Arundinacea and Phragmites Australis – Examining Effects of Water Level, Salinity, and Soil Types in a Mesocosm Experiment

Knowledge about the distribution of species along rivers and estuaries is the basis for decisions in nature conservation, but also for nature-based coastal and shore protection. Along rivers and estuaries, abiotic conditions affect plant traits, especially close to the marsh edge, and thus determine the distribution of plant species. Phragmites australis and Phalaris arundinacea occur along the German Elbe in the inland river and in the estuary, but the distribution of both species is locally and regionally inhomogeneous. We therefore simulated abiotic conditions of respective Elbe sections in a mesocosm experiment and investigated the influence of soil type, salinity, water level, and plant provenance on plant traits of P. australis and P. arundinacea. We compared growth-related and mechanical plant traits of both species. Productivity of P. arundinacea was less affected by sandy soil than that of P. australis. P. australis was insensitive to salinity and water level fluctuations, while traits of P. arundinacea responded to these factors. Furthermore, mechanical properties within a species were mainly dependent on plant growth. P. arundinacea was more flexible than P. australis, which can be attributed to morphological differences and differences in plant tissue. Plant provenance did not affect the response of plant traits to abiotic conditions. Our study provides clues for understanding the distribution patterns of P. australis and P. arundinacea.