Ecological niches of an introduced species Typha laxmannii and native Typha species in Austria.
We studied fruit morphology, germination and growth of juvenile plants and clonal ramets of the non-native species Typha laxmannii and the two common native species Typha angustifolia and Typha latifolia in Lower Austria by means of morphological measurements, germination tests in an environmental test chamber and garden experiments with different water and nutrient levels. The ecological niche of T. laxmannii was close to the niches of the native species T. latifolia and T. angustifolia. All species were light-dependent and quick germinating under suitable conditions. Fruit morphology of T. laxmannii was very similar to that of T. angustifolia, but viability and germination of T. laxmannii were comparable to that of T. latifolia. All three species were profiting from higher water and nutrient levels in the experiments. Only minor advantages or disadvantages of T. laxmannii compared to the native species were detected, hence a direct replacement of them is not expectable. Additional factors like the availability of diaspores in the study area of the Tullnerfeld and Danube valley could be more crucial for the present distribution of T. laxmannii than differences in ecological niches of species themselves.