Untersuchungen zur Populationsdynamik von Senecio jacobaea und anderer Senecio-Arten Studies on the population dynamics of Senecio jacobaea and other Senecio species

A longterm experiment was carried out on two extensive grassland areas to examine the development and the spreading patterns of Senecio jacobaea, Senecio aquaticus, Senecio erucifolius and Senecio inaequidens. For this purpose, 80 plants of the four different species were planted on both experimental sites. The Intensity of cultivation in the areas varied regarding different cutting treatments. The cut crop was generally worn. Periodically number and state of development of Senecio plants were determined. By the end of 2012, the species Senecio aquaticus and Senecio inaequidens could no longer be detected on the two experimental plots and only some very few, last plants form Senecio erucifolius were found. In contrast, Senecio jacobaea plants first declined considerably by 2012 to about 40% of the initinal plant density and then in beginning of 2013 a distinct increase by seedling was assessed, so that the initial planting density was exceeded. From summer 2013, therefore, the scheme of the experimental design was changed with the aim to displace Senecio jacobaea from the area. In order to avoid the blossom of the plants, 3 or more cuts were carried out. In addition, a fertilization treatment was introduced in order to increase the competitiveness of the grasses. A positive impact of these measures was already detected in 2014 by a partial decline in Senecio jacobea density.