Anwendung von Feuer zur Pflege und Erhaltung von Heidekraut-Trockenrasen-Komplexen in der Porphyrkuppenlandschaft des unteren Saaletals

Abstract

Klein, S.; Jäger, U. G., Tischew, S.: Use of fire for conservation and regeneration of complexes of heather and dry grasslands in the landscape of porphyry outcrops in the lower Saale-valley. – Hercynia N.F. 42 (2009): 217–238.The effects of controlled fire on a grass-rich dwarf shrub heathland (Calluna vulgaris) were investigated in a landscape of porphyry outcrops characterized by a slightly continental climate. In a field experiment, changes in vegetation structure, diaspore bank as well as the carbon and nitrogen pool in plant biomass and soil were assessed. After six months, the vegetation height on fire treated plots was lower than on control plots. Under field conditions 50 % of the individuals of Calluna vulgaris showed stem base sprouting in the first year after fire application. In the field, a very low and sparse seedling emergence rate was noticed only in the second year after fire. In a greenhouse experiment with standardized soil samples, first seedlings emerged after six months. However, the number of germinated seedlings of Calluna vulgaris was significantly increased by fire application. There was a considerable decrease of the aboveground carbon- and nitrogen pool, but only negligible changes in soil chemistry. The main reason for the moderate regeneration of Calluna vulgaris under field conditions is considered to be the diagnosed overaged of the heather stand (19 years) as well as the intense competition by grasses (Agrostis capillaris, A. vinealis). Furthermore, heather regeneration may be limited by high seedling mortality and reduced vitality of individuals due to climatic constrains (e.g. low precipitation) in the study area. Thus, it is concluded that controlled fire contributes to the regeneration of heather stands by increasing the germination rate of their seed bank and temporarily reducing competition intensity.