Population Dynamics and Within-Tussock-Succession in a Carex sempervirens Subalpine Grassland in the Swiss Alps

Abstract

Tussock-forming graminoids play an important role in high-altitude grasslands. In tussocks many other plant species can grow, forming small communities. However, little is known about such small-scale vegetation, especially dur- ing succession. In an abandoned subalpine pasture in the Swiss National Park, we studied population dynamics and within-tussock vegetation of Carex sempervirens in four successional grassland stages (i.e. early, young, mature and se- nescent) distinguished at community level. At population level, we observed a succession process encompassing both di- rectional and cyclic elements. In agreement with a decrease in grazing pressure and tussock vitality, similarity of the vege- tation within tussocks decreased from the early to the senescent stage. Within-tussock vegetation of the early stage was more similar to that of the young stage than to that of the mature and the senescent stage. Fuzzy ordination revealed a similar pathway of succession in C. sempervirens tussocks as observed at community level. We conclude that succes- sional transition from grassland to forest may encompass more than one C. sempervirens cycle and with each cycle floris- tic composition both inside and outside C. sempervirens tussocks will become more similar to the subsequent forest stage.