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

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 during 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 senescent) distinguished at community level. At population level, we observed a succession process encompassing both directional and cyclic elements. In agreement with a decrease in grazing pressure and tussock vitality, similarity of the vegetation 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 successional transition from grassland to forest may encompass more than one C. sempervirens cycle and with each cycle floristic composition both inside and outside C. sempervirens tussocks will become more similar to the subsequent forest stage.