Regeneration of Nardus stricta subalpine grasslands in the Giant Mountains (Krkonoše)

The origin of Nardus stricta dominated subalpine grassland (Nardo-Caricion rigidae alliance) is a frequently discussed topic in the Giant Mountains (Karkonosze in the Czech Republic). Many researchers considered them, as secondary stands arisen after Pinus mugo removal and by consequent oligotrophization of original plant communities, caused by long-term rough grazing and hay making activities without manuring. On the contrary, they are recognized as natural due to inability of generative reproduction of N. stricta and the very slow vegetative spread there. The aim of this study was to find proofs for generative reproduction of mat grass in subalpine conditions of the Giant Mountains. We identified a Pinus mugo nursery with arable land abandoned in 1956 and compared its vegetation with that of the surrounding area. Dense and homogenous sward dominated by N. stricta developed during the succession on the old arable land for 48 years, and it is an indisputable proof of generative reproduction of N. stricta there. Synthesizing historical facts on human activities in the past and the results of our contemporary vegetation analysis, we conclude that the Nardo-Caricion rigidae grassland was capable to spread relatively quickly, when agricultural activities above the upper timber line were introduced.