Control of Molinia caerulea by cutting management on sub-alpine grassland

There has been a considerable expansion of Moliniacaerulea after the cessation of cutting management of Nardus stricta sub-alpine grasslands in the Giant Mts. (Krkonoše/Karkonosze/Riesengebirge, the Czech Republic) in the last 50 years. The aim of this study was to investigate whether the reestablishment of traditional management (one cut per year in late July) could reverse Molinia encroachment and help to restore the original Nardus grassland.The cover of Molinia significantly decreased from 79% to 7%, the height of the canopy from 45 to 14 cm, biomass production from 313 to 54 g m−2 and panicle density from 129 to 18/m2 after 6 years of cutting management. During the course of the experiment, no seedlings of Nardus were recorded in mown plots, although Nardus was common in the neighborhood. After Molinia retreat bare ground was partly colonized by Avenella flexuosa and partly remained free of vegetation. No significant effect of cutting management on species richness per 1 m2 was recorded. Cutting significantly decreased K availability in the soil, although the amount of K removed was only 8 g/m2 over 6 years. The N:P, N:K and K:P ratios in the plant biomass were not significantly affected by mowing compared to the unmanaged control, indicating P and K limitation but not N limitation in both treatments.Reestablishment of traditional management (one cut per year in late July) reversed Molinia encroachment but did not increase species richness or restore the original Nardus grassland over 6 years.