Leaf phenology of three dominant limestone grassland plants matching the disturbance regime

Question: Does interspecific variation in leaf phenology among Grassland species help to explain the differences in species' performance under contrasting disturbance regimes. Location: Merishausen, northern Switzerland. Methods: Seasonal variations in leaf production and mortality were assessed for three species of nutrient-poor limestone Grasslands: Brachypodium pinnatum, Bromus erectus and Salvia pratensis; each of these species tends to become dominant under a contrasting form of management. Their phenological characteristics were compared with their performance in plots differently managed for 21 years: (1) mowing in July; (2) mowing in October; (3) controlled burning in February; and (4) no biomass removal. Results: The species-specific phenological patterns of leaf production and leaf mortality are associated with the abundance of the three species under the different management regimes. B. erectus, with relatively short-lived leaves and leaf production late in the season dominates plots mown annually in June; it has almost disappeared from plots with winter burning. B. pinnatum, with production maxima of the long-lived leaves early in the season, does not tolerate June mowing but is most abundant in plots burnt in winter when the species has no living leaves. S. pratensis, a species with long-lived leaves but fast senescence of all the leaves in autumn, dominates plots mown in October. In unmown plots, all species are equally abundant. Conclusions: The seasonal pattern of leaf production and mortality strongly influence biomass and nutrient loss due to the management, and the growth that can be realized between the disturbances. A species may become dominant if it 'fits' into the particular management regime, whereas a mismatch between phenological pattern and disturbance regime leads to its elimination from the community.