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

Abstract

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 longlived 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.