Establishment of grassland species in monocultures: different strategies lead to success.

The establishment pattern of monocultures of 61 species common to Central European semi-natural grasslands was analysed in a field experiment. The objectives were to identify key traits for successful establishment, defined in terms of above-ground biomass production, and to characterize the degree of niche overlap with respect to the use of above-ground resources, such as light and space. Four months after sowing, 15 species reached an above-ground biomass of more than 400 g m(-2). Highly productive monocultures adopted extremely different strategies of space filling in terms of canopy height, biomass density and centre of gravity of vertical biomass distribution. Regression tree analysis identified (1) the number of seedlings and (2) a trade-off between the development of a large number of small-sized shoots of species with intensive clonal growth in contrast to the establishment of fewer large-sized shoots as the two most important traits for successful establishment. Further variables associated with high above-ground biomass production by individual species were traits known to be relevant to the relative growth rate of herbaceous species, such as specific leaf area, leaf nitrogen or allocation between shoots and roots. The principle finding of this study is that the success of the 15 most productive species was not based on a single pathway but on a variable combination of traits. There are clearly many possible combinations of morphological and physiological features that will result in a species becoming productive, and these combinations differ among species in a local species pool.