Article

Astragalus peterfii lav., a narrow endemie species, currently occurs in on ly 2 close localities and has been classified as endangered and/or rare in different Romanian and European red lists of plants. The goal of this study has been the evaluation of differences in terms of resource allocation between two populations located in contrasting habitats (near-closed meadows, within the Suatu 1 Natural Reserve and open vegetation on eroded soils) and the influence of community structure on the distribution pattern of ramets. The Astragalus ramets from the eroded, open lands invest much resource in vegetative regeneration by sprouting, but are fonned of small shoots. On the contrary, the ramets developed in near-close grasslands tend to produce taller shoots, more flowers and a larger proportion of fertile shoots, whereas a trade-off is reached by minimizing the resource investment in vegetati ve reproduction (growth of new shoots). The spatial aggregation of ramets is probably a consequence of both vegetati ve spreading and short-range dispersal of seeds. The differences in scale of aggregation detected along a coenocline from Stipa-rich grasslands (Stipion lessingianae) to Carex humilis-dominated lawns (Festuca rupicalae-Caricetum humilis) are due to a dramatic decline in ramets density. This observed pattern along with the negative correlation between the cover values of A. peterfii and C. humilis support the hypothesis that the forrner species multiplication is inhibited in closedsod lawns dominated by the latter species. The population of A. peterfii settled in Stipa-rich grasslands reaches the highest levels of ramet density, fertility and fitness, probably because of the gaps occurring among the large grass tussocks. In order to get a genetically vigorous population of A. peterfii, the reserve manàgement planning must take into consideration the maintenance ofthe slightly open Stipa communities.