B. Papp szerk.: Studia Botanica Hungarica 37. 2006 (Budapest, 2006)

Dobolyi, Konstantin: Study of the population dynamics of Linum dolomiticum Borbás (Linaceae)

lying population sizes, assessing and following up on the status of endangered species and their likelihood of survival and/or extinction. In the framework of this monitoring project the mapping of the total distribution area of Linum dolomiticum was made in 2001 and 2004 at a scale of 1 : 200 (DOBOLYI 2001, 2004). Purpose of this mapping was to follow up on the changes of at least 0.5 m in diameter of the Linum dolomiticum patches. The narrowly endemic Linum dolomiticum has only one population, situated in a region of 1 km

2 in the Buda Hills near Pilisszentiván (Hungary). It consists of several stands separated by closed forest. Characteristic habitat of this species is open and closed dolomite rock grasslands (DOBOLYI 2003a, 2005c/). The spatial pattern of the distribution of Linum dolomiticum is not homogenous, i.e. the individuals do not occur randomly on the ground, but usually form groups and patches of size of 0.01-3 m

2 (DOBOLYI 2004). Although the total area of distribution is standing under nature protection, Linum dolomiticum is considered to be an endangered species (HORVÁTH et al. 1995). Important threatening factors are tourism, several kinds of sport activity (first of all cross-country motorbiking) and spontaneous spreading of the introduced black pine (Pinus nigra) plantations through its upcoming seedlings. Since dynamic processes have a crucial role in the survival of endangered species, the process of distribution mapping was coupled with a survey of the population dynamics of Linum dolomiticum between 2001 and 2005. The purpose of this complex study was: - to determine the size of the population; - to follow up on the change of the number of individuals; - to establish the rate of the new and the extinct individuals; - to determine the seed production; - to make observations on the spreading and reproduction strategy. In this paper I present a summary of the results of this five-year demographic and monitoring study. MATERIAL AND METHODS A sample area of 64 m

2 was marked in the field for following up on the individual changes, consisting of 16 sample squares (size of 2 m x 2 m), which are marked by numbered iron pegs. Linum dolomiticum individuals were localised by a net of hole size of 10 cm x 10 cm stretched on the sample squares and a map of the individuals was outlined at a scale of 1 to 14 in 2001 (DOBOLYI 2001). Exact number of the individuals was determined in the sample area by counting. (According to DNS studies, average size of individuals is 5-15 cm (MAJOR and DOBOLYI 2006). Mapping of the individuals was repeated in 2003 and 2005 with the same method as was made in 2001 (DOBOLYI 2003b, 2005b). Maps made in 2001, 2003 and 2005 were projected to each other to determine the changes of the indi-