Summary 0The relationship between size and~oristic composition of the seed bank and veg! etation dynamics was studied between 0865 and 0885 in 9[64 ha of an abandoned Cirsietum rivularis meadow[ The plot was divided into 099!m 1 "09 × 09 m# quadrats and sampled 4!yearly to map the vegetation and determine the soil seed bank[

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The crystal structures of [C(NH 2 ) 3 ] 3 [Sb 2 Br 9 ] (Gu 3 Sb 2 Br 9 ) at 300 K and of [C(NH 2 ) 3 ] 3 [Sb 2 Cl 9 ] (Gu 3 Sb 2 Cl 9 ) at 90 and 300 K are determined. The compounds crystallize in the monoclinic space group: C2/c. The structure is composed of Sb 2 X 3− 9 (X = Cl, Br) ions, which form two-dimensional layers through the crystal, and guanidinium cations. In Gu 3 Sb 2 Br 9 the structural phase transformation of the first-order type is detected at 435/450 K (on cooling/heating) by the DSC and dilatometric techniques. The dielectric relaxation process in the frequency range between 75 kHz and 5 MHz over the low temperature phase indicates reorientations of weakly distorted guanidinium cations. The proton 1 H NMR second-moment and spin-lattice relaxation time, T 1 , temperature runs for the polycrystalline Gu 3 Sb 2 Br 9 sample indicate a complex cation motion. A significant dynamical non-equivalence of two guanidinium cations was found. The possible mechanism of the phase transition in Gu 3 Sb 2 Br 9 is discussed on the basis of the results presented.

The objective of the study was to describe the life-history pattern of the biennial species Cirsium palustre. It has been demonstrated that under optimum conditions in the greenhouse individuals live 1.5 to 2 years, in a mown meadow 2 to 3 years, and during the plant succession in abandoned meadows they prolong their life to several years. This is accompanied by a gradual decrease of C. palustre population size. A relationship between the life-history pattern differences during a plant succession and the population abundance dynamics has been found. Reproductive-phase age is correlated with the rosette size. In spite of the occurrence of many limiting factors during a succession (closed plant cover, shading by macroforbs, willows) C. palustre survives until the formation of forest communities. Its persistence is favoured by: protracted life history, attainment the reproductive phase at different ages (not only in the second year), formation of a permanent seed bank, air-borne seeds and the emergence and survival of seedlings under the canopy of several-year old rosettes during a strong competition. The arresting of juvenile individuals under the rosettes for several years has been termed the "rosette mechanism". Cirsium palustre can be included among facultative biennials. In every conditions a proportion of individuals in a population attain the flowering phase in life year 2. During a succession the proportions of "triennial" and "quadriennial" forms, and at the terminal stage - of perennial monocarpic forms increase