engleski

Biogeographical processes of species-rich Mediterranean grasslands (Scorzonero- Crysopogonetalia): case study of Ćićarija (Croatia)

It is widely discussed how landscape fragmentation affects floristic richness. The effects vary in time and might depend on the specific character of vegetation. Many previous studies in habitats occupied by plants of low dispersal ability (e.g. forests or wetlands) recognized fragmentation as a major cause of biodiversity decline. This is a great ecological problem especially in Europe, where traditional land use change is being observed. Influence of landscape fragmentation on grassland vegetation is poorly recognized as dispersal abilities of plants inhabiting these ecosystems vary significantly. Landscape fragmentation effects on biodiversity should be also analyzed at different scales. Scorzonero-Crysopogonetalia is one of the most common Mediterranean grasslands community and of great environmental and economic interest. The aim of this study is to examine whether abundance and plant species distribution in grasslands of Ćićarija (Croatia) change significantly in relation to management (pasture /meadow, extensive management /abandonment) and topographic variables. Vegetation sampling was performed in 98 plots of 10x10 meter in 49 patches (Braun-Blanquet method, 1964). The size of every isolated grassland patch was estimated on the basis of available orthophotomaps. Parameters describing shape and spatial distribution of the patches (landscape metrics) were calculated on the basis of vector data using Quantum GIS and FRAGSTATS software. Ortophotomaps and field measurements were used to estimate distances to the nearest patch of the same type (nearest neighbor distance). Examined grassland types (Carici humilis- Centaureetum rupestris Horvat 1931 (pastures) and Brachypodium rupestre variant (abandoned sites), meadows Danthonio-Scorzoneretum villosae Horvat & Horvatić in Horvatić 1958, abandoned meadows Anthoxantho-Brometum erecti Poldini 1980 are dependant on management and isolation therefore the availability of plants. Plant communities composition is especially related to landscape parameters such as: MPS, ED and MPFD. Conservation probably should rather be focused on larger fragments of grasslands, which potentially can provide conditions for a higher number of plants. In practice identification of isolated small patches that cannot be colonized from neighboring areas is important for conservation practices. Management should also be focused on increasing the connectivity between larger sized grassland patches.

Mediterranean grasslands; Scorzonero-Chrysopogonetalia; Biogeographical processes; Ćićarija

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