hrvatski

Loss of grassland habitats in Mediterranean parts of Croatia - an example on altitudinal gradient from littoral to subalpine belt

Change in lifestyles and economy in majority of Mediterranean countries includes abandonment of traditional cattle-breeding and agriculture. This causes change of grassland habitats and their succession to climazonal vegetation, which is almost regularly forest vegetation. To trace these changes, grasslands and their remnants from all altitudinal belts were researched. Evergreen vegetation belt (alliance Quercion ilicis) was researched on the island of Molat, while southern slopes of the Mt. Velebit and area of Danilo and Pokrovnik (in the hinterland of the town Šibenik) as representatives of different altitudinal belts of deciduous vegetation (alliances Quercion pubescentis and Fagion sylvaticae). Eumediterranean belt of evergreen vegetation has the largest loss of biodiversity caused by succession of grassland vegetation toward macchias. Ratio of species richness on grasslands and closed macchias is app. 6:1, with almost complete loss of herbaceous species, especially therophytes. The real loss of biodiversity is even larger when it is considered that majority of endemic species are herbaceous species of the open habitats. The very same process occurs in the vegetation belts of deciduous zone, but it is relatively slower and, it does not result in so dense and dark shrubblands. Therefore, maintenance of larger number of species is allowed, but the general physiognomy of landscape is strongly changed. Beside the common tree species characteristic for alliance Quercion pubescentis, Juniperus oxycedrus can occur with very high abundance and form very dense evergreen shrubberies, which have biodiversity loss similar to those in evergreen belt. In this zone grasslands used as pastures were spread on large areas. Very strong degradation of soil, steep slopes and exposition to wind have slowed the succession. On the other side, grasslands used as meadows are developed on deeper soils and almost flat terrains protected from wind. Such position allows more rapid succession especially when main tree species is Pinus nigra. The belt above 1200 m a.s.l. belongs to the alliance Fagion. Thin layer of soil, strong influence of wind and relatively shorter growing season do not allow as much as rapid succession as in lower altitudes, but here it occurs by grow of dense, procumbent shrubs Arctostaphyllos uva-ursi, Juniperus nana and J. sabina, which also change composition of grassland communities although the general physiognomy seems unchanged. The processes of succession and habitat change which lead to loss of open grasslands are one of the main processes in vegetation dynamics in all vegetation belts in Mediterranean parts of Croatia. In spite that this process in each belt has different velocity and that different species are included, it leads to loss of biodiversity on species, habitat and landscape level.

grassland; Mediterranean; habitat loss; plant biodiversity

nije evidentirano

engleski

Loss of grassland habitats in Mediterranean parts of Croatia - an example on altitudinal gradient from littoral to subalpine belt

Change in lifestyles and economy in majority of Mediterranean countries includes abandonment of traditional cattle-breeding and agriculture. This causes change of grassland habitats and their succession to climazonal vegetation, which is almost regularly forest vegetation. To trace these changes, grasslands and their remnants from all altitudinal belts were researched. Evergreen vegetation belt (alliance Quercion ilicis) was researched on the island of Molat, while southern slopes of the Mt. Velebit and area of Danilo and Pokrovnik (in the hinterland of the town Šibenik) as representatives of different altitudinal belts of deciduous vegetation (alliances Quercion pubescentis and Fagion sylvaticae). Eumediterranean belt of evergreen vegetation has the largest loss of biodiversity caused by succession of grassland vegetation toward macchias. Ratio of species richness on grasslands and closed macchias is app. 6:1, with almost complete loss of herbaceous species, especially therophytes. The real loss of biodiversity is even larger when it is considered that majority of endemic species are herbaceous species of the open habitats. The very same process occurs in the vegetation belts of deciduous zone, but it is relatively slower and, it does not result in so dense and dark shrubblands. Therefore, maintenance of larger number of species is allowed, but the general physiognomy of landscape is strongly changed. Beside the common tree species characteristic for alliance Quercion pubescentis, Juniperus oxycedrus can occur with very high abundance and form very dense evergreen shrubberies, which have biodiversity loss similar to those in evergreen belt. In this zone grasslands used as pastures were spread on large areas. Very strong degradation of soil, steep slopes and exposition to wind have slowed the succession. On the other side, grasslands used as meadows are developed on deeper soils and almost flat terrains protected from wind. Such position allows more rapid succession especially when main tree species is Pinus nigra. The belt above 1200 m a.s.l. belongs to the alliance Fagion. Thin layer of soil, strong influence of wind and relatively shorter growing season do not allow as much as rapid succession as in lower altitudes, but here it occurs by grow of dense, procumbent shrubs Arctostaphyllos uva-ursi, Juniperus nana and J. sabina, which also change composition of grassland communities although the general physiognomy seems unchanged. The processes of succession and habitat change which lead to loss of open grasslands are one of the main processes in vegetation dynamics in all vegetation belts in Mediterranean parts of Croatia. In spite that this process in each belt has different velocity and that different species are included, it leads to loss of biodiversity on species, habitat and landscape level.

grassland; Mediterranean; habitat loss; plant biodiversity

nije evidentirano