부산대학교 도서관

EWALD (Folia Geobot. 38: 357--366, 2003, this issue) stated that in Central Europe the number of calcifrequent species is higher than the number of acidofrequent species, while the range of acidofrequent communities is larger than that of the calcifrequent ones. All the explanations considered in his paper are based on an evolutionary spatial and temporal scale. In this paper we are trying to prove that local effects might also be important. Five open rock grassland communities on different bedrocks, viz. rhyolite (acidic), andesite (slightly acidic), calcareous sandstone (slightly calcareous), limestone (calcareous) and dolomite (calcareous) were chosen for the analysis. Two parameters of the species-area curve (i.e., local richness and the slope of log area-species richness line) were estimated based on all species and on rock specialist species separately. With this method we could simultaneously study three attributes of diversity: local species number, the slope of log area-species richness line, and species pool size. We found that the size of the regional species pool is determined by local effects through local richness (slopes do not differ significantly). Consequently, in this case weathering is a more important characteristic for bedrocks than the Ca 2+ content. The extremely high number of rock species on dolomite is also determined by local effects; the fine, continuously changing pattern of microhabitats makes the role of competition weaker. The slope of log area-species richness line, calculated for the rock specialist species is unambiguously higher on the calcareous grasslands. The difference can be explained by the smaller species pool on acidic rocks caused by the lower speciation ability. This is supported by the fact that the endemic species of dry habitats are concentrated on the calcareous ones. One possible explanation for the lower speciation ability could be that adaptation to acidic habitats is more difficult than to calcareous ones.... [ABSTRACT FROM AUTHOR]