Vegetation-environment relationships in dry calcareous grassland
2005
Janisova, M.(Slovak Academy of Sciences, Bratislava (Slovak Republic). Institute of Botany)
Relationships between dry grassland vegetation and environmental factors were investigated at a small scale. Dry calcareous grasslands of Festucetalia valesiacae were studied in Povazsky Inovec Mts (western Slovakia). Species frequency data were collected on a transect located in south-north direction across the ridge so that the vegetation of southern slope, the top plateau and northern slope was involved. Nine environmental factors were measured in basic sample units including topographic, pedological and biological characteristics. Three main environmental factors were found to be responsible for differentiation of the studied vegetation types, intensity of solar irradiation playing the crucial role among them. The second most important factor was soil depth, and the slope had also a significant effect. The complex environmental factor indicated as xericity can be characterized as a gradient of increasing solar irradiation, pH, and soil skeleton content and decreasing content of both humus and fine soil particles. In analysis of the southern slope after excluding the role of aspect data set variation was explained mostly by soil properties: soil depth, humus content and pH. On the northern slope the most important factors were solar irradiation followed by soil depth. The effect of environmental variables upon cryptogams and phanerogams seems to be different. As expected, the vascular plants were controlled by the same factors that were confirmed to be relevant for the whole species set: solar irradiation, soil depth and slope. In cryptogams, solar irradiation plays obviously a minor role and soil properties together with the vegetation cover seem to be the limiting factors affecting their distribution.
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