Ultraviolet absorbance of methanolic leaf extracts of three forest floor species of beech forests in temperate zones were studied along an elevational gradient. Forest floor plants are exposed to differing levels of stress from UV-B radiation depending on the ecological niche they occupy. As expected, there were clear differences in the concentration of UV absorbing pigments in leaves along an elevational gradient between the spring geophyte exposed to full radiation and the species growing in forest shade after frondescing. With A. nemorosa there was a qualitative and quantitative variation in the absorption of methanolic leaf extracts in the UV-B radiation range. The correlation between the absorption at 280 and 320nm and the elevation of the sampling points was statistically highly significant. There was no variation in the absorption of methanolic flower extracts along the elevational gradient studied. The degree of absorption in flower extracts was higher in the UV-B radiation range than that in the leaf extracts. With both S. fuchsii and V. myrtillus , no correlation was established between the absorption in the methanolic leaf extracts from the shaded plants and the elevation of the sampling points. The study of plants from sunlit sites showed that a pigment synthesis can also be induced with S. fuchsii and V. myrtillus as a result of a greater sunlight exposure and consequently UV-B radiation. The leaves of sunlit plants showed a consistently higher absorption in the UV-B radiation range than the leaves of plants from shaded sites of the same elevation. Whilst with S. fuchsii the absorption at 280nm of sunlit leaves increased with the elevation of the sampling points, with V. myrtillus no correlation could be established between the absorption in the UV-B radiation range and the elevation of the sampling sites.
Archives of Nature Conservation and Landscape Research
Volume 41, 2002 - Issue 2