Diversity of bryophytes in show caves in Slovenia and relation to light intensities

Abstract

In subterranean environments phototrophic organisms can grow only in the proximity of light sources. In a study from eight Slovenian show caves: Črna jama, Kostanjeviška jama, Krška jama, Pekel pri Zalogu, Pivka jama, Postojnska jama, Škocjanske jame, Županova jama and two mines, Idrija mer­cury mine and Mežica lead and zinc mine, equipped for tourist visits, 37 taxa of Bryophyta and Pteridophyta were identified. The most frequent organisms were mosses Amblystegium ser­pens, Brachythecium sp., Eucladium verticillatum and Fissidens taxifolius. The highest diversity of bryophytes was recorded in Mežica mine with16 identified taxa where lamps are on con­tinuously. Bryophytes were collected at wide range of photo­synthetic photon flux densities (PPFD) from 0.2 to 530.0 μmol photons/m2/s. Eucladium verticillatum had the highest span of PPFDs, ranging from 1.4 to 530.0 μmol photons/m2/s. Bryo­phytes compensate for low PPFD withlonger exposure to light irradiance. Cratoneuron filicinum identified in Mežica mine de­veloped sporophytes at 2.1 and 2.4 μmol photons/m2/s, in Post­ojnska jama Brachythecium salebrosum developed sporophytes at 4.7 μmol photons/m2/s. Recolonization of lampenflora in show caves where bleachis applied to prevent its growthis still successful at sites that are exposed to long periods of irradiance and highPPFDs.