UV-B and Biosphere

Current phase-out schedules of the production and emission of CFC's indicate that chlorine loading in the stratosphere is not yet at its maximum. The recovery of stratospheric ozone is estimated to take time and ele­ vated levels of UV-B radiation are expected to occur throughout most of the next century. Despite numerous physiological studies of UV-B effects on plants, often grown in climate chambers, knowledge of UV-B effects on organisms and processes in natural aquatic or terrestrial ecosystems is poor. Currently it appears that UV-B radiation is not just an environmental stress' factor to plants. In various ways, which are incompletely understood, UV-B affects a wide range of physiological and ecological processes. Remarkably, recent field studies indicate that enhanced UV-B does not markedly affect photosynthesis, growth and primary production, but rather interferes with plant morphogenesis and plant and ecosystem functions relating to the secondary metabolism. This special issue and book UV-B and Biosphere is an attempt to cover this range and to report the progress made in the research of ecological effects of enhanced solar UV-B radiation. The papers in this book formed the basis of an international workshop entitled' UV-B and Biosphere' , December 15-18, 1995, in Wageningen, The Netherlands. A first reaction of Hans de Boois on the number of papers and sessions scheduled from Friday to Sunday morning was: far too many.

Inhalt

UV-B and Aquatic Ecosystems. 1. UV-B Effects in Aquatic Ecosystems; D.-P. Häder. 2. UV-damage to Plant Life in a Photobiologically Dynamic Environment: The Case of Marine Phytoplankton; W.W.C. Gieskes, A.G.J. Buma. 3. Effects of Acute and Chronic UV-B exposure on a Green Alga: A Continuous Culture Study Using a Computer-Controlled Dynamic Light Regime; A. Veen, et al. 4. Role of Ultraviolet-B Radiation on Bacterioplankton and the Availability of Dissolved Organic Matter; G.J. Herndl, et al. 5. Physiological and Structural Changes in the Chloroplast of the Green Alga Micrasterias denticulata by UV-B Simulation; C. Lütz, et al. UV-B and Terrestrial Ecosystems: General and Methodological Aspects. 6. Uses of Biological Spectral Weighting Functions and the Need of Scaling for the Ozone Reduction Problem; M.M. Caldwell, S.D. Flint. 7. Outdoor Supplementation Systems for Studies of the Effects of Increased UV-B; A.R. McLeod. 8. In Assessing Biological UV-B Effects, Natural Fluctuations of Solar Radiation Should be Taken into Account; R. Santas, et al. UV-B and Physiology of Terrestrial Plants. 9. Beneficial Effects of Enhanced UV-B Radiation under Field Conditions: Improvement of Needle Water Relations and Surviving Capacity of Pinus pinea L. Seedlings During the Dry Mediterranean Summer; Y. Manetas, et al. 10. UV-B Radiation Effects on the Mediterranean Ruderal Dittrichia viscosa; M. Stephanou, V. Manetas. 11. Effects of Solar UV-B Radiation on Growth, Flowering and Yield of Central and Southern European Bush Bean Cultivars (Phaseolus vulgaris L.);M. Saile-Mark, et al. 12. Morphological and Physiological Response of bean Plants to Supplemental UV Radiation in a Mediterranean Climate; F. Antonelli, et al. 13. The Effects of Enhanced UV-B Radiation on Germination and Seedling Development of Plant Species of a Dune Grassland Ecosystem; M. Tosserams, et al. 14. Leaf Thickness and UV-B Absorbing Pigments of Plants in Relation to an Elevational Gradient Along the Blue Mountains, Jamaica; J. Rozema, et al. 15. Reaction of Savanna Plants from Botswana on UV-B Radiation; W.H.O. Ernst, et al. 16. The Impact of Elevated UV-B (280-320 nm) Radiation Levels on the Reproduction Biology of a Highland and Lowland Population of Silene vulgaris. Interactions of UV-B with Environmental Factors. 17. Effects of UV-B Radiation on Terrestrial Plants and Ecosystems: Interaction with CO2 Enrichment; J. Rozema, et al. 18. Effects of Increasing UV-B Radiation and Atmospheric CO2 on Photosynthesis and Growth: Implications for Terrestrial Ecosystems; J.H. Sullivan. 19. The Combined Effects of CO2 and Supplemental UV-B Radiation on Faba Bean: Leaf Optical Properties, Pigments, Stomatal Index and Epidermal Cell Density; A.J. Visser, et al. 20. Effects of Solar Ultraviolet-B Radiation, Temperature and CO2 on Growth and Physiology of Sunflower and Maize Seedlings; U. Mark, M. Tevini. 21. Combined Effects of Enhanced UV-B Radiation and Nitrogen Deficiency on the Growth, Composition and Photosynthesis of Rye (Secale cereale); G. Deckmijn, I. Impens. UV-B and Terrestrial Ecosystems. 22. Effects of Enha