||Björn L O, Callaghan T V, Johnsen I, Lee J A, Manetas
Y, Paul N D, Sonesson M, Wellburn A R, Coop D, Heide-Jørgensen H
S, Gehrke C, Gwynn-Jones D, Johanson U, Kyparissis A, Levizou E, Nikolopoulos
D, Petropoulou Y, Stephanou M. 1997. The effects of UV-B radiation on European
heathland species. Plant Ecol. 128:252-264.
The effects of enhanced UV-B radiation on three examples of European
shrub-dominated vegetation were studied in situ. The experiments were
in High Arctic Greenland, northern Sweden and Greece, and at all sites
investigated the interaction of enhanced UV-B radiation (simulating
a 15% reduction in the ozone layer) with artificially increased precipitation.
The Swedish experiment also involved a study of the interaction between
enhanced UV-B radiation and elevated CO2 (600 ppm). These field studies
were supported by an outdoor controlled environment study in the United
Kingdom involving modulated enhancement of UV-B radiation in combination
with elevated CO2 (700 ppm). Effects of the treatments on plant growth,
morphology, phenology and physiology were measured. The effects observed
were species specific, and included both positive and negative responses
to the treatments. In general the negative responses to UV-B treatments
of up to three growing seasons were small, but inc1uded reductions in
shoot growth and premature leaf senescence. Positive responses included
a marked increase in flowering in some species and a stimulation of
some photosynthetic processes. UV-B treatment enhanced the drought tolerance
of Pinus pinea and Pinus halepensis by increasing leaf cuticle thickness.
In general, there were few interactions between the elevated CO2 and
enhanced UV-B treatments. There was evidence to suggest that although
the negative responses to the treatments were small, damage may be increasing
with time in some long-lived woody perennials. There was also evidence
in the third year of treatments for effects of UV-B on insect herbivory
in Vaccinium species. The experiments point to the necessity for long-term
field investigations to predict the likely ecological consequences of
increasing UV-B radiation.