Outdoor supplementation systems for studies of the effects of increased UV-B radiation

Studies of the effects of increases in ultraviolet-B (UV-B) radiation on plants and terrestrial ecosystems have been undertaken using a variety of methods including: controlled-environment cabinets, glasshouses, outdoor filtration and outdoor supplementation using fluorescent UV-B lamps. Outdoor supplementation systems provide a method of study which creates only small alterations to the microclimate and the number of such studies has increased during the past 3 years. These supplementation systems differ in their methods of operation, equipment, UV-B exposure regime and experimental design. This essay surveys the systems currently developed, considers problems associated with their use and discusses these in relation to the interpretation of biological effects.