ABSTRACT
The radiation from the sun is, in many ways, beneficial to the biosphere. Photosynthesis is, in a way, the start of all biochemistry and other life processes. Before biological evolution began, solar radiation, and especially ultraviolet radiation, played an important role in the chemical evolution leading to the appearance of life. Solar Ultraviolet-B (UV-B) radiation is attenuated by naturally fluctuating levels of stratospheric ozone, which occurs mainly at heights of 17–30 km. Mechanisms enabling organisms to cope with UV-B radiation are important to living cells and any processes leading to damage or impairment of these mechanisms need to be carefully evaluated. Stratospheric ozone absorbs most solar UV-B and all solar Ultraviolet-C radiation emitted from the sun. Many effects of UV-B on plants, especially at the lower levels encountered in the Arctic, can be regarded as photomorphogenesis, i.e. regulation of plant development by radiation, rather than damage.
