Effects of elevated UV-B radiation on UV-absorbing pigments and leaf anatomy of a sedge, Eriophorum russeolum

Long-term effects of elevated ultraviolet-B (UV-B) on the sedge Eriophorum russeolum were studied in a subarctic fen at Sodankyla in northern Finland for three consecutive growing seasons (2003-2005). Supplemental UV-B exposure (63%, 37% and 21% above ambient in 2003,2004 and 2005, respectively) was conducted using fluorescent UV-lamps. The experimental plots were divided into three treatments (n = 10): ambient control, UV-A control and elevated UV-B. Elevated UV-B transiently increased the amount of cell-wall bound UV-absorbing pigments in E. russeolum leaves during the first exposure year, but the concentrations of soluble UV-absorbing compounds, total chlorophyll and carotenoids were not affected. Enhanced UV-B did not affect the leaf anatomy or senescence of E. russeolum. Additionally, there were no changes in carbon or nitrogen content and decomposition rate of E. russeolum leaves. These results show that E. russeolum responds to elevated UV-B radiation primarily by producing UV-absorbing compounds. Hence, projected UV-B radiation levels in the near future will not reduce vitality of E. russeolum.