LONDON (Reuters) - If Santa Claus is in search of extra reindeer this Christmas, he is unlikely to find any of Rudolph's cousins going spare in Scandinavia. Because of a sharp decline in the growth of lichen, the favourite food of reindeer, farmers in Scandinavia have had to reduce their herds, Britain's New Scientist magazine said on Wednesday. This has left Scandinavians facing a Christmas without traditional dishes such as reindeer with potatoes and lingonberry sauce. In Norway and Sweden, reindeer are herded exclusively by the semi-nomadic Sami, or Lapp people, who alone have access to the lichen grazing lands. Lichen growth follows a 20-year cycle and this year is at its lowest point, so the herds have been culled to prevent overgrazing, leaving Scandinavians' demand for reindeer meat far exceeding supply. Sweden has previously imported the meat from Russia's Kola peninsular when domestic stocks are low, but this year the European Union has banned the imports, New Scientist said. It quoted an EU commission spokesman as saying there was too great a risk that the Russian reindeer would carry foot and mouth disease and brucellocis into the EU.