Trafalgar Square death, and the square did not open until 1844. The Nelson's Column at its centre is guarded by four lion statues. A number of commemorative statues and sculptures occupy the square, but the Fourth Plinth, left empty since 1840, has been host to contemporary art since 1999. The square has been used for community gatherings and political demonstrations, including Bloody Sunday in 1887, the culmination of the first Aldermaston March, anti-war protests, and campaigns against climate change. A Christmas tree has been donated to the square by Norway since 1947 and is erected for twelve days before and after Christmas
Christmas tree cultivation urine samples. The average Christmas tree receives roughly a half of an ounce (14 g) of pesticide over its lifetime. The BBC's "Gardening" website called buying Christmas trees directly from the farm, "the most environmentally friendly way of getting a tree". Other positive environmental attributes have been given live Christmas trees as well. Researchers at the University of Nebraska included the reuse of natural Christmas trees as mulch and, in larger quantities, piled up as soil erosion barriers, among the benefits of live tree use. Other positive reuses included fish habitat in private ponds and backyard bird feeders. Since 2004,