在东北兴安岭和长白山的林海里,白桦是阔叶树中分布最广、数量最多的一种树木,约占阔叶树种的一半以上。白桦林所以这样繁茂,《魏书》记载说,鲜卑族的祖先原来居住在乌洛侯族的西北,即今天嫩江以西的大兴安岭一带,他们曾在山上“凿石为祖宗之庙”。后来鲜卑族南下,进入中原, Betula platyphylla is one of the most widely distributed and abundant species in broad-leaved trees in the forests of the Hinggan Mountains and Changbai Mountains in northeastern China, accounting for more than half of broadleaf tree species. The birch forest so lush, “Wei” records that Xianbei ancestors lived in the northwestern Ulohur, that is, today’s Nen River west of Daxinganling area, they had in the mountains, “Chisel for the ancestral temple.” Xianbei later south, into the Central Plains,