白榆(U lmus Pumi ld L.)是北温带落叶乔木,原产亚洲东北部的中国、苏联、蒙古、朝鲜等国,大体分布于北纬32～53度,东经74～134度。我国白榆分布面积约占世界白榆的3/4以上,是华北、东北、西北及长江以北广大地区主要的造林用材树种。白榆具有速生、材质好、抗逆性强、尤其耐干旱、耐脊薄特性,是宁夏山川防护林、用材林和四旁绿化的优良乡土树种,造 Ulmus pumi ld L. is a north temperate deciduous tree native to Northeast China, China, the Soviet Union, Mongolia and North Korea. It is generally distributed between 32 and 53 degrees north latitude and 74 to 134 degrees east longitude. White elm distribution area accounts for about 3/4 of the world elm, is North China, northeast, northwest and vast areas north of the Yangtze River afforestation timber species. White elm with fast-growing, good material, strong resistance, especially drought-resistant, ridge-resistant features, is Ningxia mountains shelterbelts, timber and greening around the fine native tree species, made