对来自广西壮族自治区、云南省共计25个县(市)的381株西南桦优树的子代林进行了幼树期(2年生)的高生长性状选择。结果表明:在参试的381个家系中,幼树期高生长超过对照的优良家系有186个,占参试家系数的48.8%,其中Ⅰ级优良家系有63个,Ⅱ级优良家系有85个,Ⅲ级优良家系有38个;淘汰了195个家系,占参试家系数的51.2%,为评选适于云南热区的西南桦良种提供了阶段性依据。 381 trees of Betula alnoides from Guangxi Zhuang Autonomous Region and Yunnan Province were selected for their high growth traits in sapling (2 years old). The results showed that among the 381 tested families, there were 186 elite families with high growth height over the control in the sapling stage, accounting for 48.8% of the total, of which 63 were excellent in grade Ⅰ and 85 were rated as excellent in grade Ⅱ There were 38 elite families of Grade III, 195 families were eliminated, accounting for 51.2% of the coefficient of the test elite, which provided a staged basis for the selection of elite species of Betula alnoides in Yunnan hot zone.