白榆(Ulmus pumila,Linn.)是我区的主要乡土树种,栽培历史悠久,现尚有保存百年以上的大树。由于生长快,材质好,适应性强等,因而已成为我区营造用材林,防护林,水土保持林及四旁绿化的主要速生树种之一。但因过去对白榆良种工作缺乏认识,不重视种源和优良母树选择,盲目大量调种,致使树种良劣不齐,林木生长不良或变为“小老 Ulmus pumila (Linn.) Is the main indigenous species in our district. It has a long history of cultivation and now there are large trees preserved for more than 100 years. Due to its rapid growth, good material and strong adaptability, it has become one of the major fast-growing tree species in our region to create timber forests, shelterbelts, soil and water conservation forests and greening on all sides. However, due to the lack of understanding of the elm seeds work in the past, they did not attach importance to the selection of provenances and good parent trees and blindly adjusted them in a large amount. As a result, the tree species were in poor condition and the tree growth was poor or became "