<正>删定了接种溃疡病菌（Botryosphaeria dothidea）后两种抗性水平不同的杨树（Populus spp. ）树皮中超氧阴离子（O-2）2过氧化氧（H2O2）、超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）及膜脂过氧化产物丙二醛（MDA）含量的动态变化，分析了杨树与溃疡病菌互作中活性氧（ReactiveOxygel-Species，ROS）的产生、抗氧化酶活性及膜脂过氧化水平的变化规律及与杨树抗病性的关系。结果表明。随接仲时间的延长，两种杨树O2-产生速率和H2O2含量均有上升趋势，抗病杨树毛白杨（P. tolnentosa Cart. ）出现了较明显的“氧化爆发”，感病杨树北京杨（P. beijingen. sisHsu）则不明显；POD活性持续上升，毛白杨的上升幅度大于北京杨的；SOD、CAT活性先上升后下降。北京杨两种酶活性在后期受到的抑制更明显；APX活性则在两种杨树中变化较大。毛白杨的变幅明显比北京杨的大；MDA含量增加，表明“氧化爆发”启动了膜脂过氧化，北京杨在接种后期MDA分量大t幅上升，并且MDA含量与O2-产生速率呈显著正相关。

This paper used daily relative humidity data measured at two meteorological observing stations (an urban site and an open site in the urban forest) during the period of 16 years. The results showed that the annual course and abnormal phenomena of air humidity (i. e. RH) etc. in the urban forest area obeyed the local macroelimate law. The annual mean of the RH in the urban forest site was 2.2 more than that in urban site. The RH difference between two site was distinct, when the RH was minimum at daytime. The urban forest played an important role in supplemental air moisture near the adjacent space.