2011年4月7日讯,目前河北省林业外来有害生物已达193种,对森林生态系统的功能和结构产生了不良影响,特别是对生物多样性构成了威胁。过去5年,河北省林业有害生物年均发生面积达4.46万hm2,去年更是达到了57.8万hm2,年均增加约4万hm2。美国白蛾、春尺蠖等常发性有害生物危害加剧,天幕毛虫、舞毒蛾等偶发性有害生物暴发周期缩短。特 April 7, 2011 China’s Hebei Province forestry now has 193 alien species of pests, affecting the function and structure of forest ecosystems, especially threatening biodiversity. In the past five years, the average annual area of ​​forest pests in Hebei Province has reached 44,600 hm2, reaching 578,000 hm2 last year and an average annual increase of about 40,000 hm2. American white moth, spring scale 常 and other pests of habitual increased aggravating, celestial caterpillars, gypsy moth and other occasional pest outbreak cycle shortened. special