【摘要】 对渭北高原及陕北高原的一些林分进行次生林改造。经模型和ANOVA分析证明:改造后,林木被害程度随定植年限的变化总体遵从Logistic模型。其中,全面清坡模式林木被害程度最高,林下更新模式最低。鼢鼠对油松、侧柏和刺槐的危害年限依次为林木定植后11、9和6年,其中油松定植2～6年,侧柏1～4年,刺槐1～2年被害最严重。单个鼢鼠对油松和刺槐的危害强度主要取决于林木的定植年限,与改造模式和林地鼢鼠密度关系不大;而对侧柏的危害强度不仅取决于林木定植年限,也与林地鼢鼠密度和改造模式密切相关。林木定植年限和单个鼢鼠的危害强度是影响林木被害死亡率的关键因素,林地鼢鼠密度和改造模式是主要因素。更多还原

【Abstract】 By using the model and ANOVA analysis,the result proved that the varieties of forests damaged degree with planted ages were in accord with logistic model,after improvement of secondary forests on loess plateau.In woodland by using over-all felling,the forests damaged degree was most,using reforestation,the forests damaged degree was lowest.The ages of Chinese pine,Chinese arborvitae and Silver chain damaged by zokors were ordinal planted 11 years,9 years and 6 years.On Chinese pine by planted from 2th year to 6th year,Chinese arborvitae from first year to 4th year and Silver chain from first year to 2 year,the forests damaged degree was the most.The damaged degree,individual zokor did harm to Chinese pine and Silver chain,primarily depended on planted ages,not depended on improvement pattern and zokor density.The damaged degree of Chinese arborvitae not only depended on planted ages,but also depended on improvement pattern and zokor density.The planted ages and the harm degree of individual zokor were key factors to influence forest damaged mortality,the zokor density and the improvement pattern were main factors.更多还原