【作者】 夏博；

【导师】 骆有庆； 田呈明；

【作者基本信息】 北京林业大学 ， 森林保护学， 2012， 博士

【摘要】 云杉矮槲寄生是多年生半寄生性种子植物,近年来已成为“三江源”地区天然云杉林的毁灭性病害,严重影响了该区的生态环境建设和社会经济的可持续发展。为对云杉矮槲寄生进行科学有效的防控,有必要明确云杉矮槲寄生对寄主的致病特点,分析其在天然云杉林内大面积发生和成灾的影响因子。本文以青海省黄南州麦秀国家森林公园的云杉矮槲寄生为研究对象,通过研究云杉矮槲寄生对青海云杉、紫果云杉的针叶和当年生枝生长的影响,揭示当地云杉林在受云杉矮槲寄生侵染后影响植株生长的限制因子；通过调查云杉矮槲寄生对青海云杉天然林死亡和更新的影响,进一步阐述了云杉矮槲寄生对不同树龄寄主的危害特点；通过大量野外调查,分析影响云杉矮槲寄生大面积发生的因子,并结合云杉矮槲寄生对寄主的危害特点,分析云杉矮槲寄生在当地天然云杉林内的成灾因子；同时在云杉矮槲寄生花期化学防控技术等方面进行了探索研究,取得的主要结果如下：(1)云杉矮槲寄生的侵染导致不同寄主树种(青海云杉和紫果云杉)和不同树龄寄主(成龄和幼龄青海云杉)的针叶与当年生枝的生长量均显著降低(P<0.001);同时导致寄主受侵染枝干上的针叶N浓度和水分利用效率明显降低(P<0.001),这将导致受云杉矮槲寄生侵染寄主的生长受到氮素和水分一定程度的胁迫,本研究推断这将可能增加被侵染寄主在干旱年份里因水分胁迫导致死亡的机率。(2)通过连续3年对固定样地的监测,采用每木调查的方法,研究云杉矮槲寄生对青海云杉天然林林木生长和林分更新的影响,结果表明：与未受云杉矮槲寄生侵染的样地相比,遭受云杉矮槲寄生侵染样地内的成龄和幼龄云杉的死亡率明显更高(P<0.001)；幼龄青海云杉比成龄青海云杉的死亡率更高(35.5% vs.13.6%),前者均由云杉矮槲寄生的侵染所导致,后者则多由云杉矮槲寄生和小蠹虫共同为害所导致。当地优势种小蠹虫(主要是光臀八齿小蠹,东方拟齿小蠹和香格里拉小蠹)对已严重感病青海云杉的为害加速了树体死亡。(3)对样地内的林分郁闭度、林分类型、草本盖度、海拔、坡位、土壤有机质及全氮含量等环境因子,应用主成分分析与多元线性回归的方法建立云杉林分病情指数与各因子的回归方程。结果表明：郁闭度是影响云杉矮槲寄生在云杉林内发生机率和强度的关键因子(与病情指数呈显著负相关,P<0.001)；林分类型与病情指数显著相关(P<0.05),混交林较纯林不易发病,尤其是针阔混交林(云杉和桦树)；云杉植株的平均胸径和病情指数呈正相关(P<0.001)；林地海拔对林分病情指数起正向促进作用(P<0.05)。(4)首次在云杉矮槲寄生开花初期(5月中旬),选用40%乙烯利水剂,50%国光丁酰肼可溶性粉剂,20%国光萘乙酸粉剂和90.8%脱落酸四种植物激素对云杉矮槲寄生花芽进行防除效果试验,结果表明,浓度为1：200的国光丁酰肼可溶性粉剂和20%国光萘乙酸粉剂对云杉矮槲寄生的花芽防除效果分别可达40%和60%；浓度为1000mg/L 90.8%脱落酸使花芽脱落率可达80%以上,但不能够杀死云杉矮槲寄生的花芽；浓度为1：100,1：200和1：400的40%乙烯利水剂均能对云杉矮槲寄生的花芽防除效果达到95%以上,且未对受侵染青海云杉的针叶产生不良影响。本实验选取浓度为1：400的40%乙烯利为最佳化学防治药剂。更多还原

【Abstract】 Arceuthobium sichuanense (H. S. Kiu) Hawksworth & Wiens is a hemiparasite angiosperm that infects Picea crassifolia Kom., Picea purpurea Mast., Picea likiangensis var balfouriana (Rehd.et Wils.) Hilliex ex Slawin and Picea spinulosa (Griff.) henry in Sichuan, Qinghai Province and Xizang Autonomous Region, China, and causes severe damage to spruce forests in Qinghai-Tibet Plateau. For carrying out scientific and efficient control to the spread of dwarf mistletoe(A. sichuanense), it is essential to study the characteristics of A. sichuanense infection on its host trees, and analyze the key inducible factors of its outbreak in Qinghai Province. For revealing the growth limited factors of infected host trees, we evaluated the effects of A. sichuanense infection on needles and current-year shoots of spruce trees (P. crassifolia & P. purpurea); based on the death and regeneration influence of spruce forest by the infection of A. sichuanense, we interpreted the various infection characteristics by A. sichuanense to different ages host trees; depended on the key inducible factors about large area spread of A. sichuanense, we analyzed A. sichuanense outbreak factors in local natural spruce forest; and chemical control of A. sichuanense infection were also studied. The main results were as follows:The most apparent effect of A. sichuanense infection on two species hosts (P. crassifolia and P. purpurea trees) and different ages of hosts (mature and young trees of P. crassifolia) was a significant reduction in needle size and current-year shoot in the infected branches (P< 0.001); and the dwarf mistletoe infection also resulted in a significant decrease in needle N concentration andδ13C value of host trees (P< 0.001), which leaded the host trees growth under water and nitrogen limited in some extent. Furthermore, we inferred that the death of infected host trees may increase in drought years because of the limited water resources.Based on the investigation of 3 years (2008-2010), we researched the dwarf mistletoe infection influence to the death and regeneration of natural spruce forest. Compared to the uninfected spruce stands, there was a significantly higher death rate of spruce trees (mature and young trees of P. crassifolia) in heavily infected spruce stands (P< 0.001). The death rate of young infected trees was higher than that of mature trees (35.5% vs.13.6%), the death of young trees were all resulted from A. sichuanense infection, and the death of mature trees were mostly resulted from dwarf mistletoe infection and bark beetle attack. The local dominant species of bark beetle were Ips nitidus, Pseudips orientalis andⅠ. shangria, and the attack from dominant bark beetle species accelerated the death of heavily infected mature trees by A. sichuanense. The preliminary results showed that spruce trees in the stands severely infected by A. sichuanense were most likely killed associated with the attack from bark beetles.Principle Component Analysis and Regression was applied to evaluate the key environmental factors inducing the large area infection by A. sichuanense on spruce forest. Canopy density was significantly negative correlated with infection index of spruce forest (P< 0.001). A. sichuanense infection was likely emergence in the spruce forest with low canopy density, higher coverage of vegetation and thinner moss layer. DBH of spruce trees was significantly positive correlated with the infection index (P< 0.001). The mixed forest was less susceptible to the infection by A. sichuanense than pure spruce forest, especially the mixed forest by spruces and broad leaf species. There was a positive correlation between the infection index and elevation of study site (P< 0.05). The occurrence of A. sichuanense infection was more frequent in down slope than in middle and upper slope. Soil organic carbon and total nitrogen were both positive correlated with the infection index (P< 0.05).For carrying out scientific and efficient chemical control to the spread of A. sichuanense, four kinds of plant hormones including 40% ethephon aqueous solution,50% daminozide water solution powder,20% 1-naphthylacetic acid dust and 90.8% abscisic acid were applied to the flowering buds of A. sichuanense in May. The 50% daminozide and 20% NAA (diluted 200 fold) killed the flowering buds successfully and the mortality of flowering buds reached more than 40% and 60%, respectively. The 90.8% abscisic acid fell off the flowering buds successfully and the falling rate reached more than 80%, but it can not kill the flowering buds. The results showed that all diluted 40% ethephon (diluted 100,200 and 400 fold) killed the flowering buds successfully and the mortality of flowering buds reached nearly 100%. The 40% ethephon aqueous solution (dilution of 1:400) was the best choice because it was harmless to spruce needles and branches.更多还原