In this study, the effect of pine mistletoe (Viscum album subsp. austriacum) on basal area increment of Crimean pine and Scots pine was investigated. Dendrochronological data were collected from 223 (71 uninfected and 152 infected) Crimean pines and 195 (77 uninfected and 118 infected) Scots pines located in Kastamonu province of Turkey in 2014. Infected sample trees were classified as light, moderate or severe infection levels. Growth trends and basal area increment loses were compared between uninfected and infected trees for the periods of the last 10, 20 and 30 years. In addition, infection status of forest stands was investigated using temporary sample plots; 27 plots in Crimean pine stands and 26 plots in Scots pine. Results demonstrated that basal area increments were negatively affected by pine mistletoe for both species. Mean basal area increment losses of infected trees for the last decade were determined as 24% for Scots pine and 26% for Crimean pine. Basal area increment losses varied by infection levels (light, moderate and severe) as follows: 25%, 20% and 28% for Scots pines and 20%, 32% and 9% for Crimean pines. Scots pine stands were more severely infected by pine mistletoe than Crimean pine stands. There were negative correlations between number of infected trees and stand density for both species, while positive correlation was detected between the number of infected trees and mean diameter for Scots pine. The results of this study indicate that the pine mistletoe infection has negative effect on radial growth of Scots pine and Crimean pine trees. The results can be an important contribution to the forest management and protection activities in mistletoe-infected stands.

中文翻译：

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松槲寄生（Viscum album subsp. austriacum）对土耳其苏格兰松和克里米亚松生长的影响

在这项研究中，松槲寄生 ( Viscum album subsp. austriacum)的作用)对克里米亚松和樟子松的断面积增量进行了调查。2014 年，从位于土耳其卡斯塔莫努省的 223 棵（71 棵未感染和 152 棵感染）克里米亚松和 195 棵（77 棵未感染和 118 棵感染）欧洲赤松收集了树木年代学数据。感染的样本树分为轻度、中度或重度感染水平。比较了过去 10 年、20 年和 30 年期间未受感染和受感染树木的生长趋势和断面积增量损失。此外，还使用临时样地调查了林分的感染状况；27 块克里米亚松林地块和 26 块苏格兰赤松地块。结果表明，松槲寄生对这两个物种的断面增量都有负面影响。在过去十年中，被感染树木的平均断面积增加损失被确定为苏格兰松 24% 和克里米亚松 26%。基面积增量损失因感染程度（轻度、中度和重度）而异，如下所示：苏格兰松分别为 25%、20% 和 28%，克里米亚松分别为 20%、32% 和 9%。与克里米亚松林相比，苏格兰松林受到松槲寄生的感染更为严重。两个物种的受感染树木数量与林分密度之间存在负相关，而受感染树木数量与欧洲赤松平均直径之间存在正相关。这项研究的结果表明，松槲寄生感染对苏格兰松和克里米亚松树的径向生长有负面影响。