A fundamental question in forest insect ecology is the role of forest landscape structure, particularly the amount and spatial configuration of host tree species, in shaping the dynamics of recurring forest insect outbreaks. For forest tent caterpillar (FTC), independent studies do not converge on a singular conclusion, although all indicate that forest structure influences outbreak dynamics. These studies also vary in how they treat climate as a covariate. We evaluated the relative importance of host forest landscape composition and configuration, as well as climate, for their influence on FTC outbreak cycling in the twentieth century. We predicted that FTC outbreaks would exhibit greater synchrony and intensity within areas associated with higher abundance of host trees. We reconstructed FTC outbreaks from 1928 to 2006 using tree‐ring analysis within a well‐structured experimental landscape located in northwestern Ontario and northern Minnesota. Time‐series clustering and spatial nonparametric covariance were used to determine whether similarities in time series and patterns in spatial synchrony corresponded with land management history. Using constrained ordination, we compared statistical properties of outbreak time series to landscape variables representing host abundance, forest configuration, and climate. We found no evidence of climatic effects at the scale of this study, but a significant albeit small influence of landscape structure on outbreak dynamics. Outbreaks were more synchronous and more cyclic within managed zones containing a greater relative abundance of aspen and other hardwood host tree species, compared with the more conifer‐dominated Wilderness area. Yet, we also observed asynchronous outbreak dynamics across the study area, such that correlations with slower‐changing forest landscape variables varied starkly among outbreak pulses. Consequently, the strength of relationship between landscape variables and FTC outbreak patterns varied strongly through time—a result that may explain why short‐term studies yield conclusions that are at odds with one another. Our results speak to the importance of long time series, contrasting landscape structure, use of multivariate methods, and controlling for climatic variation when investigating the effects of forest landscape structure on the cyclic‐eruptive spatial dynamics for forest defoliators.

中文翻译：

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森林景观结构影响森林帐篷毛虫爆发的周期性喷发空间动态

森林昆虫生态学中的一个基本问题是森林景观结构，尤其是寄主树种的数量和空间构型，在塑造森林昆虫反复发作的动态中的作用。对于森林帐篷毛毛虫（FTC），尽管所有研究都表明森林结构会影响暴发动态，但独立研究并未得出一个单一结论。这些研究在将气候视为协变量的方式上也有所不同。我们评估了东道主森林景观组成和配置以及气候对20世纪FTC爆发周期的影响的相对重要性。我们预测FTC爆发将在与寄主树数量更多相关的区域内表现出更大的同步性和强度。我们使用树木年轮分析在安大略省西北部和明尼苏达州北部结构良好的实验环境中重建了1928年至2006年的FTC暴发。时间序列聚类和空间非参数协方差用于确定时间序列和空间同步模式的相似性是否与土地管理历史相对应。使用约束排序，我们将爆发时间序列的统计属性与代表寄主丰度，森林结构和气候的景观变量进行了比较。在这项研究的范围内，我们没有发现任何气候影响的证据，但是尽管景观结构对暴发动态的影响很小，但影响却很大。与以针叶树为主的荒野地区相比，在受管理的区域内暴发更同步且更具周期性，其中白杨和其他硬木寄主树种的相对丰度更高。但是，我们还观察到整个研究区域的异步暴发动态，因此与暴发脉冲之间变化较慢的森林景观变量的相关性明显不同。因此，景观变量与FTC爆发模式之间的关系强度随时间变化很大-这一结果可以解释为什么短期研究得出的结论彼此矛盾。我们的结果证明了长期序列的重要性，对比景观结构，使用多元方法，