Spatial synchrony between populations emerges from endogenous and exogenous processes, such as intra- and interspecific interactions and abiotic factors. Understanding factors contributing to synchronous population dynamics help to better understand what determines abundance of a species. This study focuses on spatial and temporal dynamics in the Eurasian red squirrel (Sciurus vulgaris) using snow-track data from Finland from 29 years. We disentangled the effects of bottom-up and top-down forces as well as environmental factors on population dynamics with a spatiotemporally explicit Bayesian hierarchical approach. We found red squirrel abundance to be positively associated with both the abundance of Norway spruce (Picea abies) cones and the predators, the pine marten (Martes martes) and the northern goshawk (Accipiter gentilis), probably due to shared habitat preferences. The results suggest that red squirrel populations are synchronized over remarkably large distances, on a scale of hundreds of kilometres, and that this synchrony is mainly driven by similarly spatially autocorrelated spruce cone crop. Our research demonstrates how a bottom-up effect can drive spatial synchrony in consumer populations on a very large scale of hundreds of kilometres, and also how an explicit spatiotemporal approach can improve model performance for fluctuating populations.

中文翻译：

---

由下而上效应驱动的红松鼠种群的大规模空间同步。

种群之间的空间同步来自内源性和外源性过程，例如种内和种间相互作用以及非生物因素。了解有助于同步种群动态的因素有助于更好地了解决定物种丰富度的因素。这项研究使用来自29年的芬兰的雪迹数据，重点研究了欧亚红松鼠（Sciurus vulgaris）的时空动态。我们使用时空上明确的贝叶斯分层方法，解决了自上而下和自上而下的作用力以及环境因素对人口动态的影响。我们发现红松鼠的丰度与挪威云杉（Picea abies）球果和捕食者，松貂（Martes martes）和北部苍鹰（Accipiter gentilis）的丰度呈正相关，可能是由于共同的栖息地偏好。结果表明，红松鼠种群在数百公里的范围内以非常长的距离同步，并且这种同步主要是由空间上自相关的云杉球果作物驱动的。我们的研究表明，自下而上的效应如何能够在数百公里的非常大的规模上推动消费者群体的空间同步，以及明确的时空方法如何改善波动群体的模型性能。