The pathogen Phytophthora cinnamomi is considered a main driver of Iberian oak decline (IOD), a forest disease which decimates holm oaks (Quercus ilex) and cork oaks (Quercus suber) in a multipurpose, silvo‐pastoral and seminatural ecosystem of 3.1 million hectares in the south‐west of Europe. Little is known about the spatial dynamics of Phytophthora cinnamomi and how forest stand characteristics affect the IOD epidemic. Here, we analyse IOD spread over several decades in one such ecosystem by means of a multilevel approach based on (a) identification of diseased sites via repeated aerial imagery at landscape scale, (b) confirmation by subsampling of soil and roots, and iii) an epidemic model accounting for host population heterogeneities. We use a 'self‐exciting' spatiotemporal point process with two additive risk components: an epidemic component represents the inoculum pressure from nearby disease foci, and a background component describes sporadic disease transmission over larger distances or from unobserved sources. Both risk components are found to increase over time, and a lagged power‐law spatial kernel provides the best fit for the observed disease pattern. We estimate that 49% of the secondary infections triggered by a primary source occur within a distance of 250 m. Our results also highlight the role of density and diversity of the host population; we find that the rate of sporadic infections in silvo‐pastoral systems (dehesas) is lower than in forests, and higher in mixed stands and shrub encroached oak lands than in pure stands. These results have direct implications for IOD management, for example the estimated spatial kernel may guide the definition of suitable target areas for localized control measures and help to quantify their success. Our results also suggest that silviculture treatments aimed at controlling the density and species composition of oak stands, as well as the abundance of shrubs, are crucial to the containment of IOD.

中文翻译：

---

疫霉菌引起的伊比利亚橡树衰落：时空分析纳入了景观尺度上宿主异质性的影响

病原菌Phytophthora cinnamomi被认为是伊比利亚橡树衰落（IOD）的主要驱动力，该疾病在多用途的牧草-牧草和半自然生态系统（占地310万公顷）中摧毁了栎木（Quercus ilex）和软木（Quercus suber）。欧洲西南部。疫霉菌的空间动力学知之甚少以及林分特征如何影响IOD流行。在这里，我们通过一种多层次的方法来分析在一个这样的生态系统中几十年来的IOD分布，该方法基于（a）通过在景观尺度上反复进行的航空影像识别患病地点，（b）通过对土壤和根的二次采样进行确认，以及iii）一个解释宿主种群异质性的流行模型。我们使用具有两个附加风险成分的“自激”时空过程：一个流行成分代表来自附近疾病灶的接种物压力，一个背景成分描述了更大距离或来自未观察到源头的零星疾病传播。发现这两种风险成分都随时间增加，并且滞后幂律空间核为观察到的疾病模式提供了最佳拟合。我们估计，由主要来源触发的继发感染中有49％发生在250 m的距离内。我们的研究结果还强调了东道国人口密度和多样性的作用；我们发现，森林-牧草系统（德赫萨斯州）的零星感染率低于森林，混合林和灌木丛生的橡木林地中的零星感染率高于纯林。这些结果对IOD管理具有直接的影响，例如，估计的空间核可指导局部控制措施的合适目标区域的定义，并有助于量化其成功。我们的研究结果还表明，旨在控制橡树林密度和物种组成以及灌木丰度的造林处理对于控制IOD至关重要。