Pests and diseases are an existential threat to trees in forests and woodlands. There is, therefore, a pressing need to use ecological and bioeconomic models to inform forest managers on control and mitigation strategies. For example, the incidence of Dothistroma needle blight in the UK has increased rapidly since the 1990s, and it is a significant threat to the productivity of commercial forestry. Climatic changes are expected to exacerbate this problem further. Control of the disease in the UK primarily focuses on good stand management through pre-commercial thinning; similar practices are widely used in commercial forests worldwide. Forest managers would benefit from evidence on the effectiveness of this precautionary strategy (in comparison to its alternatives) to reduce disease impacts and increase the value extracted from timber. In this paper, we develop a bioeconomic model to determine the economically optimal harvesting regime – in terms of thinning and rotation – of an even-aged plantation under the risk of an invading pest. We extend a Schaefer–Faustmann model to include a compartmental epidemiological system that governs timber growth and disease spread. We analyse a set of management regimes, including the timing of the final clear-felling of the forest and the timing and level of earlier thinning. Thus, in our approach, forest managers decide whether and when to thin and must balance (i) harvesting before infection destroys the timber’s value and (ii) exploiting the forest’s density-dependent growth. We use a sensitivity analysis with respect to the disease spread and impact on the tree dynamics to demonstrate that, in the presence of disease, thinning can significantly improve the net present value of the plantation if applied correctly. Furthermore, if thinning reduces the transmission rate significantly, the priority is to protect the final harvest, and rotations extend while the thinning time shortens. Our study provides a framework to help design appropriate forest management strategies in the presence of disease.

病虫害是对森林和林地树木的生存威胁。因此，迫切需要使用生态和生物经济模型来告知森林管理者控制和缓解策略。例如，英国的 Dothistroma 针叶枯病发生率自 1990 年代以来迅速增加，对商业林业的生产力构成重大威胁。预计气候变化将进一步加剧这一问题。英国对该疾病的控制主要集中在通过商业前疏伐进行良好的林分管理；类似做法广泛用于世界各地的商业林。森林管理者将从这种预防策略（与其替代方案相比）的有效性证据中受益，以减少疾病影响并增加从木材中提取的价值。在本文中，我们开发了一个生物经济学模型，以确定在有入侵害虫风险的情况下，均匀年龄的种植园在间伐和轮作方面的经济最佳收获制度。我们扩展了 Schaefer-Faustmann 模型，以包括一个控制木材生长和疾病传播的分区流行病学系统。我们分析了一套管理制度，包括森林最终皆伐的时间以及早期间伐的时间和水平。因此，在我们的方法中，森林管理者决定是否以及何时进行间伐，并且必须平衡 (i) 在感染破坏木材价值之前采伐和 (ii) 利用森林的密度依赖性生长。我们使用关于疾病传播和对树木动态影响的敏感性分析来证明，在存在疾病的情况下，如果应用得当，间伐可以显着提高种植园的净现值。此外，如果间伐显着降低了传输率，则优先考虑保护最终收获，并在缩短间伐时间的同时延长轮作。我们的研究提供了一个框架，以帮助在存在疾病的情况下设计适当的森林管理策略。