Bark beetle outbreaks and forest fires have imposed severe ecological damage and caused billions of dollars in lost resources in recent decades. The impact of such combined disturbances is projected to become more severe, especially as climate change takes its toll on forest ecosystems in the coming years. Here, we investigate the impact of multiple disturbances in a demographically heterogeneous tree population, using an age-structured difference equation model of bark beetle outbreaks and forest fires. We identify two dynamical regimes for beetle and fire dynamics. The model predicts that fire helps dampen beetle outbreaks not only by removing host trees but also by altering the demographic structure of forest stands. We show that a stand thinning protocol, which reduces the population size of the largest few juvenile classes by a small percentage, is able to significantly reduce beetle-induced tree mortality. Our research demonstrates one approach to capturing compound disturbances in a mathematical model.

近几十年来，树皮甲虫的爆发和森林大火造成了严重的生态破坏，并造成数十亿美元的资源损失。预计这种联合干扰的影响将变得更加严重，尤其是在未来几年气候变化对森林生态系统造成损害的情况下。在这里，我们使用树皮甲虫爆发和森林火灾的年龄结构差异方程模型研究了多种干扰对人口统计学异质树种群的影响。我们确定了甲虫和火动力学的两种动力学机制。该模型预测，火灾不仅可以通过清除寄主树木，还可以通过改变森林林分的人口结构来帮助抑制甲虫的爆发。我们展示了一个立式细化协议，这将最大的少数幼虫类的种群规模减少了一小部分，能够显着降低甲虫引起的树木死亡率。我们的研究展示了一种在数学模型中捕获复合干扰的方法。