Fast and slow advances toward a deeper integration of theory and empiricism.

In this article, we present a modern commentary on Ludwig, Jones, and Holling's classic paper, "Qualitative analysis of insect outbreak systems: the spruce budworm and forest," published in the Journal of Animal Ecology in 1978. In contrast to papers that become classics for advancing one big idea, Ludwig et al.'s contribution is striking for its breadth of impact. It has become a foundational reference in areas as disparate as insect ecology and management, alternative stable states, the effects of natural enemies, and the separation of time scales between fast- and slow-changing variables. Interestingly, the paper is not generally remembered as an attempt to bridge the divide between theoretical and empirical ecologists, as we will show, even though this is how the authors motivated their work. In this commentary, we examine the expected and unexpected ways Ludwig et al. (J Anim Ecol 47:315–332, 1978) have found a place in modern ecological thought. [ABSTRACT FROM AUTHOR]