What Tree-Ring Reconstruction Tells Us about Conifer Defoliator Outbreaks

摘要: Our ability to understand the dynamics of forest insect outbreaks is limited by lack long-term data describing temporal and spatial trends outbreaks, size long life span host plants, impracticability manipulative experiments at relevant scales. Population responses can be studied across varying site stand conditions, or for a few years under somewhat controlled circumstances, but it difficult study variability species that outbreak only two three times century. Fortunately, dendrochronology enables us explore decadal- century-scale scales ranging from within-tree continental. Evidence past defoliation identified, dated, sometimes quantified using variation in width morphology annual growth rings trees (Plate 7.1). Mortality events identified dated dating last ring on dead trees, release survivors, postdisturbance recruitment events. Insect distinguished weather other disturbance agents comparing nonhost trees.