In ecology textbooks prior to the 1970s, Aldo Leopold's classic story of predator control, over-population of deer, and habitat degradation on the Kaibab Plateau during the 1920s epitomized predator regulation of herbivore populations. However, the story disappeared from texts in the late 20th century after several papers noted uncertainties in estimations of the deer population and provided alternative explanations. We re-examined the case study by determining the age structure of aspen (Populus tremuloides Michx.) on the plateau. Aspen comprises the majority of deer browse in the summer, and the absence of a normal cohort of aspen from the 1920s would indicate deer over-population. The number of aspen (at 1.4 m) dating to the 1920s [...]
