Recovery of Alpine Plants after a Severe Human Disturbance in the Andes of Central Chile

Abstract

Disturbance is likely to affect multiple life stages and may be most critical in seedling germination and establishment through indirectly affecting soil properties. Following disturbance, plants establish from seeds that either exist on the site or that disperse onto the site. Here, we examined the effects of a 1-year-old severe human disturbance (approx. 1 ha) on alpine vegetation recovery in the Andes of central Chile (33°S, 60°W) at 2800 m a.s.l. during two growing seasons (2006–2007). Particularly, we assessed the effects of soil properties and seed rain on post-disturbance seedling emergence using two sets of denuded slopes of different exposure (south and northwest, respectively) and two appropriate control areas. The disturbed area on the south-facing slope was drier than its respective control, while the opposite was observed on the disturbed area on the northwest-facing slope. The differences in soil water content between both slopes coincided with the results of seedling recruiting. The south-facing slope, with a more humid undisturbed area, showed a greater number of emerging seedlings than the disturbed slope. Conversely, on the northwest-facing slope, the main recruiting of seedlings was observed on the disturbed area, while the undisturbed area showed practically no emergence of new individuals. In addition, our results indicate that seedling recruitment occurred from a persistent seed bank constituted mostly by species with long-lived and deeply viable seeds, though in this particular study, we could not corroborate it empirically. Although long-term studies are desirable to make more definitive conclusions, our results provide the first step to understanding the capacity for vegetation recovery after a severe human disturbance in the Andes of central Chile, where seed banks and soil moisture seem to play a pivotal role.