Abstract

In May 2008, Chaitén volcano entered an eruptive process, leading to one ofthe world’s largest eruptions in recent decades. The magnitude of tephra ejected by theeruption left different types of disturbances and caused diverse forms of environmentaldamage that were heterogeneously distributed across the surrounding area. We went tothe field to assess the early vegetation responses a year after the eruption in September2009. We evaluated the lateral-blast disturbance zone. We distributed a set of plots in threedisturbed sites and one in an undisturbed site. In each of these sites, in a rectangular plotof 1000 m2, we marked all standing trees, recording whether they were alive, resprouting,or dead. Additionally, in each site of 80 small plots (~4 m2), we tallied the regeneratedplants, their coverage, and the log volume. We described whether the plant regenerationwas occurring on a mineral or organic substrate (i.e., ash or leaf litter, respectively). In theblast zone, the eruption created a gradient of disturbance. Close to the crater, we foundhigh levels of devastation marked by no surviving species, scarcely standing-dead treesand logs, and no tree regeneration. At the other extreme end of the disturbance zone, thetrees with damaged crowns were resprouting, small plants were regrowing, and seedlingswere more dispersed. The main form of regeneration was the resprouting of trunks orburied roots; additionally, a few seedlings were observed in the small plots and elsewherein disturbed areas. The results suggest that the early stages of succession are shaped by lifehistory traits like dispersion syndrome and regeneration strategy (i.e., vegetative), as wasfound after other volcanic eruptions. Likewise, the distribution of biological legacies, whichis related to disturbance intensity, can cause certain species traits to thrive. For instance, inthe blow-down zone, surviving species were chiefly those dispersed by the wind, while inthe standing-dead zone, survivors were those dispersed by frugivorous birds. Additionally,we suggest that disturbance intensity variations are related to the elevation gradient. Thevarying intensities of disturbance further contribute to these ecological dynamics. The earlysuccession in the blast zone of Chaitén volcano is influenced by the interaction betweenspecies-specific life history, altitudinal gradient, and biological legacies. Further studies arerequired to observe the current successional patterns that occur directly in the blast zoneand compare these results with those obtained following other volcanic disturbances.