Unexpected Outcomes and Adaptive Restoration in Michoacán, Mexico: A Cautionary Tale from Sites with Complex Disturbance Histories

Abstract

Near the Paricutín volcano in the state of Michoacán, México, agricultural lands were covered with volcanic ash when the volcano erupted multiple times between 1943 and 1952. These lands persist today as barren and mostly devoid of vegetation. Restoration of these lands is limited by high ground surface temperatures during the dry season (close to 70°C at noon) and other factors such as damage by herbivores and storm run-off. We used mulch to overcome the main barrier represented by the high ground surface temperatures, which allowed for the reintroduction of the dominant native pine species. When we did not mulch, and particularly during dry years, pine mortality was close to 100%. This led to the unanticipated consequence of a shrub, hierba de golpe (Eupatorium glabratum), establishing in the sites where the planted trees had died. The shrub, although native, precludes the establishment of other native plant species and creates conditions that are even more of a challenge to restoration. The most efficient measure for restoring sites invaded by hierba de golpe is the elimination of the shrubs and with them the layer of volcanic ash. This case study illustrates the importance of approaching restoration as an adaptive management practice because unexpected outcomes are unavoidable, particularly in sites with complex histories of disturbance.