A key lesson is the importance of "biological legacies"—fallen trees, buried roots, seeds, gophers, amphibians—that survived the blast, thanks to snow cover, topography, or luck. Ecologists had assumed rebirth would happen from the outside in, as species from border areas encroached on the blast zone. But recovery has also come from within. Starting with a single plant Crisafulli discovered in 1981 on the barren, 3,750-acre expanse known as the Pumice Plain, purple prairie lupines became the first color in a world of sterile gray. In life they were nutrient factories, food for insects, habitat for mice and voles; in death they, and the organisms they attracted, enriched the ash, allowing other species to colonize. Gradually the blast zone began to bloom.
(image credit: Diane Cook and Len Jenshel)