The correct answer is many of the initial pioneering species actually survived the eruptions.
The salvage of ecosystems at Mount Saint Helens did not follow the usual patterns as anticipated. One unanticipated discovery, which surprised scientists was that many plant and animal species actually subsisted the eruption incidents.
Some trees were protected from the blast by snow or the adjacent topography. Some of the animals, which were hibernating survived. These survivors are known as biological legacies.
The conservative conceptions of succession indicated that the landscape would be inhabited by the local species from external to the blast region or by the non-native invasive species. However, the living legacies started to repopulate the ecosystems, while the dead legacies functioned as the source of food for the invading and the survivor species.
