bio

Pioneer species

The first organisms able to colonise a bare, hostile surface where most others cannot hold. They are typically wind-dispersed, stress-tolerant and — most importantly on volcanic ground — often nitrogen-fixers. On the Mount St. Helens pumice plain, the prairie lupine (*Lupinus lepidus*) kick-started succession through nitrogen-fixing bacteria in its roots, building islands of fertile soil for later colonists. But a pioneer is not only a benefactor: dense living lupine mats also crowded out conifer seedlings — the same plant that builds the ground can, while alive, hold back the forest.