Seed dispersal and plant establishment have been monitored since 1980 on the debris avalanche created by the eruption of Mount St. Helens. The number of plants on the deposit increased over time to a high of almost 2 plants per square meter by 1983. The number of species per 250 meter square plot have increased to a mean of 10.3 in 1983 with 76 species being present over the entire deposit. Four years after the eruption only 30 percent of the species present before the eruption had reestablished themselves, and average plant cover was less than 1 percent. By 1989, plant cover had reached 18 percent.