The return of life to Sunset Crater is part of a continuous process of change known as succession. As fresh lava and cinders age and weather, and as soil forms, this environment becomes increasingly hospitable to plants and animals. Remember that, in geologic terms, Sunset Crater Volcano is very young. After 800+ years, succession here has just begun.
The return of plant life is the most visible sign that succession is occurring. About half the monument is still barren or semi-barren cinder fields, with little obvious vegetation. Until substantial soil formation occurs and organic material increases, plant growth on cinders is essentially like hydroponics — to be successful, plants must be capable of rapidly absorbing water and water-borne nutrients, before they drain away.
The oldest pinyon pines found here are about 250 years old, and biologists believe that these very trees were the first colonists of this new landscape. The isolated vegetation “islands” of pinyon, ponderosa, and aspen we see today effectively float on the young, deep cinder deposits. Without disturbance, these islands will eventually knit together to form a forested landscape like that seen across older parts of the volcanic field. But aridity makes succession exceedingly slow.
In the meantime, these islands harbor numerous other plants, provide scarce wildlife habitat, and greatly contribute to overall biodiversity within the monument. The monument is relatively rich in plant species, with 166 documented species, including Utah juniper, cliffrose, and apache plume.