Ponderosa seedlings grow among the rocks of the Bonito lava flow
Ponderosa pine seedlings grow among the lava rocks

Each time a volcano erupts, life begins anew. Establishing life in the post-eruption environment may seem an impossible challenge, but the volcanic landscape is a reminder that the natural world has never been static, and that cycles of change are happening all around us. A closer look reveals a pink penstemon radiant against black rock, its species unique to this rugged terrain. Pinyon pines, their growth stunted by harsh conditions, offer habitat for Abert’s squirrels. Nídíshchíí, ponderosa pines, form a canopy layer over the smaller plants. Lichens add a touch of color and excrete weak acids as a byproduct of their metabolism, slowly converting the rocks to soil.

The return of life to Sunset Crater is part of a continuous process of change known as ecological succession. As fresh lava and cinders age and weather, as soil forms, this environment becomes increasingly hospitable to plants and animals. Remember that Sunset Crater Volcano is very young: a thousand years after the eruption, the land is still in the early stages of succession. Aridity makes succession exceedingly slow, and growth in this high, dry landscape is a process spanning many human lives and generations.

The return of plant life is the most visible sign that succession is occurring. The monument is relatively rich in plant species, with 166 documented species, including Utah juniper, cliffrose, and apache plume. About half of the monument is covered by cinder fields, with little visible 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 to the bottom of the cinders.

The oldest pine trees found here are about 250 years old, and biologists believe that these very trees were the first to grow in this new landscape. The isolated vegetation islands of pinyon, ponderosa, and aspen we see today are floating on the deep cinder deposits. These fragile islands of vegetation harbor numerous other plants, provide important wildlife habitat, and greatly contribute to overall biodiversity within the monument. Without disturbance, these islands will eventually knit together to form a forested landscape like that seen across older parts of the volcanic field, and the cinder fields will disappear back into the earth.


Last updated: February 15, 2022

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