Wed June 25, 2008
Earth Notes - After the Fire III
Flagstaff, AZ – Earth Notes: After the Fire III (Fire and Plants)
This month Earth Notes looks at what happens in forests after fire. In 2002, the largest wildfire in Arizona's history singed nearly half a million acres. The Rodeo-Chediski Fire, son the Mogollon Rim, has since given scientists a case study of succession in other words, seeing how plants recolonize disturbed ground.
Not all areas were affected the same way. Some areas burned lightly. Dried duff was cleared away, and native grasses came right back. But in the most severely burned places, vast tracts of ponderosa pine and Gambel oak trees were killed, and the forest basically has started over.
In these areas, shrubs that re-sprout from stumps or root crowns have become dominant. They're pioneering species like scrub oak, manzanita, juniper, New Mexico locust, and Chihuahua pine.
Ponderosa pine is not a sprouter. It comes back only from seeds. In some places its seedlings are growing, either because some mature pines survived or because fallen seeds were protected in the ground. In other places foresters have planted ponderosa seedlings.
But some researchers say the area's pine-oak forest may be replaced, across large tracts, by other species. Short-statured shrubs and trees may replace ponderosa pine and Gambel oak, which could take decades or even centuries to recover.
Forest succession is a reminder that the ecological world never stands still. Change happens, and people are just one of the factors that cause it. Next week, we'll look at one project that aims to integrate the human desire for healing with what's natural.