Courtesy of Arizona-Sonora Desert Museum

history continued

Desert ironwood trees can be found throughout the desert of the Southwest United States and Northwest Mexico. As a keystone species in the Sonoran Desert, the desert ironwood trees play an important role in both the natural and cultural landscape of the region. Based on long-term observations and repeat photography, it is estimated that ironwood trees can live for up to three hundred years, perhaps even longer. Desert ironwood trees are the most important nurse tree in the Central Gulf Coast and the Lower Colorado River Valley. The dense shade of a mature tree supports a microclimate in which dozens of other plant species grow. The canopy shelters the seeds of other species and provides a site that minimizes soil moisture evaporation, sunlight intensity, and potential damage from predators. Thus, the trees serve a valuable role in arid regions. Seeds of the trees are eaten by a host of desert animals and were once a staple food of the Seri Indians of Mexico. Moreover, Seri Indian carvers use the wood in their animal figure carvings.

Photo © Mark Klett

In 1980, chain link fencing surrounded the Desert Ironwood Tree while the area was used as a Mexican Grey Wolf off-exhibit enclosure for the Arizona Sonora Desert Museum. The animals dug dens under the tree which harmed some of its root systems. By 1993, the enclosure was modified into a Mule Deer holding area, which subjected the Desert Ironwood Tree to browsing and soil compaction for more than five years. When the area was converted into a production nursery in 1997, irrigation lines were dug in the tree’s root zone in order to support the potted plants grown under and surrounding the tree. During this time, the tree was not only endangered by damaging excavations, but also by excessive watering that threatened to upset the balance of a tree requiring naturally arid surroundings.