Date of this Version
Fire Science Brief, Issue 7, April 2008
The Middle Rio Grande of New Mexico is the most extensive, remaining bosque, or cottonwood forest in the southwest. Alterations caused by humans—damming and channeling the river, controlling floods, and planting non-native trees—have disrupted the cycles of the earlier ecosystem. Without periodic flooding, native cottonwoods cannot regenerate. Invasive exotic plants such as Tamarisk, also known as salt cedar, and Russian olive have filled in the gaps and open spaces, increased fuel loads, and continue to replace native trees and shrubs after wildfires. Cottonwoods, not a fire-adapted species, are now at risk from wildfire and replacement by invasive plants. An array of fuel treatments applied to study sites reduced invasive woody plants in the bosque. Resprout rates for exotic trees were low overall. Survival rates of transplanted native plant species were high. Restoration had various effects on birds, animals, amphibians, and reptiles of the bosque. Species that prefer a more open, less-cluttered habitat benefited, and their numbers increased. Species that prefer a closed, shrubbier habitat altered by invasives declined.