• Rocky Mountain Research Station
• 240 West Prospect
• Fort Collins, CO 80526
• (970) 498-1100

Ecosystem Responses to Invasive Plant Removal and Fuel Reduction in Cottonwood Forests of the Middle Rio Grande

In 1999, RMRS scientists initiated an interagency, collaborative project to evaluate the effectiveness of three fuel reduction treatments at sites in the Middle Rio Grande bosque and monitor their effects on groundwater, vegetation, soils, and wildlife. Cooperators on this project include Middle Rio Grande Conservancy District, Bosque del Apache National Wildlife Refuge (BDANWR), Forest Service State and Private Forestry, City of Albuquerque Open Space Division, University of New Mexico (UNM), New Mexico Department of Environment, NRCS Plants Material Center, and others. The overall project goal is to identify the most effective fuels reduction and exotic plant removal method that will preserve native plants, reduce fire risk, and have a positive or least-negative impact on hydrology, native vegetation, and wildlife communities (birds, bats, reptiles, and amphibians). The project area encompasses 12 study sites (9 treated sites, 3 control sites) along the river from Albuquerque to the BDANWR. Treatments include combinations of mechanical removal of woody fuels and invasive plants, prescribed fire, and revegetation with native shrubs. Treatments were implemented from 2002 to 2004, and post-treatment data collection is almost complete.

Preliminary analyses of vegetation data suggest that treatments were successful in reducing invasive woody plants and resprout rates for saltcedar and Russian olive were low (< 20%) while saving desirable native trees from burning. Mechanical impacts of treatments and layers of chipped and distributed slash reduced herbaceous plant cover and richness, reducing risk of wild fire. Bird species richness was not significantly affected by treatments, but fewer nests were found for mid-story nesting species, likely due to the loss of mid-story habitat provided by saltcedar and Russian olive. Bat activity increased on treated sites, likely due to the greater openness of the understory. Most of the common lizard and amphibian species present prior to treatment appear to persist or fluorish after treatments. Our results were used by land managers to design larger-scale Tamarisk removal treatments in cottonwood-dominated woodlands, were communicated to Congress in relation to support needed for the Salt Cedar and Russian Olive Control Demonstration Act. Results are enabling federal, state, and private partners to to evaluate the ecological costs and benefits of fuel and invasive plant removal in riparian woodlands, including how to best achieve specific goals such as suppressing exotic plants, increasing groundwater availability, reducing fire risk, and maintaining native flora and fauna.

More information on this study may be found in "Monitoring bird populations in relation to fuel loads and fuel treatments in riparian woodlands with tamarisk and Russian olive understories" and "Herpetological communities of the Middle Rio Grande Bosque" in the Monitoring Science and Technology Symposium Proceedings (2006) RMRS-P-37-CD; and "A soil compaction study on the effects of restoration measures in the Middle Rio Grande bosque" M.S. thesis (Water Resources Program, Univ. of NM). Preliminary results have been presented at a variety of conferences including the 2005 Tamarisk Symposium (Grand Junction, CO), 2005 Western Wetlands Conference (Denver, CO), the 2006 meeting of the NM/AZ Chapters of The Wildlife Society (Flagstaff, AZ), and the 2006 Tamarisk Symposium (Ft. Collins, CO). Other information transfer activities include a tour for staffers of 4 New Mexico congressional representatives (March 2, 2006). Related information may be found in "Emergence of Annual Cicadas in a New Mexico Riparian Forest: Ecosystem Consequences of a Shift from Flood to Wildfire Disturbance. Ecol. Appl. 16(4), 2006, pp 1608-1618.