Impacts of Fire in Oak Savanna Ecosystems of the Southwestern Borderlands Region

Book excerpt: Changes in natural fire regime caused by drought, overgrazing and an aggressive fire suppression policy have caused declines in biological diversities, reduction in herbaceous productivity, "unnaturally high" tree densities, and accumulations of flammable surface fuels in the oak savannas of the Southwestern Borderlands Region. Re-introducing a more natural fire regime into the oak savannas in this region is expected to improve or reverse these landscape changes and, in doing so, improve landscape productivity and biological diversity. Twelve small watersheds in the oak savannas on the eastern slope of the Peloncillo Mountains of southwestern New Mexico were established to provide a basis to enhance the level of knowledge of the oak savanna ecosystems in the region and to determine the effects of cool-season and warm-season prescribed burning treatments on the natural resources and ecosystem functioning of oak savanna communities in the region. A wildfire on five watersheds added another dimension to the study. All of the three burning events were low severity fires. The information monitored before and after the burns consisted of hydrologic processes including streamflow and precipitation, channel sediment, side-slope soil movement (both soil erosion and soil deposition), post-fire water repellency, and ecological components including tree overstories, canopy cover, herbaceous understories, loadings of flammable fuel fractions, ground cover, and mammals and birds.