Short-term response of woody plants to fire in a Rio Grande riparian forest, Central New Mexico, USA

Abstract

Both fire frequency and severity have increased in riparian vegetation in the southwestern United States in recent years, but the role of fire in these ecosystems is still not well understood. I monitored short-term responses of riparian vegetation to a wildfire at two established study sites. Fire severity reflected the amount of organic debris present before the fire, which reflected flooding history at the two sites: severity was lower at the site with a more extensive flooding history. Only native cottonwoods Populus deltoides located in an area that had been regularly flooded retained viable above-ground tissue 2 years after the fire, but 40–80% of trees at both sites produced shoot sprouts. No other woody species retained viable above-ground tissue. Seventy-three percent of willows Salix gooddingii were sprouting four months after the fire, but only about 55% of exotic saltcedars Tamarix ramosissima were sprouting. Sprouting of native shrubs was higher at the site with the lower fire severity. Reducing current fuel load, either by restoring flooding or by mechanical removal, is needed to lessen the impact of fires on riparian forests along the Rio Grande.