Effects of wildfire on riparian trees in southeastern Arizona

Abstract

We measured fire damage to 250 riparian trees in 2003–2004, and again in 2012–2013, in a southeastern Arizona grassland burned by wildfires in 2002, 2009, or both. Following a single fire, combined mortality or survival only by ground-level resprout was 64% for desert willow (Chilopsis linearis), 57% for Fremont cottonwood (Populus fremontii), 48% for Arizona walnut (Juglans major), 32% for velvet ash (Fraxinus velutina), and 25% for Wright's sycamore (Platanus wrightii). A second fire burned 120 of the trees that happened to have been less damaged by the first fire. Distinctions among species in overall fire damage persisted after the second fire but to a lesser degree. By the conclusion of our study, 26% of the 250 trees had died completely while another 32% survived only as relatively small resprouts. We conclude that the fires substantially reduced both the abundance and crown volume of mature riparian trees in the study area.