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Snags are important components of wildlife habitat, providing nesting and feeding sites for over 75 species of animals in the southwestern United States. Wildfires can increase or decrease the availability of snags to wildlife by killing live trees or incinerating snags. Our objectives were to describe dynamics and spatial patterns of fire-killed snags in ponderosa pine (Pinus ponderosa) forests of northern Arizona and predict the probability of snag use by cavity nesters. We established six 1-ha plots following two recent fires that occurred in northern Arizona (Hochderffer fire of 1996 [H96] and Pumpkin fire of 2000 [P00]) to determine ponderosa pine snag availability and use by wildlife as evidenced by presence of excavated cavities. For comparison, six paired 1-ha plots in nearby unburned areas were sampled with burned plots. For the twelve 1 ha plots, field methods included mapping and measuring 15 characteristics for 668 snags (630 in burned and 38 in unburned plots) 4 years post-fire on the H96 fire,and1010snags(996 inburned and14inunburnedplots) 1yearpost-fire ontheP00fire.We remeasured characteristicsof all snags in 2003. Most burned snags were standing 3 years after fire, but 7 years after fire, 41% had fallen. Snags in burned plots wereclumped wheninitiallymeasuredandremeasured. After7years,snagsinburnedplotsthatwere stillstandingwere straight, large diameter trees in denser clumps. Density of excavated cavities was similar between burned (3.0 ha 1 ) and unburned (2.2 ha 1 )plots,eventhoughburnedareas producedmuchhigherdensities ofsnags.Snags(bothburnedandunburned)thatwere most likely to contain excavated cavities were large diameter with broken tops. This evidence of cavity nester use indicates that in ponderosa pine forests in the southwest, retaining large diameter snags is important to cavity nesters regardless of snag origin. If salvage logging is to occur in severely burned ponderosa pine in the southwest, retaining straight, large diameter snags in clumps will help maintain snags for cavity-excavating species. # 2005 Elsevier B.V. All rights reserved. |
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