Recommendations for snag retention in southwestern mixed-conifer and ponderosa pine forests: History and current status

Snags provide habitat for numerous species of wildlife. Several authors have provided recommendations for snag retention in southwestern mixed-conifer and ponderosa pine (Pinus ponderosa) forests. Most recommendations were presented in terms of minimum snag density and/or size. I summarized the history of recommendations for snag retention in these forest types, and used data from a current study of snag populations (conducted within Coconino and Kaibab National Forests, north-central AZ, USA, 1997 through 2012) to assess congruence between existing snag populations and various recommendations. Most recommendations were based on studies of cavity-nesting birds; therefore, this analysis emphasized characteristics of snags containing excavated nest cavities. Proportions of plots that met minimum management targets varied among recommendations, ranging from 34% to 100% in mixed-conifer forest and from 7% to 95% in ponderosa pine forest. Failure to meet density targets often was caused by a shortage of snags that met minimum size criteria rather than by a shortage of snags. Many snags containing excavated nest cavities did not meet the minimum size criteria in some recommendations. It may be possible to reduce those minimum size criteria while still providing substrates for cavity-nesting birds. Studies explicitly linking snag size and density to demography of cavity-nesting birds are badly needed, however, as are studies documenting ecologically sustainable snag densities. Until such data are available, managers should continue to emphasize snag recruitment and retention, with the focus on larger snags, and to ensure that snags are well-distributed, but not uniformly distributed, across the landscape. (c) 2016 The Wildlife Society.