Relationship Between Standing Dead Wood Dynamics and Bird Communities within North Carolina Pine Plantations
Abstract
Snags (standing dead wood) are an important resource within all forest ecosystems. A prominent guild of birds within forests of North America depends upon snags for foraging, roosting and nesting. This guild includes both primary and secondary cavity nesters. A study of birds within Weyerhaeuser plantations in coastal North Carolina during the breeding seasons of 1997 and 1998 revealed a diverse community of both primary and secondary cavity nesters. Examination of patterns across the management cycle suggested that commercial thinning operations were important events that drove snag availability and the associated bird community. From a population perspective, snag availability reflects the balance between snag losses due to falling and recruitment associated with tree mortality. Understanding the population dynamics of snags and how they are influenced by management/harvest operations is essential to achieving an understanding of how pine plantations fit within the broader landscape in terms of value to wildlife species. Studies were conducted during the spring and summer of 2002 on the Weyerhaeuser Company J&W management tract located within the coastal plain of North Carolina. Snag and bird surveys were conducted within 35 study plots consisting of 5 replicates of 7 different stand age classes. Snags were surveyed to quantify the population dynamics of snags within pine plantations and to determine how or if these snag dynamics are influenced by timber operations. Birds were surveyed to determine how the bird community responds to snag availability/dynamics. A total of 1,186 snags were identified and characterized within the 35 study blocks. Total snag numbers peaked 1-2 years after the first commercial thin and overall snag numbers declined as the plantation stands matured. Although density was lower, snags within the older age classes were larger, had undergone more decomposition and were more likely to support cavities. Results of bird surveys showed that species richness increased with stand age and that the guild of birds the utilize snags and cavities were not frequently detected until after the first commercial thin. Commercial thinning events appear to be quite beneficial to birds that utilize snags and cavities. A side-effect of this management technique is the creation of snags that provide foraging, roosting and nesting sites for these bird species.
