Significance of forest structure for at-risk terrestrial vertebrate species in an open-canopied pine forest

Background/Question/Methods In 2005, Van Lear and others highlighted the ecological significance of longleaf pine (Pinus palustris) forests for at-risk species dependent on this declining ecosystem. This paper reviewed losses of more than 97 percent acreage prior to 1700, championed restoration efforts for this once-common ecosystem, and called for increased attention to habitat requirements of associated at-risk species. In the current presentation, we explore habitat requirements of sixteen southeastern terrestrial vertebrates categorized as special concern, candidate, threatened, or endangered species. We also estimate ranges of factors in forest structure that are most relevant to some of the species. 

Results/Conclusions We determine that almost 90 percent of at-risk terrestrial vertebrates in this region share a general habitat requirement for grassland and/or open-canopied forest, during some or all of their lives. Open-canopied species include 4 birds, 2 mammals, 2 amphibians, and 6 snakes. Assessment of requirements for each species indicates that there is little direct reliance on specific plant species but rather a strong need for habitat structure created by frequent burning. In addition, some of the at-risk vertebrates have requirements that seem to be satisfied by broad categories of plants (pines, legumes, grasses, etc.) rather than specific species. Although conservation biologists and land managers have long understood the relationship between habitat structure and many of the at-risk species, there has been little attempt to aggregate species into management categories that promotes ecosystem-level management. Aggregating species highlights the most immediately useful types of land management actions that are likely to improve habitat. This aids in prioritization of conservation actions and provide a basis for ranking sites with disparate current conditions, for example recently planted longleaf pine plantations compared to mature second-growth longleaf forests that have been subjected to fire-exclusion. We suggest that estimating time and effort required to create an open-canopy habitat will aid in prioritizing conservation efforts for at-risk vertebrates. Because habitat structure is critical for the majority of at-risk species, reclaiming fire-excluded degraded stands may often be worth the cost because appropriate structure will be re-established sooner than if areas are cleared and replanted. We suggest that conservation efforts in other ecosystems, especially open-canopied, fire-maintained, pine-dominated forests are likely to benefit from aggregating species of concern as a way to prioritize management actions. Examples include Ponderosa (P. ponderosa) or shortleaf (P. echinata) pine forests.