Houston ChandlerViews:
Habitat loss and degradation are the leading causes of biodiversity imperilment. As natural systems are converted to other uses, broken into smaller fragments, and/or impaired by inputs and interactions with human-dominated landscapes, the species that rely on these systems disappear. Such declines can even occur on protected landscapes where habitat quality can erode if not managed appropriately. While there are many challenges to effective habitat management and restoration, creating or maintaining high-quality habitat for imperiled species is a central tenet of conservation biology.
Working with collaborators at Virginia Tech, we recently had a paper published in the journal Conservation Science and Practice. This research highlighted some of the work that has been done to restore habitat for Reticulated Flatwoods Salamanders.
Pine Flatwoods and Flatwoods Salamanders
Reticulated (Ambystoma bishopi) and Frosted (Ambystoma cingulatum) Flatwoods Salamanders are two sister species that are native to the southeastern U.S. Historically, these species occurred across parts of four states (Alabama, Florida, Georgia, and South Carolina). Both species have declined precipitously over many decades and now persist at only a handful of sites in Florida and Georgia. Consequently, both species are listed on the U.S. Endangered Species List and face an uncertain future.
Flatwoods salamanders have a fairly typical pond-breeding amphibian life cycle. Adult salamanders spend most of their time underground in longleaf pine flatwoods and make seasonal migrations into breeding wetlands (typically from October–December). These wetlands are ephemeral in nature and generally hold water for several months during the winter and spring before drying in late spring or summer. Eggs are laid terrestrially in dry wetland basins before hatching into aquatic larvae. Larval salamanders then develop in the aquatic environment for 3–4 months before metamorphosing into adults and migrating back into terrestrial habitats.
Pine flatwoods are a type of longleaf pine forest typically found in wet, low-lying areas of the southeastern Coastal Plain. These habitats are characterized by an overstory of longleaf and slash pine and an understory composed of a diverse assemblage of herbaceous vegetation (grasses and forbs). Seasonally flooded wetlands are typically dispersed throughout these landscapes. One of the driving factors for declines in flatwoods salamander populations, especially in protected landscapes, is a lack of growing-season fire in wetland systems. A lack of fire effects within wetlands creates a complete vegetation shift to communities dominated by woody shrubs with no herbaceous vegetation. This makes the habitat unsuitable for flatwoods salamander reproduction and has been a common outcome for historically fire-maintained wetlands across the Southeast. Even prescribed fires can fail to replicate the historical disturbance regime in these systems because they are often set during periods when the wetlands are flooded.
Salamander Research on Eglin Air Force Base
Eglin Air Force Base, located in the Florida Panhandle, has long been considered one of the few remaining strongholds for flatwoods salamanders. However, monitoring data indicated that even these populations had declined significantly by the early 2000s. A severe drought during the 2007 breeding season further exacerbated the situation. During this same period, the long-term consequences of weak fire effects had become apparent in many breeding wetlands, even in areas with well-maintained uplands. The result was that multiple breeding wetlands that were historically occupied by salamanders appeared to no longer support salamander populations, and the habitat quality was declining over time.
The Haas Lab at Virginia Tech has led a long-term research and recovery project on Eglin Air Force Base’s flatwoods salamander populations. Part of this project has been a long-term, annual monitoring effort of potential breeding wetlands on base. These efforts began in 2003 and are still ongoing today. From January–April, at least three 30-minute dipnet surveys were completed if there was sufficient standing water to conduct a survey. These surveys were occasionally supplemented with nighttime spotlighting surveys in areas with sensitive habitat or very low water levels. At the same time, active efforts were made to restore flatwoods salamander habitat (see below), and the current research examines how salamander occupancy has changed along with the amount of suitable breeding habitat.
Habitat Restoration
The long-term effects of habitat degradation in flatwoods salamander breeding wetlands have created a strong need to actively manage wetland habitats. On Eglin Air Force Base, this work began over a decade ago with experimental treatments designed to understand how vegetation responded to various management activities. Over time, the management activities have been refined and improved upon. In general, restoration typically starts with the manual removal of woody shrubs through herbicide applications and eventual cutting of standing dead wood. Additional follow-up treatments, along with fire effects, can continue to improve habitat quality, although it can take several years for herbaceous vegetation to respond. Ultimately, maintenance and continued management are generally needed, or wetlands will revert back to their fire-suppressed state. A full guide to wetland habitat restoration for flatwoods salamanders (although also applicable to many other southeastern amphibians) is included in the appendix of this paper.
Over the last decade, the amount of suitable breeding habitat for flatwoods salamanders on Eglin Air Force Base has more than doubled. This habitat improvement was observed across wetlands that have been consistently occupied by flatwoods salamanders and in sites that have never been occupied by salamanders. Most importantly, the total amount of suitable breeding habitat more than doubled in seven wetlands where salamander populations disappeared in the early part of the project before being reoccupied after habitat improvements. While difficult to quantify, increases in habitat quality and the overall amount of habitat have also likely increased the total number of salamanders occurring at known breeding sites.
Salamander Response to Management
From 2003–2024, we estimated that flatwoods salamanders occupied 21 of the 46 potential breeding sites surveyed during at least one breeding season. The annual extinction probability was exceeded by the probability of colonization through natural dispersal, leading to an increase in the number of occupied sites by 2024. The number of occupied sites decreased in the early years of the study in response to severe drought and then remained relatively constant for many years. The number of occupied sites increased to 17 in 2020 and remained high through the end of the study. Using this long-term salamander dataset, along with measured environmental variables, the best predictors of occupancy by salamanders were the proximity of a wetland to other wetlands and the amount of suitable breeding habitat. Movements leading to apparent colonization events averaged just 84 m, and colonization probability became negligible at sites separated by more than 500 m.
Conservation Implications
This work demonstrates an increase in flatwoods salamander occupancy in response to active habitat management that significantly increased the amount of suitable breeding habitat across the landscape. Restoration of wetland habitat can often appear daunting, especially on landscapes with large numbers of degraded wetlands. However, in this case, field staff made meaningful gains in habitat quality by focusing on improving habitat in manageable sections across numerous wetlands. Our results highlight that spatial clustering of wetlands is important for the long-term persistence of this species. Thus, restoration activities for flatwoods salamanders should consider the spatial relationships between wetlands to have the highest chances of success. Overall, flatwoods salamander conservation efforts will not succeed without a concerted and focused effort to restore habitat in both breeding wetlands and surrounding uplands.
This research was led by Dr. Amanda Martin and a team of researchers from Virginia Tech. I worked on the larger flatwoods salamander project for both my MS and PhD research projects. The habitat restoration work discussed here would not have been possible without the contributions of a large group of people dedicated to improving outcomes for flatwoods salamanders. The full publication is available here.
Learn more about flatwoods salamanders, one of our priority species.
