Salamanders
Project Investigator
Robert K. Swihart (Retired), Purdue University, (765) 494-3575, rswihart@purdue.edu
Terrestrial plethodontid salamanders are an ideal group of species to monitor forest ecosystem integrity and biodiversity across the eastern United States. They play a significant role in nutrient recycling by consuming vast quantities of invertebrates and in turn serve as prey items for other forest species. They are sensitive to environmental stresses, and they are often the most abundant vertebrates in deciduous forests.
However, our current knowledge of the effects of timber harvesting on salamander populations is incomplete. Most studies suffer from a lack of replication among various silvicultural treatments and focus solely on immediate post-treatment responses. The terrestrial salamander portion of the Hardwood Ecosystem Project is designed to evaluate the effects of timber harvesting on the diversity, abundance, and demographics of woodland salamanders. Beginning in May 2007, a total of 66 coverboard grids (30 boards per grid) were placed within the 9 study areas. The coverboard grids were checked every other week from September through November. In the spring of 2008, nearly 2000 quadrat surveys (1x1m plots) were added to the coverboard sampling and the sampling period was extended to include Spring sampling in addition to the Fall sampling. We used the first years of data to evaluate the immediate response of plethodontid salamander populations in regenerating forests < 5 years old (MacNeil and Williams 2014). More recently, analysis was extended to the decade following the initial timber harvesting (Ochs, Saunders, and Swihart 2022). Ten species were counted under coverboards, with eastern red-back and zigzag salamanders dominating captures. Salamander declines were lagged, occurring 4-11 years post-harvest in clearcuts and patch cuts. Declines coincided with drops in levels of coarse woody debris and a regional drought. Negative effects of harvest extended from harvest boundaries only 20 m into surrounding forest. Salamander counts were unaffected by either midstory removal or removal of roughly 50% of overstory in shelterwoods.
Key Papers:
- Ochs, A. E., Saunders, M. R., & R.K. Swihart. 2022. Response of terrestrial salamanders to the decade following timber harvest in hardwood forests. Forest Ecology and Management, 511, 120159
- Ochs, A. E., Swihart, R.K. and M.R. Saunders. 2024. A comprehensive review of the effects of roads on salamanders. Landscape Ecology, 39:77. https://doi. org/10.1007/s10980-024-01867-3.
- MacNeil, J.E. and R.N.Williams. 2014. Effects of timber harvests and silvicultural edges on terrestrial salamanders. PLoS ONE, 9(12):e114683