Salamanders
Project Investigator
Robert K. Swihart (Retired), Purdue University, (765) 494-3575, rswihart@purdue.edu
Land-dwelling salamanders are great indicators of forest health across the eastern United States. They help recycle nutrients by eating vast numbers of insects. In turn, they serve as food for larger forest animals. They are sensitive to environmental stress, and they are often the most common vertebrates in these forests.
However, we still do not fully know how logging affects salamander populations. Most studies lack repeated tests across different harvest styles and only look at immediate post-treatment results. The salamander portion of the Hardwood Ecosystem Experiment tests how logging affects salamander diversity, counts, and population trends over time.
In May 2007, researchers placed 66 coverboard grids across 9 study areas. Teams checked the boards every two weeks from September through November. In spring 2008, scientists added nearly 2,000 small plot surveys and expanded checks to include both spring and fall. Early data showed immediate salamander responses in young forests under 5 years old. A later study tracked responses over the decade following harvest.
Researchers counted ten species under the boards, with red-backed and zigzag salamanders being the most common. Salamander drops were delayed, occurring 4 to 11 years after logging in clearcuts and patch cuts. These drops matched times of lower dead wood levels and a regional drought. Negative logging impacts extended only 20 meters past harvest borders into the surrounding forest. Meanwhile, removing midstory trees or cutting half the overstory trees did not affect salamander counts.
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