A comprehensive review of the effects of roads on salamanders

Context

Road expansion has raised concerns regarding road effects on wildlife and ecosystems within the landscape. Salamanders, critical ecosystem components and bioindicators, are vulnerable to road impacts due to habitat loss, migrations, and reliance on stream health. Systemic reviews considering the effects of different road types on salamanders are lacking.

Objectives

We summarize 155 studies of road effects on salamanders, including paved, unpaved, and logging roads, hiking trails, railroads, and powerlines. We examine trends in road type, study area, and impacts on salamanders; summarize current knowledge; and identify knowledge gaps.

Methods

We used Web of Science for literature searches, completed in January 2023. We reviewed and summarized papers and used Chi-squared tests to explore patterns in research efforts, research gaps, and impacts on salamanders.

Review

Roads had negative effects on salamanders through direct mortality, damaging habitat, and fragmenting populations. Traffic and wetland proximity increased negative impacts in some studies; abandoned logging roads showed negative effects. Positive effects were limited to habitat creation along roads. Habitat creation and under-road tunnels with drift fencing were effective mitigation strategies. Non-passenger vehicle roads were critically understudied, as were mitigation strategies such as bucket brigades and habitat creation along roads.

Conclusions

With road networks expanding and salamander populations declining, managers must account for road effects at landscape scales. The effects of non-paved roads on salamanders are poorly understood but critically important as such roads are frequently located in natural areas. Managers should incorporate mitigation strategies and work to reduce road impacts on vulnerable wildlife.