Factors Affecting Fish and Amphibian Habitats Under Different Erosion Control Dam Types with Implications for Forested Mountain Stream Management: A Case in a Small Watershed, Republic of Korea

Erosion control dams (ECDs) in forested mountain streams are key pieces of infrastructure for disaster risk reduction, but they have also been reported to disturb the hydro-geomorphic balance of stream ecosystems. Open-type ECDs have increasingly been used to mitigate the loss of longitudinal connectivity caused by closed-type ECDs; however, quantitative comparisons between the two types remain scarce. We evaluated the presence of fish (Rhynchocypris oxycephalus) and amphibian (Glandirana emeljanovi) using logistic regression analysis in a forested mountain stream on Mt. Oseo, Republic of Korea, where closed- and open-type ECDs were installed in sequence. The best-fit models indicated different habitat preferences: R. oxycephalus responded to hydro-geomorphic parameters, whereas G. emeljanovi responded to riparian forest vegetation and soil parameters as well. Although six parameters varied significantly between the sections divided by the two types of ECDs, all observed values fell within the ranges previously reported for mountain streams in natural conditions. Bayesian Network Analysis further identified crown density, stream-bed slope, and number of step pools as high-level parameters that can be regulated through erosion control works, including engineering and forestry techniques. These findings link the presence of both species to stream conditions and are translated into an ecosystem management framework, filling a knowledge gap where comparable studies are scarce.