Sediment transport by the burrowing activity of snow vole (Chionomys nivalis) in subalpine prairies of the Parâng Mountains (Romania): quantitative modelling and methodological perspectives

Abstract Over the last decades, animal activity has been explored and reported as a potential source of natural hazards, such as the destruction of a beaver dam potentially triggering a flash flood downriver. However, the sediment source or sediment budget related to animal activity has received very little attention from geoscientists to date. The main goal of this study is to quantify the biogenic activity of the European snow vole (Chionomys nivalis) as a sediment source in the subalpine prairies of the Parâng Mountains, Southern Carpathians. Only the direct action of this rodent was analyzed, namely the spatial distribution and frequency of burrowing, quantitative analysis of the mounds, and rate of sediment excavation and mass transfer caused by burrowing and tunnel digging. To do this, 838 burrows and mounds were mapped and measured in eleven plots, and excavated volumes of sediment and mass transfers were calculated following three approaches: 1) measuring the weight of excavated debris; 2) measuring the dimensions of excavated debris; and 3) measuring burrow dimensions. The fieldwork revealed three preferred aspects: south, southeast, and west. The amount of displaced soil was highly variable depending on the approach used, ranging from 3.41 m3/ha to 21.08 m3/ha. As such, snow vole biogenic activity, which is due to the long-term opening of the landscape for traditional transhumance and sheep farming, should be considered to be an important sediment source in the subalpine and alpine prairies of the Parâng Mountain.