Scots pine roots (Pinus sylvestris L.) as dendrogeomorphological indicators of soil erosion on a hiking trail in the Brodnica Lakeland, Poland NE

Abstract

Trampling on hiking trails leads to vegetation degradation, promoting soil erosion. Erosion removes the topsoil, causing lasting changes and exposing tree roots. Yet, little is known about the environmental factors affecting soil erosion rates determined from tree root analysis. This study, exclusively utilizing microscopic preparations, examines tree root anatomical changes on a lowland trail in Brodnica Lakeland. It aims to understand the temporal and spatial variability of soil erosion rates using dendrogeomorphological records of Scots pine (Pinus sylvestris L.) roots. Up to 64 % of samples show exposure due to continuous denudation, significantly shaping the trail’s relief. Abrupt exposures and secondary growth occur in only 22 % and 14 %, respectively. The average soil erosion rate, calculated from 76 root exposures at the Bachotek site, is 1.93 ± 0.82 mm/year, ranging from 0.71 to 3.80 mm/year, with recently exposed roots exhibiting the highest average soil erosion values on the hiking trail. 45 % of root samples exhibit above-average erosion rates. Statistical analyses reveal that erosion rates (ER) are influenced by soil compaction (COM), bulk density (BULK), root orientation (ASP), and exposure length (EXP). Higher compaction and bulk density correlate with increased erosion, while roots parallel to the trail experience more erosion. Conversely, greater root exposure length leads to decreased erosion rates. These findings suggest that soil erosion on the hiking trail primarily results from gradual geomorphological processes. Wood anatomical analyses of pine roots confirm the role of trampling in initiating and accelerating these processes, altering the trail’s subsurface soil layers, and indirectly affecting soil erosion dynamics. Scots pine roots prove valuable as indicators of the temporal and spatial variability of soil erosion along the lowland trail.