QUANTIFYING SOIL EROSION FROM HIKING TRAIL IN A PROTECTED NATURAL AREA IN THE SPANISH PYRENEES

Recreational activities may impose adverse impacts on the environment of natural landscapes and protected areas owing to persistent tourist influx. Here, we use a dendrogeomorphic approach to estimate soil erosion induced by hikers at trails in the Ordesa and Monte Perdido National Park (north-eastern Spain). For the first time, exposed roots of Pinus uncinata Ramond ex DC and Fagus sylvatica L. were used on the Iberian Peninsula to reconstruct the timing and amount of soil erosion induced by hikers based on dendrogeomorphology. In addition, we propose a new characterization of ground microtopography using a microtopographic profile gauge and validate results of this approach with 3D point clouds derived from terrestrial laser scanning. Determination of the first year of root exposure was based on the analysis of changes in roots, at both the macroscopic and tissue levels. Analysis shows that a distinctive footprint is observable at macroscopic and microscopic scales following initial exposure and thus confirms results of previous work realized with roots of other tree species (e.g. Pinus sylvestris L.). Our results also indicate that a characterization of erosion based on microtopographic profiles can replace terrestrial laser scanning measurements, which are often difficult to obtain in remote areas. Estimates of soil erosion ranged between 3.1 +/- 1.5 and 8.9 +/- 4.3 mm y(-1) (or 52.7 +/- 25.5 to 151.3 +/- 73.1 t ha(-1) y(-1)). The approach deployed here could help improve management of and access to natural protected areas and thus reduce the potentially negative impacts of recreational activities on these sensitive environments. Copyright (c) 2017 John Wiley & Sons, Ltd.