Assessing Fractional Cover in the Alpine Treeline Ecotone Using the WSL Monoplotting Tool and Airborne Lidar

Abstract

ABSTRACTAs forest cover in mountain areas impacts headwater properties like habitat extent and downstream water resources, it is important to assess and understand the changes that occur across forest transition zones like the alpine treeline ecotone (ATE). Such changes occur slowly and manifest at decadal to century time scales; however, the present benchmark spatial resolution for land cover analysis from oblique repeat photographs, 100 m, is insufficient to analyze anticipated changes in ATE over a century-scale. In this research note, fractional cover classification of the ATE is achieved through oblique photography analysis with the WSL Monoplotting Tool. Seven oblique photographs of the West Castle Watershed (Alberta, Canada), collected by the Mountain Legacy Project, were gridded to a 20-m resolution and assigned canopy cover classes by manual interpretation. Four canopy cover classes (i.e., no cover, low vegetation, partial canopy, full canopy) were compared to lidar-derived fractional cover. The extraction of canopy cover information from oblique photography at a resolution of 20 m introduces the ability to assess and quantify changes in the ATE using century-scale oblique photographic records.