Tundra Vegetation Heights Derived from Traditional High-Resolution Air Photos, Toolik Lake, Alaska

Vegetation is responding to climatic warming with changes in species composition, density, and distribution. While satellite remote sensing is being used to map broad Arctic trends, more plot-level studies are needed to elucidate complex ecosystem interactions. This study used aerial photos to derive a point cloud which was then used to estimate vegetation height. In August 1995, color-infrared (CIR) aerial photographs at 1:3000 resolution were obtained near Toolik Lake, Alaska. Agisoft Metashape was utilized to generate a point cloud of the 1-hectare plot. This was then classified into ground/non-ground points to generate both a digital surface model (DSM) and digital terrain model (DTM). Differences between the DTM and DSM yielded estimates of tundra canopy height. These were then compared to 68 field measurements of vegetation height from 1995 along several transects. Mean estimated canopy heights were 6.7cm and observed heights were 5.9 cm. This baseline of historic vegetation characteristics can be compared to modern vegetation measurements. Using modern photogrammetric techniques on historic aerial photos may provide long-term estimates of change in vegetation heights.