NCCN landscape change monitoring polygons in and around Mount Rainier, North Cascades, and Olympic National Parks for 1987-2017

As part of Vital Signs Monitoring, the North Coast and Cascades Network (NCCN) of the National Park Service (NPS) developed a protocol for monitoring landscape change using Landsat satellite imagery. The protocol was implemented at Mount Rainier (MORA) in 2013, North Cascades (NOCA) 2012, and Olympic National Parks (OLYM) in 2014 using LandTrendr (Landsat-based Detection of Trends in Disturbance and Recovery) algorithms developed by the Environmental Monitoring, Analysis, and Process Recognition Lab (eMapR) (formerly the Laboratory for Applications of Remote Sensing in Ecology (LARSE)) at Oregon State University.

The dataset was generated by running LandTrendr in Google Earth Engine for the period from 1987 to 2017 and then aggregating disturbance pixels for a given year into patches based on adjacency rules and minimum mapping unit of 0.8 hectares (2 acres). Disturbance patches were then reviewed and human labeled using ten categories of landscape change. Eight categories were mapped at MORA and NOCA: Avalanche, Blowdown, Clearing, Defoliation, Development, Fire, Mass Movement, and Riparian Change. Ice Damage and Coastal Change were added for OLYM only. Ice Damage category captures changes in vegetation damaged by heavy, long-lasting snow and ice followed by severe winds and generally characterized by broken tree branches. Coastal Change category captures partial to complete vegetation removal due to storm surges or other factors unique to the coastal foredune and strand. The Avalanche category captures long, linear change which partially or completely removes vegetation from the valley wall following a release of a large mass of snow down a mountain side. Clearings are areas under forest management where practices vary from thinning to clearcuts. The Development category captures changes associated with complete and persistent removal of vegetation and transformation to a built landscape. Changes due to Fire vary in intensity from full canopy removal to partial burns that leave behind a mixture of dead and scorched trees. The Mass Movement category includes both landslides found on valley walls and debris flows associated with streams. Defoliation is a change type in which the forest cover remains but has declined due to insect infestation, disease or drought. Riparian Change disturbance events are restricted to valley floors alongside major streams and rivers and capture areas where either conifer or broadleaf vegetation previously existed and has been converted to river channel. Change due to Blowdown is evidenced by broken or topped trees, generally due to wind but sometimes to root rot.