Landsat-based monitoring of landscape dynamics in the North Cascades National Park Service Complex: 1985-2009

Antonova, Natasha; Copass, Catharine; Clary, Shelby

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 dynamics using Landsat satellite imagery. The protocol was implemented at North Cascades National Park Service Complex (NOCA) in 2012 using LandTrendr (Landsat-based Detection of Trends in Disturbance and Recovery) algorithms developed by the Laboratory for Applications of Remote Sensing in Ecology (LARSE) at Oregon State University. We mapped eight categories of landscape change that occurred at NOCA and surrounding areas from 1985 to 2009: Avalanches, Clearing, Development, Fire, Mass Movements, Progressive Defoliation, Riparian, Tree Topplings. 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 singed trees. The Mass Movement category includes both landslides found on valley walls and debris flows associated with streams. Progressive Defoliation is a change type in which the forest cover remains but has declined due to insect infestation, disease or drought. Riparian changes are restricted to the 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 Tree Toppling is evidenced by broken or topped trees, generally due to wind but sometimes to root rot. Only changes larger than 0.8 ha (2 ac) and for which the duration of the period of landscape change was less than 4 years were mapped. Approximately 60,000 ha (5.65%) of the study area underwent detectable change at some point during the 25 year period of analysis, affecting about 2% of NOCA and about 7% of the areas outside the park boundary. The annual average area impacted by landscape change within the study area was just over 2000 ha. Within the park boundary, the annual average area undergoing change was about 250 ha. Clearing was the major change type within the study area over the last 25 years, followed by Fire. Clearing occurred predominately outside the park boundary. Inside the park, Fire was the most significant agent of landscape change, followed by Progressive Defoliation and Avalanches. The inter-annual variability in the total area experiencing landscape change was considerable. From 1985 to 2009, the greatest amount of change outside the park boundary occurred in 1986; 2006 and 2007 were also significant. Within the NOCA boundary, 2006 was the year with the greatest change detected followed by 1994 and 2003. An analysis of the size of change patches showed that, on average, Avalanches, Mass Movements and Riparian changes are smaller but more numerous, whereas Fires tend to be larger but fewer. Progressive Defoliation events tend to affect large areas of the park and are represented by numerous small events.

Landsat-based monitoring of landscape dynamics in the North Cascades National Park Service Complex: 1985-2009

Series

Collections