Timber harvests in northern Colorado and southern Wyoming support the local economy, reduce the risk of extreme wildfires, maintain forest health in the absence of fire, and help protect critical infrastructure from falling trees. Past harvests, along with extensive tree mortality from the mountain pine beetle outbreak, have left a mosaic of ecological legacies on the forested landscape. It is critical to understand these legacies in order to properly manage forests for the future; however, comprehensive harvest histories are not always readily available. For this reason, Ben Delatour Scout Ranch (BDSR), Bioenergy Alliance Network of the Rockies (BANR), and the Colorado State Forest Service (CSFS) partnered with DEVELOP to investigate forest harvest history and tree mortality from the mountain pine beetle in the study area over a 25 year period, from 1987 to 2012.
The DEVELOP team created a historical map designating the major changes in forested land cover using Landsat 5 Thematic Mapper imagery, masked for clouds and transformed with the tasseled cap transformation (Tcap). The resulting Tcap bands (brightness, greenness, and wetness) were used in conjunction with the Landsat-based Detection of Trends in Disturbance and Recovery (LandTrendr) model to map past harvests and beetle disturbance in the region. The LandTrendr output, combined with ancillary datasets, helped to develop an accurate accounting of land cover changes in northern Colorado and southern Wyoming.