Aerial detection surveys in the United States

Abstract

Summary Aerial detection survey, also known as aerial sketchmapping, involves observing forest change events from an aircraft and documenting them manually onto a map. Data from aerial surveys have become an important component of the Forest Health Monitoring program, a national program designed to determine the status, changes and trends in indicators of forest condition. Aerial surveys are an effective and economical means of monitoring and mapping common forest disturbances such as tree damage and tree mortality caused by insects and disease. Information from aerial surveys can be considered the first stage in a multi-stage or multi-phase sampling design. Aerial sketchmap surveys have been used in the United States since the 1940s. Today, the United States Department of Agriculture (USDA) Forest Service, State and Private Forestry, Forest Health Protection, together with other federal, state and county cooperators conducts annual sketchmap surveys across all land ownerships. Between 2002 and 2006 an annual average of 1 800 000 km2 of forested lands were aerially surveyed within the United States alone. Traditionally, forest damage has been sketchmapped on United States Geological Survey paper-base maps. Recently, the USDA Forest Service's Forest Health Technology Enterprise Team (FHTET) developed a digital aerial sketchmapping system that automates this process, allowing users to digitise polygons directly onto a touch-screen linked to a global positioning system (GPS) unit and computer or onto a tablet PC with an integrated GPS.