US Forest Service Research and Development Characterizing Forest Change with Satellite Imagery and FIA Data - Rocky Mountain Research Station - RMRS - US Forest Service
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Characterizing Forest Change with Satellite Imagery and FIA Data

One of the major developments in the second half of the twentieth century was an increased awareness of the central role of disturbance in forest ecology. With widespread media coverage of hurricanes, fires, insect outbreaks, and harvests, everyone is now aware that forests are dynamic places. The Intermountain West (IMW) Forest Inventory and Analysis (FIA) unit is collaborating with NASA, the University of Maryland, and other Forest Service researchers to map historical disturbances across the country. There are several practical reasons to find out exactly how dynamic our forests can be. First, an understanding of the historical likelihood of disturbance is beneficial in the planning and management of forests for uses such as wildlife habitat, timber, recreation, and other development. Second, accounting for the carbon flux involved with disturbance would be central to any carbon accounting system that might be adopted in the future. Carbon accounting is an important element in predictions concerning global warming. Third, the history of natural and human-caused disturbance is central to a basic characterization of an ecosystem, particularly if that history can be mapped across a landscape.

Biennial Landsat satellite imagery from 1984 to 2002 has been acquired for 30 areas (each 185 by 185 km), nine of which are in the IMW. Change detection algorithms have been developed that use FIA plot data to identify disturbances and estimate their effects on forest structure. Several of the study areas (Figure 1---red "Prototype" scenes) were chosen by FIA analysts to look at specific disturbance trends. In the IMW, disturbances of particular interest include: fire, harvest at higher elevations, and drought-related die-off in pinyon-juniper woodlands. Each disturbance will be mapped at a 30-m spatial resolution, and will have an associated estimate of lost biomass. Re-growth trajectories will also be produced for each disturbance, enabling study of factors that affect forest recovery.

FIA's extensive network of forest inventory plots allows thorough characterization of the overall status of the nation's forests. This project will add a spatial element to traditional FIA disturbance reporting. Maps of disturbance can be used to update habitat or fuel maps, support landscape-level studies of edge effects, and prioritize recovery and rehabilitation efforts. Leveraging of FIA data with satellite imagery in this way may open up open up new perspectives of how disturbance operates in our forests over both time and space.

More information on these methods can be found in: Healey, S.P.; Yang, Z.; Cohen, W.B.; Pierce, D.J. 2006. Application of two regression-based methods to estimate the effects harvest on forest structure using Landsat data. Remote Sensing of Environment 101:115-116.

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Last Modified: Monday, 28 April 2008 at 17:16:34 EDT (Version 1.0.5)