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Land Use / Land Cover Change
Fiscal Year 2003 Accomplishments |
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Updated 24 January 2006
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Land Use /
Land Cover Change |
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USGCRP Decision-Support Resources Development and Related Research on Human Contributions and Responses Climate Variability and Change Observing and Monitoring the Climate System International Research and Cooperation
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Projections of Land Use and Land Cover Change:National projections of changes in land use and land cover were updated as part of a national renewable resources assessment, designed in part to support global climate change analyses. In this assessment, future climate was assumed to reflect current trends. Projected land-use changes include deforestation due to pressures to develop rural land as the human population expands—a larger area than that converted from other rural lands (e.g., agriculture) to forestry. More than 70 million acres of U.S. rural land are projected to be converted to urban and developed uses between the present and 2025. The majority of the 70 million acres is projected to come from forestland, thereby reducing the carbon storage potential of terrestrial ecosystems. Substantial shifting of agricultural and other lands to forest use is also projected, which would significantly reduce the net effect on total forest area. On remaining forestland, investment is projected to increase in certain areas, with a 14-million-acre increase in planted pine area in the South during the next 50 years. This investment is expected to result in a significant increase in sequestered carbon per acre for such treated lands. The amount of gross area changes in land uses and land covers is a multiple of net area changes, which is important for carbon accounting. New Enhanced National Land-Cover Database:The USGS, with significant support from EPA, NASA, NOAA, and USDA, is developing a new National Land Cover Database (NLCD). The 2001 NLCD, slated for completion in 2005, is being developed using circa-2001 Landsat 7 remote-sensing data. The 2001 NLCD will complement the recently completed 1992 NLCD, but will be enhanced through the generation of additional land-cover attributes and will have expanded geographic coverage (all 50 states). The new database includes significant advances over the 1992 data set. It includes land cover, percent tree cover, and percent impervious surface cover data layers. In a parallel effort between USGS and the USDA Forest Service, the same Landsat data and NLCD layers are being further interpreted into natural vegetation data layers. The collective set of NLCD land cover data products is a crucial input to regional hydrology, climatology, biogeochemistry, and ecosystem-functioning investigations. (See Figure 15)
Land Use/Land Cover Change in the Amazon Region:The Amazon Basin contains the largest intact tropical forest biome in the world. It is a region undergoing rapid transformation by land use and land cover change, with potentially profound effects on climate change, the hydrologic cycle, and ecosystem structure and biodiversity. Research underway has been utilizing the assets of Earth Observing System satellites and associated data and information systems to measure and assess these changes. Findings to-date confirm that forest degradation from fragmentation and logging has become an important disturbance in addition to deforestation. The area under selective logging is now 10-fold higher than it was in 1992. While not a significant disturbance prior to 1999, as some reports that did not use Earth observations had suggested, logging now represents roughly 30-40% of the total annual disturbance in Amazonian forests. This trend toward degradation as an important form of ecosystem disturbance is also being seen in other parts of the tropics, such as Southeast Asia, and presents new methodological and observation challenges. Future research will focus on refining the use of continuous fields measurement of forest density, using the vastly improved detection capabilities of instruments aboard the Landsat and Terra satellites. Additional work is underway to extend the work in the Amazon to a prototype global monitoring system in support of the United Nations Tropical Forest Assessment.
Assessment of Global Forest Extent:Through the use of global measurements obtained by the Terra satellite, data products have been derived assessing the extent of forests and other properties of the Earth's land cover. The data provide consistent estimates of the extent of tree cover, independent of varying definitions of "forest." This is an improvement on previously produced assessments based on Landsat data. The data set, which is freely available, provides inputs to a range of terrestrial models and provides a baseline against which future changes in forest cover can be assessed. (See Figure 17)
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