This data set is a subset of the 1-km global tree cover data set (DeFries et al. 1999) developed at the Laboratory for Global Remote Sensing Studies (LGRSS) at the University of Maryland. The subset was created for the study area of the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) in South America (i.e., latitude 10° N to 25° S, longitude 30° to 85° W). The data are in ASCII GRID format.
Characterization of terrestrial vegetation from the Advanced Very High Resolution Radiometer (AVHRR) on the global to regional scale has traditionally been accomplished through the use of classification schemes with discrete numbers of vegetation classes. Representation of vegetation in a limited number of homogeneous classes does not account for the variability within land cover, nor does the portrayal recognize transition zones between adjacent cover types. An alternative paradigm to describing land cover as discrete classes is to represent land cover as continuous fields of vegetation characteristics by means of a linear mixture model approach. This prototype data set (DeFries et al. 1999) contains 1-km cells which estimate (1) percent tree cover, (2) percentage cover for two layers representing leaf longevity (evergreen and deciduous), and (3) percentage cover for two layers estimating leaf type (broadleaf and needleleaf).
Data acquired in 1992-1993 from NOAA's AVHRR at a 1-km spatial resolution and processed under the guidance of the International Geosphere Biosphere Programme (IGBP) were used to derive the tree cover, leaf type and leaf longevity maps. Each pixel in the layers has a value between 10 and 80 percent. These layers can be directly used as parameters in models or aggregated into more conventional land cover maps. For the latter, the product offers the flexibility to derive land cover maps based on user's requirements for a particular application. The product is intended for use in terrestrial carbon cycle models, in conjunction with other spatial data sets such as climate and soil type, to obtain more consistent and reliable estimates of carbon stocks.
More information can be found at http://daac.ornl.gov/daacdata/lba/land_use_land_cover_change/tree_cover-1km/comp/glcftree_readme.pdf
LBA was a cooperative international research initiative led by Brazil. NASA was a lead sponsor for several experiments. LBA was designed to create the new knowledge needed to understand the climatological, ecological, biogeochemical, and hydrological functioning of Amazonia; the impact of land use change on these functions; and the interactions between Amazonia and the Earth system. More information about LBA can be found at http://www.daac.ornl.gov/LBA/misc_amazon.html.
Cite this data set as follows:
DeFries, R. S., M. Hansen, J. R. G. Townshend, A. C. Janetos, and T. R. Loveland. 2003. LBA Regional Tree Cover from AVHRR, 1-km, 1992-1993 (DeFries et al.). Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/686.
DeFries, R. S., M. Hansen, J. R. G. Townshend, A. C. Janetos, and T. R. Loveland. 1999. Global 1km Data Set of Percent Tree Cover Derived from Remote Sensing. Available on-line [http://glcf.umiacs.umd.edu] from the Global Land Cover Facility, University of Maryland Institute for Advanced Computer Studies, College Park, Maryland, U.S.A.
Information about the data file formats, tree cover classes, and the procedure used to create the LBA subset are in the following file: http://daac.ornl.gov/daacdata/lba/land_use_land_cover_change/tree_cover-1km/comp/glcftree_readme.pdf.