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CONSTRUCTION OF A CARBON BUDGET OF MEXICO: A PILOT STUDY ANAYSIS 
OF LAND-USE AND LAND-USE CHANGE MAPS IN VERACRUZ 
Ralph H. Riley 
Michael J. Schuft 
NCASI 
US EPA Environmental Research Laboratory 
200 SW 35th Street 
Corvallis, OR 97333, USA 
ISPRS Commission VII / Working Group 10 
ABSTRACT 
Efforts are underway to construct a carbon budget of Mexico using GIS/remote sensing technologies and 
field studies of carbon stocks. One remote sensing resource potentially available to this effort is the set of 
land-use and land-use change map products being developed by the North American Landscape 
Characterization (NALC) Program. Results are presented from a pilot study of the Catemaco region of 
Veracruz, Mexico. we evaluate the use of these map produces for estimating carbon standing stocks and 
carbon exchange between terrestrial ecosystems and the atmosphere. Landsat MSS imagery for 1986 and 
1990 were analyzed using a post-classification change detection technique appropriate for the NALC 
imagery. The carbon content of terrestrial ecosystems is estimat2d from literature sources; two field 
sampling projects designed to improve estimates the carbon content of vegetation and soils of Mexico are 
just beginning. An Anderson Level II classification of the imagery was achieved, with forest, second- 
growth/distributed forest and non-forest land-use distinguished. The largest forest patches, limited to the 
steeper slopes of volcanoes, have experienced a net loss of forest cover between 1986 and 1990, in 
agreement with two other studies of primary forest cover loss in this region. In the landscape as a whole, 
however, many pastoral and agricultural lands in 1986 now signature as secondary forests. Decision rules 
ere used to estimate the carbon consequences of current and historical land-use transitions. we estimate 
the landscape as whole to have a net o carbon to the atmosphere due to historical forest conversion, but 
recent forest regrowth has offset some losses. Analyses of the spatial distribution of forest patches, 
carbon stocks and carbon fluxes are presented. Methodologies for the extension of carbon analyses to the 
national level using the NALC products are discussed as well as alternate sources of spatially explicit 
land-use and land-use change information. 
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