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In the mountainous region of northern Laos, land use is changing drastically as affected by the combined pressure of increasing population and governmental regulation on landuse. Land use is strongly related to the ecosystem carbon stock as well as to food security and sustainability of forest resources. However, quantitative geo-spatial land use information is still quite limited. The objective of our study was the regional assessment of land use and carbon stock capacity under the present and alternative land-use scenarios. We derived the chrono-sequential changes in land use and stand age (fallow length) through polygon-based classification of highresolution and time-series satellite images with the support of in situ spectral measurements and field survey. The area of slash-and-burn land-use has been increasing consistently to date with the annual rate of 3-5% in the past decade. In average, 77% was abandoned after a single year cropping. The slash-and-burn area with fallow periods shorter than 4 years was approximately 64%. The ecosystem carbon stock was assessed based on synthesis of the land use and groundbased measurements of carbon in the soil and fallow vegetations. The chrono-sequential average of ecosystem carbon stock showed a large variation (up to 33 tC/ha per year) depending on the cropfallow cycle patterns. Results suggested that the ecosystem carbon stockwould continue decreasing under the present land-use condition with short fallow cycle. It was also suggested that the carbon sink capacity of ecosystem would be recovered or enhanced by alternative land-use/ecosystem managements that would allow longer fallow periods. © 2009 by Taylor and Francis Group, LLC.
