Monitoring secondary tropical forests using space-borne data: implications for Central America

Tropical secondary forests, which play an important role in carbon sequestration, may be monitored using space-borne sensors. Secondary forest biomass or age estimation from space-borne data may be used to quantify the carbon sink these forests represent. At current capabilities, roughly three successional stages up to 15 years of age may be identified from Landsat TM data. Using synthetic aperture radar, reliable biomass estimates may be made up to approximately 60 tons/ha. The potential for overcoming these limitations is reviewed, including the synergy of radar and optical imagery and the unprecedented spatial and spectral resolutions of new sensors. Most of the available literature to date is from the Amazon; in this paper, applicability to Central America is considered, which has a much more heterogeneous landscape and the dynamics of secondary growth have a special significance in the framework of conservation biology and carbon sequestration. We conclude that critical issues in this region will be topographical correction and stratification according to ecological and site quality variables.