Despite the potential utility of remote sensing for monitoring, key methodological challenges must be considered in the design of a remote sensingbased monitoring project (Kennedy et  al., 2009). Evaluating the arc of a remote-sensing-based project requires balancing cost and bene‰t for different remote sensing technologies and analytical techniques, as well as availability of suf‰cient independent reference data to train and validate those data and algorithms. A key component of the potential bene‰t of a given technology is the extent to which the changes of interest on the ground affect the spectral signal (diagnostic contrasts in re˜ectance of electromagnetic energy from different parts of the spectrum) on which the detection of change is based. For a remote sensing monitoring project to be successful, the expected changes must be reliably captured with the remote sensing technologies that are affordable.