Monitoring arid land vegetation change with remote sensing: an example from southern Arizona

Remote sensing techniques were found to detect changes occurring over a period of years in relatively sparse desertscrub and semiarid grassland. Satellite data were sensitive to changes in total cover when the magnitude of change was at least 10 to 15%. Large-scale aerial photos were sensitive to changes of smaller magnitude and could also discriminate between plant growth form and in some cases plant species identity. Neither type of remotely sensed data could detect small changes in community structure such as the immigration of new species, some of which could have long-term ecological significane. -Authors