uhl is the founder of imazon, a research institute located in the city of belém. pará state says that 50% of all private land must be maintained in forest. until recently, that was very hard to monitor. now, using a system of satellites casearcher carlos sousaiing s, cadoust that. okgps is realowhat it allows us to do is to pickp signals from the satellites. and through ocess of triangulation we can locate oursels verr and through ocess to within about ten meters. four... ey've gour sateites now. we are... probably... in this... area. mm-hmm. narrator: if the government chooses, it can use gps to locate property lines on satlite photographs of the landscape. they can then determine how much of a farmer's land has beenleared but enforcement is stty. anotg problem is thenefficient way the cleared land is being used. the most common farming and grazing method here requires the farmer to cut tousands ofirm spe,it dry.llit set by farmers during the dry season to release the nutrients from the vegetation. but the soil's productivity disappears, sometimes in one or two y