By Ana Ionova BOM JARDIM, Brazil – Amid corn fields and pastures, miles of barbed wire enclose an island of pristine rainforest, likely next in line to be razed. Just beyond, in the Gurupi Biological Reserve, a web of dusty roads splinters the canopy, leading deep into one of the last slices of protected forest in this part of the Brazilian Amazon — and signaling that it, too, is under attack. The Gurupi Biological Reserve stretches 341,650 hectares (844,235 acres) across the southwestern corner of Brazil’s Maranhão state. Under federal protection since 1988, this region of dizzying biodiversi…