By Ana Ionova RIO PINDARÉ INDIGENOUS TERRITORY, Brazil – Under the emerald canopy of the Amazon rainforest, Janaína Guajajara peered into a murky pool of water barely larger than a bathtub. Along its margins, delicate buriti (Mauritia flexuosa) seedlings sprouted from the soil. “This here was totally dry before – but the plants have restored it,” she said, waving to the fledgling palm trees. “They’ve rescued it.” The humble pool, tucked in a patch of forest in the Rio Pindaré Indigenous Territory, in the Brazilian state of Maranhão, is actually a crucial part of a much bigger water system in t…