The Selva Zoque , which includes the Chimalapas rain forest, is an area of great ecological importance in Mexico. Most of the forest lies in the state of Oaxaca but parts are in Chiapas and Veracruz. It is the largest tract of tropical rainforest in Mexico, and contains the majority of terrestrial biodiversity in the country. The forest includes the Selva El Ocote, a federally protected biosphere reserve, but is otherwise not yet protected. Despite the rich ecology of the region, a 2003 study that focused on bird populations stated that "the fauna of the heart of the Chimalapas, including its vast rainforests, have seen little or no study". As it is an impoverished region, efforts to preserve the ecology are often at odds with demands to improve the economy.