As the population increases in Guatemala's Petén region, home to the largest protected tropical forest north of the Amazon, so does the deforestation. From 1997-1999, a team of researchers developed a new environmental module for Guatemala's Demographic and Health Survey (DHS) that analyzed the rapidly changing population-environment dynamics in this frontier region. According to anthropologist Liza Grandia, "The integrated DHS has been a critical part of developing ... programs linking health and population with the environment," which have lowered Petén's total fertility rate from 6.8 to 5.8 children per woman in just four years.