Our research addresses the collapse of a civilization and the consequences of deforestation in the tropics. The ancient Maya reached a high population density, deforested much of their environment, and caused significant soil erosion in southern Mexico and northern Central America by about 800 AD. In the next century their civilization declined over large areas, with populations reduced by 90% in some regions. Our goals are to: 1) understand the interactions between the ancient Maya and their environment that contributed to the collapse of their civilization in northwest Belize, Central America, and 2) to assess the impact of ancient Maya land use, ending 1200 years ago, on the present environment. To do this we will study archaeology, geology, and ecology at the same research sites and overlay the results to reveal connections among ancient land use, ancient impacts on soil and topography, and the present soil characteristics and tree species composition of a tropical forest. We will work in an area where there was a variety of intensive ancient Maya land uses, but where there has been little disturbance since the collapse of the Maya and the re-growth of the forest beginning c. 1200 years ago, which means that the footprint of the ancient Maya in our study area should be more evident than in other places. The study will be carried out in the 250,000-acre Rio Bravo Conservation and Management Area, administered by the Programme for Belize (PfB), a Belizean conservation organization, and be conducted under the auspices of the PfB Archaeology Project, operated by the University of Texas at Austin. Humans increasingly affect the planet, for example, by deforesting the landscape and accelerating soil erosion. These changes could lead to "tipping points", when ecosystems suddenly change radically and no longer support agriculture, provide adequate water, or otherwise supply human needs. Scientists need to study these impacts and suggest how to mitigate the present changes and prevent future tipping points. But we can also learn by studying tipping points reached in the past, such as the collapse of the ancient Maya described above. To understand that collapse we are combining social science (archaeology), geo-science, and ecological science to study past events at sites of ancient Maya civilization in present-day Belize. Archaeologists in our team will study past land use. Geo-archaeologists will study past topography and soils. Ecologists will study past and present forest environments. Our work is guided by a model connecting ancient land use, deforestation and soil erosion, consequences for the environment, and responses by the ancient Maya to these landscape changes. In addition to understanding past events we are interested in the long-term consequences of ancient deforestation for the present-day forests. The similarities and differences between ancient deforestation (after which the modern, fairly diverse forest re-grew in Belize) and modern deforestation could provide clues to the consequences of modern land use and provide recommendations for improved use. Another goal for us is to create a model collaboration between social, geological, and biological scientists for the study of the ancient Maya and the modern forest, and that can be a general model for studying and managing environmental problems.