Biogeomorphological Wetland Formation and Long-term Human Interactions in Mesoamerica

Our recent work shows that wetlands in Mesoamerica are declining rapidly in recent decades from agricultural expansion and deforestation.  We have also shown the long human use of these wetlands over at least the last 2,000 years and possibly since the middle Holocene through several studies in Belize, Mexico, and Guatemala.  In this paper we use high resolution surface mapping based on Lidar that covers more than 500 square kilometers of forested areas with field-based biogeomorphological and archaeological verification to study the formation of Pre-Columbian indigenous wetland agricultural complexes. We present three examples from both our well-studied and newly studied sites in a range of wetland settings from perennial to seasonal riverine and karst depressions under different water chemistries.  The first well-known example is from the fluviokarst Rio Bravo Watershed in Belize that provides an example of how wetlands formed over the last two millennia under starkly different chemical conditions from low to high solute loads (mostly sulfate and calcium carbonate).  Second, we consider little known wetland canal and field systems in the seasonal, karst, upland depressions in Guatemala. Third, we consider more little-known riparian wetlands of the coastal Plain of Tabasco and Campeche.  For each region, we consider geomorphologic factors such as water and soil chemistry, biological factors such as vegetation change, and the evidence we have, from excavations, of human management of these systems.  We also compare more ‘natural’ and more anthropogenic models for their formation.  Next, we provide a new, updated estimate of the areal extent and human importance of these wetland complexes.  Finally, we consider how our findings are relevant for ‘natural’ and polycultural wetland restoration.