Climate and agricultural history from the Petén Campechano in the Late Holocene Maya lowlands of southern Mexico

Multiple approaches were used to investigate agricultural and forestry practices of the Preclassic Maya in the Petén Campechano, southwestern Yucatan Peninsula, Mexico. Palaeoenvironmental inferences were based on pollen and geochemical data from sediment cores collected in lakes Silvituc and Uxul, and the Oxpemul Reservoir. These water bodies are near three archaeological sites that supported agricultural activity between ca. 900 bc and ad 750. After ca. ad 500 the area was under the control of the Kaan Dynasty. These sites show patterns similar to those in sediments from Lake Petén Itzá, northern Guatemala, but they are different from records from the northeastern part of the Peninsula at Lake Chichancanab. Changes in the patterns of abundance, increase and decrease of maize pollen, relative to that of other crops (Cucurbitaceae and Chenopodiaceae) reflect changes with respect to their cultivation and importance. High clay and gypsum content in the sediments may be related to deforestation, agriculture, and intervals of greater rainfall. Changes in sediment elemental concentrations were associated with droughts and human activities during the Classic Period after ad 250. The Classic droughts were more severe and prolonged than those of the Preclassic and thus had a greater impact for inhabitants of the Petén Campechano. This led to a cultural collapse by the seventh century, whereas settlements farther north on the Yucatan Peninsula persisted until the tenth century. Gradually increasing precipitation during the Postclassic (ad 1350–1850), contemporary with the Little Ice Age (LIA), is consistent with the paleoclimate history of the Guatemalan Petén. The response of ecosystems to droughts revealed the water vulnerability of the region and its influence on the sustainability of Maya settlements.