Mangrove history during middle- and late-Holocene in Pacific south-eastern Mexico

A paleoecological analysis of a 6-m-long sedimentary sequence from the La Encrucijada Biosphere Reserve (RBLE) from southern Pacific Mexico provides detailed information about past vegetation changes between 6200 and 700cal. yr BP. Highest percentages of mangrove pollen in pollen zone I (from 6200 to 5400cal. yr BP) suggest moister and warmer conditions than at present related with global rates of sea-level rise and northward position of the Intertropical Convergence Zone (ITCZ), suppressing El Nino-Southern Oscillation (ENSO) events. Drier conditions and decreasing rates of sea-level rise at 5400-4500cal. yr BP are evidenced in pollen zone II by the lowest percentages of mangrove pollen and highest presence of disturbance pollen. Recovery of mangroves and tropical forests occurred from 4500cal. yr BP, suggesting moister conditions. Agricultural activities are recorded around 4900, 4700 and 2400cal. yr BP, although human occupation was scarce in the mangrove area. ENSO variability correlates to mangrove pollen variation between 3600 and 2400cal. yr BP. A protracted drought is observed at 1300-700cal. yr BP characterized by proportions in montane forest pollen and may be related with southern oscillation of the ITCZ and the Classical Mayan Demise.