Holocene mire development and climatic change from a high Andean Plantago rigida cushion mire

A pollen diagram of a 225 cm long core from a small Plantago rigida cushion mire (Turbera de Calostros) in the grassparamo belt at 3730m altitude in the Paramo de Chingaza, Eastern Cordillera of Colombia, records the last 8500 years of Holocene vegetational history. Three radiocarbon dates (8410 ± 160 BP, 7230 ± 1340 BP and 5980 ± 75 BP) provide a time frame. Pollen of taxa of zonal grassparamo and subparamo vegetation are dominant and pollen of subandean (lower montane) forest elements are overrepresented due to upslope aeolian pollen supply to this high-elevation site. Eight pollen zones were recognized and reflect, on a regional scale, a sequence of altitudinal shifts of the upper forest line (oscillating between 3000-3100 and 3500m) and synchronous changes in the composition of the Andean (upper montane) forest. Based on the radiocarbon dates and using the pollen density record, dates of changes in environmental conditions are estimated c. 8700, 8600, 7800, 7500, 6650, 5200, 300 and 100BP. Correlation with other palaeoecological records from this part of the Eastern Cordillera is discussed. Each pollen zone represents a characteristic phase in the local development of the Plantago rigida mire.