Patterns of recent charcoal accumulation in sediments of a glacial lake in the páramo of Parque Nacional Chirripó, Costa Rica

The development of fire histories from sedimentary charcoal analysis requires an interpretation of the charcoal stratigraphy. This interpretation can be improved with knowledge of recent patterns of charcoal accumulation in the basins under study. To improve reconstructions of paramo fire history from glacial lake sediments in Costa Rica, I retrieved a series of short sediment cores from a glacial lake where previous studies confirmed repeated watershed fires at intervals throughout the Holocene. The cores were taken along a transect that crossed the lake, including the deepest point, and were sampled at contiguous 1-cm intervals. Analysis of these cores revealed the pattern of charcoal accumulation in the lake sediments following recent fire events. A comparison of different macroscopic size classes of charcoal particles indicates little difference in the pattern between size classes. The results suggest that wind-generated currents and fluvial deposition strongly influence the pattern of charcoal accumulation along the transect. Sediment accumulation rates were estimated based on a radiocarbon date, and used to construct charcoal influx diagrams. The temporal resolution of the charcoal record was estimated by interpreting the charcoal influx diagrams.