Vegetation and wildfire history of Ocate Mesa, Northern New Mexico, USA

Pollen and charcoal records are developed from Ocate Bog (2905 m, 9530 ft) on Ocate Mesa east of the Sangre de Cristo Mountains in northern New Mexico. The records extend from 12,090 to 410 cal yr BP based on 19 radiocarbon dates. The vegetation on the mesa at present is a mixed conifer and ponderosa pine forest. Pollen percentages and accumulation rates show a continuous mixed conifer forest with only modest changes during the Holocene. The seasonal water level of the spring-fed bog declined temporarily during a period from 6050 to 3230 cal yr BP. A series of Tauber pollen traps identified the level of pollen taxa represented by local versus long-distance transport. A noteworthy discovery is abundant pollen of the circumboreal emergent Menyanthes trifoliata in clayey peat dated 12,090 to 8500 cal yr BP: this may have been its south-most record in North America. The charcoal record documents a history of only rare local wildfires from 12,090 to 8700 cal yr BP. After that period the concentration and influx of charcoal particles dramatically increased to high levels that persisted throughout the rest of the Holocene. Charcoal influx is particularly high during the arid middle Holocene. The highest accumulation of charcoal occurs between 2000 and 1000 cal yr BP, especially during a short-term drought 1610 to 1440 cal yr BP. Peaks in charcoal influx occur on average every 691 years or 1.45 peaks per 1000 years. High charcoal influx is matched by more rapid sedimentation in the bog. (C) 2020 Published by Elsevier B.V.