Reconstruction of the Late Pleistocene to Late Holocene vegetation transition using packrat midden and pollen evidence from the Central Mojave Desert

摘要

The Mojave Desert of the American West is characterized by plant species that reflect a unique mixture of winter precipitation and summer monsoon climate. Currently, the Mojave Desert experiences a strong summer monsoonal pattern with weak winter precipitation. Data from pollen and packrat midden analyses have revealed a history of Mojave Desert vegetation during the transition from the late Pleistocene to late Holocene (~17500 Cal. years B.P. to ~ 1200 Cal. years B.P.) that highlight a summer dominated monsoonal pattern, similar to those in the greater American Southwest. We compare pollen data from a lava tube in the Cima volcanic field, located in south-central region of the Mojave Desert, with plant macrofossil data from several woodrat midden localities in the region. The record for the Cima volcanic field reveals a vegetation history spanning the last ~ 8300 Cal. years B.P., with data from ancient woodrat middens detailing the record from ~17500 Cal. years B.P. to 7,800 Cal. years B.P. A Bryson macro-physical climate model for the transition from the late Pleistocene to the Late Holocene was created and compared to our findings to assess possible relationships between climatic variations and the arrival of diagnostic plant species within the Mojave Desert.