Holocene upland and wetland dynamics in the Chihuahuan Desert, Cuatrocienegas Mexico

The Cuatrocienegas Basin, Coahuila MX, has the highest rate of endemism in North America and has been the source of a rich aridlands, paleoenvironmental history in the Chihuahuan Desert of North America. Understanding the recent past of the Cuatrocienegas Basin contextualizes how aridland terrestrial and wetland systems may respond to ongoing climate warming and the potential aridification in already water-limited regions. A 12.3 m long sediment core dated to similar to 13,500 cal yr BP was collected from Poza Cortador and examined for pollen to reconstruct the Holocene terrestrial and wetland history of the Basin. The terrestrial record indicates a transition from woodland to desert environments by similar to 7500 cal yr BP. This transition is characterized more by the decrease in conifer and oak pollen abundances relative to desert taxa rather than a sudden appearance of new pollen types. Wetlands appear more stable than the terrestrial record, possibly because of groundwater buffering of the wetland surface. Alternatively, there might be less obvious changes because of the overall pollen diversity of identified wetland pollen types selected in this study. Significant aridity in both the terrestrial and wetland environments is inferred between 5000 and 3000 cal yr BP based on poor pollen preservation. The record of the last 3000 cal yrs reflects the resilience of both the terrestrial and wetland systems to prolonged drought and provides hope that this unique system may have resiliency to some aspects of future climate change if the hydrologic connectivity can remain intact.