Paleohydrology and growth of a desert ciénega

A ∼7000-year record of sediment accumulation from the San Bernardino ciénega in southeastern Arizona/northeastern Sonora records changes in effective moisture. Periods of rapid sedimentation between ca. 700 to 1100 cal yr BP and ca. 4100 to 4400 cal yr BP at San Bernardino are associated with a highstand at pluvial Lake Cochise, the presence of aquatic pollen taxa in New Mexican packrat middens and periods of incision in river channels in the San Pedro and Santa Cruz river valleys. These results suggest that ciénega deposits represent records of hydrological change and, as such, are important but under-utilized repositories of paleoclimatic information. These results also inform ciénega restoration efforts by highlighting the importance of subsurface and surface water flow through these environments. Effective restoration requires the development of conditions where groundwater maintains surface vegetation and seasonal floods are allowed to inundate the surface.