Pollen reentrainment: Contributions to the pollen rain in an arid environment

Atmospheric pollen was sampled from native vegetation at the Desert Laboratory, University of Arizona, Tucson, Arizona, USA, using a Burkard trap. The pollen counts disclosed two conditions of pollen preservation (1) pollen with the intine visible, and (2) pollen characterized either by loss of the intine or by a crumpled exine. The former was thought to be freshly discharged, the latter to be reentrained from depositional surfaces. 11% of the atmospheric pollen collected was reentrained. Winds accompanying convective summer storms enhanced pollen reentrainment. Chenopodiaceae-Amaranthus and Gramineae, morphologically smooth pollen taxa, totaled 86% of the reentrained pollen during 1981-82. Pollen from soils appeared to be a major source of reentrained pollen. The amount of reentrainment varied seasonally; reentrainment concentration was greatest during the summer, whereas, the percent of reentrained pollen was greatest during the winter. Pollen reentrainment has the potential to bias fossil pollen records in arid environments particularly in seasons when primary pollen production is low, e.g. winter.