Modern pollen in the Grand Canyon, Arizona

Abstract

Two surface pollen transects were collected from the Grand Canyon, Arizona. One transect consisted of 22 samples collected at river level through the inner gorge, a river distance of 362 km; the other went from the South Rim to the North Rim across the canyon and comprised 25 samples. Both transects show close agreement between local vegetation and modern pollen rain despite large quantities of arboreal pollen drifting into the canyon from upper elevation and rim communities. Pinus pollen averaged 19.3 percent at river level, all of it drifting in from the canyon rims; Quercus pollen, also drifting in, was 5.7 percent. Juniperus, which does occur occasionally at river level, averaged 17.7 percent. The major vegetation communities have different pollen spectra, comprised mostly of local pollen types. The distribution of several plants, particularly Ephedra torreyana, E. nevadensis and Franseria, is clearly recognized in the pollen counts. Chenopodiaceae‐Amaranthus pollen types vary with the amount of available habitat space and soil salinity.