The association of land cover with aeolian sediment production at Jornada Basin, New Mexico, USA

We investigated amounts and particle size distributions (PSDs) of aeolian sediments collected at five heights in five ecosystem types at the Jornada Basin, Chihuahuan Desert, New Mexico, USA. Particle size distributions, mass fluxes, and percent of dust-sized (<= 50 mu m) mass flux were determined for all heights and all ecosystem types. Differences between sites were determined using ANOVA followed by Tukey-Kramer post hoc tests to find groupings. For creosote shrublands, grasslands, and two tarbush-dominated alluvial flats, samples collected at 5, 10, and 20 cm had >80% sand-sized (>50 mu m) particles, while one playa and tarbush site yielded similar to 45% dust-sized particles at 5 and 10 cm. The transition from saltation to suspension was similar to 20 cm for most sites. Two mesquite dune sites and an anthropogenically devegetated site, all with high overall mass fluxes, shifted to suspension at similar to 50 cm. Highest dust fluxes occurred at the devegetated site, followed by the playa, a mesquite site with unvegetated "streets," and tarbush sites. These field observations are consistent with laboratory-based dust emission experiments and remote sensing studies in the Chihuahuan Desert. Playas and tarbush sites are major dust producers due to high proportions of fines, whereas the mesquite site produces much dust because of greater overall mass flux. Mesquite dunes covering most of the basin likely produce the most dust overall, though playas and tarbush-dominated alluvial flats (which cover about 8%) can emit large amounts of dust. Continuing shrubland encroachment will likely increase dust emissions from the Jornada Basin, as well as in other arid regions. (C) 2011 Elsevier B.V. All rights reserved.