Spatial and temporal variability of rural dust flux from Colorado Plateau landscapes, southeastern Utah, USA

Background/Question/Methods

Aeolian dust generated from rural dryland environments influences nutrient availability, soil fertility, plant interactions, and water-holding capacity. Vegetation, ground cover, land-use, and climate patterns affect dust flux in different ways. Measuring dust emission and deposition can reveal spatial and temporal patterns of dust flux, informing geologic, atmospheric, and ecological models at multiple temporal and spatial scales, as well as elucidating important controls on wind erosion processes. Previous studies have documented the effects of these variables on dust flux in several dryland settings yet very few have focused on Colorado Plateau landscapes. We have developed a network of 108 horizontal dust collectors spanning numerous types of ecosystems, soil types, land-use histories, and geologic bedrock settings covering about 4400 square km across southeastern Utah.   

            Samples were collected every 3-4 months from the dust collectors at heights of 15 cm to one meter between mid-2008 and present. Line transects were established at each collection site to measure vegetation cover and soil properties. Dust-flux patterns were calculated on total sediment collected over the sampling period, normalized to the size of the sediment trap and number of days in a sampling period (reported as grams m^-2 day^-1).

Results/Conclusions

Dust flux peaked during the spring months in all plant-community types, likely due to higher surface wind speeds typical of this season. Pinyon-Juniper woodland, perennial grassland, Artemisia tridentata shrubland, Coleogyne ramosissima shrubland, and Atriplex spp. shrubland averaged 6, 6.4, 11.09, 101.4, 138.1 g m^-2 d^-1 respectively during the spring. Dust flux was lowest during the winter period when surface wind speeds are commonly low, and snow periodically covers the surface. Pinyon-Juniper woodland, perennial grassland, Artemisia tridentata shrubland, Coleogyne ramosissima shrubland, and Atriplex spp. shrubland averaged 1.5, 1.1, 2.2, 6.6, and 7.5 g m^-2 d^-1 respectively during the winter. Seasonal dust flux variation was highest in shrublands and lowest in both perennial grasslands and Pinyon-Juniper woodlands. Surfaces dominated by perennial grass consistently had the lowest flux rates. Atriplex spp.-dominated-shrubland consistently exhibited higher dust flux than Artemisia spp.- and Coleogyne ramosissima-dominated shrublands. The year 2009 was significantly dustier than 2010 (59.06 vs. 9.14 g m^-2 d^-1) averaged over all plant communities, with Coleogyne and Atriplex plant communities contributing the most to overall flux rates. In contrast, temporal dust-flux patterns from Pinyon-Juniper woodland, perennial grassland, and Artemisia tridentata shrubland, three of the most prevalent plant communities, were nearly indistinguishable but still showed higher dust flux in 2009 versus 2010.