On the development of a magnetic susceptibility-based tracer for aeolian sediment transport research

Abstract

Aeolian processes – the erosion, transport, and deposition of sediment by wind – play important geomorphological and ecological roles in drylands. These processes are known to impact the spatial patterns of soil, nutrients, plant-available water, and vegetation in many dryland ecosystems. Tracers, such as rare earth elements and stable isotopes have been successfully used to quantify the transport and redistribution of sediment by aeolian processes in these ecosystems. However, many of the existing tracer techniques are labor-intensive and cost-prohibitive, and hence simpler alternative approaches are needed to track aeolian redistribution of sediments. To address this methodological gap, we test the applicability of a novel metal tracer-based methodology for estimating post-fire aeolian sediment redistribution, using spatio-temporal measurements of low-field magnetic susceptibility (MS). We applied magnetic metal tracers on soil microsites beneath shrub vegetation in recently burned and in control treatments in a heterogeneous landscape in the Chihuahuan desert (New Mexico, USA). Our results indicate a spatially homogeneous distribution of the magnetic tracers on the landscape after post-burn wind erosion events. MS decreased after wind erosion events on the burned shrub microsites, indicating that these areas functioned as sediment sources following the wildfire, whereas they are known to be sediment sinks in the undisturbed (e.g. not recently burned) ecosystem. This experiment represents the first step toward the development of a cost-effective and non-destructive tracer-based approach to estimate the transport and redistribution of sediment by aeolian processes. © 2018 John Wiley & Sons, Ltd.