Does timing or location matter? The influence of site variability and short-term variations in precipitation on magnetic enhancement in loessic soils

Abstract

The magnetic properties of soils are often used to quantify soil development and reconstruct past climates in regions where other recorders of paleoclimate are unavailable. Soil-based paleoclimate reconstructions rely on transfer functions that link soil-magnetic properties to the climatic conditions during pedogenesis. Recently, the reliability of these transfer functions has been discussed, but the variability of soil magnetic properties at a given site is poorly known. This study analyzes multiple cores of a loessic soil that have been collected at one locality over the timespan of five years. An extensive magnetic characterization of these cores shows that the soil magnetic signal and any climate proxies derived from magnetic data are reproducible between cores from one site and do not depend on short-term (annual or seasonal) fluctuations in precipitation. Therefore, the observed scatter in existing soil-climate transfer functions is likely due to variation in microclimates, soil drainage, and pedogenesis processes. Rather than sampling existing sites multiple times, existing transfer functions are best improved by careful site selection that controls non-climate-related soil forming factors as well as possible.