Altitudinal variations of soil magnetic and geochemical properties in central China

Abstract

Soil degradation has become a global environmental issue endangering sustainable management. Presently, limited knowledge is available on the effects of climatic factors and land use on soil environmental conditions in the mountainous regions. This study explored altitudinal variations in soil magnetic parameters and geochemical elements based on 89 surface soil samples collected along an elevational gradient (16–2088 m) in central China. Soil low frequencies, anhysteretic remanent magnetization, and saturation isothermal remanent magnetization generally increased with declining elevation, while total carbon, total nitrogen, total phosphorus, potassium, and magnesium increased with rising elevation. Redundancy analysis showed that temperature, precipitation, forests, and croplands totally accounted for 19.73% of the total variance in magnetic and geochemical parameters. Low-elevation samples were positively related to temperature, precipitation, and croplands, while middle- and high-elevation samples were positively related to forests. Warmer and moist conditions at lowland region can enhance chemical weathering of bedrocks and promote the production of magnetic substances, probably accounting for the enrichment of Fe, Al, Ti, and magnetic minerals in lowland soils. In addition, urban dusts are an important source of magnetic minerals in lowland surface soils. In contrast, relatively low temperature can slow decomposition rates of organic matter, probably accounting for the enrichment of soil total carbon and total nitrogen at the high-elevation sites. Taken together, the combination of magnetic and geochemical indicators can provide valuable insights into the impacts of climatic factors and land use on soil environmental conditions in this mountain–lowland ecoregion, as well as in other similar regions.