Spatial decoupling of soil nitrogen cycling in an arid chenopod pattern ground

Abstract

Patterned ground is a characteristic landscape form in arid zones across the globe and is caused by the redistribution of runoff. The vegetation is concentrated in groves, which receive runoff water from the bare soil surface of the intergroves. Despite many soil chemical and physical investigations, biogeochemical cycles are not described for this landscape form. This study focuses on the distinct features of the nitrogen (N) and carbon (C) cycle in intergrove and grove areas of chenopod pattern-ground soils of the Australian rangelands. The N concentration of grove soils is low compared with the intergrove soil because of a close link between the N cycle in the topsoil and the plant primary production. In grove soils, denitrification including emission of N2O dominated the N cycle, whereas in intergrove soils, abiotic N2O uptake is the sole fate of atmospheric N2O. The intergrove soils appear to be generally poor in bacterial quantity and diversity, and lacking denitrification by bacteria, which has an impact on the C cycle as well. Production of CO2 and consumption of CH4 were substantially lower than grove soils. There was partitioning of key biogeochemical processes between the intergrove and grove soils, which results in a spatially decoupled soil N and C cycle in arid chenopod, pattern-ground ecosystems.