Soil ecological stoichiometry characteristics under different types of biological soil crusts in the hilly Loess Plateau region, China

Abstract

Biological soil crusts (biocrusts) play an important role in soil nutrient accumulation and cycling. We examined the relationship between soil nutrient characters and biocrusts types, with six typical types of biocrusts in the hilly Loess Plateau region, including light cyanobacterial crust, dark cyanobacterial crust, cyanobacterial with moss crust (mixed crusts), moss crust, Diploschistes spp. crust, and Nostoc commune crust. The variations of soil carbon (C), nitrogen (N), phospho-rus (P) concentrations and stoichiometric ratios of biocrustal layer and the subsoil under different types of biocrusts were investigated. The results showed that there were significant differences in C, N, P concentrations and stoichiometric ratio among different biocrusts types. The concentrations and stoichiometric ratios of C, N, P in the biocrustal layer were significantly higher than those of 0-10 cm soil beneath biocrusts. The concentrations of C and N significantly decreased with the increases of soil depth across all the biocrusts types. P content showed no variation between soil layers. The concentrations and stoichiometric ratios of C, N, P of moss crust were significantly higher than those of other biocrusts,with C, N, and P content of 27.07, 2.42 and 0.67 g·kg-1. In soil layer of 0-2 cm, the concentrations and stoichiometric ratios of C, N, P under N. commune crust were significantly higher than those of other biocrusts.