The effects of soil microbial and physiochemical properties on resistance and resilience to copper perturbation across China

There has been a debate on the relationship between soil microbial diversity and soil resilience. Moreover, the key soil properties that drive soil resistance and resilience are seldom known. Therefore, we conducted an integrative study with the aim of investigating the effects of soil microbial diversity and abundance along with soil physiochemical properties on soil resistance and resilience. A total of 24 soil samples were collected throughout China from the north (Harbin, N45 degrees 45'56; E126 degrees 38'42) to the south (Xishuangbanna, N22 degrees 0'22; E100 degrees 47'44). The soil microbial diversity based on bacterial 16S rRNA gene fragments was determined using terminal restriction fragment length polymorphism. The 165 rRNA gene was quantified using real-time PCR. Soil physiochemical properties, including soil pH, total carbon and nitrogen concentrations; sand and clay proportions; and soil cation exchange capacity, were also determined. Soil resistance and resilience were determined by measuring the substrate induced respiration (SIR) rate one day and sixty days after the application of 100 mg kg(-1) Cu2+ perturbation, respectively. The results showed that there was no significant correlation between soil microbial diversity and soil resistance and resilience of SIR to Cu2+ perturbation. The resistance was positively correlated with soil pH, while the resilience was negatively correlated with the proportion of sand. Both correlations were significant (P < 0.05). Because the soil pH exhibited a spatial variation that decreased from north to south in China, the soil resistance showed a similar trend. The exponential and polynomial regression models were optimal for pH-resistance and sand proportion-resilience relationships, respectively. Our results suggest that soil microbial functional resistance and resilience is decided by soil properties that immobilize heavy metals rather than by microbial diversity and abundance. (C) 2016 Elsevier B.V. All rights reserved.