2.4 Statistical analysis
One-way analysis of variance (least significance difference method) was used to test for significant differences in biomass, soil physical and chemical indicators, and organic carbon and nitrogen storage between different methods and soil layers. The Pearson correlation coefficient was used to analyse the correlation between plant biomass and nutrient indicators, and all data were analysed using SPSS 21.0 (with a significance level of 0.05). Principal component analysis (PCA) of plant biomass and nutrient indicators was conducted using Origin 2018.