Soil organic matter decomposition and carbon sequestration in temperate coniferous forest soils affected by soluble and insoluble spruce needle fractions

In this study, we focused on the effects of soluble, insoluble and whole-tissue coniferous needle fractions on soil organic matter (SOM) decomposition and C storage in soil fractions. In addition, the effect of future increased C input was tested by applying a doubled amount of the soluble fraction (whole-tissue + soluble fraction). 13C-labelled needles were produced from spruce seedlings in growth chambers and needle fractions were added to the coniferous forest soil in laboratory microcosms. CO2 respired during incubation from the microcosms was partitioned into needle- and SOM-derived components. After seven months, soils were destructively harvested and analysed for C content in soil fractions and microbial community composition.The soluble, insoluble and whole-tissue fractions resulted in cumulative priming (increased SOM-derived CO2 relative to unamended controls) of 25 ± 8%, 40 ± 1%, and 39 ± 7%, respectively. The doubled soluble-C addition caused a slightly lower priming (38 ± 2%) than the whole-tissue fraction alone. The addition of needle fractions did not significantly affect the C content of soil fractions. However, the soluble fraction retained in soil was mainly found adsorbed onto mineral particles, whereas the insoluble and whole-tissue fractions occurred mainly as free particulate organic matter or adsorbed onto mineral particles. The insoluble and whole-tissue fraction led to increased fungal abundance and decreased abundance of G+ bact...
Source: Soil Biology and Biochemistry - Category: Biology Source Type: research