The response of soil respiration to land-use change depends on soil microbial community being regulated by edaphic factors in the Loess Plateau, China

Land-use change has significant influences on soil respiration (Rs) in terrestrial ecosystems. Soil microbes play critical roles in soil carbon cycling. Nevertheless, the specific mechanism of how changes in soil microbial properties are linked to the variation of Rs rate during land-use change still remains poorly understood, especially in the Loess Plateau, China. Here, the characteristics of Rs rate and soil microbial community following the land-use change from farmland to plantation/grassland were analyzed via an automated soil CO2 flux system and high-throughput 16S rDNA gene sequencing. The afforestation altered soil microbial diversity and community composition, which was mainly explained by soil pH, temperature, organic matter, nitrate, alkali-hydrolyzed nitrogen, and available phosphorus. The biomarkers of Bacteroidetes, Firmicutes, and Thaumarchaeota were found in farmland soil at the phylum level. The afforestation also significantly decreased Rs rate, which was closely related to Shannon's index, Simpson's index, and some microbial taxa, such as Bacteroidetes, Firmicutes, Nitrospirae, and Acidobacteria. Bacteroidetes, and Firmicutes were particularly expected to be important drivers of high Rs rate in farmland soil. Moreover, the microbial interaction was probably also an important factor affecting Rs rate. Our results indicate that the response of Rs to land-use change depends on soil microbial community being regulated by soil physicochemical properties in the Loess Plateau, China.

Automated summary

Land-use change has a significant influence on soil respiration in terrestrial ecosystems, with soil microbes playing a critical role in soil carbon cycling. However, the specific mechanisms linking changes in soil microbial properties to variations in respiration rate during land-use change are poorly understood, especially in the Loess Plateau, China. This study analyzed the characteristics of respiration rate and soil microbial community following a land-use change from farmland to plantation/grassland using a soil CO2 flux system and gene sequencing. Afforestation altered soil microbial diversity and composition, primarily influenced by pH, temperature, organic matter, nitrate, alkali-hydrolyzed nitrogen, and available phosphorus. Bacteroidetes, Firmicutes, and Thaumarchaeota were identified as biomarkers in farmland soil at the phylum level. Afforestation also significantly decreased respiration rate, which was closely related to Shannon's index, Simpson's index, and certain microbial taxa including Bacteroidetes, Firmicutes, Nitrospirae, and Acidobacteria. Bacteroidetes and Firmicutes were particularly identified as important drivers of high respiration rate in farmland soil. Additionally, microbial interactions were likely an important factor affecting respiration rate. These findings highlight the influence of soil microbial communities regulated by physicochemical properties on the response of respiration to land-use change in the Loess Plateau, China.