Quantitative response relationships between net nitrogen transformation rates and nitrogen functional genes during artificial vegetation restoration following agricultural abandonment

A comprehensive understanding of how microbial associated with nitrogen (N) cycling respond to artificial vegetation restoration is still lacking, particularly in arid to semi-arid degraded ecosystems. We compared soil net N mineralization rates and the abundance of bacteria, archaea, and eleven N microbial genes on the northern Loess Plateau of China during the process of artificial vegetation restoration. The quantitative relationships between net N mineralization rates and N microbial genes were determined. We observed a significant difference of net transformation rates of NH4 (+)-(N) (R-a), NO3--N (R-d), and total mineralization (R-m), which rapidly decreased in 10-year soils and steadily increased in the 10-30-year soils. Different N functional microbial groups responded to artificial vegetation restoration distinctly and differentially, especially for denitrifying bacteria. Stepwise regression analysis suggested that R-a was collectively controlled by AOA-amoA and Archaea; R-d was jointly governed by narG, napA, nxrA, and bacreria; and R-m was jointly controlled by napA, narG, nirK, nirS, norB, nosZ, and nxrA.