Artificial reforestation has less diverse soil nitrogen-cycling genes than natural restoration

Reforestation is effective in restoring ecosystem functions and enhancing ecosystem services of degraded land. The three most commonly employed reforestation methods of natural reforestation, artificial reforestation with native Masson pine (Pinus massoniana Lamb.), and introduced slash pine (Pinus elliottii Engelm.) plantations were equally successful in biomass yield in southern China. However, it is not known if soil ecosystem functions, such as nitrogen (N) cycling, are also successfully restored. Here, we employed a functional microarray to illustrate soil N cycling. The composition and interactions of N-cycling genes in soils varied significantly with reforestation method. Natural reforestation had more superior organization of N-cycling genes, and higher functional potential (abundance of ammonification, denitrification, assimilatory, and dissimilatory nitrate reduction to ammonium genes) in soils, providing molecular insight into the effects of reforestation. The diversity and interaction of nitrogen-cycling genes in the soils of three reforestation methods were studied. The three reforestation methods were naturally restored secondary forests (NRSF), artificial reforestation with native Masson pine (Pinus massoniana Lamb.) (ARMP), and introduced slash pine (Pinus elliottii Engelm.) plantations (ARSP). Each reforestation method included 15 replicates (plots) in red soil region in southern China. After DNA extraction and outlier (ARMP1, NRSF2, and NRSF7) checked, 14, 14, and 11 microarray replicates were obtained for ARSP, ARMP, and NRSF, respectively.