Natural forest restoration enhanced abundance and changed composition of soil phosphorus cycling genes compared with plantations

How and to what extent forest restoration type influences phosphorus (P) cycling genes on abundance, diversity, and composition remain poorly understood, limiting the assessment of forest restoration types. Using a high-throughput functional gene microarray, we compared the abundance, diversity, and composition of P cycling genes in naturally restored natural secondary forests, artificially restored native Masson pine plantations, and introduced slash pine plantations in the red soil region of southern China. The abundance of P cycling genes, particularly phytase genes involved in organic P mineralization, was the highest in soils of natural secondary forests, followed by native Masson pine plantations, and finally, introduced slash pine plantations. The correlation between P cycling gene abundance and available P content exhibited an inverse pattern. P cycling gene composition varied significantly among the three forest restoration types. The similarity of P cycling gene composition in native Masson pine plantations to that of natural secondary forests was larger than that observed in introduced slash pine plantations. The vegetation-related factors of the ShannonWiener diversity index of trees, litter stock, tree biomass, and fine root surface area, and soil properties of total P, available P, clay content, silt content, and pH, significantly correlated with the P cycling gene composition. Maintaining high tree diversity is critical for supporting a high abundance of P cycling genes, which is beneficial for maintaining a high P status and active P cycling in forest soils. Natural forest restoration enhanced the abundance and changed the composition of soil P cycling genes compared with plantations.