Successions of Soil phoD And gcd Microbial Communities Along a Chronosequence of Sand-Fixation Forest

Revegetation by planting shrubs on moving sand dunes is widely used to control desertification in arid/semi-arid areas. The soil microbial community can gradually recover along with plantation development. The purposes of this study were (1) to investigate the responses of microbial communities involved in the mineralization of soil organic phosphorus (OP) and dissolution of inorganic P (IOP) to the development of sand-fixation plantation and (2) to discuss the interactions between P turnover microbial communities and soil properties. We detected the diversities of soil phoD gene (one of the Pho regulons encoding alkaline phosphomonoesterases) and gcd gene (encoding glucose dehydrogenase) and the compositions of phoD and gcd communities by using the high-throughput Illumina MiSeq sequencing technique in a chronosequence of Caragana microphylla plantations (0-, 10-, 20-, and 37-year plantations and a native C. microphylla shrub forest) in Horqin Sandy Land, northeast China. Soil properties including soil nutrients, enzymatic activity, and P fractions were also determined. The abundance of phoD and gcd genes linearly increased with the plantation age. However, the diversity of soil phoD microbes was more abundant than that of gcd. The phoD gene abundance and the fractions of total OP and IOP were positively correlated with the activity of phosphomonoesterase. Actinobacteria and Streptomycetaceae were absolutely dominant phoD taxa, while Proteobacteria and Rhizobiaceae were absolutely dominant gcd taxa. Plantation development facilitated the progressive successions of soil phoD and gcd communities resulting from the asymmetric increase in the abundance of dominant taxa. Soil total N, NH4-N, and available K were the main factors affecting the structures of phoD and gcd communities, while pH was not the main influencing factor in such arid and nutrient-poor sandy soil. Many phoD or gcd operational taxonomic units were classified into Rhizobium and Bradyrhizobium, suggesting the coupling relationship between soil P turnover and N fixation.