Soil Microbial Community Succession Based on PhoD and Gcd Genes along a Chronosequence of Sand-Fixation Forest

Abstract

Revegetation by planting shrubs on moving sand dunes is widely used to control desertification in arid/semi-arid areas. The soil including microbial community can gradually be improved 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) in the development of sand-fixating plantation and (2) to discuss the interactions between P turnover microbial communities and soil properties. We assessed the compositions of soil phoD gene (one of the Pho regulons encoding alkaline phosphomonoesterases) and gcd gene (encoding glucose dehydrogenase) in microbial community by using high-throughput Illumina MiSeq sequencing 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 the dominant phoD taxa, while Proteobacteria and Rhizobiaceae were the dominant gcd taxa. Plantation development facilitated the progressive successions of soil phoD and gcd communities resulting from the increase in the abundance of dominant taxa. Total soil N, NH4-N, and available K were the main factors affecting the structures of phoD and gcd communities, while pH was not significantly influencing factor in such arid and nutrient-poor sandy soil. Many phoD or gcd OTUs were classified into Rhizobium and Bradyrhizobium, suggesting the coupling relationship between soil P turnover and N fixation.