Abstract
Fast expansion of forest conversion to monoculture plantations has profound effects on ecosystem structure and functions. Through altering litter and rhizodeposition composition as well as one-sided effects on soil chemical properties, monoculture plantations may tremendously decrease biodiversity and functions of soil microorganisms. We investigated the impacts of conversion of natural evergreen and deciduous broad-leaf forest (Forest) to four 5-year old monoculture plantations (plantations), such as Camellia oleiferaAbel. (Oil), Amygdalus persica (Peach), Myrica rubra (Lour.) S. et Zucc.(Berry) and Cunninghamia lanceolata (Lamb.) Hook. (Fir), on soil properties and bacterial community and its driving factors using the high-throughput sequencing technique. Soil organic carbon, and total nitrogen decreased up to 59%-83% and pH increased by 0.31 units following the forest conversion. The changes in soil properties and bacterial communities were depended on the type of the plantation. Bacterial diversity increased by 6.5% after forest conversion. The relative abundances of Acidobacteria, Proteobacteria, Bacteroidetes and Actinobacteria in the Forest were remarkably higher compared with all plantations, whereas that of Chloroflexi and Planctomycetes was less. All plantations had low abundance of Acidobacteria, while the highest abundance of Proteobacteria, Actinobacteria and Planctomycetes was observed under Peach. The co-occurrence patterns of bacterial communities identified rare taxa rather than abundant taxa as central players in bacterial network. The redundancy analysis indicated that the variation in the composition of bacterial community was mainly driven by soil pH, organic carbon and total nitrogen content. Therefore, good management practices, such as reasonable fertilization and soil erosion prevention, need to be developed for monoculture plantations to mitigate the depletion of nutrients and to enhance microbial functioning after forest conversion.