The Differences in Soil Microbial Community Structure and Functional Diversity among Poplar Plantations at Different Ages in the Songliao Plain

【Objective】The aim of this paper to analyze the changes in soil microbial community structure and functional group characteristics of poplar plantations at different ages, reveal the impact of stand age on soil microorganisms, and provide a scientific basis for soil fertility maintenance and sustainable management of poplar plantations.【Method】Populus×euramevicana ‘I-214’ plantations at ages of 2, 4, 7, 10, and 14 years were selected in Xinmin City, Liaoning Province. The soil physical and chemical properties of the 0−20 cm soil layer were measured, and the high-throughput sequencing technology was used to analyze the differences in soil bacterial and fungal community structures and functional diversity among I-214 poplar plantations of different stand ages. 【Result】The study showed that the contents of soil organic carbon, nitrate nitrogen, available potassium, and available phosphorus all exhibited a trend of decrease followed by an increase among differents ages. The dominant bacterial phyla in the soil were Proteobacteria and Acidobacteriota, and the relative abundance of Proteobacteria increased with age. The dominant fungal phyla were Ascomycota and Basidiomycota, and their relative abundances were hardly affected by stand age. The Shannon index of soil bacteria first decreased and then increased with stand age, reaching the highest at 2 years old. The redundancy analysis showed that soil bulk density, pH, available potassium and available phosphorus content were the main soil factors that significantly affected soil bacterial communities, while total nitrogen and nitrate nitrogen content were the main soil factors that significantly affected soil fungal communities. Functional prediction of soil microbial communities showed that the relative abundance of bacterial communities involved in carbon and nitrogen transformation increased with age. 【Conclusion】 In the I-214 poplar plantation in the Songliao Plain, the relative abundance of Proteobacteria, the dominant bacterial community in the soil, increased with the increase of age, while the relative abundance of Acidobacteria increased first and then decreased with the increase of age, but the dominant fungal community was hardly affected by stand age. Soil bulk density, pH, available potassium, available phosphorus, total nitrogen and nitrate nitrogen content are the main soil factors affecting soil microbial communities. The relative abundance of bacterial communities involved in soil nitrogen transformation functions such as soil nitrogen fixation and carbon transformation functions such as Phototrophy increased with the increase of age. The Shannon index of soil bacteria, the relative abundance of carbon transformation functional communities, and the nutrient contents of soil nitrate nitrogen, available potassium, and available phosphorus all showed a significant decreasing trend starting from the 10-year-old, indicating that the 10-year-old poplar plantation in the Songliao Plain may be at a critical change point of soil fertility, microbial community structure, and functional diversity. At this stage, it is necessary to consider adopting appropriate management measures to maintain soil fertility, microbial community structure, and functional diversity. © 2024 Chinese Society of Forestry. All rights reserved.