Plant managements but not fertilization mediate soil carbon emission and microbial community composition in subtropical Eucalyptus plantations

Abstract Background and Aims The diversity of plant functional groupsin plantations affects soil carbon, but we have limited understanding of the underlying mechanisms for how to plant management affects soil carbon dynamics. Methods We conducted a 3-year manipulation experiment of plant functional groups that included understory removal, tree root trenching, and fertilization treatments in 2-year-old and 6-year-old Eucalyptus plantations in the subtropical region, to explore soil carbon emission and microbial community composition. Results Soil respiration was significantly suppressed by understory removal (-38%), tree root trenching (-41%), and their interactions (-54%), but that fertilization alone and in interactions had no significant effect. Soil bacterial and fungal communities were also affected by understory removal and tree root trenching. Soil respiration, physicochemical characteristics, microbial diversity, and community composition were significantly affected by plantation age. Reductions in soil carbon emissions were associated with reductions in plant functional groups and soil microbial groups, while increases in soil respiration were associated with soil physicochemical factors, soil temperature, and plantation age. Conclusion Our findings highlight that plant managements are of great significance to the soil carbon emission processes in afforested plantations.