Effect of nitrogen and phosphorus fertilization on the temporal dynamics of soil microbial community and multifunctionality in young and mature subtropical forests

The impact of fertilization on the temporal dynamics of soil microbial community and function along subtropical forest succession is not well understood. The study aims to explore how the seasonal changes in fungal and bacterial communities and multifunctionality respond to fertilization in two subtropical forest stages.

Here, we examined soil bacterial and fungal communities using Illumina Miseq sequencing and soil multifunctionality index in a 4-year experiment of nitrogen (N) and phosphorus (P) addition in three growth seasons in young and mature stages in a Chinese subtropical forest.

Our results showed that 10-22.44% variation of total, saprotrophic, ectomycorrhizal (EM) and pathogenic fungal communities were explained by fertilization (2.5-4.5%), forest stage (2.1-2.5%), season (2.3-12.52%) and soil variables (6.8-12.8%). In addition, 8.1-9.9% variation of total, oligotrophic and copiotrophic bacterial communities were explained by fertilization (2.5-3.8%), forest stage (0.7-1.1%), season (2.2-2.7%) and soil variables (5.3-6.6%). Furthermore, the temporal dynamics of the community composition of total, saprotrophic, and EM fungi, but not pathogenic fungi and bacterial groups, were affected by N fertilization in the young forest and by P fertilization in the mature forest (except for saprotrophic fungi). Additionally, the temporal dynamics of soil multifunctionality index was affected by N fertilization in the mature forest, but not in the young forest, and not by P fertilization in either forest stage.

This study revealed that fertilization influenced the temporal dynamics of the soil fungal community and multifunctionality index, but not the bacterial community. However, these effects varied by forest successional stages and fertilization type, underscoring the need to consider both forest stage and fertilization when assessing the impacts of nutrient addition on soil microbes in subtropical forests.