Effects of daytime and nighttime warming on soil microbial diversity

The global temperature is continuously rising, and the impacts of nighttime warming (NW) and daytime warming (DW) on ecosystems have drawn widespread attention. However, most studies on the effects of daytime and nighttime warming on ecosystems have focused primarily on aboveground processes, but little is known about how they affect underground processes, particularly soil microorganisms. Therefore, we examined the effects of daytime and nighttime experimental warming (CK: control, DW: daytime warming, NW: nighttime warming, DW + NW: daily warming) on soil bacterial and fungal diversities at the Experimental Station of Zengcheng Forestry Science Research Institute in Guangdong, China. The results showed that, compared with the CK treatment, the NW rather than DW treatment significantly increased the abundance-based coverage estimator (ACE) diversity index of bacteria and fungi. Fungal beta diversity significantly differed between the DW and NW treatments, while there was no significant difference in bacterial beta diversity. Our research indicated that the NW treatment creates a more favourable microenvironment than the DW treatment, accelerating the mineralization of soil carbon, nitrogen, and phosphorus nutrients, which may be the reason for changes in microbial diversity. Our study provides important theoretical support and practical guidance for predicting the impact of global climate change on the diversity of microbial ecosystems.