Temperate grassland soil nitrifiers are more sensitive to nitrogen addition than simulated warming

Abstract

Soil nitrogen transformations are influenced by both global climate change and human activities. Nitrification, affected by ammonia-oxidizing and nitrite-oxidizing microorganisms, is one of the crucial N transformation processes. However, the impact of environmental change on the diversity and community structure of these microorganisms in grassland ecosystems remains poorly understood. This study explored the alpha diversity and community structures of N-cycling microorganisms in response to simulated warming and N addition in a temperate steppe. The results showed that N addition significantly increased the taxon richness of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria but significantly decreased the diversity of total archaea. Also, N addition significantly changed the community structures of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and total archaea and bacteria. However, warming had no effect on the whole microbiome alpha and beta diversity. The alternations of microbial communities were mainly induced by changes in soil pH and inorganic N concentrations. This study illustrates that the temperate grassland microbial communities are more sensitive to N addition than simulated warming under future climate change scenes.