Changes in atmospheric nitrogen deposition and precipitation patterns can have a profound impact on the carbon cycle process in terrestrial ecosystems. However, it is unclear how the two interact to influence the process of heterotrophic respiration mediated by soil microorganisms, and whether the effects of rainfall increase and rainfall reduction on soil heterotrophic respiration are consistent.
Based on this, this study explored the effects of nitrogen addition, rainfall increase by 50% and rainfall reduction by 50% on soil heterotrophic respiration through a field control experiment for 4 years (2017-2020) in the subtropical-warm temperate climate transition zone. The results showed that nitrogen addition reduced soil microbial biomass nitrogen by 13.8% and community bacteria/fungal ratio by 1.23%. The increase and decrease of rainfall did not affect the concentration of phospholipid fatty acids (PLFAs) of each component microorganism, but the decrease of rainfall increased the ratio of gram-positive bacteria to gram-negative bacteria by 1.94%. The enhancement of soil heterotrophic respiration (28.4%) under rainfall increase treatment may be caused by the increase of microbial biomass nitrogen due to the improvement of soil water availability. Although nitrogen addition and rainfall reduction had no effect on soil heterotrophic respiration, there was an interaction between the two. This paper highlights the important role of multifactorial studies of global change in assessing soil carbon sinks.
The results were published in the international mainstream journal "Plant and Soil" under the title "Effects of nitrogen addition and changing precipitation on soil heterotrophic respiration in a climate transitional forest". Feng Jiayin, a young teacher of the Global Change Ecology Laboratory, is the first author of the paper, and Professor Wan Shiqiang is the corresponding author. The research was supported by the National Natural Science Foundation of China and the introduction of high-level talents from Hebei University.