Microbes in tropical forests play a crucial role in soil health and carbon storage. Adding nitrogen to these forests can change the types of microbes present and impact soil carbon levels. By studying two tropical forests, researchers found that adding nitrogen increased microbial biomass but decreased certain types of carbon in the soil. In one forest, nitrogen led to more bacteria and less labile carbon, while in another forest, fungi increased and carbon associated with soil storage decreased. The activities of these microbes also changed with nitrogen, affecting how carbon is stored and cycled in the soil. This shows that different tropical forests respond differently to nitrogen additions, which can have big effects on their ecosystems.