The article by Steven D. Allison and Jennifer B. H. Martiny addresses the importance of microbial community composition in ecosystem processes, particularly in the context of global change. Despite the critical role of microorganisms in ecosystem functions, their composition is often overlooked in ecosystem models due to methodological challenges and the overwhelming diversity of microbial taxa. The authors review recent experiments to assess whether microbial community composition is resistant, resilient, or functionally redundant in response to disturbances such as elevated CO2, mineral fertilization, temperature changes, and C amendments. They find that microbial composition is generally sensitive to these disturbances and does not recover quickly, indicating that microbial communities are not resilient. Furthermore, changes in microbial composition often affect ecosystem process rates, suggesting that microbial taxa are not functionally redundant. To incorporate microbial community composition into ecosystem models, the authors propose a framework that links microbial phylogeny, physiological traits, and disturbance responses. This framework aims to improve predictions of ecosystem processes under global change by accounting for the complex interactions among microbial taxa. The authors emphasize the need for more empirical data to define microbial functional groups and their responses to disturbances, highlighting the potential of metagenomic and metatranscriptomic approaches to advance this field.The article by Steven D. Allison and Jennifer B. H. Martiny addresses the importance of microbial community composition in ecosystem processes, particularly in the context of global change. Despite the critical role of microorganisms in ecosystem functions, their composition is often overlooked in ecosystem models due to methodological challenges and the overwhelming diversity of microbial taxa. The authors review recent experiments to assess whether microbial community composition is resistant, resilient, or functionally redundant in response to disturbances such as elevated CO2, mineral fertilization, temperature changes, and C amendments. They find that microbial composition is generally sensitive to these disturbances and does not recover quickly, indicating that microbial communities are not resilient. Furthermore, changes in microbial composition often affect ecosystem process rates, suggesting that microbial taxa are not functionally redundant. To incorporate microbial community composition into ecosystem models, the authors propose a framework that links microbial phylogeny, physiological traits, and disturbance responses. This framework aims to improve predictions of ecosystem processes under global change by accounting for the complex interactions among microbial taxa. The authors emphasize the need for more empirical data to define microbial functional groups and their responses to disturbances, highlighting the potential of metagenomic and metatranscriptomic approaches to advance this field.