Background and Aims <p>Rainfall changes significantly impact soil respiration in dryland ecosystems. Biocrusts complicate the relationship between soil respiration and rainfall changes. However, their response to altered rainfall patterns and the mechanisms that govern soil respiration remain poorly understood.</p> Methods <p>We performed a field manipulative experiment to simulate changes in rainfall regimes (-75%, -50%, -25%, 0%, + 10%, + 15%, + 40%) in a biocrust-dominated dryland ecosystem on the Chinese Loess Plateau.</p> Results <p>We found that rainfall has a dual impact on soil respiration. Changes in rainfall directly affect soil respiration. Soil respiration decreased by 24%, 65%, and 69% as rainfall declined by 25%, 50%, and 75%. Conversely, it increased by 27%, 23%, and 42% when rainfall rose by 10%, 15%, and 40%. Rainfall changes also indirectly affect soil respiration by regulating soil moisture and the coverage of moss biocrusts. Our results emphasized that soil moisture was the pivotal factor in modulating the response of soil respiration to rainfall changes. The coverage of cyanobacteria and lichen biocrusts or the soil total carbon content did not regulate soil respiration, whereas a notable positive correlation was found between the coverage of moss biocrusts and soil respiration.</p> Conclusions <p>Our study demonstrates that both simulated increase and decrease rainfall significantly impact soil respiration. The increase in soil moisture and coverage of moss biocrusts associated with increased rainfall promotes soil respiration. This finding improves model predictions of climate change impacts on soil carbon cycling in dryland ecosystems.</p>