Soil respiration (R_S) is one of the most important carbon fluxes in terrestrial ecosystems, and it is considered as a keystone in predicting ecosystem functioning. Changes in climate and land use may alter R_S, triggering feedbacks between R_S and other ecosystem components. Different factors might simultaneously alter R_S, but the consequences of the interactive effects for ecosystems functioning remain poorly understood. Here, the impact of the expected changes in climate were analysed in a factorial field study over two consecutive years in a Mediterranean savannah ecosystem. We assessed how the interaction of changes in climate with grazing legacy and habitat structure influences R_S. We simulated different climate scenarios (ambient, drier, warmer, and drier and warmer conditions) forecasted for the study area at three adjacent sites with different grazing legacies (high, medium, and low) and for the two most important habitat types (open grasslands and under tree canopy). We also considered other factors that could affect R_S, such as soil organic C, microbial biomass or net primary productivity, unravelling the direct and indirect effects of the factors controlling R_S over time by using structural-equation models (SEMs). Overall, R_S was higher under tree canopy than in open grasslands, and high grazing intensity tended to alter R_S differently through seasons. Warming scenario consistently increased R_S, while drought reduced it (especially in moist seasons), with a moderate increase of R_S resulting from the combination of warming and drought. Tree canopy modulated the impact of climate on R_S. The SEM analyses identified soil moisture, temperature, grazing legacy and canopy as the main factors controlling R_S, although they presented seasonal variations in the size and direction of their effects. Thus, the projected changes in climate can deeply alter ecosystem functioning of carbon sequestration, although their impact can be modulated by canopy cover and management activities.

土壤呼吸（R _S）是陆地生态系统中最重要的碳通量之一，被认为是预测生态系统功能的基石。气候和土地利用的变化可能会改变R _S，从而触发R _S与其他生态系统组成部分之间的反馈。不同的因素可能会同时改变R _S，但对于生态系统功能的交互作用的后果仍然知之甚少。在这里，通过连续两年在地中海大草原生态系统中进行的析因研究，分析了预期气候变化的影响。我们评估了气候变化与放牧遗产和栖息地结构之间的相互作用如何影响R _S。我们模拟了三个相邻地点，不同放牧遗产（高，中，低）研究区域和两个最重要的栖息地类型（开放草地）的不同气候情景（环境，干燥，温暖以及干燥和温暖的条件）的预测并在树冠下）。我们还考虑了其​​他可能影响R _S的因素，例如土壤有机碳，微生物生物量或净初级生产力，通过使用结构方程模型（SEM）揭示了随时间推移控制R _S的因素的直接和间接影响。总体而言，树冠下的_RS高于空旷草地，并且高放牧强度往往会随季节而不同地改变_RS。变暖情景持续增加R_硫，而干旱则使干旱减少（特别是在潮湿季节），而暖化和干旱的结合导致_硫的适度增加。树冠调节了气候对R _S的影响。的SEM分析发现，土壤湿度，温度，放牧遗留和冠层作为控制R中的主要因素_小号，尽管它们中呈现了它们的效果的大小和方向的季节性变化。因此，尽管气候变化的影响可以通过冠层覆盖和管理活动来调节，但预计的气候变化可以深刻改变碳固存的生态系统功能。