Current climate change and increasing populations’ growth enhance soil and ecosystem services vulnerability. Meteorological models predicted an increase in summer drought and higher air temperature with more frequent occurrence of extreme events like heat-waves and drought. Intensity and duration of these events may affect structure and functions of ecosystems and thereby the biodiversity and the functions of soil. The amendment of soils with composts could be an alternative to prevent and mitigate the effects of drought and heat waves in the Mediterranean agroecosystems. The objectives of this work were to characterize the effects of short and long-term high temperature and/or drought perturbation on soil Mediterranean microbial communities (structures and functions) and to study the impacts of compost amendment on short and long-term functional and taxonomic responses of microbial communities subjected to drought and high temperature. Our work allowed us to evaluate the influence of each factor (drought or high temperature) within the combined perturbation (drought and high temperature) on microbiological and physico-chemical soil properties. The effects of this combined perturbation induced similar or different responses of each of perturbations applied individually involving positive and negative effects on the microbial community. This work had shown threshold resistance duration inducing a change in taxonomic and functional microbial community structure after high temperature and drought perturbation. This abrupt shift in the community response did not allow resilience. Compost amendments improved the physico-chemical soil structure and stimulated indigenous soil microorganisms. However, it seemed that seasonal soil variations history rather than compost amendment influences soil microbial stability
