Resumen: High rates of vapor pressure deficit (VPD) can severely decrease plant productivity by reducing stomatal conductance, which might be exacerbated during Mediterranean summers due to soil water deficit. In this study, we monitored the response of holm oak, the archetype of Mediterranean trees, to changes in VPD during a summer drought period to evaluate the effects and consequences on gas exchange of the two water stresses (atmospheric and soil). Measurements were performed on trees growing in an experimental plantation over two summers with moderate drought stress by using three different methods: at the leaf level with an infrared gas analyzer, using a whole-plant chamber for short-term monitoring at the tree level, and measuring the canopy temperature for long-term monitoring. The three methods provided negative relationships between leaf conductance and VPD but with discrepancies probably associated with the measurement scale. Overall, the results showed that atmospheric and soil water stress had an additive effect. Under well-watered conditions, an increase in VPD was partially compensated by a reduction in stomatal conductance, resulting in a slight increase in the transpiration rates. With soil water deficit, the response to VPD resulted in a further decrease in stomatal conductance, reducing transpiration as a water saving strategy. The decrease in conductance in response to VPD was transitory, recovering to initial values as soon as the VPD decreased, both under well-watered and drought conditions. Due to this high sensitivity to atmospheric drought, the maximum carbon gain rates of holm oak were restricted to a short environmental window, which might modulate its physiological performance and natural distribution. Idioma: Inglés DOI: 10.1016/j.agrformet.2022.109218 Año: 2022 Publicado en: AGRICULTURAL AND FOREST METEOROLOGY 327 (2022), 109218 [13 pp.] ISSN: 0168-1923 Factor impacto JCR: 6.2 (2022) Categ. JCR: FORESTRY rank: 3 / 69 = 0.043 (2022) - Q1 - T1 Categ. JCR: AGRONOMY rank: 6 / 88 = 0.068 (2022) - Q1 - T1 Categ. JCR: METEOROLOGY & ATMOSPHERIC SCIENCES rank: 16 / 94 = 0.17 (2022) - Q1 - T1 Factor impacto CITESCORE: 10.7 - Agricultural and Biological Sciences (Q1) - Earth and Planetary Sciences (Q1) - Environmental Science (Q1)