Matias Bentkowski is carrying out his internship at the EFNO unit of INRAE. The aim is to study the impact of summer drought on tree regeneration. The field experiment is done using the OPTMix research facility. It consists of measuring water stress and the annual growth of seedlings of Scots pine and Sessile oak under different natural conditions (competition with understory vegetation, level of lighting due to the forest cover, pressure of browsing and fraying by deer). The field measurements will take place during 3 months (June, July and August). The tree seedlings will be regularly measured throughout the summer period. The aim is to estimate the impact of different natural factors on forests regeneration.