The rapid climate change towards warming is largely associated with a significant emission of greenhouse gases (carbon dioxide, methane, etc.), and therefore, forest plantations began to be considered in a completely different aspect for them. Preservation or expansion of forest areas is largely seen as a way to store atmospheric carbon to balance the powerful emissions of carbon dioxide into the atmosphere. The aim of the study was to study the effect of drought on the rate of CO2 exchange in pedunculate oak leaves. The object of the study was oak seedlings at the age of 2 months, grown in laboratory conditions from acorns under controlled conditions. After this period, one variant continued to grow with regular watering of 70% of the MMC (control), the second variant was kept without irrigation of 15% of the MMC (experiment). Fixation of CO2 exchange in oak leaves was carried out under illumination of 800 FAR every 30 minutes on a photosynthesis monitor RTM-48A. It has been established that a more intense CO2 exchange is observed in the variant with periodic irrigation, and on average 3-6 μmol CO2 / m2 *s higher than in the variant without irrigation, which is largely determined by the stomatal conductivity of the leaf. In the variant with periodic irrigation, the stomatal conductivity averages 1.6 mm/s versus the variant without irrigation 0.36 mm/s. Apparently, this is due to the ability of the leaf surface to more intense transpiration, due to which both a decrease in leaf temperature (on average by 0.6–1.1°C) and maintenance of stomatal turgor occur. With a strong lack of moisture, oak plants have a low level of CO2 metabolism, which negatively affects their depositing ability. With a low intensity of CO2 exchange, there is a weak accumulation of spare substances, which increases the risk of serious damage under the action of extreme ambient temperatures.