We analyzed the peculiarities of seasonal dynamics of stem sap flow in Siberian larch trees (Larix sibirica Ledeb.), Motyginsky provenance cultivated on the territory of the "Pogorelsky Bor" research station (Krasnoyarsk forest-steppe, 56.36°N, 92.95°E). Continuous measurements of stem sap flow were carried out during the growing seasons 2014 and 2015 using the energy-balance method with 30-minute resolution. Studied trees grow in different location of the larch coenosis (at the boundary and inside the cenosis) but in similar climatic and edaphic conditions.  Seasonal sap flow dynamics of these trees is characterized by high correlation (R = 0.77-0.94) while the absolute diurnal amplitudes is highly different as well as the dates of the sap-flow start and end (i.e. the start and end dates of the vegetation season). Using the eco-physiological BS-model, the transpiration with daily and seasonal resolution was calculated which is closely correlated with the intensity of stem sap flow (R≈80% at P> 0.95). With help of the BS-model verified by the dynamics of the sap flow, we calculated seasonal dynamics of transpiration, photosynthesis, stomata conductance and soil moisture. We analyzed the seasonal dynamics of stomata conductance in relation to soil moisture variations and concluded that the trees not suffer from prolonged water stress in the vegetation seasons of 2014-2015. Meanwhile, the trees experienced a short-term water deficit at specific time intervals when the stomata conductance was driven by soil moisture.