Mechanisms of survival of Pinus sylvestris L. in drought in anthropogenically polluted territory

The aim of the research is to study the reaction norm of morphological, physiological and biochemical characteristics of Scots pine (Pinus sylvestris L.) in optimal years and survival mechanisms of natural and urbanized ecosystems in moderate and severe drought ex situ and ex vivo. The objects of research are forest plantations of Scots pine near the reserve (Voronezh region, control) and a forest strip along the highway “Don” (Voronezh, experimental facility). In the research, we carried out the study of the reaction norm of seed productivity traits (seed fullness, number of seeds per cone), water regime (moisture deficiency, total amount of moisture, colloid-bound water content) and proline content in field and laboratory experiments ex situ and ex vivo on the scale of "optimal years - moderate - severe drought". As a result, significant differences between populations in response to drought of different intensity were established. It was shown that moderate hydrothermal stress expands the reaction norm of the analyzed traits in the control population: the maximum range of variability is observed in moderate drought; the minimum - in optimal years and severe drought ex situ and ex vivo. A single algorithm for variability of the generative and vegetative spheres of trees indicates that the control population is in a state of equilibrium, having a wide range of opportunities for adaptation in a moderate drought. The experimental object develops in the mode of a slightly non-equilibrium system: the maximum variability of traits is observed in optimal years and severe drought, and low, on the contrary, with moderate stress. The mechanisms of pine survival in drought in an anthropogenically polluted territory are discussed. According to the data obtained, the vegetative and generative spheres of trees of the experimental population respond differently to the increased hydrothermal load: the adaptive mechanisms of the vegetative sphere are aimed at maintaining homeostasis, and a more stable internal environment protects the genetic material of forming seeds from destruction.