HISTORY AND CONSEQUENCES OF THE INTRODUCTION OF FRAXINUS PENNSYLVANICA MARSHALL IN THE ASTRAKHAN STATE RESERVE
The works on the introduction of Fraxinus pennsylvanica Marshall in the 1940s and 1970s had a strong influence on the flora of the Astrakhan State Reserve. Currently, phytocenoses with Fraxinus pennsylvanica are common in all three areas of the reserve and are beginning to play an increasingly prominent role not only in gallery forests, but also as significant edifiers of meadow phytocenoses. The extremely high intensity of seed reproduction of Fraxinus pennsylvanica leads to the active replacement of valuable native willow forests of the reserve with ash. The lack of effective measures to control the spread of Fraxinus pennsylvanica on the territory of the lower reaches of the delta and the reserve, combined with modern hydrological conditions, contributes to the active settlement and constant advancement of ash formations along the islands of the lower zone of the surface delta towards the sea edge. The most significant consequences of the introduction of Fraxi-nus pennsylvanica into the phytocenoses of the lower reaches of the Volga Delta are: impoverishment of the species composition of woodlands, oppression up to the complete loss of the grass layer under the canopy of ash forests, reduction in the value of land as nesting sites for birds and mammals. The only factor that most effectively restricts the spread of Fraxinus pennsylvanica along the lower reaches of the Volga delta is the maximum preservation of the Salix alba L. stand by maintaining a favorable hydrological regime and ensuring optimal timing and levels of spring-summer high water, as well as protecting the of gallery forests from fires.