Эколого-биологические аспекты формирования дубрав на возвышенностях и равнинных ландшафтах Нижнего Поволжья

Abstract

The article presents data on the current topic of conservation and reproduction of oak forests in the arid conditions of the Lower Volga region on various relief elements. The article contains the result of long-term studies of oak forests of the Lower Volga region, the main predominant species of which is the petiolate oak (Quercusrobur L.). It was found that on soils of the Lower Volga region poor in humus composition with dissected relief and difficult weather conditions, the plantations of the petiolate oak fully justified themselves. It was revealed that oaks have good growth on chestnut, light chestnut and chernozem soils, and moderate on sandy, biologically stable, moreover, species with a high content of chlorophyll show the best performance. It was determined that the most effective way to create oak forests is to exclude 25-40% of the parent trees that showed the worst results during research. Otherwise, the plantings may face a decline in radial growth, loss of part of the crown and often shrinkage. Рurpose of the research. Bio-ecological assessment of species of the genus Quercus, aspects of the formation of oak forests on uplands and flat landscapes for afforestation in arid conditions of the south of the European territory of Russia. The object of research was the plantings of the pedunculate oak (Quercusrobur L.), which has an extensive range. Observations were carried out in the Volgograd region in the arboretum collections of the Federal Research Center of Agro-ecology of the Russian Academy of Sciences, at the Shemyakinskaya dacha – the oak grove of the Uryupinsky forestry, geographical oak cultures in the Oktyabrsky forestry, genetic and breeding complexes of oak in the Novoanninsky forestry, in the Rossoshansky forestry of the Voronezh region, the system of protective forest plantations in the Bogdinsky forestry of the Astrakhan region and the Elistinsky forestry of the Republic of Kalmykia. Research methodology. The water content in oak leaves was determined by the weight method by the hour during the day (1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 12 h, 24 h). Weather conditions and oak habitats were studied using the sites "Climate monitor" and "Agroatlas". The typology of forest growing conditions within the ALMR was characterized taking into account the forest suitability of soils developed by VNIALMI (now the Federal Research Centre for Agro-ecology, Complex Reclamation and Protective Afforestation). Based on the analysis of the results of all experimental materials, an integral indicator of the frost resistance of prototypes and control was calculated. Individual indicators of reproductive processes of clones were compared with the characteristics of control trees, revealing their correlations. The chlorophyll content was measured using the MS-100 device. Statistical data processing was carried out in the programs Statistica and Fractan. Research results and discussion. The intensity of growth of this species is determined by the geographical environment and the conditions of the place of growth. According to the results of the research, the petiolate oak showed excellent ecological and geographical plasticity and the ability to grow and develop in various conditions – from fine-grained leached sands of the Astrakhan and Elista experimental stations to light chestnut and dark chestnut soils of the Volgograd region, chernozem soils of the Novoanninsky and Uryupinsky forestry. The best growth and development were distinguished by the plants of the petiolate oak in conditions of macro-subsidence with dark-colored humus soils. A high percentage of oak trees with good condition were noted by the authors on micropropagations, meadow-chestnut slightly saline soils. There were no oak trees in good condition on flat, settled areas with the presence of saline spots. In the southern part of the Lower Volga region (Elista), oak forests with an age of 30 years or more are in poor condition, characterized by low growth rates and trunk diameter. In the Kamyshinsky arboretum, the annual growth of oaks decreases with increasing age, but the plants are characterized by the best resistance to high summer and low winter air temperatures, undemanding to soil conditions. Conclusion. Oaks of 30 years of age have good characteristics in the Novoanninsky forestry, which belongs to the moderately arid zone and is distinguished by chernozem soils. The upland ecotype prevails in this zone (85 %), the floodplain ecotype has the largest crown projection, an increase of 25 cm is observed in the oak ecotype of this zone, which determines the requirements for the soil and climatic conditions of the introduction regions.