Increasing the Biodiversity of the Dendroflora of Sparsely Wooded Regions by Adapted Representatives of the Genus Robinia L.

Abstract

Purpose of the study: to substantiate the prospects of using various species, varieties and forms of the genus Robinia in protective afforestation and landscaping of settlements in dry-steppe and semi-desert zones of southern Russia. It is established that the main limiting factors affecting the growth, development and condition of representatives of the genus Robinia in the Volgograd region are winter temperatures up to −37 °C, as well as poor moisture availability and uneven distribution of precipitation during the growing season in combination with extremely low temperatures in the autumn–winter period. All representatives of the generic complex belong to the group of plants that start late and finish the vegetative period late. Phenological atypicity is in the lower half of the normal range, with indicators from +1 °C to 0, which indicates a high level of adaptation to the climatic conditions of the region. In the process of long-term acclimatization, many introduced species have developed a number of genotypic adaptations and are currently able to tolerate extreme winter temperatures up to −37 °C. An assessment of potential drought resistance based on the water-retaining ability of the leaves showed that higher rates of water-resistance capacity (76.8% water loss) are typical of R. neomexicana, which has a natural distribution area in the western arid part of the North American continent. R. viscosa var. hartwegii, with a natural distribution in the areas of the monsoon subtropical climate of eastern North America, is distinguished by low indicators (94.1% water loss), as are clonal decorative forms of R. pseudoacacia: f. pyramidalis and f. umbraculifera (97.6–95.8% water loss), which are common only in culture and characterized by a whole complex of low indicators of bioecological stability. The data obtained by us allow us to recommend the following assortment of species and forms of Robinia for protective afforestation and landscaping in the arid territories of southern Russia: R. pseudoacacia, R. neomexicana var. neomexicana, R. neomexicana var. rusbyi and R. pseudoacacia x R. neomexicana.