Yatsenko O. A., Zaytseva I. O.,Bondar O. E.

Oles Honchar Dnipropetrovsk National University

ECOLOGICAL POTENTIAL OF ACER L. SPECIES UNDER INTRODUCTION IN DNEPROPETROVSK BOTANICAL GARDEN

Acclimatization and introduction of plants are the main way of enrichment of cultural dendroflora. Success of introduction depends on conformity between ecological needs of plants and complex of external factors. Therefore, an estimation of introduction success and prospects of involving of new species in the certain introductional area will help to increase diversity of cultural flora. These assessments are especially important in the steppe zone, where the development of indigenous woody vegetation is limited by drought conditions. In accordance with this thesis, the aim of our study was to analyze the process of introduction of genus  Acer  L. in Botanical Garden of Dnipropetrovsk National University.

Among decorative woody breeds,  Acer  L. is interesting for researchers because of its species and form diversity (Kohno, 1968, 1982). In its natural area most of maple species are related to condition of temperate and humid climate, i. e. they have mesophytic properties and are characterized by different level of drought resistance in the introduction area (Zaytseva, 2004). Therefore, one of the objectives of the study was to determine the prospects of introduction of species with corresponding ecological potential to the steppe conditions culture.

The introduction process of maple in Botanical Garden of DNU was carried out. According to the inventory lists, in the middle of the last century during the early formation of dendrological collection, the collection consisted of fifteen species and five forms of maple. There was a gradual decrease in the number of examples and taxa. A few species, notably A. betulifolium  Max.,  A. mono  L.,  A. palmatum  Thunb. , A. rubrum L.,   and  A. saccharum March.,  were planted in the number of 3–5 examples ( A. rubrum  – 11 inst.) and were less resistant, so dropped out of the collection for 20–25 years after planting. Species  A. ginnala  Max.and  A. trautvetteri Medw  also had shown low resistance in the region of introduction. The number of these examples was decreasing fivefold during first period of cultivation and was 5 and 1 examples respectively. The number of  A. ginnala  examples has been decreasing, and now there is one tree of  A. ginnala  and one of  A. trautvetteri  in the DBG. This indicates the lack of maple stability in the introduction area.

The natural range of all these species is in high humidity regions. For example, index of humidity is 5,8–6,3 in Japan, 3,8–4,1 in the Far East, 3,5–4,8 in the Caucasian region and 1,0–1,5 in the Atlantic region of North America, which is significantly higher than in Steppe Dnieper region (0,8). The minimum temperature of the least stable species natural regions is equal to or greater than that of Steppe Dnieper region. Despite the fact that the maples of these regions are adopting to low winter temperature they have shown insufficient result during the introduction. All decorative forms of a maple from the Atlantic region of North America have also been unstable.

Since Mediterranean species  A.monspessulanum , Central Asian species  A. semenovi i  and Far Eastern species  A. ginnala  are light-loving, unlike other examples of genus, reducing the number of examples of this species may be the result of the unfavorable location in dense plantings in the shadow sectors of the Botanical Garden’s dendrarium.

A. mono  and  A. palmatum  have re-introduced in recent years. The collection has replenished with new species of maple ( A. laetum  С. A. Mey.,  A. velutinum  Bois. і  А . ibericum Bieb. (Caucasis)  A. mandshuricum  Maxim. (Far East),  A. cissifolium  K. Koch. (Japan),  A. hersii  Rehd. (Central China). Bearing in mind the results of the analysis of collection  Acer L. dynamics in DBG, these plants can be sufficiently unstable in Steppe Dnieper region. The preliminary estimates of the ecological potential of the newly collectioned species in accordance with the criteria of botanical-geographical origin and eco-climatical compliance can be used to predict the result of the introduction process in the Steppe zone of Ukraine.