Common ash (Fraxinus excelsior L.) in Ukrainian forests and its successful natural regeneration

Abstract

The natural distribution area of common ash (Fraxinus excelsior L.) in the forests of Europe and Ukraine has been determined through the analysis of scientific works of Ukrainian and foreign researchers. According to the reference materials on the current state of Ukrainian forests (25 administrative regions), it is established that ash forests cover an area of about 150,000 ha or 2.4% of the total area of the country’s forests. Among them, common ash stands account for almost 87% or 130,000 ha; the rest are stands of introduced ash species, namely F. pennsylvanica Marsh., F. americana L., and F. lanceolata Borkh. The average age of ash stands is 59 years. Only 6.4% (8,300 ha) of the total area of ash forests is covered by pure ash stands, and the remaining area (93.6% or 121,700 ha) are mixed ones. It is revealed that the optimal natural and climatic conditions for the emergence, preservation and successful growth of natural regeneration of ash trees are fresh and moist fertile sites (rich in minerals) with well-drained soils, the light of at least 5–6% of that on an open space, and without abundant live ground cover. The highest number of seed regeneration of ash, about 7,000–8,000 stems ha−1 on average, was found under the canopy of mixed (ash share in the composition was 10 to 20% by stock) old (over 100 years old) stands with a relative density of stocking of 0.7–0.8. Promoting the natural seed regeneration of ash trees can be an effective way of increasing the sustainability of such stands and will ensure their preservation in the forests of Ukraine and in deciduous forests of Europe as a whole.

Forest Site and Stand Structure Affecting the Distribution of Emerald Ash Borer, Agrilus planipennis Fairmaire, 1888 (Coleoptera: Buprestidae), in Eastern Ukraine

“…An analysis shows that Fraxinus sp. is rather abundant in the forest (see Figure 1), as well as in the shelter belts and urban plantings of Ukraine [13,39], suggesting that the lack of a host plant does not hinder the expansion of EAB in Ukraine. At the same time, in the Luhansk region, Fraxinus sp.…”

“…At the same time, in the Luhansk region, Fraxinus sp. in the forest is represented on 12.3 thousand hectares, in the Kharkiv region on 7 thousand hectares, in the Kyiv region on 6.1 thousand hectares, and in the Sumy region on 12.8 thousand hectares [13]. However, there are regional variations, such as EAB's absence in the Sumy region [14], but it is present in Kyiv [10].…”

“…A sufficient number of host trees is a second important condition (besides climate) for EAB spread [12]. In Ukraine, ash forests encompass approximately 150,000 hectares, or 2.4% of the total forested area [13]. Among them, F. excelsior stands are dominant, covering nearly 87% or 130,000 hectares, while the remainder are predominantly F. pennsylvanica.…”