Introduction
Large forests play an important role in the steppe zone, especially in the regions most problematic for forest planting. Negative impacts of climate change become worsened as most pine forests are of artificial origin and are single-layer even-age pure stand. One of the largest forest areas in Donetsk Region is the forests in the State Enterprise (SE) “Lymanske Forest Economy” located in the Siversky Donets River basin. The great importance of these forests for the region is reflected in forest management specificities in. Its largest share (72%) is occupied by forests of conservational, scientific, historical and cultural purposes.
The aim of the study was to analyze the main stand characteristics and the condition of the pine stands in SE “Lymanske Forestry”.
Materials and Methods
The pine stands’ characteristics were studied using the data given in the Forest Fund database as of 01.01.2011 and generally accepted methods in forest mensuration. The condition of trees and stands was determined in accordance with the Sanitary Forests Regulations in Ukraine. At that, 18 sample plots (circular and polygonal) were surveyed for detailed assessment of the condition and structure of pine forests on a typological basis in July-August 2019. The Field-Map technology developed by experts from the Institute of Forest Ecosystem Research (Czech Republic) was used for works on sample plots and primary data processing.
Results
In most sites, stands of dominant tree species correspond to their forest types. However, they have a simplified structure. Thus, the share of pure pine stands is 94.2% of the area. The stands of VI, VII and VIII age classes cover the largest areas – 20.4%, 19.6% and 18.4% accordingly. Furthermore, the II productivity class stands occupy the largest area, namely 43.6%. The share of the I productivity class stands is 30.5% and the stands of the III productivity class cover 16.2% of the area. As for the density of stocking, the stands with that index of 0.8 occupy 47.7% of the area, the stands with the index of 0.7 – 24.3% and those with the index of 0.9 – 14.0%. The forest stands have uneven density of stocking.is. At that, the root rot foci are present there. The polygonal test plots were laid in the interspaces; the circular plots were laid, to compare, in damaged and undamaged parts of the stands. The carried out assessment showed that the health of the stands in the control plots was weakened (health condition indices of 2.27–2.87) and that in the damaged plots is severely weakened (health condition indices of 3.13–3.23). In areas damaged by forest fires, trees condition tends to deteriorate with increasing height and perimeter of fire damages.
Conclusions
The ratio of relief types determines a typological structure of the forests of SE “Lymanske Forest Economy”. Fresh and dry infertile pine forest types and fresh fairly infertile oak and pine forest types cover the largest areas in pine terraces. At that, the pine stands with the medium productivity class prevail: the average site index is I,7; the average density of stocking is 0.76. Comparative analysis of the forest inventory data and field studies showed that there is a necessity to specify forest types and define principal species. The health condition of the pine stands is weakened and severely weakened which is brought about by unfavorable conditions for the stands growth, anthropogenic impact (changes in hydrological regime caused, in particular, by the extraction of minerals and water intakes, and forest fires in 2014) and diseases. The worst condition was observed in the areas damaged by fires (health condition index excluding dead-standing tree was 2.49–2.70).
1 Fig., 5 Tables, 9 Refs.

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Стан, структура і продуктивність соснових лісів ДП «Лиманське ЛГ»

Тривалими польовими дослідженнями доведено, що в північному Степу України чим пізніше відновлюється весняна веґетація озимої пшениці, тим меншою є врожайність. При цьому час відновлення веґетації має значний вплив на врожайність різновікових посівів. У разі надраннього відновлення веґетації (III декада лютого) врожайність  посівів з сівбою у період з кінця серпня до початку жовтня є майже однаковою і становить від 6,44 до 6,96 т/га. У випадку пізнього відновлення веґетації (початок квітня) найбільш високу врожайність формують посіви з сівбою з 10 по 25 вересня. Їх врожайність у середньому за роки досліджень становила 3,86–3,91 т/га. Чим коротшим є період від переходу температури через 0 0С до +5 0С, тим більшою є врожайність озимої пшениці. У середньому за роки досліджень врожайність озимої пшениці за тривалості періоду від переходу температури через 0 0С до +5 0С до 10 днів становила 6,04 т/га, а в разі подовження цього періоду до 30 і більше днів зменшувалася до 3,76 т/га. 
It has been established that in the Northern Steppe of Ukraine the beginning of spring vegetation of winter wheat starts at different periods of time. The earliest vegetation (February 22) was observed in 1990, and the latest vegetation (April 4) was in 2003. Therefore, it has been suggested to distinguish the very early (the third decade of February) beginning of vegetation, early beginning of vegetation (the first–second decade of March), middle-time vegetation (the third decade of March) and late beginning of vegetation (the first decade of April) of winter wheat. During the whole period of observations from 1986 to 2005, the  very early beginning of vegetation was observed during 3 years (15%), early vegetation – 4 years (20%), middle-time vegetation – 8 years (40%), and late vegetation – 5 years (25%). 
The analysis of winter wheat productivity shows that the later is the beginning of spring vegetation, the less productivity of winter wheat. During the very early spring vegetation in the third decade of February,  productivity is twice as large as compared with the late vegetation in the first decade of April. On average, over the years of the study, these indicators were 6.74 and 3.28 t/ha respectively. In the very early vegetation (the 3rd decade of February), productivity of the mixed-age crops is almost the same and ranges from 6.44 to 6.96 t/ha. During the late vegetation (early April), the highest productivity is formed by the crops sown from the 10th to the 25th of September. Their average productivity during the years of the study was 3.86–3.91 t/ha. With this period of spring vegetation, the productivity of crops sown on September 2nd and October 2nd is almost the same and is 2.99 and 2.88 t/ha respectively, but significantly higher than the productivity of crops sown on August 25th. 
For the formation of winter wheat harvest, the change of the average daily temperature above 0 °C is important, as well as the duration of the period from that time to the beginning of spring vegetation. That is the steady increase in average daily air temperature to more than +5 °С. The increase in the period of time from the date of the change of the average daily air temperature above 0 °C to the beginning of spring vegetation causes the decrease in the productivity of winter wheat. During the years when the duration of this period was up to 10 days, the productivity of winter wheat averaged 6.04 t/ha, and during the years with this period of more than 30 days, the productivity decreased to 3.76 t/ha. 
The shorter period from the change of the average daily air temperature above 0 °C to the time of the beginning of spring vegetation, the higher the dependence of the level of winter wheat productivity on the sowing terms. If this period is longer than 30 days, the highest productivity was formed by crops sown on September 17th and September 25th, and during the years when this period lasted from 10 to 20 days, higher productivity was provided by the crops sown from September 10th to September 25th. 
With the duration of the period from the date of the change of the average daily air temperature above 0 °C to the beginning of spring vegetation to 20 days, the productivity of winter wheat crops with early sowing on September 2nd and October 2nd is almost the same. The crops sown on September 2nd with the duration of this period up to 10 days formed productivity of 5.44 t/ha, and the crops sown on October 2nd – 5.56 t/ha. At the same time, if the duration of this period exceeds 20 days, the crops sown on October 2nd form a considerably higher productivity than the crops sown on September 2nd.

https://journals.pdaa.edu.ua/visnyk/article/download/1062/1504

Врожайність пшениці озимої залежно від погодних умов у ранньовесняний період в умовах північного Степу України

The issue of pine forest stands health condition and mortality at the scale of one state enterprise (SE "Lymanske Forest Economy"), located in the Northern part of the Steppe zone of Ukraine, is considered.
For the study data from two repeated observations at 8 permanent plots, laid in 2019, in forest stands with varying degrees of mortality and those damaged by fire was used. A re-survey was carried out in 2020. Using the GIS Field-Map, trees were mapped at the permanent plots and their health condition, mortality, and damage were assessed. For the background assessment of pine forests condition, the results of observations at 7 forest monitoring plots (I level) (surveys of 2015 and 2020) were used. The source of climate data was the online resource ClimateCharts.net.
It was found out that over the last 10 years, due to climate change, the temperature in the region increased and the amount of precipitation decreased, which led to the appearance of a dry period in August, which is unfavourable for the growth of pine forests at the limit of their range. Groundwater levels have changed, as evidenced by the drying of Lake Lyman during 2013-2020. Obtained results showed, that the condition of pine stands in the monitoring plots significantly deteriorated compared to 2015. Currently, the condition of pine forests are considered as "weakened" and "severely weakened" (the health condition index (HCI) of living trees varied from 1.53 to 2.70), the average defoliation and mortality of trees have increased significantly. In weakened stands, the proportion of trees with damage increases over time, in particular, due to the colonization of stem insects. Forest fires pose a significant threat to the pure artificial pine forests that predominate in the region. As a result of fires, the condition of the stands deteriorated (HCI 2.49–2.70) and the number of dead trees increased.

/pdf/dynamics-of-pine-stands-condition-in-se-lymanske-forest-1y5jo1z6b5.pdf

Olexiy B. Prihodko

Papers

Dynamics of pine stands condition in SE “Lymanske Forest Economy”