Agricultural business depends not only on financial and economic factors, but also on natural and climatic conditions, which necessitates continuous development, which is based on adaptation to unpredictable and random conditions of the internal and external environment. The goal is to develop a methodological approach to assessing agricultural business system flexibility, which will provide an opportunity to study the ability of agricultural producers of various sizes to adapt to unpredictable changes, taking into account the internal and external environment. On the basis of a comparative analysis of modern approaches to the definition of flexibility, a definition of the concept of "flexibility of business systems" is proposed. The method of evaluation of agricultural business system flexibility has been developed that includes operational, structural, and strategic flexibility.

This study focused on the occurrence of xylophagous beetles and nematodes in the different parts of Pinus sylvestris L. trees of different health condition in the pure stands in Zhytomyr region (Central Polissya). Stem fragments with thin, thick and transitional bark, branches and twigs were examined in each of 12 model trees. Xylophagous beetles were identified by adults or by galleries. Nematodes were isolated from wood samples in the laboratory using the Baermann method and identified by morphometric characteristics. Among 10 species of xylophagous beetles, Ips acuminatus (frequency 16.7%; dominance 17.9%) and I. sexdentatus (frequency 11.1%, dominance 54.6%) dominated, which prefer the fragments with thin and thick bark respectively. No xylophagous beetle was found in the healthy and slightly weakened trees. Among 15 nematode species, 40% were saproxylic, 33.3% entomophilic, 13.3% phytophagous, and by 6.7% predators and species associated with fungi. An entomophilic nematodes Cryptaphelenchus macrogaster f. acuminati was common in all parts of stem and branches (frequency of occurrence 25–33.3%). An entomophilic nematodes Parasitorhabditis acuminati and a predator Fuchsia buetschlii acuminati had the highest frequency of occurrence (41.7%) under the thin bark and in the branches. The frequency of these species in colonized with xylophagous insects stem fragments with thin bark was significantly higher than in respective not colonized fragments.

Over the past decades, the increase in occurrence of fires has caused degradation of the forest ecosystem and caused impacts to the environment. The aim of this study was to reveal the peculiarities of Scots pine health condition dynamics in the first 2 years after August fire and to estimate the rate of tree colonisation by stem insects in Central Polissya. Scots pine health condition for the first 2 years after summer ground fire in August 2016 and the rate of tree colonisation by stem insects was studied in Zhytomyr region, Western Ukraine. Stem scorch height was measured for every fire-damaged tree, and the index of fire damage severity was calculated. Vital trees health condition worsened more intensively in the sample plot with the lowest relative stocking density and the highest stem scorch by fire. Generally, the forest health condition has worsened in post-fire period in fire damaged stands. However, 23.1% of trees recovered health condition from category ‘drying-up’ to ‘severely weakened’. In fire-damaged stands, the number of species of stem insects has increased from 8 to 11 during the first 2 years of fire damage. Bark beetles were represented by Tomicus piniperda (Linnaeus, 1758), Tomicus minor (Hartig, 1834), Ips acuminatus (Gyllenhal, 1827) and Ips sexdentatus (Boerner, 1767). Jewel beetles included Anthaxia quadripunctata (Linnaeus, 1758), Phaenops cyaneus (Fabricius, 1775), Melanophila acuminata (DeGeer, 1774) and Chalcophora mariana (Linnaeus, 1758). Longhorn beetles included Monochamus galloprovincialis (Olivier, 1795), Pogonocherus fasciculatus (Degeer, 1775) and Acanthocinus aedilis (Linnaeus, 1758). Tree colonisation by stem insects in the year of fire damage was comparable with control stand, because insect swarming completed before this disturbance. Maximal occurrence of stem insects in 2017 in fire-damaged stand increased up to 66.7% (for I. sexdentatus). The percentage of trees colonised by any insect species at fire-damaged and healthy pine stands differed significantly. The occurrence of stem insects depended mainly on the ratio of trees with different health condition. Our results demonstrate data of tree damage from fire and tree health index as a strong predictor of post-fire mortality of Scots pine and bark beetle occurrence.

У дубових насадженнях Житомирської області комахи-листогризи весняного комплексу з початку ХХІ століття утворили два спалахи масового розмноження – у 2002–2008 і 2010–2018 рр. Максимальну з початку ХХІ століття площу осередків комах-листогризів (понад 3000 га) відзначено в державних підприємствах (ДП) «Бердичівське ЛГ», «Житомирське ЛГ» та «Городницьке ЛГ», а питому площу осередків – у ДП «Городницьке ЛГ» (633,5 га на 1000 га). Найбільші площі осередків хвороб у дубових насадженнях припадають на поперечний рак дуба (збудник – бактерія Pseudomonas quercus Schem), трутовик дубовий несправжній (Phellinus robustus Bourd. et Galz.) та опеньок осінній (Armillaria sp.). Збільшення площ осередків поперечного раку дуба відзначено в роки згасання спалахів весняного комплексу комах-листогризів – у 2008 і 2013 рр. Найбільші площі осередків шкідливих організмів виявлено в ДП «Бердичівське ЛГ».

Forest resources are an integral part of economic, social and ecological development of the state. Making decisions as for the change and improving the system of forestry and the mechanism of management of it should be based on the results of comprehensive evaluation of implementation their functions by forest fund. The research is based on application of integrating estimation method to economic objects. The main functions of forest resources include productive, socio-economic, protective and preserving function. The method of evaluation of lamas their functions is developed, which is based on the method of integral evaluation and regulation of performing indicators implementation of specific functions. System of indicators is selected, which reflect the performance of the forest resources of each determined function. It was ascertained that degree of execution of their functions by forests of the four most radioactively contaminated districts of Zhytomyr oblast as one of the worst-affected by Chornobyl Nuclear Power Plant disaster differs significantly. This applies especially to provisional and protection functions.