Maksym Netsvetov’s research while affiliated with National Academy of Sciences of Ukraine and other places

This study presents the first detailed dendrochronological research of old trees in Olexandria park, a historical landscape garden established by the Branicki family in the late 18th century in Ukraine. By analyzing tree-ring data from the oldest trees in the park, we aimed to refine our understanding of its developmental stages and verify long-held historical narratives. Our results reveal that native species, Quercus robur and Pinus sylvestris, are the oldest tree specimens in the park, with the piths dating back to the late 18th century respectively. This suggests that the initial stage (1787–1791) of park development may have begun earlier than previously thought or that existing old-growth forest trees were integrated into the park's design. Additionally, the age of the oldest non-native species indicates they were planted during the third stage of development (1815–1865), with further plantings occurring during the fourth stage (1865–1918). Our study supports the idea that this historical park has been continuously modified and developed throughout its history from the late 18th to early 20th century. Contrary to some long-held narratives, most of the studied trees are not gifts from Catherine II or Grigory Potemkin, nor were they planted by the Romanov family; rather, some are older than previously expected.

A major challenge for forestry and nature conservation is the adaptation of forests to climate change, as there are many different climate projections, uncertain about which one will prove accurate. We aimed to estimate current and future changes in the potential ranges of common and cultivated native and exotic tree species in Europe. We also aimed to identify the main climatic factors influencing tree species ranges and to determine whether range changes can be explained by functional traits. We used occurrences of 20 native and 12 non-native tree species from the Global Biodiversity Information Facility (GBIF) database, supplemented by data from other published and non-published sources (e.g. forest inventories, literature, or datasets). We predicted the potential species distributions using the MaxEnt method, based on randomly selected occurrences from grid cells with a resolution of 0.25° and bioclimatic variables for current and future climatic conditions (four SSPs, four GCMs, and two periods). In addition, we used plant traits from the TRY and BIEN databases. We demonstrated that conifers ranges are mainly influenced by thermal factors, while deciduous tree ranges are primarily influenced by summer precipitation. Except for Pinus strobus, all the conifers studied are expected to lose more area than they gain. Most economically important native broadleaves will also be negatively affected by climate change. Conversely, less economically important species such as Acer pseudoplatanus, Prunus avium, or Sorbus torminalis are likely to gain climatically optimal areas. Non- native broadleaved species, that are considered invasive in Europe, are likely to benefit from climate change. Their predicted range expansion is positively correlated with seed mass, specific leaf area, and wood density - traits associated with slow growth typical of late-successional trees. In contrast, range contraction is associated with species with low trait values characteristic of conifers and pioneer broadleaves. Therefore, future forests in Central Europe would undergo substantial functional changes in the future that may affect forest biodiversity and ecosystem services. Hence, the transformation of forests from monocultures to mixed forests, with different variable importance shaping its ranges, may help to plan tree-stands which are more resilient to climate change and extreme weather events.

Two European pine species, Pinus sylvestris and Pinus nigra, are experiencing dieback as a result of the increasing frequency and intensity of extreme climatic events. Recent species distribution models predicted shrinkage of ecological niches in the near future and shifted their habitat range towards the northeast. Consequently, P. sylvestris may contract its range and P. nigra may expand in Central Europe. To test whether native pine species have an advantage over introduced pine species in acclimation to a novel climate in Central Europe, we investigated the climate sensitivity and vitality of P. sylvestris, P. nigra and P. rigida. We sampled mature stands of each pine species at three sites in Central Europe, for which we determined climate-growth relationships: temporal stability of temperature and precipitation correlations with tree-ring width and resilience indices. Based on remote sensing data, we assessed differences in surface reflectance and photosynthetic activity obtained from the normalised difference vegetation index (NDVI). Our analyses revealed that the climate sensitivity and surface reflectance of pines are not due to their nativeness in Central Europe but better explained by local site conditions. The specificity and variability of drought events may determine both the homogeneous and diverse susceptibility of species to a negative water balance. Therefore, the character of future climatic extremes seems to be the key to understanding the acclimation of native and non-native pine species in Central Europe. Because our study do not provide evidence of the superiority of non-native pine species over P. sylvestris, and the potential impacts of introduced species on local habitats seem poorly understood in the face of climate change, we urge particular caution in introducing species with unrecognized invasive potential.

Alien tree species are considered both a threat to nature conservation and a base for forest management. We compiled species occurrences from biodiversity databases, forest inventories, and literature data. We modeled the availability of potential niches using the MaxEnt method and bioclimatic variables for current conditions, 2041–2060, and 2061–2080 periods. We used four climate scenarios: SSP126, SSP245, SSP370, and SSP485. The results confirm our hypotheses that, (i) coniferous species will contract, and deciduous trees will expand their climatic niche, (ii) a significant part of the areas where the studied species currently occur will be outside their climatic optimum in the coming decades; (iii) changes in the climatic optimum distribution will be greater in the 2041–2060 period than in 2061–2080. These predicted shifts are relevant for evidence-based management in sites already occupied by the studied alien trees. Our results are also relevant to the development of prevention and early detection measures in areas predicted to become climatically suitable for the studied species.

The Chornobyl accident on 26 April 1986, caused tree death near the nuclear power plant and affected forest ecosystems throughout the Chornobyl exclusion zone. Thirty years after the accident, the radiation continues to exert its disastrous effects on the surviving trees. However, the extent to which continuous exposure to radiation over several decades has affected the radial growth of trees and their sensitivity to climate variability remains poorly understood. In this study, we used common dendrochronological approaches to investigate Scots pine trees' radial growth and its sensitivity to climatic variables, i.e. air temperature, amount of precipitation, and drought, in two stands that received sub-lethal and moderate radiation doses after the Chornobyl accident. To track changes in radial growth, we performed a pointer-year analysis using two techniques - normalization in a moving window (Neuwirth et al., 2007) and the bias-adjusted standardized growth change (Buras et al., 2022). To assess the growth-to-climate relationship, we used the double-moving window approach. Additionally, to evaluate the differences in these relationships between the two study stands, we applied the Full-Duration at Half-Maximum method FDHM (Weik, 2000). The effects of drought episodes were evaluated using growth resistance and recovery indices (Lloret et al., 2011). The stand exposed to sub-lethal radiation dose shows a significant reduction in radial growth in 1986 with a deflection period of one year. In contrast, the stand exposed to moderate dose of radiation demonstrates no significant decrease in growth either in 1986 or in subsequent years. The use of the moving response function and FDHM allowed us to detect several mutual patterns in the growth-to-climate relationships unrelated to the Chornobyl accident. Thus, the results of the study indicate that the sub-lethal radiation dose had a dual effect on the trees: it reduced their radial growth and jeopardized the physiological ability of the trees to respond to the extreme spring and summer drought in the year of the accident. In conclusion, our results suggest a non-specific growth response to radioactive contamination and emphasize the need for reliable indicators, particularly at the level of wood anatomy.

The extensive radioactive fallout resulting from the 1986 Chornobyl accident caused tree death near the nuclear power plant and perturbed trees communities throughout the whole Chornobyl exclusion zone. Thirty years into the post-accident period, the radiation continues to exert its fatal effects on the surviving trees. However, to what extent the continuous multi-decadal radiation exposure has affected the radial tree growth and its sensitivity to climate variation remains unascertained. In this comparative study, we measure the Scots pine radial growth and quantify its response to climate at two sites along the western track of the nuclear fallout that received significantly different doses of radiation in 1986. The common features of the two sites allow us to disentangle and intercompare the effects of sub-lethal and moderate radiation doses on the pine's growth and climatic sensitivity. We extend the response function analysis by making the first use of the Full-Duration at Half-Maximum FDHM method in dendrochronology and apply the double-moving window approach to detect the main patterns of the growth-to-climate relationships and their temporal evolution. The stand exposed to sub-lethal radiation shows a significant radial growth reduction in 1986 with a deflection period of one year. The stand exposed to moderate radiation, in contrast, demonstrates no significant decrease in growth either in 1986 or in the following years. Beyond the radiation effects, the moving response function and FDHM enabled us to detect several mutual patterns in the growth-to-climate relationships, which are seemingly unrelated to the nuclear accident. To advance our predictive understanding of the response of forest ecosystems to a massive radioactive contamination, future studies should include quantitative wood anatomy techniques.

Wild service tree (Sorbus torminalis) is a rare, endangered, relict species, that is protected by law in many European countries. Outside the species distribution range, the trees are usually planted in botan­ical gardens, parks, arboretums, and at the roadside. Such old introduced trees are an important source of knowledge about species’ acclimation process and current growth-limiting factors in the new environment. In Kyiv, the oldest live S. torminalis trees have been planted in botanical gardens and arboretums after the 1950s. In addition, some trees of this species are preserved in front of the historical building Liberman’s mansion, but the year of their planting remains unknown. Regarding dendroclimatological investigations of this species are scarce and have been provided only in Central European forests, a detailed analysis of the species growth-to-climate relationships should be performed not only the species’ natural range but also in its secondary ranges. In this article, we studied three S. torminalis trees in a historical place in Kyiv to determine their age and evaluate environmental conditions driving the growth of this rare species out of its natural range in Kyiv. To reach our goal we used the dendrochronological approaches, i.e. tree-ring dating, partial correlation analysis using stationary and moving time windows. Our results showed that S. torminalis trees were planted after the last building owner S. Liberman’s death (1917). The studied trees are the oldest of known alive S. torminalis trees in Kyiv. Dendroclimatological re­sults revealed S. torminalis is sensitive to higher air temperature and moisture excess in the period of wood formation in Kyiv. S. torminalis trees at 2 Bankova Street are the oldest species examples in Kyiv and have important historical, cultural, and scientific values. S. torminalis species could be widely used in urban forestry, particularly in regions with projected soil moisture shortening.

Based on the collected data set (758 observations for the period 2007-2021) on the dates of the nuptial flight for 73 species of ants, an analysis of possible time shifts due to global climate changes has been carried out. It was found that for Eastern Europe and Asia, for most species of ants, the dates of nuptial flight were shifted by at least two weeks earlier in comparison with the data for Western Europe. In a cold climate, there are significant changes, towards earlier dates, in the phenology of nuptial flight for two species: Lasius flavus (P<0.05) and Polyergus rufescens (P<0.01). The corresponding rates of change are 3.9 and 6.25 days per year. In other types of climate, no significant changes in the phenology of the nuptial flight were found. Taking into account the boundaries of future climatic zones in temperate and arid zones, such changes were recorded for several species. Solenopsis fugax in temperate climates shows a tendency to delay flight at a rate of 6 days per year (P<0.05). Within the predicted boundaries of the arid climate, the flight phenology delay was recorded for Lasius niger (5.8 days per year; P<0.01) and Messor sp. (4.4 days per year; P<0.05). At the same time, for Polyergus rufescens, there is a tendency to an earlier flight at a rate of eight days per year (P<0.05). No connection was found between the date of nuptial flight and the geographic distance between populations (or locations). ABSTRAK Berdasarkan set data yang dikumpulkan (758 pemerhatian dalam tempoh 2007-2021) ke atas masa penerbangan untuk pengawanan bagi 73 spesies semut, analisis perubahan masa yang disebabkan oleh isu pemanasan global telah dijalankan. Didapati kebanyakkan masa untuk Serangga 2022, 27(1): 152-179 Stukalyuk et al. ISSN 1394-5130 153 penerbangan pengawanan spesies semut dari Eropah Timur dan Asia telah berubah sekurang-kurangnya awal dua minggu berbanding dengan spesies dari Eropah Barat. Pada musim sejuk, terdapat perubahan signifikan terhadap tempoh masa awal ke atas fenologi untuk penerbangan pengawanan ke atas dua spesies; Lasius flavus (P<0.05) dan Polyergus rufescens (P<0.01). Kadar perubahan tersebut adalah 3.9 dan 6.25 hari per tahun. Pada musim lain, tiada perbezaan signifikan ke atas fenologi penerbangan pengawanan didapati. Dengan mengambil kira faktor sempadan pada zon iklim sederhana dan zon iklim gersang, beberapa perubahan direkodkan untuk beberapa spesies. Solenopsis fugax di zon iklim sederhana menunjukkan keupayaan untuk melewatkan penerbangan pada kadar enam hari per tahun (P<0.05). Dalam jangkaan sempadan pada zon iklim gersang, fenologi penerbangan direkodlan lewat ke atas Lasius niger (5.8 hari per tahun; P<0.01) dan Messor sp. (4.4 hari per tahun; P<0.05). Pada masa yang sama, Polyergus rufescens, berupaya untuk mempercepatkan penerbangannya pada kadar lapan hari per tahun (P<0.05). Tiada hubungan didapati di antara penerbangan pengawanan dan jarak geografi antara populasi (atau lokasi).