Abstract:Ukraine is a country of the Mid-Latitude ecotone-a transition zone between forest zone and forestless dry lands. Availability of water defines distribution of the country's forests and decreases their productivity towards the south. Climate change generates a particular threat for Ukrainian forests and stability of agroforestry landscapes. This paper considers the impacts of expected climate change on vulnerability of Ukrainian forests using ensembles of global and regional climatic models (RCM) based on Scenarios B1, A2, A1B of the Intergovernmental Panel for Climate Change, and a "dry and warm" scenario A1B+T−P (increasing temperature and decreasing precipitation). The spatially explicit assessment was provided by RCM for the WMO standard period (1961-1990), "recent" (1991-2010) and three future periods: 2011-2030, 2031-2050 and 2081-2100. Forest-climate model by Vorobjov and model of amplitude of flora's tolerance to climate change by Didukh, as well as a number of specialized climatic indicators, were used in the assessment. Different approaches lead to rather consistent conclusions. Water stress is the major limitation factor of distribution and resilience of flatland Ukrainian forests. Within Scenario A1B, the area with unsuitable growth conditions for major forest forming species will substantially increase by end of the century occupying major part of Ukraine. Scenario A1B+T−P projects even a more dramatic decline of the country's forests. It is expected that the boundary of conditions that are favorable for forests will shift to north and northwest, and forests of the xeric belt will be the most vulnerable. Consistent policies of adaptation and mitigation might reduce climate-induced risks for Ukrainian forests.Keywords: Ukrainian forests; climate change; xeric belt; predictions of state and distribution of forests over 21st century; Mid-Latitude ecotone
Oak (Quercus robur L.) forest stands are among the most common forest formations in the forest-steppe zone of Ukraine. Investigations of the patterns of distribution of trees by diameter and the dynamics of the commodity structure of mature oak stands of coppice origin were carried out based on the forest survey data from 28 temporary sample plots, on the sites designated for the final felling in the Left-Bank Forest Steppe of Ukraine (Sumy, Kharkiv, and Poltava Regions). We distributed trees by diameter classes and technical suitability categories. To establish the commodity structure of the stand, we selected model trees that corresponded to the average size of trees in terms of diameter classes and their qualitative characteristics. Then, we constructed a model tree stem profile using Institute of Forest Ecosystems Research (IFER)’s method of “6 points”. Based on stands’ structure and quality condition as well as on the growth tables, the commodity structure dynamics table for the changes in the commodity structure for the coppice oak stands in the Left-Bank Forest Steppe of Ukraine has been developed. The results of the analysis of wood stock dynamics showed that the maximum average increment of class A and B wood is 90–100 years. Therefore, the age of technical maturity and the associated age for the final felling in commercial oak forests of second site class and above should be assigned to 91–100 years.
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