Approaches to research and classification of forest fuel

Abstract Forests of Ukraine and the whole world in recent decades are regularly exposed to uncontrolled large wildfires. In Ukraine, huge forest areas were burnt in 2009, 2014 and 2015. In 2018, even the northern Scandinavian countries suffered from forest fires. Global climate change (increasing average temperature and aridity) is expected to contribute to the increasing number and area of fires in the future. The occurrence of fire is impossible without the presence of a source of fire, oxygen and fuel (so-called triangle of fire), but only forest fuel (FF) can be controlled by forestry treatment or by prescribed fire. Effective fire management is impossible without the knowledge of the distribution and qualitative characteristics of FFs. This article provides brief information on the history of research studies on FF in Ukraine and in the countries of the former Soviet Union and the factors that influence the formation of reserves and structure of FF. According to those research articles, the most important factors were soil and climatic conditions and characteristics of plantations. Information about the trends in accumulation of FFs in the Ukrainian pine forests is given. After the evaluation of the research works about FF, it was concluded that the study of fuel in Ukraine is fragmentary, and such studies should be continued, but necessarily after the unification of the methods of sampling and recording data about FF. In the future, this work allows the mapping of FF at the national level. The need to continue collecting field data from forest ecosystems is indicated by the use of new world-class methods for the development of fuel models, taking into account the local conditions.