EN
In addition to physical defenses, chemical defenses are the most effective way to protect plants from adverse biotic factors (phytophagous insects, other herbivores and pathogenic fungi). This requires extra effort from plants to produce secondary defense metabolites at the expense of production of primary metabolites directly linked to the growth and development of plants. There are three main groups of defensive compounds (alkaloids, phenolic compounds and terpenoids). All defensive compounds are rich in carbon. Depending on the chemical formula, carbon makes up from about 40% to over 85% of the molecular weight of various defense compounds. It is not possible to calculate the total carbon mass accumulation in all defense compounds. In this paper we discuss the content of defensive compounds and carbon with respect to defense strategy of plants, functional groups of woody species (coniferous and deciduous trees), tree species, tree biomass components (leaves, branches, bark, roots, etc.) and many other internal (age of trees, age of leaves, stage of development, origin, etc.) as well as external factors, related to soil and climatic conditions