Data on seasonal dynamics of the elemental composition (C, N, P, K, S, Ca, Mg) and diurnal dynamics of water regime variables of common silver birch (Betula pendula var. pendula) and Karelian birch (Betula pendula var. carelica) in plants with normal and abnormal development of the trunk conducting tissues in natural habitats (southern Karelia) are presented. Seasonal dynamics of the elemental composition of leaf and branch tissues and diurnal dynamics of water regime variables were identical in all investigated forms of Betula pendula. At the same time, differences in absolute values of mineral nutrient content in tissues of the two forms, and a greater range of variation of nutrient content in Karelian birch were detected, depending on external environmental conditions. Possible reasons for such differences are discussed. «Exchange process index /environmental factor» correlations and interrelations between exchange processes' variables also were investigated. The ranges of air temperature and relative humidity at which maximal driving force of the water flux (WPmin) in birch trees are observed were quite substantial, i.e. the process may reach a high level in a wide range of variation of hydrometeorological variables, suggesting the species is adapted to a wide range of growth conditions.