Аннотация:A detailed study of the vegetative–detrital cover (VDC) of pine ecosystems of the Mari Zavolzhye demonstrated that, depending on its origin, a specific hydrothermal soil regime is formed in each type of forest. It has been established that the VDC has the highest moisture capacity in lichen–mossy pine forests in comparison to lichen–pine forests. For the first time, based on the VDC parameters, a scale has been proposed to estimate the rate of the biological cycle. It is established that the most important indicators are the
thickness of the VDC, ash content, and hydrolytic acidity.