The study is devoted to determining regularities in the dynamics of inventory indices of forest stands of Siberian larch in the lower flow of the Angara River. In this forest stands area forest Siberian larch forms forest stands of two main groups of for-est types - mossy and grassy groups. For forest stands of green group of types of the wood there are tables of the course of growth constructed on a bonitet basis by E.N. Falaleev and V.S. Polyakov. Similar tables for forest stands of Siberian larch of herbal group of forest types are missing. The aim of the study was to build a sketch for the table of the growth course for forest stands of larch of the grassy group of forest types, which allows filling in gaps in taxonomic database standards for the as-sessment of forests of the Lower Angara Region. The methodological basis for the study was the work by N.V. Tretyakov. The study is based on ma-terials of field taxation of 858 sites. The statistical processing of the series of average inventory indi-ces of the forest stands and the analysis of peculi-arities of the variability of inventory indices of forest stands within the groups corresponding to certain age classes was carried out. To approximate the dynamics of the main forest inventory indices of forest stands - the average diameter, average height and stock exponential function was used. The adequacy of the obtained mathematical mod-els is confirmed by calculation of coefficients of de-termination and standard error. The calculation of the remained inventory indices of forest stands, included in the sketch for the table of course of growth was carried out on the known dependencies used in taxation calculations. At the final stage of the work on the basis of the determined regularities of the dynamics of average inventory indices the standard was built, allowing to determine the de-signing of farming activity in forest stands of larch of grassy groups of forest types in the region stud-ied.