Abstract <p>A change in the age structure of the population of endemic <i>Oxytropis chankaensis</i> Jurtzev was analyzed at seven sites on the western coast of the Lake Khanka. Data obtained demonstrate an association between the structure, age composition, and spatial distribution of the species' coenopopulations and the water level in the lake. Under relatively stable conditions, most of coenopopulations are normal, optionally incomplete, with a left-sided spectrum. When the water level rises, a sharp decrease in the ability to restore the coenopopulation at the “Astrakhanka” site and, on the contrary, some its increase at the “Troitskoye” and “Novokachalinsk” sites are noted; this demonstrates r-strategy of the species for survival: annual increase in not only the seed bank, but also in young plants.</p>