[Original Russian Text published in Ekologiya, 2023, No. 2, pp. 83–93.] We compared the reindeer forage stocks at two landfills in the southern part of the Yamal Peninsula for the period from the early 1930s to 2017–2019. Data from [30] was used to characterize the feedstock in the 1930s. Feedstocks in the 1930s and 2017–2019 in plant communities in the basins of the the Erkatayakha and Baidaratayakha rivers were compared in the following vegetation divisions: lichen and shrub tundras; moss and grass tundras; shrub tundra; meadow communities; and bogs. The following hypotheses were tested: (1) the total supply of feed in Yamal decreased since the 1930s; (2) the decrease in stocks affected the lichen component to the greatest extent. Both hypotheses were confirmed. The general changes in the stocks and structure of food in the plant communities of South Yamal over the 85–87 years include delichenization, a decrease in the mass of lichens and the proportion of lichen food. The average stock of lichen fodder from the 1930s to 2017–2019 decreased by 5 times in the communities at the Erkatayakha test site and by 2 times at the Baidaratayakha test site. The mass of green fodder for 85–87 years has not changed. Thus, the change in the masses of economically important components of tundra vegetation over a uniquely long period, almost 90 years, has been characterized. Keywords: Yamal, southern tundra, reindeer, pastures, overgrazing, delichenization, herbification, feed reserves, community productivity.