Dynamics and long-term cyclic changes in the number of some populations of forest subspecies of the reindeer

The population of the forest subspecies of the reindeer is declining rapidly; its range has divided into several isolated areas. For conservation purposes, a full study of its population characteristics is necessary, with an emphasis on population dynamics. To reveal the cyclical fluctuations in different populations, we used long-term data from the Yugansky, Sayano-Shushensky Baikalsky and Kuznetsky- Alatau nature reserves (zapoveniks) and from the Verkhne-Kondinsky sanctuary (zakaznik).The influence of the anthropogenic factor is excluded due to the strict protection rules in these territories. Besides, we estimated the influence of annual average air temperature and precipitation on the forest reindeer population dynamics in the Yugansky Nature Reserve. In calculations we used spectral analysis software. In all the studied territories except for the Baikalsky Nature Reserve, the populations are gradually and reliably declining. In the Baikalsky Nature Reserve a slight, statistically unreliable increase in the reindeer numbers is noted. In all the examined territories during a sufficient observation period of at least 20-30 years, the reindeer populations demonstrate power-dominant 15-20 year cyclic fluctuations. In the mid-frequency range, we revealed low-power 5- and 7-year cycles. In the high-frequency range (2-4 years), stable cycles are observed in all territories. In the Yugansky Nature Reserve, the correlation between the reindeer population dynamics cycling and precipitation and air temperatures was revealed. For each harmonic component of the population cycling, there are corresponding harmonics of these climatic parameters similar in period value. The most accurate adjustment is observed to the average annual precipitation values, which probably play a more significant role in the life of these ruminants compared to average annual temperatures.