The paper discusses microclimatically differentiated habitats and seeks causal relationships between the sylvicolous populations of rodents and floristic factors. The dataset indicated the presence of a cyclical gradient with an assumed amplitude of 3 to 5 years. By comparing the outputs of the modified Morisita’s index and multidimensional, spatiotemporal models of environmental preferences, the hypothesis was confirmed that Clethrionomys glareolus responds to higher densities of Apodemus flavicollis as a result of overproduction of beech and oak. In high-altitude climax spruce forests without a dominant deciduous component, C. glareolus exhibits a significantly random distribution during peak years. This phenomenon corresponds to a strategy where C. glareolus resists competitive pressure from A. flavicollis. During the phases of progression and latency, the species are more closely tied to environmental resources. Depending on stand structure, but with an emphasis on the herbaceous layer, significant interspecies differences in preferences for this component were confirmed. The preference rate was subject to the phase of the population cycle. The affinity of A. flavicollis for increasing height and grass cover was confirmed, along with a negative correlation with this gradient for C. glareolus.