Two pyrogenic cycles (two succession series) of ecosystems in the boreal forest belt are characterized. One cycle is associated with the subbelt of subgolets (subalpine) spruce and larch forests, and the other, with the subbelt of taiga spruce and larch forests. The bird population at different stages of succession are compared. Quantitative analysis utilizes measures of inclusion and similarity. The avian faunistic and ecological complexes, as well as forest layer aggregations, are considered. As is shown, the ecosystems at the early stage of succession play a significant role in the spread of the Chinese ornithofaunistic complex against the background of prevalence of the Siberian complex. The species involved in both cycles belong to the forest ecological complex. The bird population in the succession systems at later stages and native ecosystems of two subbelts are more similar to one another as compared with the succession systems of the same subbelts at early stages.