Fir forest demography using matrix projections: Anomaly precipitation due to climatic change decrease population viability

•Fir forest is a mono-specific forest and from late or climax successional state.•The most realistic scenarios suggest an imminent extinction of fir forests in study area.•The most important diameter size class that contributes to λ is >50 cm dbh followed for <10–20.•Matrices linked to climatic variation offer a useful tool to explore the growth of populations.