Long-term monitoring of a permanent plot revealing the disturbance-recovery regime of the coniferous forest in subalpine Changbai Mountain of northeast China

Abstract

Abstract Understanding long-term successional changes in old-growth forests affected by natural disturbance is particularly important in the context of contemporary climate changes. Quantitative descriptions of natural disturbance regimes require direct observations of tree populations over multiple decades, yet such studies are rare in the late-successional forest, particularly in the subalpine coniferous forest. Thus, we use four decades (1981–2022) monitoring of permanent plot in old-growth forest to reveal how tree species composition and structure changed. Results indicated that there was a significant decrease in the total density and basal area and standing volume, which was caused by the gradual decline of large Picea jezoensis var. komarovii. Meanwhile, Betula ermanii dominance increased over time. Analysis of spatial distribution patterns suggested that gap formation facilitated Betula ermanii adults and Picea jezoensis var. komarovii offspring naturally regenerate to coexist. Future canopy composition would mainly depend on a balance between Betula ermanii 's saplings probability of entering the canopy layer and the co-dominants’ survival there. Taken together, we concluded that the late-successional spruce-fir forest is dynamic and does not show quasi-equilibrial properties at a small scale, whereas, climax vegetation is a complex shifting mosaic that is comprised of patches in different successional stages. Natural disturbance is the main reason for maintaining the climax vegetation distribution pattern. In the absence of large catastrophic disturbances, we expect the mosaic pattern may persist for long under a certain climate regime.