Does life form affect tree species assembly? A demographic study across the life history of a temperate forest in Japan

In this study, the dominant mechanism that defines species assembly in an old-growth temperate forest was investigated by analyzing specificity of demographic parameters relation to life history stage, testing hypotheses early stages should be more critical for sub-canopy than canopy species. Data 17 major tree Ogawa Forest Reserve (OFR) Japan were analyzed, together with data from (seed production, seed dispersal, and seedling emergence) dbh-based transition probability survival (5–80 cm). Both datasets subjected principal components analysis (PCA): one included dbh < 35 cm all (small-sized trees [SSAS]) other ≥ 55 (large-sized [LSS]). The most influential growth–survival trade-off at small-to-middle-sized (dbh: 10–40 cm), which captured a moderate proportion variation (24.3%–26.4%). At these stages, some Quercus characterized higher growth, Fagus Acer shade tolerance. Behavior during early-to-late second important dimension, SSAS, showed high as differed between SSAS- LSS-based PCAs. relationship functional traits PCA axis dimensions varied type dimension. OFR closely associated maximum height, proxy form, specific leaf area This finding implies significant role stable coexistence maintaining mutual claims vertical light resources allowing efficient use space. However, there no association wood density variables. Our study shows interspecies relationships vary stage are forests, where entire must considered focusing on difference forms.