Demographic Rates of Tree Species in Subtropical Forests Vary Across Ontogenetic Stages Regardless of Their Biogeographical Origin and Leaf Habit

ABSTRACT Subtropical forests, particularly the Araucaria Forest, host tree species of both temperate and tropical origins that exhibit contrasting ecological strategies, which may shift across ontogenetic stages. However, whether and how biogeographic origin, leaf habit, and ontogenetic stage influence population growth and demographic rates of tree species remains an open question. This study aimed to quantify the demographic rates of 31 tree species, considering different biogeographic origins (tropical or temperate) and leaf habits (evergreen or deciduous), and comparing them between two ontogenetic stages (juveniles and adults) in the Araucaria Forest, within the subtropical portion of the Brazilian Atlantic Forest. Demographic parameters were assessed through tree recruitment, mortality, and turnover rates of juveniles and adults, and the population growth rates of trees in mature forests over approximately five years. We used generalized linear models to evaluate how biogeographic origin, leaf habit, and ontogenetic stage shape demographic rates. We found that recruitment, mortality, and turnover rates varied across ontogenetic stages, with juveniles exhibiting higher annual rates than adults. In contrast, population growth rates were not associated with biogeographic origins and leaf habits. Variation in demographic rates reflects distinct responses between juveniles and adults related to species life histories and ontogenetic shifts, likely driven by differences in environmental pressures experienced throughout their life cycle. These ontogenetic shifts highlight the importance of including juvenile trees in long‐term ecological studies, as this may provide key insights into population and overall forest dynamics.