Data and code from: Soil mediates the impact of functional traits on tree growth and survival across life stages in a temperate forest

Trait-based approaches are widely used to understand variation in plant
demographic performance, yet their predictive power is often limited by
context dependence. In particular, trait–demography relationships may
shift across life stages and be modulated by local abiotic and biotic
conditions. However, few studies have simultaneously examined how
ontogeny, soil fertility, and neighborhood trait composition jointly shape
the outcomes of trait–performance relationships. Here, we integrate
long-term demographic data, functional traits, and soil variables from a
20-ha warm temperate forest dynamics plot to evaluate how three key
traits, specific leaf area (SLA), leaf dry matter content (LDMC), and wood
density (WD), affect tree growth and survival across seedling, sapling,
and adult stages. We also examine how these effects, including
neighborhood interactions for trait dissimilarity, are modified by soil
fertility. Our study showed that soil fertility modulated trait effects on
tree performance, which varied across life stages. Direct trait effects
were detected primarily at the adult stage, where adult survival increased
with WD but decreased with LDMC. In contrast, at the seedling and sapling
stages, trait effects on survival were largely contingent on soil
nutrients. Increasing soil organic matter, moisture, and available
potassium intensified the negative effects of conservative traits (LDMC
and WD) on seedling and sapling survival, while alleviating the negative
effects of acquisitive traits (SLA). Seedlings exhibited lower survival
when surrounded by heterospecific neighbors with dissimilar SLA. The
negative effect of SLA dissimilarity among neighboring seedlings on
seedling survival was amplified in soils rich in organic matter, moisture,
and available potassium, whereas between seedlings and neighboring trees,
it was alleviated under higher nitrogen and phosphorus availability. Our
results demonstrate the importance of explicitly considering life stage,
local abiotic conditions, and biotic neighborhood context. This
multidimensional approach offers new insights into trait-based mechanisms
underlying forest community dynamics across life stages.