How do traits vary across ecological scales? A case for trait‐based ecology

TLDR

Despite the growing importance of functional traits, it remains unclear how trait variation changes across ecological scales, hindering assessment of scale‑dependent effects. The study aims to partition variance in leaf mass area and leaf dry matter content across six nested ecological scales in lowland tropical rainforests. The authors quantified trait variance at the site, plot, species, tree, strata, and leaf levels to achieve this partitioning. Plot‑level variance is negligible despite high species turnover, while within‑species variation matches species‑level variation, supporting trait‑based environmental filtering and a shift from species‑ to trait‑based ecology.

Abstract

Despite the increasing importance of functional traits for the study of plant ecology, we do not know how variation in a given trait changes across ecological scales, which prevents us from assessing potential scale-dependent aspects of trait variation. To address this deficiency, we partitioned the variance in two key functional traits (leaf mass area and leaf dry matter content) across six nested ecological scales (site, plot, species, tree, strata and leaf) in lowland tropical rainforests. In both traits, the plot level shows virtually no variance despite high species turnover among plots and the size of within-species variation (leaf + strata + tree) is comparable with that of species level variation. The lack of variance at the plot level brings substantial support to the idea that trait-based environmental filtering plays a central role in plant community assembly. These results and the finding that the amount of within-species variation is comparable with interspecific variation support a shift of focus from species-based to trait-based ecology.