Components of leaf-trait variation along environmental gradients

Area of Science:

• Plant functional ecology
• Vegetation modelling
• Eco-physiology

Background:

• Leaf area (LA), mass per area (LMA), nitrogen per unit area (Narea), and leaf-internal to ambient CO2 ratio (χ) are key plant traits.
• Understanding how these traits vary with environmental factors is crucial for ecological and modeling studies.

Purpose of the Study:

• To investigate how variation in LA, LMA, Narea, and χ, both within and between species, relates to environmental gradients.
• To compare the contributions of within-species acclimation/adaptation versus species selection to trait-environment relationships.

Main Methods:

• Measured 705 species across 116 Australian sites along a north-south transect.
• Quantified trait-environment responses using multiple regression.
• Compared within- and between-species responses using ANOVA and trait-gradient analysis.

Main Results:

• Leaf traits (LA, LMA, Narea) and χ varied largely independently among species.
• Across sites, χ and LA increased with temperature and decreased with vapor pressure deficit and soil pH; LMA and Narea showed the opposite pattern.
• Within-species variability explained most geographical variation in χ (>90%), but less for LA (<10%), with LMA and Narea intermediate.

Conclusions:

• Acclimation, adaptation, and species selection interact to create predictable trait-environment relationships.
• The relative importance of acclimation/adaptation versus species selection varies significantly among different plant traits.