Scaling of leaf area with biomass in trees reconsidered: Constant metabolically active sapwood volume per unit leaf area with height growth

Hypoallometric (slope<1) scaling between metabolic rate and body mass is often regarded as near-universal across organisms. However, there are compelling reasons to question hypoallometric scaling in woody plants, where metabolic rate=leaf area. This leaf area must provide carbon to the metabolically active sapwood volume (VMASW). Within populations of a species, variants in which VMASW increases per unit leaf area with height growth (e.g. ⅔ or ¾ scaling) would have proportionally less carbon for growth and reproduction as they grow taller. Therefore, selection should favor individuals in which, as they grow taller, leaf area scales isometrically with shoot VMASW (slope=1). Using tetrazolium staining, we measured total VMASW and total leaf area (LAtot) across 22 individuals of Ricinus communis and confirmed that leaf area scales isometrically with VMASW, and that VMASW is much smaller than total sapwood volume. With the potential of the LAtot-VMASW relationship to shape factors as di..., , , # Scaling of leaf area with biomass in trees reconsidered: constant metabolically active sapwood volume per unit leaf area with height growth

A brief summary of dataset contents, in the context of the methodology followed, is given below.

* We tested leaf area-metabolically active sapwood volume relationship in *Ricinus communis* L.(Euphorbiaceae). We used the tetrazolium test to estimate volume of metabolically active sapwood volume. We cut each individual into segments 30 or 50 cm long (50 cm for plants above 2 m tall), and we measured the length, basal diameter, and apical diameter of each segment. 2 cm thick discs from each segment were placed into a solution of 2,3,5-triphenyl-2H- tetrazolium chloride (TTC), see Material and Methods for details of protocol. The TTC stain identifies the regions of metabolically active xylem and colours them red.
* Estimating metabolically active sapwood area and volume - ImageJ 1.52a (Schneider et al., 2012) was used to calculate the total are...