Do Functional Traits Relate Metabolic Scaling Theory to Observed Growth Rate?

• Main Author: Wilson, Ashley Anne
• Other Authors: Enquist, Brian J.
• Language: en_US
• Published: The University of Arizona. 2015
• Online Access: http://hdl.handle.net/10150/578901

To model plant growth, ecologists have integrated metabolism into allometric equations, most notoriously known in the West Brown Enquist model, which is an extension of the all-inclusive Metabolic Scaling Theory (MST) (West et al. 1999). This formula takes form of the power function Ṁ = βMᶿ, where β is the allometric normalization constant, M is total biomass, θ is a scaling exponent, and Ṁ is the metabolic and thus growth rate of the organism. Kleiber's law assumes that M should scale to the ¾ power, and the WBE model supports this claim. To test this, we measured the growth rate of 64 trees on Mount Bigelow, Arizona and showed that Ṁ scales in proportion to M. While there are many external factors that influence plant growth, we focused on modeling two types of functional traits: leaf-based and hydraulic-based. Our results show that the theoretical Ṁ from both equations are significantly different than 1, and we conclude that the WBE model may not include all variables relating to plant growth.