Metabolic Scaling Applied to Native Woody Savanna Species in the Pantanal of Nhecolândia

Abstract

Scaling invariance in living systems emerges from complex interactions of organisms with the physical world. According to the Metabolic Scaling Theory (MST), the way that energy and materials are distributed generally follows an invariant power law scaling with the body mass, independent on the species and the environment. Such generalization has been defined universal or ubiquitous, which is however not broadly accepted. For native woody savanna species in the Nhecolândia landscape, the scaling between trunk diameter and the whole plant body mass as d ~ m ^3/8 follows MST prediction. Nevertheless, empirical data and model suggest biomass allocation beyond 50% to branches for trunk diameters above 18 cm, whereas root–trunk ratio does not vary significantly with plant size. The elevated water table explains such biomass allocation by limiting vertical root growth while enhancing branch growth to cope with evapotranspiration. Therefore, empirical deviations from MST scaling exponents of biomass partitioning for these plants can be understood as ecohydrological adaptations to conspicuous physical constraints.