Elaboration of a Novel Theory for the Scaling of Plant Form, Function, and Diversity

University Of Arizona, Tucson AZ

Investigators

Abstract

0129144 Brian Enquist This award will support field research to obtain data for assessing assumptions and predictions of a new theoretical model for scaling plant anatomical and physiological attributes from within individuals to populations, and even ecosystems. The ultimate goal of this research is to expand and elaborate a general theoretical and mechanistic framework for scaling in biology. This framework is based on evolutionary and physical first principles, integrating how specific attributes of organismal form and function change with organismal size (allometry) and how such changes influence ecological and evolutionary phenomena. Field and laboratory assessments are necessary to (i) advance future efforts to scale anatomical and physiological attributes of individuals and (ii) to link how attributes of organisms at the level of the individual ramifies (scales) across plant populations, communities, and ecosystems. This project focuses on understanding plant vascular form and function. It will provide the base-line allometric data for woody plant species necessary to assess numerous predictions of theoretical models. Specifically, the research will focus on intensive anatomical and physiological measurements of four tree species which span a range of environmental gradients and are functionally diverse (including the three major classes of vascular structure; ring-, diffuse-, and non-porous vascular plants). Standardized measurements of anatomical and hydrodynamic attributes of individuals will be used to evaluate the model. For example, specific measurements will be made to determine how total leaf area, the number of branches, length of branches, total water flux/photosynthetic rate, stem conductivity, leaf specific conductivity, tracheid/vessel radius, the proportion of conductive and non conductive tissue, and water content scale with changes in plant mass and with branch diameter. Such information will be critical for (1) future elaboration of new theoretical models; (2) understanding scaling of physiological attributes of plants; and (3) investigating the evolutionary and ecological implications of allometry in biology. These three research directions will form the core of Dr. Enquist's research program as a new faculty member at the University of Arizona, and this award will support the building of a graduate program in biological scaling.