Silicon and the plant economics spectrum: a trait-based approach at the interface of physiological and ecosystem ecology.
Over the past three decades, plant ecologists have become increasingly interested in studying functional traits to better understand how terrestrial plants allocate their resources. This led to a prominent ecological theory: the ‘fast-slow’ plant economics spectrum, which describes a universal spectrum of plant economics comprising key plant properties. The spectrum runs from fast-growing species with traits associated to rapid resource acquisition to slow-growing species having traits involved in conservation of resources and investing more resources in anti-herbivore defenses. Although major nutrients have been included in the spectrum, the concentration of silicon (Si) in plant tissues has long been ignored, a significant omission given that vascular plants contain Si in widely variable concentrations, in some cases far exceeding those of macronutrients. Most previous ecological studies have considered Si as an anti-herbivore defense and structural component, which can substitute for carbon-based defense compounds, rather than integral to other aspects of plant eco-physiological strategies. The aim of SiliConomic is to leverage functional trait-based approaches to build an eco-physiological understanding of the role of Si in terrestrial ecosystems and determine its position in the plant economics spectrum. To do so, key characteristics of plant eco-physiological/defense strategies will be measured in Mediterranean shrubland/rangeland ecosystems along a unique long-term natural soil fertility gradient spanning two million years of ecosystem development, and a long-term fertilization/grazing experiment. A plant growth experiment under controlled conditions will be conducted to develop a mechanistic understanding of underlying processes. The project represents the first attempt to integrate Si in the plant economics spectrum, is based on exceptional environmental gradients and collaboration with world-leading researchers, and is of global interest in plant ecology.