The nine classes of plant-plant replacement

Abstract

Current models of plant community dynamics have fallen short both of conceptualizing plant communities well and of giving researchers a tool that accurately predicts their dynamics. Here I present a new idea of how that conceptual model should be constructed. I begin with the observation that space is a critical component of plant life and how it changes determines—to a large extent—how individual plants change. I then define that space as consisting of the phyto-space, which the phyto-mass (biomass plus necromass) occupies, and the neighborhood space around that phyto-space where a plant can influence, and be influenced by, other plants. I posit that it is how plants that make up a community replace themselves over time, as their phyto-spaces and neighborhood spaces change, that is the fundamental process of plant community dynamics. Those plant-plant replacements fall into nine distinct classes that extend the concept of replacement to include new space created not just by whole plant mortality, but also by plant tissue loss.  Finally, I suggest that because most plant-plant replacements involve seeds, seedlings and saplings, the mechanisms and tolerances of predation, pathogens, germination, herbivory and seedling/sapling competition will be most critical in determining the plant-plant replacements in any plant community and its resulting dynamics.